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-rw-r--r--lib/libz/compress.cat31334
1 files changed, 914 insertions, 420 deletions
diff --git a/lib/libz/compress.cat3 b/lib/libz/compress.cat3
index bcd9add..02bb9c9 100644
--- a/lib/libz/compress.cat3
+++ b/lib/libz/compress.cat3
@@ -2,16 +2,19 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
NAME
compress, zlibVersion, deflateInit, deflate, deflateEnd, inflateInit,
- inflate, inflateEnd, deflateInit2, deflateSetDictionary, deflateCopy,
- deflateReset, deflateParams, deflateTune, deflateBound, deflatePrime,
- deflateSetHeader, inflateInit2, inflateSetDictionary, inflateSync,
- inflateCopy, inflateReset, inflatePrime, inflateGetHeader,
+ inflate, inflateEnd, deflateInit2, deflateSetDictionary,
+ deflateGetDictionary, deflateCopy, deflateReset, deflateParams,
+ deflateTune, deflateBound, deflatePending, deflatePrime,
+ deflateSetHeader, inflateInit2, inflateSetDictionary,
+ inflateGetDictionary, inflateSync, inflateCopy, inflateReset,
+ inflateReset2, inflatePrime, inflateMark, inflateGetHeader,
inflateBackInit, inflateBack, inflateBackEnd, zlibCompileFlags,
- compress2, compressBound, uncompress, gzopen, gzdopen, gzsetparams,
- gzread, gzwrite, gzprintf, gzputs, gzgets, gzputc, gzgetc, gzungetc,
- gzflush, gzseek, gzrewind, gztell, gzeof, gzdirect, gzclose, gzerror,
- gzclearerr, adler32, adler32_combine, crc32, crc32_combine -- zlib gen-
- eral purpose compression library
+ compress2, compressBound, uncompress, uncompress2, gzopen, gzdopen,
+ gzbuffer, gzsetparams, gzread, gzfread, gzwrite, gzfwrite, gzprintf,
+ gzputs, gzgets, gzputc, gzgetc, gzungetc, gzflush, gzseek, gzrewind,
+ gztell, gzoffset, gzeof, gzdirect, gzclose, gzclose_r, gzclose_w,
+ gzerror, gzclearerr, adler32, adler32_z, adler32_combine, crc32, crc32_z,
+ crc32_combine — zlib general purpose compression library
SYNOPSIS
#include <zlib.h>
@@ -50,6 +53,10 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
uInt dictLength);
int
+ deflateGetDictionary(z_streamp strm, Bytef *dictionary,
+ uInt *dictLength);
+
+ int
deflateCopy(z_streamp dest, z_streamp source);
int
@@ -66,6 +73,9 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
deflateBound(z_streamp strm, uLong sourceLen);
int
+ deflatePending(z_streamp strm, unsigned *pending, int *bits);
+
+ int
deflatePrime(z_streamp strm, int bits, int value);
int
@@ -79,6 +89,10 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
uInt dictLength);
int
+ inflateGetDictionary(z_streamp strm, Bytef *dictionary,
+ uInt *dictLength);
+
+ int
inflateSync(z_streamp strm);
int
@@ -88,9 +102,15 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
inflateReset(z_streamp strm);
int
+ inflateReset2(z_streamp strm, int windowBits);
+
+ int
inflatePrime(z_streamp strm, int bits, int value);
int
+ inflateMark(z_streamp strm);
+
+ int
inflateGetHeader(z_streamp strm, gz_headerp head);
int
@@ -126,6 +146,10 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
uncompress(Bytef *dest, uLongf *destLen, const Bytef *source,
uLong sourceLen);
+ int
+ uncompress2(Bytef *dest, uLongf *destLen, const Bytef *source,
+ uLong *sourceLen);
+
gzFile
gzopen(const char *path, const char *mode);
@@ -133,15 +157,24 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
gzdopen(int fd, const char *mode);
int
+ gzbuffer(gzFile file, unsigned size);
+
+ int
gzsetparams(gzFile file, int level, int strategy);
int
gzread(gzFile file, voidp buf, unsigned len);
int
+ gzfread(voidp buf, z_size_t size, z_size_t nitems, gzFile file);
+
+ int
gzwrite(gzFile file, voidpc buf, unsigned len);
int
+ gzfwrite(voidpc buf, z_size_t size, z_size_t nitems, gzFile file);
+
+ int
gzprintf(gzFile file, const char *format, ...);
int
@@ -172,6 +205,9 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
gztell(gzFile file);
int
+ gzoffset(gzFile file);
+
+ int
gzeof(gzFile file);
int
@@ -180,6 +216,12 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
int
gzclose(gzFile file);
+ int
+ gzclose_r(gzFile file);
+
+ int
+ gzclose_w(gzFile file);
+
const char *
gzerror(gzFile file, int *errnum);
@@ -192,40 +234,45 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
adler32(uLong adler, const Bytef *buf, uInt len);
uLong
+ adler32_z(uLong adler, const Bytef *buf, z_size_t len);
+
+ uLong
adler32_combine(uLong adler1, uLong adler2, z_off_t len2);
uLong
crc32(uLong crc, const Bytef *buf, uInt len);
uLong
+ crc32_z(uLong adler, const Bytef *buf, z_size_t len);
+
+ uLong
crc32_combine(uLong crc1, uLong crc2, z_off_t len2);
DESCRIPTION
This manual page describes the zlib general purpose compression library,
- version 1.2.3.
+ version 1.2.11.
- The zlib compression library provides in-memory compression and decom-
+ The zlib compression library provides in-memory compression and decom‐
pression functions, including integrity checks of the uncompressed data.
This version of the library supports only one compression method
(deflation) but other algorithms will be added later and will have the
same stream interface.
Compression can be done in a single step if the buffers are large enough
- (for example if an input file is mmap'ed), or can be done by repeated
- calls of the compression function. In the latter case, the application
- must provide more input and/or consume the output (providing more output
- space) before each call.
+ or can be done by repeated calls of the compression function. In the
+ latter case, the application must provide more input and/or consume the
+ output (providing more output space) before each call.
The compressed data format used by default by the in-memory functions is
the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
around a deflate stream, which is itself documented in RFC 1951.
- The library also supports reading and writing files in gzip(1) (.gz) for-
+ The library also supports reading and writing files in gzip(1) (.gz) for‐
mat with an interface similar to that of stdio(3) using the functions
that start with "gz". The gzip format is different from the zlib format.
gzip is a gzip wrapper, documented in RFC 1952, wrapped around a deflate
- stream. This library can optionally read and write gzip streams in mem-
- ory as well.
+ stream. This library can optionally read and write gzip and raw deflate
+ streams in memory as well.
The zlib format was designed to be compact and fast for use in memory and
on communications channels. The gzip format was designed for single-file
@@ -235,7 +282,7 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
The library does not install any signal handler. The decoder checks the
consistency of the compressed data, so the library should never crash
- even in case of corrupted input.
+ even in the case of corrupted input.
The functions within the library are divided into the following sections:
@@ -258,8 +305,8 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
The deflateInit() function initializes the internal stream state
for compression. The fields zalloc, zfree, and opaque must be
initialized before by the caller. If zalloc and zfree are set to
- Z_NULL, deflateInit() updates them to use default allocation
- functions.
+ NULL, deflateInit() updates them to use default allocation func‐
+ tions.
The compression level must be Z_DEFAULT_COMPRESSION, or between 0
and 9: 1 gives best speed, 9 gives best compression, 0 gives no
@@ -293,12 +340,11 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
avail_in are updated and processing will resume at this point for
the next call to deflate().
- Provide more output starting at next_out and update next_out and
+ Generate more output starting at next_out and update next_out and
avail_out accordingly. This action is forced if the parameter
- flush is non-zero. Forcing flush frequently degrades the com-
- pression ratio, so this parameter should be set only when neces-
- sary (in interactive applications). Some output may be provided
- even if flush is not set.
+ flush is non-zero. Forcing flush frequently degrades the com‐
+ pression ratio, so this parameter should be set only when neces‐
+ sary. Some output may be provided even if flush is not set.
Before the call to deflate(), the application should ensure that
at least one of the actions is possible, by providing more input
@@ -307,8 +353,10 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
application can consume the compressed output when it wants, for
example when the output buffer is full (avail_out == 0), or after
each call to deflate(). If deflate() returns Z_OK and with zero
- avail_out, it must be called again after making room in the out-
- put buffer because there might be more output pending.
+ avail_out, it must be called again after making room in the out‐
+ put buffer because there might be more output pending. See
+ deflatePending(), which can be used if desired to determine
+ whether or not there is more output in that case.
Normally the parameter flush is set to Z_NO_FLUSH, which allows
deflate() to decide how much data to accumulate before producing
@@ -317,13 +365,35 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
If the parameter flush is set to Z_SYNC_FLUSH, all pending output
is flushed to the output buffer and the output is aligned on a
byte boundary, so that the decompressor can get all input data
- available so far. (In particular, avail_in is zero after the
- call if enough output space has been provided before the call.)
+ available so far. (In particular avail_in is zero after the call
+ if enough output space has been provided before the call.)
Flushing may degrade compression for some compression algorithms
- and so it should be used only when necessary.
+ and so it should be used only when necessary. This completes the
+ current deflate block and follows it with an empty stored block
+ that is three bits plus filler bits to the next byte, followed by
+ four bytes (00 00 ff ff).
+
+ If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed
+ to the output buffer, but the output is not aligned to a byte
+ boundary. All of the input data so far will be available to the
+ decompressor, as for Z_SYNC_FLUSH. This completes the current
+ deflate block and follows it with an empty fixed code block that
+ is 10 bits long. This assures that enough bytes are output in
+ order for the decompressor to finish the block before the empty
+ fixed codes block.
+
+ If flush is set to Z_BLOCK, a deflate block is completed and
+ emitted, as for Z_SYNC_FLUSH, but the output is not aligned on a
+ byte boundary, and up to seven bits of the current block are held
+ to be written as the next byte after the next deflate block is
+ completed. In this case, the decompressor may not be provided
+ enough bits at this point in order to complete decompression of
+ the data provided so far to the compressor. It may need to wait
+ for the next block to be emitted. This is for advanced applica‐
+ tions that need to control the emission of deflate blocks.
If flush is set to Z_FULL_FLUSH, all output is flushed as with
- Z_SYNC_FLUSH, and the compression state is reset so that decom-
+ Z_SYNC_FLUSH, and the compression state is reset so that decom‐
pression can restart from this point if previous compressed data
has been damaged or if random access is desired. Using
Z_FULL_FLUSH too often can seriously degrade compression.
@@ -336,23 +406,27 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
greater than six to avoid repeated flush markers due to avail_out
== 0 on return.
- If the parameter flush is set to Z_FINISH, pending input is pro-
+ If the parameter flush is set to Z_FINISH, pending input is pro‐
cessed, pending output is flushed and deflate() returns with
- Z_STREAM_END if there was enough output space; if deflate() re-
- turns with Z_OK, this function must be called again with Z_FINISH
- and more output space (updated avail_out but no more input data,
- until it returns with Z_STREAM_END or an error. After deflate()
- has returned Z_STREAM_END, the only possible operations on the
- stream are deflateReset() or deflateEnd().
-
- Z_FINISH can be used immediately after deflateInit() if all the
- compression is to be done in a single step. In this case,
- avail_out must be at least the value returned by deflateBound()
- (see below). If deflate() does not return Z_STREAM_END, then it
- must be called again as described above.
+ Z_STREAM_END if there was enough output space. If deflate() re‐
+ turns with Z_OK or Z_BUF_ERROR, this function must be called
+ again with Z_FINISH and more output space (updated avail_out but
+ no more input data, until it returns with Z_STREAM_END or an er‐
+ ror. After deflate() has returned Z_STREAM_END, the only possi‐
+ ble operations on the stream are deflateReset() or deflateEnd().
+
+ Z_FINISH can be used in the first deflate call after
+ deflateInit() if all the compression is to be done in a single
+ step. In order to complete in one call, avail_out must be at
+ least the value returned by deflateBound() (see below). Then
+ deflate() is guaranteed to return Z_STREAM_END. If not enough
+ output space is provided, deflate() will not return Z_STREAM_END,
+ and it must be called again as described above.
deflate() sets strm->adler to the Adler-32 checksum of all input
- read so far (that is, total_in bytes).
+ read so far (that is, total_in bytes). If a gzip stream is being
+ generated, then strm->adler will be the CRC-32 checksum of the
+ input read so far. (See deflateInit2() below.)
deflate() may update strm->data_type if it can make a good guess
about the input data type (Z_BINARY or Z_TEXT). If in doubt, the
@@ -363,12 +437,13 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
deflate() returns Z_OK if some progress has been made (more input
processed or more output produced), Z_STREAM_END if all input has
been consumed and all output has been produced (only when flush
- is set to Z_FINISH), Z_STREAM_ERROR if the stream state was in-
- consistent (for example, if next_in or next_out was NULL),
+ is set to Z_FINISH), Z_STREAM_ERROR if the stream state was in‐
+ consistent (for example, if next_in or next_out was NULL or the
+ state was inadvertently written over by the application), or
Z_BUF_ERROR if no progress is possible (for example, avail_in or
avail_out was zero). Note that Z_BUF_ERROR is not fatal, and
deflate() can be called again with more input and more output
- space to continue processing.
+ space to continue compressing.
int deflateEnd(z_streamp strm);
@@ -385,23 +460,23 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
int inflateInit(z_streamp strm);
The inflateInit() function initializes the internal stream state
for decompression. The fields next_in, avail_in, zalloc, zfree,
- and opaque must be initialized before by the caller. If next_in
- is not Z_NULL and avail_in is large enough (the exact value
- depends on the compression method), inflateInit() determines the
- compression method from the zlib header and allocates all data
- structures accordingly; otherwise the allocation will be deferred
- to the first call to inflate(). If zalloc and zfree are set to
- Z_NULL, inflateInit() updates them to use default allocation
- functions.
+ and opaque must be initialized before by the caller. In the cur‐
+ rent version of inflate(), the provided input is not read or con‐
+ sumed. The allocation of a sliding window will be deferred to
+ the first call of inflate() (if the decompression does not com‐
+ plete on the first call). If zalloc and zfree are set to NULL,
+ inflateInit() updates them to use default allocation functions.
inflateInit() returns Z_OK if successful, Z_MEM_ERROR if there
- was not enough memory, Z_VERSION_ERROR if the zlib library ver-
- sion is incompatible with the version assumed by the caller. msg
- is set to null if there is no error message. inflateInit() does
- not perform any decompression apart from reading the zlib header
- if present: this will be done by inflate(). (So next_in and
- avail_in may be modified, but next_out and avail_out are un-
- changed.)
+ was not enough memory, Z_VERSION_ERROR if the zlib library ver‐
+ sion is incompatible with the version assumed by the caller or
+ Z_STREAM_ERROR if the parameters are invalid, such as a null
+ pointer to the structure. msg is set to null if there is no er‐
+ ror message. inflateInit() does not perform any decompression.
+ Actual decompression will be done by inflate(). So next_in,
+ avail_in, next_out, and avail_out are unused and unchanged. The
+ current implementation of inflateInit() does not process any
+ header information — that is deferred until inflate() is called.
int inflate(z_streamp strm, int flush);
inflate() decompresses as much data as possible, and stops when
@@ -414,66 +489,87 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
Decompress more input starting at next_in and update next_in and
avail_in accordingly. If not all input can be processed (because
- there is not enough room in the output buffer), next_in is up-
- dated and processing will resume at this point for the next call
- to inflate().
+ there is not enough room in the output buffer), then next_in and
+ avail_in are updated accordingly, and processing will resume at
+ this point for the next call to inflate().
- Provide more output starting at next_out and update next_out and
- avail_out accordingly. inflate() provides as much output as pos-
+ Generate more output starting at next_out and update next_out and
+ avail_out accordingly. inflate() provides as much output as pos‐
sible, until there is no more input data or no more space in the
output buffer (see below about the flush parameter).
Before the call to inflate(), the application should ensure that
at least one of the actions is possible, by providing more input
and/or consuming more output, and updating the next_* and avail_*
- values accordingly. The application can consume the uncompressed
- output when it wants, for example when the output buffer is full
- (avail_out == 0), or after each call to inflate(). If inflate()
- returns Z_OK and with zero avail_out, it must be called again af-
- ter making room in the output buffer because there might be more
- output pending.
+ values accordingly. If the caller of inflate() does not provide
+ both available input and available output space, it is possible
+ that there will be no progress made. The application can consume
+ the uncompressed output when it wants, for example when the out‐
+ put buffer is full (avail_out == 0), or after each call to
+ inflate(). If inflate() returns Z_OK and with zero avail_out, it
+ must be called again after making room in the output buffer be‐
+ cause there might be more output pending.
The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
- Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush
- as much output as possible to the output buffer. Z_BLOCK re-
- quests that inflate() stop if and when it gets to the next de-
- flate block boundary. When decoding the zlib or gzip format,
- this will cause inflate() to return immediately after the header
- and before the first block. When doing a raw inflate, inflate()
- will go ahead and process the first block, and will return when
- it gets to the end of that block, or when it runs out of data.
+ Z_FINISH, Z_BLOCK or Z_TREES. Z_SYNC_FLUSH requests that
+ inflate() flush as much output as possible to the output buffer.
+ Z_BLOCK requests that inflate() stop if and when it gets to the
+ next deflate block boundary. When decoding the zlib or gzip for‐
+ mat, this will cause inflate() to return immediately after the
+ header and before the first block. When doing a raw inflate,
+ inflate() will go ahead and process the first block, and will re‐
+ turn when it gets to the end of that block, or when it runs out
+ of data.
The Z_BLOCK option assists in appending to or combining deflate
- streams. Also to assist in this, on return inflate() will set
+ streams. To assist in this, on return inflate() always sets
strm->data_type to the number of unused bits in the last byte
- taken from strm->next_in, plus 64 if inflate() is currently de-
+ taken from strm->next_in, plus 64 if inflate() is currently de‐
coding the last block in the deflate stream, plus 128 if
inflate() returned immediately after decoding an end-of-block
code or decoding the complete header up to just before the first
- byte of the deflate stream. The end-of-block will not be indi-
+ byte of the deflate stream. The end-of-block will not be indi‐
cated until all of the uncompressed data from that block has been
- written to strm->next_out. The number of unused bits may in gen-
+ written to strm->next_out. The number of unused bits may in gen‐
eral be greater than seven, except when bit 7 of data_type is
set, in which case the number of unused bits will be less than
- eight.
+ eight. data_type is set as noted here every time inflate() re‐
+ turns for all flush options, and so can be used to determine the
+ amount of currently consumed input in bits.
+
+ The Z_TREES option behaves as Z_BLOCK does, but it also returns
+ when the end of each deflate block header is reached, before any
+ actual data in that block is decoded. This allows the caller to
+ determine the length of the deflate block header for later use in
+ random access within a deflate block. 256 is added to the value
+ of strm->data_type when inflate() returns immediately after
+ reaching the end of the deflate block header.
inflate() should normally be called until it returns Z_STREAM_END
or an error. However if all decompression is to be performed in
a single step (a single call to inflate), the parameter flush
should be set to Z_FINISH. In this case all pending input is
processed and all pending output is flushed; avail_out must be
- large enough to hold all the uncompressed data. (The size of the
- uncompressed data may have been saved by the compressor for this
- purpose.) The next operation on this stream must be inflateEnd()
- to deallocate the decompression state. The use of Z_FINISH is
- never required, but can be used to inform inflate() that a faster
- approach may be used for the single inflate() call.
+ large enough to hold all the uncompressed data for the operation
+ to complete. (The size of the uncompressed data may have been
+ saved by the compressor for this purpose.) The use of Z_FINISH
+ is not required to perform an inflation in one step. However it
+ may be used to inform inflate() that a faster approach can be
+ used for the single inflate() call. Z_FINISH also informs
+ inflate() to not maintain a sliding window if the stream com‐
+ pletes, which reduces its memory footprint. If the stream does
+ not complete, either because not all of the stream is provided or
+ not enough output space is provided, then a sliding window will
+ be allocated and inflate() can be called again to continue the
+ operation as if Z_NO_FLUSH had been used.
In this implementation, inflate() always flushes as much output
- as possible to the output buffer, and always uses the faster ap-
- proach on the first call. So the only effect of the flush param-
- eter in this implementation is on the return value of inflate(),
- as noted below, or when it returns early because Z_BLOCK is used.
+ as possible to the output buffer, and always uses the faster ap‐
+ proach on the first call. So the effects of the flush parameter
+ in this implementation are on the return value of inflate() as
+ noted below, when inflate() returns early when Z_BLOCK or Z_TREES
+ is used, and when inflate() avoids the allocation of memory for a
+ sliding window when Z_FINISH is used.
If a preset dictionary is needed after this call (see
inflateSetDictionary() below), inflate() sets strm->adler to the
@@ -483,30 +579,34 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
total_out bytes) and returns Z_OK, Z_STREAM_END or an error code
as described below. At the end of the stream, inflate() checks
that its computed Adler-32 checksum is equal to that saved by the
- compressor and returns Z_STREAM_END only if the checksum is cor-
+ compressor and returns Z_STREAM_END only if the checksum is cor‐
rect.
- inflate() will decompress and check either zlib-wrapped or gzip-
- wrapped deflate data. The header type is detected automatically.
- Any information contained in the gzip header is not retained, so
- applications that need that information should instead use raw
- inflate; see inflateInit2() below, or inflateBack() and perform
- their own processing of the gzip header and trailer.
+ inflate() can decompress and check either zlib-wrapped or gzip-
+ wrapped deflate data. The header type is detected automatically,
+ if requested when initializing with inflateInit2(). Any informa‐
+ tion contained in the gzip header is not retained unless
+ inflateGetHeader() is used. When processing gzip-wrapped deflate
+ data, strm->adler32 is set to the CRC-32 of the output produced
+ so far. The CRC-32 is checked against the gzip trailer, as is
+ the uncompressed length, modulo 2^32.
inflate() returns Z_OK if some progress has been made (more input
processed or more output produced), Z_STREAM_END if the end of
the compressed data has been reached and all uncompressed output
has been produced, Z_NEED_DICT if a preset dictionary is needed
- at this point, Z_DATA_ERROR if the input data was corrupted (in-
+ at this point, Z_DATA_ERROR if the input data was corrupted (in‐
put stream not conforming to the zlib format or incorrect check
- value), Z_STREAM_ERROR if the stream structure was inconsistent
- (for example, if next_in or next_out was NULL), Z_MEM_ERROR if
- there was not enough memory, Z_BUF_ERROR if no progress is possi-
- ble or if there was not enough room in the output buffer when
+ value, in which case strm->msg points to a string with a more
+ specific error), Z_STREAM_ERROR if the stream structure was in‐
+ consistent (for example, next_in or next_out was NULL, or the
+ state was inadvertently over by the application), Z_MEM_ERROR if
+ there was not enough memory, Z_BUF_ERROR if no progress was pos‐
+ sible or if there was not enough room in the output buffer when
Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
inflate() can be called again with more input and more output
space to continue compressing. If Z_DATA_ERROR is returned, the
- application may then call inflateSync() to look for a good com-
+ application may then call inflateSync() to look for a good com‐
pression block if a partial recovery of the data is desired.
int inflateEnd(z_streamp strm);
@@ -534,25 +634,39 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
The windowBits parameter is the base two logarithm of the window
size (the size of the history buffer). It should be in the range
- 8..15 for this version of the library. Larger values of this pa-
- rameter result in better compression at the expense of memory us-
+ 8..15 for this version of the library. Larger values of this pa‐
+ rameter result in better compression at the expense of memory us‐
age. The default value is 15 if deflateInit() is used instead.
+ For the current implementation of deflate(), a windowBits value
+ of 8 (a window size of 256 bytes) is not supported. As a result,
+ a request for 8 will result in 9 (a 512-byte window). In that
+ case, providing 8 to inflateInit2() will result in an error when
+ the zlib header with 9 is checked against the initialization of
+ inflate(). The remedy is to not use 8 with deflateInit2() with
+ this initialization, or at least in that case use 9 with
+ inflateInit2().
+
windowBits can also be -8..-15 for raw deflate. In this case,
- -windowBits determines the window size. deflate() will then gen-
+ -windowBits determines the window size. deflate() will then gen‐
erate raw deflate data with no zlib header or trailer, and will
- not compute an Adler-32 check value.
+ not compute a check value.
- windowBits can also be greater than 15 for optional gzip encod-
+ windowBits can also be greater than 15 for optional gzip encod‐
ing. Add 16 to windowBits to write a simple gzip header and
trailer around the compressed data instead of a zlib wrapper.
- The gzip header will have no file name, no extra data, no com-
+ The gzip header will have no file name, no extra data, no com‐
ment, no modification time (set to zero), no header crc, and the
- operating system will be set to 255 (unknown). If a gzip stream
- is being written, strm->adler is a crc32 instead of an adler32.
+ operating system will be set to the appropriate value, if the op‐
+ erating system was determined at compile time. If a gzip stream
+ is being written, strm->adler is a CRC-32 instead of an Adler-32.
+
+ For raw deflate or gzip encoding, a request for a 256-byte window
+ is rejected as invalid, since only the zlib header provides a
+ means of transmitting the window size to the decompressor.
- The memLevel parameter specifies how much memory should be allo-
- cated for the internal compression state. memLevel=1 uses mini-
+ The memLevel parameter specifies how much memory should be allo‐
+ cated for the internal compression state. memLevel=1 uses mini‐
mum memory but is slow and reduces compression ratio; memLevel=9
uses maximum memory for optimal speed. The default value is 8.
See <zconf.h> for total memory usage as a function of windowBits
@@ -567,29 +681,36 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
this case, the compression algorithm is tuned to compress them
better. The effect of Z_FILTERED is to force more Huffman coding
and less string matching; it is somewhat intermediate between
- Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
- fast as Z_HUFFMAN_ONLY, but gives better compression for PNG im-
- age data. The strategy parameter only affects the compression
- ratio but not the correctness of the compressed output, even if
- it is not set appropriately. Z_FIXED prevents the use of dynamic
- Huffman codes, allowing for a simpler decoder for special appli-
- cations.
+ Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be
+ almost as fast as Z_HUFFMAN_ONLY, but gives better compression
+ for PNG image data. The strategy parameter only affects the com‐
+ pression ratio but not the correctness of the compressed output,
+ even if it is not set appropriately. Z_FIXED prevents the use of
+ dynamic Huffman codes, allowing for a simpler decoder for special
+ applications.
deflateInit2() returns Z_OK if successful, Z_MEM_ERROR if there
- was not enough memory, Z_STREAM_ERROR if a parameter is invalid
- (such as an invalid method). msg is set to null if there is no
- error message. deflateInit2() does not perform any compression:
- this will be done by deflate().
+ was not enough memory, Z_STREAM_ERROR if any parameter is invalid
+ (such as an invalid method), or Z_VERSION_ERROR if the zlib li‐
+ brary version (zlib_version) is incompatible with the version as‐
+ sumed by the caller (ZLIB_VERSION). msg is set to null if there
+ is no error message. deflateInit2() does not perform any com‐
+ pression: this will be done by deflate().
int deflateSetDictionary(z_streamp strm, const Bytef *dictionary, uInt
dictLength);
- Initializes the compression dictionary from the given byte se-
- quence without producing any compressed output. This function
- must be called immediately after deflateInit(), deflateInit2(),
- or deflateReset(), before any call to deflate(). The compressor
- and decompressor must use exactly the same dictionary (see
- inflateSetDictionary()).
+ Initializes the compression dictionary from the given byte se‐
+ quence without producing any compressed output. When using the
+ zlib format, this function must be called immediately after
+ deflateInit(), deflateInit2 or deflateReset(), and before any
+ call of deflate(). When doing raw deflate, this function must be
+ called either before any call of deflate(), or immediately after
+ the completion of a deflate block, i.e. after all input has been
+ consumed and all output has been delivered when using any of the
+ flush options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or
+ Z_FULL_FLUSH. The compressor and decompressor must use exactly
+ the same dictionary (see inflateSetDictionary()).
The dictionary should consist of strings (byte sequences) that
are likely to be encountered later in the data to be compressed,
@@ -602,30 +723,53 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
Depending on the size of the compression data structures selected
by deflateInit() or deflateInit2(), a part of the dictionary may
in effect be discarded, for example if the dictionary is larger
- than the window size in deflate() or deflate2(). Thus the
- strings most likely to be useful should be put at the end of the
- dictionary, not at the front. In addition, the current implemen-
- tation of deflate() will use at most the window size minus 262
- bytes of the provided dictionary.
+ than the window size provided in deflateInit() or deflateInit2().
+ Thus the strings most likely to be useful should be put at the
+ end of the dictionary, not at the front. In addition, the cur‐
+ rent implementation of deflate() will use at most the window size
+ minus 262 bytes of the provided dictionary.
Upon return of this function, strm->adler is set to the Adler-32
value of the dictionary; the decompressor may later use this
- value to determine which dictionary has been used by the compres-
+ value to determine which dictionary has been used by the compres‐
sor. (The Adler-32 value applies to the whole dictionary even if
- only a subset of the dictionary is actually used by the compres-
+ only a subset of the dictionary is actually used by the compres‐
sor.) If a raw deflate was requested, then the Adler-32 value is
not computed and strm->adler is not set.
deflateSetDictionary() returns Z_OK if successful, or
- Z_STREAM_ERROR if a parameter is invalid (such as NULL
- dictionary) or the stream state is inconsistent (for example if
- deflate() has already been called for this stream or if the com-
- pression method is bsort). deflateSetDictionary() does not per-
- form any compression: this will be done by deflate().
+ Z_STREAM_ERROR if a parameter is invalid (e.g. dictionary being
+ NULL) or the stream state is inconsistent (for example if
+ deflate() has already been called for this stream or if not at a
+ block boundary for raw deflate). deflateSetDictionary() does not
+ perform any compression: this will be done by deflate().
+
+ int deflateGetDictionary(z_streamp strm, Bytef *dictionary uInt
+ *dictLength);
+
+ Returns the sliding dictionary being maintained by deflate().
+ dictLength is set to the number of bytes in the dictionary, and
+ that many bytes are copied to dictionary. dictionary must have
+ enough space, where 32768 bytes is always enough. If
+ deflateGetDictionary() is called with dictionary equal to NULL,
+ then only the dictionary length is returned, and nothing is
+ copied. Similary, if dictLength is NULL, then it is not set.
+
+ deflateGetDictionary() may return a length less than the window
+ size, even when more than the window size in input has been pro‐
+ vided. It may return up to 258 bytes less in that case, due to
+ how zlib's implementation of deflate() manages the sliding window
+ and lookahead for matches, where matches can be up to 258 bytes
+ long. If the application needs the last window-size bytes of in‐
+ put, then that would need to be saved by the application outside
+ of zlib.
+
+ deflateGetDictionary() returns Z_OK on success, or Z_STREAM_ERROR
+ if the stream state is inconsistent.
int deflateCopy(z_streamp dest, z_streamp source);
- The deflateCopy() function sets the destination stream as a com-
+ The deflateCopy() function sets the destination stream as a com‐
plete copy of the source stream.
This function can be useful when several compression strategies
@@ -633,21 +777,20 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
processing the input data with a filter. The streams that will
be discarded should then be freed by calling deflateEnd(). Note
that deflateCopy() duplicates the internal compression state
- which can be quite large, so this strategy is slow and can con-
+ which can be quite large, so this strategy is slow and can con‐
sume lots of memory.
deflateCopy() returns Z_OK if successful, Z_MEM_ERROR if there
was not enough memory, Z_STREAM_ERROR if the source stream state
- was inconsistent (such as zalloc being NULL). msg is left un-
+ was inconsistent (such as zalloc being NULL). msg is left un‐
changed in both source and destination.
int deflateReset(z_streamp strm);
This function is equivalent to deflateEnd() followed by
- deflateInit(), but does not free and reallocate all the internal
- compression state. The stream will keep the same compression
- level and any other attributes that may have been set by
- deflateInit2().
+ deflateInit(), but does not free and reallocate the internal com‐
+ pression state. The stream will leave the compression level and
+ any other attributes that may have been set unchanged.
deflateReset() returns Z_OK if successful, or Z_STREAM_ERROR if
the source stream state was inconsistent (such as zalloc or state
@@ -657,25 +800,43 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
The deflateParams() function dynamically updates the compression
level and compression strategy. The interpretation of level and
- strategy is as in deflateInit2(). This can be used to switch be-
+ strategy is as in deflateInit2(). This can be used to switch be‐
tween compression and straight copy of the input data, or to
switch to a different kind of input data requiring a different
- strategy. If the compression level is changed, the input avail-
- able so far is compressed with the old level (and may be
- flushed); the new level will take effect only at the next call to
- deflate().
-
- Before the call to deflateParams(), the stream state must be set
- as for a call to deflate(), since the currently available input
- may have to be compressed and flushed. In particular,
- strm->avail_out must be non-zero.
-
- deflateParams() returns Z_OK if successful, Z_STREAM_ERROR if the
- source stream state was inconsistent or if a parameter was in-
- valid, or Z_BUF_ERROR if strm->avail_out was zero.
+ strategy. If the compression approach (which is a function of
+ the level) or the strategy is changed, and if any input has been
+ consumed in a previous deflate() call, then the input available
+ so far is compressed with the old level and strategy using de‐
+ flate(strm, Z_BLOCK). There are three approaches for the com‐
+ pression levels 0, 1..3, and 4..9, respectively. The new level
+ and strategy will take effect at the next call of deflate().
+
+ If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and
+ it does not have enough output space to complete, then the param‐
+ eter change will not take effect. In this case, deflateParams()
+ can be called again with the same parameters and more output
+ space to try again.
+
+ In order to assure a change in the parameters on the first try,
+ the deflate stream should be flushed using deflate() with Z_BLOCK
+ or other flush request until strm.avail_out is not zero, before
+ calling deflateParams(). Then no more input data should be pro‐
+ vided before the deflateParams() call. If this is done, the old
+ level and strategy will be applied to the data compressed before
+ deflateParams(), and the new level and strategy will be applied
+ to the the data compressed after deflateParams().
+
+ deflateParams() returns Z_OK on success, Z_STREAM_ERROR if the
+ source stream state was inconsistent or if a parameter was in‐
+ valid, or Z_BUF_ERROR if there was not enough output space to
+ complete the compression of the available input data before a
+ change in the strategy or approach. Note that in the case of a
+ Z_BUF_ERROR, the parameters are not changed. A return value of
+ Z_BUF_ERROR is not fatal, in which case deflateParams() can be
+ retried with more output space.
int deflateTune(z_streamp strm, int good_length, int max_lazy, int
- nice_length, int max_chain)
+ nice_length, int max_chain);
Fine tune deflate()'s internal compression parameters. This
should only be used by someone who understands the algorithm used
@@ -689,29 +850,50 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
deflateInit2(), and returns Z_OK on success, or Z_STREAM_ERROR
for an invalid deflate stream.
- uLong deflateBound(z_streamp strm, uLong sourceLen)
+ uLong deflateBound(z_streamp strm, uLong sourceLen);
- deflateBound() returns an upper bound on the compressed size af-
+ deflateBound() returns an upper bound on the compressed size af‐
ter deflation of sourceLen bytes. It must be called after
- deflateInit() or deflateInit2(). This would be used to allocate
- an output buffer for deflation in a single pass, and so would be
- called before deflate().
-
- int deflatePrime(z_streamp strm, int bits, int value)
+ deflateInit() or deflateInit2(). and after deflateSetHeader(),
+ if used. This would be used to allocate an output buffer for de‐
+ flation in a single pass, and so would be called before
+ deflate(). If that first deflate() call is provided the
+ sourceLen input bytes, an output buffer allocated to the size re‐
+ turned by deflateBound(), and the flush value Z_FINISH, then
+ deflate() is guaranteed to return Z_STREAM_END. Note that it is
+ possible for the compressed size to be larger than the value re‐
+ turned by deflateBound() if flush options other than Z_FINISH or
+ Z_NO_FLUSH are used.
+
+ int deflatePending(z_streamp strm, unsigned *pending, int *bits);
+
+ deflatePending() returns the number of bytes and bits of output
+ that have been generated, but not yet provided in the available
+ output. The bytes not provided would be due to the available
+ output space having been consumed. The number of bits of output
+ not provided are between 0 and 7, where they await more bits to
+ join them in order to fill out a full byte. If pending or bits
+ are NULL, then those values are not set.
+
+ deflatePending(returns) Z_OK if success, or Z_STREAM_ERROR if the
+ source stream state was inconsistent.
+
+ int deflatePrime(z_streamp strm, int bits, int value);
deflatePrime() inserts bits in the deflate output stream. The
intent is that this function is used to start off the deflate
- output with the bits leftover from a previous deflate stream when
- appending to it. As such, this function can only be used for raw
- deflate, and must be used before the first deflate() call after a
- deflateInit2() or deflateReset(). bits must be less than or
- equal to 16, and that many of the least significant bits of value
- will be inserted in the output.
-
- deflatePrime() returns Z_OK if successful, or Z_STREAM_ERROR if
- the source stream state was inconsistent.
+ output with the bits left over from a previous deflate stream
+ when appending to it. As such, this function can only be used
+ for raw deflate, and must be used before the first deflate() call
+ after a deflateInit2() or deflateReset(). bits must be less than
+ or equal to 16, and that many of the least significant bits of
+ value will be inserted in the output.
+
+ deflatePrime() returns Z_OK if successful, Z_BUF_ERROR if there
+ was not enough room in the internal buffer to insert the bits, or
+ Z_STREAM_ERROR if the source stream state was inconsistent.
- int deflateSetHeader(z_streamp strm, gz_headerp head)
+ int deflateSetHeader(z_streamp strm, gz_headerp head);
deflateSetHeader() provides gzip header information for when a
gzip stream is requested by deflateInit2(). deflateSetHeader()
@@ -720,15 +902,15 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
name, and comment information in the provided gz_header structure
are written to the gzip header (xflag is ignored - the extra
flags are set according to the compression level). The caller
- must assure that, if not Z_NULL, name and comment are terminated
- with a zero byte, and that if extra is not Z_NULL, that extra_len
+ must assure that, if not NULL, name and comment are terminated
+ with a zero byte, and that if extra is not NULL, that extra_len
bytes are available there. If hcrc is true, a gzip header CRC is
included. Note that the current versions of the command-line
version of gzip(1) do not support header CRCs, and will report
- that it is a "multi-part gzip file" and give up.
+ that it is a “multi-part gzip file” and give up.
If deflateSetHeader() is not used, the default gzip header has
- text false, the time set to zero, and os set to 255, with no ex-
+ text false, the time set to zero, and os set to 255, with no ex‐
tra, name, or comment fields. The gzip header is returned to the
default state by deflateReset().
@@ -752,74 +934,106 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
the error code Z_DATA_ERROR instead of trying to allocate a
larger window.
+ windowBits can also be zero to request that inflate use the win‐
+ dow size in the zlib header of the compressed stream.
+
windowBits can also be -8..-15 for raw inflate. In this case,
-windowBits determines the window size. inflate() will then
process raw deflate data, not looking for a zlib or gzip header,
- not generating a check value, and not looking for any check val-
+ not generating a check value, and not looking for any check val‐
ues for comparison at the end of the stream. This is for use
with other formats that use the deflate compressed data format
such as zip. Those formats provide their own check values. If a
- custom format is developed using the raw deflate format for com-
+ custom format is developed using the raw deflate format for com‐
pressed data, it is recommended that a check value such as an
- Adler-32 or a crc32 be applied to the uncompressed data as is
+ Adler-32 or a CRC-32 be applied to the uncompressed data as is
done in the zlib, gzip, and zip formats. For most applications,
the zlib format should be used as is. Note that comments above
on the use in deflateInit2() applies to the magnitude of
windowBits.
- windowBits can also be greater than 15 for optional gzip decod-
+ windowBits can also be greater than 15 for optional gzip decod‐
ing. Add 32 to windowBits to enable zlib and gzip decoding with
automatic header detection, or add 16 to decode only the gzip
format (the zlib format will return a Z_DATA_ERROR). If a gzip
- stream is being decoded, strm->adler is a crc32 instead of an
- adler32.
+ stream is being decoded, strm->adler is a CRC-32 instead of an
+ Adler-32. Unlike the gunzip(1) utility and gzread() (see below),
+ inflate() will not automatically decode concatenated gzip
+ streams. inflate() will return Z_STREAM_END at the end of the
+ gzip stream. The state would need to be reset to continue decod‐
+ ing a subsequent gzip stream.
inflateInit2() returns Z_OK if successful, Z_MEM_ERROR if there
- was not enough memory, Z_STREAM_ERROR if a parameter is invalid
- (such as a null strm). msg is set to null if there is no error
- message. inflateInit2() does not perform any decompression apart
- from reading the zlib header if present: this will be done by
- inflate(). (So next_in and avail_in may be modified, but
- next_out and avail_out are unchanged.)
+ was not enough memory, Z_VERSION_ERROR if the zlib library ver‐
+ sion is incompatible with the version assumed by the caller, or
+ Z_STREAM_ERROR if the parameters are invalid, such as a null
+ pointer to the structure. msg is set to null if there is no er‐
+ ror message. inflateInit2() does not perform any decompression
+ apart from possibly reading the zlib header if present: actual
+ decompression will be done by inflate(). (So next_in and
+ avail_in may be modified, but next_out and avail_out are unused
+ and unchanged.) The current implementation of inflateInit2()
+ does not process any header information — that is deferred until
+ inflate() is called.
int inflateSetDictionary(z_streamp strm, const Bytef *dictionary, uInt
dictLength);
- Initializes the decompression dictionary from the given uncom-
+ Initializes the decompression dictionary from the given uncom‐
pressed byte sequence. This function must be called immediately
after a call to inflate() if that call returned Z_NEED_DICT. The
dictionary chosen by the compressor can be determined from the
- Adler-32 value returned by that call to inflate(). The compres-
+ Adler-32 value returned by that call to inflate(). The compres‐
sor and decompressor must use exactly the same dictionary (see
deflateSetDictionary()). For raw inflate, this function can be
- called immediately after inflateInit2() or inflateReset() and be-
- fore any call to inflate() to set the dictionary. The applica-
- tion must ensure that the dictionary that was used for compres-
- sion is provided.
+ called at any time to set the dictionary. If the provided dic‐
+ tionary is smaller than the window and there is already data in
+ the window, then the provided dictionary will amend what's there.
+ The application must ensure that the dictionary that was used for
+ compression is provided.
inflateSetDictionary() returns Z_OK if successful, Z_STREAM_ERROR
- if a parameter is invalid (such as NULL dictionary) or the stream
- state is inconsistent, Z_DATA_ERROR if the given dictionary
- doesn't match the expected one (incorrect Adler-32 value).
+ if a parameter is invalid (e.g. dictionary being NULL) or the
+ stream state is inconsistent, Z_DATA_ERROR if the given dictio‐
+ nary doesn't match the expected one (incorrect Adler-32 value).
inflateSetDictionary() does not perform any decompression: this
will be done by subsequent calls of inflate().
+ int inflateGetDictionary(z_streamp strm, Bytef *dictionary, uInt
+ *dictLength);
+
+ Returns the sliding dictionary being maintained by inflate().
+ dictLength is set to the number of bytes in the dictionary, and
+ that many bytes are copied to dictionary. dictionary must have
+ enough space, where 32768 bytes is always enough. If
+ inflateGetDictionary() is called with dictionary equal to NULL,
+ then only the dictionary length is returned, and nothing is
+ copied. Similary, if dictLength is NULL, then it is not set.
+
+ inflateGetDictionary() returns Z_OK on success, or Z_STREAM_ERROR
+ if the stream state is inconsistent.
+
int inflateSync(z_streamp strm);
- Skips invalid compressed data until a full flush point (see above
- the description of deflate() with Z_FULL_FLUSH) can be found, or
- until all available input is skipped. No output is provided.
+ Skips invalid compressed data until a possible full flush point
+ (see above the description of deflate() with Z_FULL_FLUSH) can be
+ found, or until all available input is skipped. No output is
+ provided.
+
+ inflateSync() searches for a 00 00 FF FF pattern in the com‐
+ pressed data. All full flush points have this pattern, but not
+ all occurrences of this pattern are full flush points.
- inflateSync() returns Z_OK if a full flush point has been found,
- Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no
- flush point has been found, or Z_STREAM_ERROR if the stream
- structure was inconsistent. In the success case, the application
- may save the current value of total_in which indicates where
- valid compressed data was found. In the error case, the applica-
- tion may repeatedly call inflateSync(), providing more input each
- time, until success or end of the input data.
+ inflateSync() returns Z_OK if a possible full flush point has
+ been found, Z_BUF_ERROR if no more input was provided,
+ Z_DATA_ERROR if no flush point has been found, or Z_STREAM_ERROR
+ if the stream structure was inconsistent. In the success case,
+ the application may save the current value of total_in which in‐
+ dicates where valid compressed data was found. In the error
+ case, the application may repeatedly call inflateSync(), provid‐
+ ing more input each time, until success or end of the input data.
- int inflateCopy(z_streamp dest, z_streamp source)
+ int inflateCopy(z_streamp dest, z_streamp source);
Sets the destination stream as a complete copy of the source
stream.
@@ -837,17 +1051,30 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
int inflateReset(z_streamp strm);
This function is equivalent to inflateEnd() followed by
- inflateInit(), but does not free and reallocate all the internal
- decompression state. The stream will keep attributes that may
- have been set by inflateInit2().
+ inflateInit(), but does not free and reallocate the internal de‐
+ compression state. The stream will keep attributes that may have
+ been set by inflateInit2().
inflateReset() returns Z_OK if successful, or Z_STREAM_ERROR if
the source stream state was inconsistent (such as zalloc or state
being NULL).
- int inflatePrime(z_stream strm, int bits, int value)
+ int inflateReset2(z_streamp strm, int windowBits);
+
+ This function is the same as inflateReset(), but it also permits
+ changing the wrap and window size requests. The windowBits pa‐
+ rameter is interpreted the same as it is for inflateInit2. If
+ the window size is changed, then the memory allocated for the
+ window is freed, and the window will be reallocated by inflate()
+ if needed.
+
+ inflateReset2() returns Z_OK if success, or Z_STREAM_ERROR if the
+ source stream state was inconsistent (such as zalloc or state be‐
+ ing NULL), or if the windowBits parameter is invalid.
- This function inserts bits in the inflate input stream. The in-
+ int inflatePrime(z_stream strm, int bits, int value);
+
+ This function inserts bits in the inflate input stream. The in‐
tent is that this function is used to start inflating at a bit
position in the middle of a byte. The provided bits will be used
before any bytes are used from next_in. This function should
@@ -856,10 +1083,45 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
bits must be less than or equal to 16, and that many of the least
significant bits of value will be inserted in the input.
+ If bits is negative, then the input stream bit buffer is emptied.
+ Then inflatePrime() can be called again to put bits in the buf‐
+ fer. This is used to clear out bits left over after feeding
+ inflate() a block description prior to feeding it codes.
+
inflatePrime() returns Z_OK if successful, or Z_STREAM_ERROR if
the source stream state was inconsistent.
- int inflateGetHeader(z_streamp strm, gz_headerp head)
+ long inflateMark(z_streamp strm);
+
+ This function returns two values: one in the lower 16 bits of the
+ return value, and the other in the remaining upper bits, obtained
+ by shifting the return value down 16 bits. If the upper value is
+ -1 and the lower value is zero, then inflate() is currently de‐
+ coding information outside of a block. If the upper value is -1
+ and the lower value is non-zero, then inflate() is in the middle
+ of a stored block, with the lower value equaling the number of
+ bytes from the input remaining to copy. If the upper value is
+ not -1, then it is the number of bits back from the current bit
+ position in the input of the code (literal or length/distance
+ pair) currently being processed. In that case the lower value is
+ the number of bytes already emitted for that code.
+
+ A code is being processed if inflate() is waiting for more input
+ to complete decoding of the code, or if it has completed decoding
+ but is waiting for more output space to write the literal or
+ match data.
+
+ inflateMark() is used to mark locations in the input data for
+ random access, which may be at bit positions, and to note those
+ cases where the output of a code may span boundaries of random
+ access blocks. The current location in the input stream can be
+ determined from avail_in and data_type as noted in the descrip‐
+ tion for the Z_BLOCK flush parameter for inflate().
+
+ inflateMark() returns the value noted above, or -65536 if the
+ provided source stream state was inconsistent.
+
+ int inflateGetHeader(z_streamp strm, gz_headerp head);
inflateGetHeader() requests that gzip header information be
stored in the provided gz_header structure. inflateGetHeader()
@@ -868,32 +1130,32 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
stream, head->done is zero until the header is completed, at
which time head->done is set to one. If a zlib stream is being
decoded, then head->done is set to -1 to indicate that there will
- be no gzip header information forthcoming. Note that Z_BLOCK can
- be used to force inflate() to return immediately after header
- processing is complete and before any actual data is decom-
- pressed.
+ be no gzip header information forthcoming. Note that Z_BLOCK or
+ Z_TREES can be used to force inflate() to return immediately af‐
+ ter header processing is complete and before any actual data is
+ decompressed.
The text, time, xflags, and os fields are filled in with the gzip
header contents. hcrc is set to true if there is a header CRC.
(The header CRC was valid if done is set to one.) If extra is
- not Z_NULL, then extra_max contains the maximum number of bytes
- to write to extra. Once done is true, extra_len contains the ac-
- tual extra field length, and extra contains the extra field, or
- that field truncated if extra_max is less than extra_len. If
- name is not Z_NULL, then up to name_max characters are written
- there, terminated with a zero unless the length is greater than
- name_max. If comment is not Z_NULL, then up to comm_max charac-
- ters are written there, terminated with a zero unless the length
- is greater than comm_max. When any of extra, name, or comment
- are not Z_NULL and the respective field is not present in the
- header, then that field is set to Z_NULL to signal its absence.
- This allows the use of deflateSetHeader() with the returned
- structure to duplicate the header. However if those fields are
- set to allocated memory, then the application will need to save
- those pointers elsewhere so that they can be eventually freed.
+ not NULL, then extra_max contains the maximum number of bytes to
+ write to extra. Once done is true, extra_len contains the actual
+ extra field length, and extra contains the extra field, or that
+ field truncated if extra_max is less than extra_len. If name is
+ not NULL, then up to name_max characters are written there, ter‐
+ minated with a zero unless the length is greater than name_max.
+ If comment is not NULL, then up to comm_max characters are writ‐
+ ten there, terminated with a zero unless the length is greater
+ than comm_max. When any of extra, name, or comment are not NULL
+ and the respective field is not present in the header, then that
+ field is set to NULL to signal its absence. This allows the use
+ of deflateSetHeader() with the returned structure to duplicate
+ the header. However if those fields are set to allocated memory,
+ then the application will need to save those pointers elsewhere
+ so that they can be eventually freed.
If inflateGetHeader() is not used, then the header information is
- simply discarded. The header is always checked for validity, in-
+ simply discarded. The header is always checked for validity, in‐
cluding the header CRC if present. inflateReset() will reset the
process to discard the header information. The application would
need to call inflateGetHeader() again to retrieve the header from
@@ -903,18 +1165,18 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
if the source stream state was inconsistent.
int inflateBackInit(z_stream *strm, int windowBits, unsigned char FAR
- *window)
+ *window);
Initialize the internal stream state for decompression using
inflateBack() calls. The fields zalloc, zfree and opaque in strm
must be initialized before the call. If zalloc and zfree are
- Z_NULL, then the default library-derived memory allocation rou-
- tines are used. windowBits is the base two logarithm of the win-
- dow size, in the range 8..15. window is a caller supplied buffer
- of that size. Except for special applications where it is as-
- sured that deflate() was used with small window sizes, windowBits
- must be 15 and a 32K byte window must be supplied to be able to
- decompress general deflate streams.
+ NULL, then the default library-derived memory allocation routines
+ are used. windowBits is the base two logarithm of the window
+ size, in the range 8..15. window is a caller supplied buffer of
+ that size. Except for special applications where it is assured
+ that deflate() was used with small window sizes, windowBits must
+ be 15 and a 32K byte window must be supplied to be able to decom‐
+ press general deflate streams.
See inflateBack() for the usage of these routines.
@@ -924,15 +1186,17 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
of the library does not match the version of the header file.
int inflateBack(z_stream *strm, in_func in, void FAR *in_desc, out_func
- out, void FAR *out_desc)
+ out, void FAR *out_desc);
inflateBack() does a raw inflate with a single call using a call-
- back interface for input and output. This is more efficient than
- inflate() for file I/O applications in that it avoids copying be-
- tween the output and the sliding window by simply making the win-
- dow itself the output buffer. This function trusts the applica-
- tion to not change the output buffer passed by the output func-
- tion, at least until inflateBack() returns.
+ back interface for input and output. This is potentially more
+ efficient than inflate() for file I/O applications, in that it
+ avoids copying between the output and the sliding window by sim‐
+ ply making the window itself the output buffer. inflate() can be
+ faster on modern CPUs when used with large buffers.
+ inflateBack() trusts the application to not change the output
+ buffer passed by the output function, at least until
+ inflateBack() returns.
inflateBackInit() must be called first to allocate the internal
state and to initialize the state with the user-provided window
@@ -945,41 +1209,41 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
reads zip or gzip files and writes out uncompressed files. The
utility would decode the header and process the trailer on its
own, hence this routine expects only the raw deflate stream to
- decompress. This is different from the normal behavior of
- inflate(), which expects either a zlib or gzip header and trailer
- around the deflate stream.
+ decompress. This is different from the default behavior of
+ inflate(), which expects either a zlib header and trailer around
+ the deflate stream.
inflateBack() uses two subroutines supplied by the caller that
are then called by inflateBack() for input and output.
- inflateBack() calls those routines until it reads a complete de-
- flate stream and writes out all of the uncompressed data, or un-
+ inflateBack() calls those routines until it reads a complete de‐
+ flate stream and writes out all of the uncompressed data, or un‐
til it encounters an error. The function's parameters and return
types are defined above in the in_func and out_func typedefs.
inflateBack() will call in(in_desc, &buf) which should return the
number of bytes of provided input, and a pointer to that input in
- buf. If there is no input available, in() must return zero --
- buf is ignored in that case -- and inflateBack() will return a
- buffer error. inflateBack() will call out(out_desc, buf, len) to
- write the uncompressed data buf[0..len-1]. out() should return
- zero on success, or non-zero on failure. If out() returns non-
- zero, inflateBack() will return with an error. Neither in() nor
- out() are permitted to change the contents of the window provided
- to inflateBackInit(), which is also the buffer that out() uses to
- write from. The length written by out() will be at most the win-
+ buf. If there is no input available, in() must return zero — buf
+ is ignored in that case — and inflateBack() will return a buffer
+ error. inflateBack() will call out(out_desc, buf, len) to write
+ the uncompressed data buf[0..len-1]. out() should return zero on
+ success, or non-zero on failure. If out() returns non-zero,
+ inflateBack() will return with an error. Neither in() nor out()
+ are permitted to change the contents of the window provided to
+ inflateBackInit(), which is also the buffer that out() uses to
+ write from. The length written by out() will be at most the win‐
dow size. Any non-zero amount of input may be provided by in().
For convenience, inflateBack() can be provided input on the first
call by setting strm->next_in and strm->avail_in. If that input
is exhausted, then in() will be called. Therefore strm->next_in
must be initialized before calling inflateBack(). If
- strm->next_in is Z_NULL, then in() will be called immediately for
- input. If strm->next_in is not Z_NULL, then strm->avail_in must
- also be initialized, and then if strm->avail_in is not zero, in-
+ strm->next_in is NULL, then in() will be called immediately for
+ input. If strm->next_in is not NULL, then strm->avail_in must
+ also be initialized, and then if strm->avail_in is not zero, in‐
put will initially be taken from strm->next_in[0 ..
strm->avail_in - 1].
The in_desc and out_desc parameters of inflateBack() are passed
- as the first parameter of in() and out() respectively when they
+ as the first parameter of in() and out(), respectively, when they
are called. These descriptors can be optionally used to pass any
information that the caller-supplied in() and out() functions
need to do their job.
@@ -990,23 +1254,23 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
Z_STREAM_END on success, Z_BUF_ERROR if in() or out() returned an
error, Z_DATA_ERROR if there was a format error in the deflate
stream (in which case strm->msg is set to indicate the nature of
- the error), or Z_STREAM_ERROR if the stream was not properly ini-
+ the error), or Z_STREAM_ERROR if the stream was not properly ini‐
tialized. In the case of Z_BUF_ERROR, an input or output error
- can be distinguished using strm->next_in which will be Z_NULL
- only if in() returned an error. If strm->next is not Z_NULL,
- then the Z_BUF_ERROR was due to out() returning non-zero. (in()
- will always be called before out(), so strm->next_in is assured
- to be defined if out() returns non-zero.) Note that
- inflateBack() cannot return Z_OK.
+ can be distinguished using strm->next_in which will be NULL only
+ if in() returned an error. If strm->next is not NULL, then the
+ Z_BUF_ERROR was due to out() returning non-zero. (in() will
+ always be called before out(), so strm->next_in is assured to be
+ defined if out() returns non-zero.) Note that inflateBack() can‐
+ not return Z_OK.
- int inflateBackEnd(z_stream *strm)
+ int inflateBackEnd(z_stream *strm);
All memory allocated by inflateBackInit() is freed.
inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if
the stream state was inconsistent.
- uLong zlibCompileFlags(void)
+ uLong zlibCompileFlags(void);
This function returns flags indicating compile-time options.
@@ -1024,45 +1288,45 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
Compiler, assembler, and debug options:
- 8 DEBUG
- 9 ASMV or ASMINF -- use ASM code
- 10 ZLIB_WINAPI -- exported functions use the WINAPI
+ 8 ZLIB_DEBUG
+ 9 ASMV or ASMINF — use ASM code
+ 10 ZLIB_WINAPI — exported functions use the WINAPI
calling convention
11 0 (reserved)
One-time table building (smaller code, but not thread-safe if
true):
- 12 BUILDFIXED -- build static block decoding tables
+ 12 BUILDFIXED — build static block decoding tables
when needed
- 13 DYNAMIC_CRC_TABLE -- build CRC calculation tables
+ 13 DYNAMIC_CRC_TABLE — build CRC calculation tables
when needed
14,15 0 (reserved)
Library content (indicates missing functionality):
- 16 NO_GZCOMPRESS -- gz* functions cannot compress (to
+ 16 NO_GZCOMPRESS — gz* functions cannot compress (to
avoid linking deflate code when not needed)
- 17 NO_GZIP -- deflate can't write gzip streams, and
- inflate can't detect and decode gzip streams (to
+ 17 NO_GZIP — deflate can't write gzip streams, and in‐
+ flate can't detect and decode gzip streams (to
avoid linking CRC code)
18-19 0 (reserved)
Operation variations (changes in library functionality):
- 20 PKZIP_BUG_WORKAROUND -- slightly more permissive
- inflate
- 21 FASTEST -- deflate algorithm with only one, lowest
+ 20 PKZIP_BUG_WORKAROUND — slightly more permissive in‐
+ flate
+ 21 FASTEST — deflate algorithm with only one, lowest
compression level
22,23 0 (reserved)
The sprintf variant used by gzprintf (zero is best):
- 24 0 = vs*, 1 = s* -- 1 means limited to 20 arguments
+ 24 0 = vs*, 1 = s* — 1 means limited to 20 arguments
after the format
- 25 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not
+ 25 0 = *nprintf, 1 = *printf — 1 means gzprintf() not
secure!
- 26 0 = returns value, 1 = void -- 1 means inferred
+ 26 0 = returns value, 1 = void — 1 means inferred
string length returned
Remainder:
@@ -1071,10 +1335,10 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
UTILITY FUNCTIONS
The following utility functions are implemented on top of the basic
- stream-oriented functions. To simplify the interface, some default op-
+ stream-oriented functions. To simplify the interface, some default op‐
tions are assumed (compression level and memory usage, standard memory
- allocation functions). The source code of these utility functions can
- easily be modified if you need special options.
+ allocation functions). The source code of these utility functions can be
+ modified if you need special options.
int compress(Bytef *dest, uLongf *destLen, const Bytef *source, uLong
sourceLen);
@@ -1084,8 +1348,8 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
buffer. Upon entry, destLen is the total size of the destination
buffer, which must be at least the value returned by
compressBound(sourcelen). Upon exit, destLen is the actual size
- of the compressed buffer. This function can be used to compress
- a whole file at once if the input file is mmap'ed.
+ of the compressed data. compress() is equivalent to compress2()
+ with a level parameter of Z_DEFAULT_COMPRESSION.
compress() returns Z_OK if successful, Z_MEM_ERROR if there was
not enough memory, or Z_BUF_ERROR if there was not enough room in
@@ -1107,11 +1371,11 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
the output buffer, or Z_STREAM_ERROR if the level parameter is
invalid.
- int compressBound(uLong sourceLen)
+ uLong compressBound(uLong sourceLen);
- compressBound() returns an upper bound on the compressed size af-
+ compressBound() returns an upper bound on the compressed size af‐
ter compress() or compress2() on sourceLen bytes. It would be
- used before a compress() or compress2() call to allocate the des-
+ used before a compress() or compress2() call to allocate the des‐
tination buffer.
int uncompress(Bytef *dest, uLongf *destLen, const Bytef *source, uLong
@@ -1120,41 +1384,76 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
The uncompress() function decompresses the source buffer into the
destination buffer. sourceLen is the byte length of the source
buffer. Upon entry, destLen is the total size of the destination
- buffer, which must be large enough to hold the entire uncom-
+ buffer, which must be large enough to hold the entire uncom‐
pressed data. (The size of the uncompressed data must have been
- saved previously by the compressor and transmitted to the decom-
+ saved previously by the compressor and transmitted to the decom‐
pressor by some mechanism outside the scope of this compression
- library.) Upon exit, destLen is the actual size of the com-
- pressed buffer. This function can be used to decompress a whole
+ library.) Upon exit, destLen is the actual size of the uncom‐
+ pressed data. This function can be used to decompress a whole
file at once if the input file is mmap'ed.
uncompress() returns Z_OK if successful, Z_MEM_ERROR if there was
not enough memory, Z_BUF_ERROR if there was not enough room in
- the output buffer, or Z_DATA_ERROR if the input data was cor-
- rupted or incomplete.
+ the output buffer, or Z_DATA_ERROR if the input data was cor‐
+ rupted or incomplete. In the case where there is not enough
+ room, uncompress() will fill the output buffer with the uncom‐
+ pressed data up to that point.
+
+ int uncompress2(Bytef *dest, uLongf *destLen, const Bytef *source, uLong
+ *sourceLen);
+
+ Same as uncompress(), except that sourceLen is a pointer, where
+ the length of the source is *sourceLen. On return, *sourceLen is
+ the number of source bytes consumed.
gzFile gzopen(const char *path, const char *mode);
+ This library supports reading and writing files in gzip (.gz)
+ format with an interface similar to that of stdio, using the
+ functions that start with "gz". The gzip format is different
+ from the zlib format. gzip is a gzip wrapper, documented in RFC
+ 1952, wrapped around a deflate stream.
+
The gzopen() function opens a gzip (.gz) file for reading or
writing. The mode parameter is as in fopen(3) ("rb" or "wb") but
- can also include a compression level (wb9) or a strategy: `f' for
- filtered data, as in "wb6f"; `h' for Huffman only compression, as
- in "wb1h", or `R' for run-length encoding as in "wb1R". (See the
- description of deflateInit2() for more information about the
- strategy parameter.)
+ can also include a compression level (wb9) or a strategy: ‘f’ for
+ filtered data, as in "wb6f"; ‘h’ for Huffman only compression, as
+ in "wb1h", or ‘R’ for run-length encoding as in "wb1R", or ‘F’
+ for fixed code compression as in "wb9F". (See the description of
+ deflateInit2() for more information about the strategy parame‐
+ ter.) ‘T’ will request transparent writing or appending with no
+ compression and not using the gzip format.
+
+ ‘a’ can be used instead of ‘w’ to request that the gzip stream
+ that will be written be appended to the file. ‘+’ will result in
+ an error, since reading and writing to the same gzip file is not
+ supported. The addition of ‘x’ when writing will create the file
+ exclusively, which fails if the file already exists. On systems
+ that support it, the addition of ‘e’ when reading or writing will
+ set the flag to close the file on an execve(2) call.
+
+ These functions, as well as gzip, will read and decode a sequence
+ of gzip streams in a file. The append function of gzopen() can
+ be used to create such a file. (Also see gzflush() for another
+ way to do this.) When appending, gzopen() does not test whether
+ the file begins with a gzip stream, nor does it look for the end
+ of the gzip streams to begin appending. gzopen() will simply ap‐
+ pend a gzip stream to the existing file.
gzopen() can be used to read a file which is not in gzip format;
in this case gzread() will directly read from the file without
- decompression.
+ decompression. When reading, this will be detected automatically
+ by looking for the magic two-byte gzip header.
- gzopen() returns NULL if the file could not be opened or if there
- was insufficient memory to allocate the (de)compression state;
- errno can be checked to distinguish the two cases (if errno is
- zero, the zlib error is Z_MEM_ERROR).
+ gzopen() returns NULL if the file could not be opened, if there
+ was insufficient memory to allocate the gzFile state, or if an
+ invalid mode was specified (an ‘r’, ‘w’, or ‘a’ was not provided,
+ or ‘+’ was provided). errno can be checked to determine if the
+ reason gzopen() failed was that the file could not be opened.
gzFile gzdopen(int fd, const char *mode);
- The gzdopen() function associates a gzFile with the file descrip-
+ The gzdopen() function associates a gzFile with the file descrip‐
tor fd. File descriptors are obtained from calls like open(2),
dup(2), creat(3), pipe(2), or fileno(3) (if the file has been
previously opened with fopen(3)). The mode parameter is as in
@@ -1162,55 +1461,152 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
The next call to gzclose() on the returned gzFile will also close
the file descriptor fd, just like fclose(fdopen(fd), mode) closes
- the file descriptor fd. If you want to keep fd open, use gz-
- dopen(dup(fd), mode).
-
- gzdopen() returns NULL if there was insufficient memory to allo-
- cate the (de)compression state.
+ the file descriptor fd. If you want to keep fd open, use “fd =
+ dup(fd_keep); gz = gzdopen(fd, mode);”. The duplicated descrip‐
+ tor should be saved to avoid a leak, since gzdopen() does not
+ close fd if it fails. If you are using fileno() to get the file
+ descriptor from a FILE *, then you will have to use dup(2) to
+ avoid double-closing the file descriptor. Both gzclose() and
+ fclose() will close the associated file descriptor, so they need
+ to have different file descriptors.
+
+ gzdopen() returns NULL if there was insufficient memory to allo‐
+ cate the gzFile state, if an invalid mode was specified (an 'r',
+ 'w', or 'a' was not provided, or '+' was provided), or if fd is
+ -1. The file descriptor is not used until the next gz* read,
+ write, seek, or close operation, so gzdopen() will not detect if
+ fd is invalid (unless fd is -1).
+
+ int gzbuffer(gzFile file, unsigned size);
+
+ Set the internal buffer size used by this library's functions.
+ The default buffer size is 8192 bytes. This function must be
+ called after gzopen() or gzdopen(), and before any other calls
+ that read or write the file. The buffer memory allocation is al‐
+ ways deferred to the first read or write. Three times that size
+ in buffer space is allocated. A larger buffer size of, for exam‐
+ ple, 64K or 128K bytes, will noticeably increase the speed of de‐
+ compression (reading).
+
+ The new buffer size also affects the maximum length for
+ gzprintf().
+
+ gzbuffer() returns 0 on success, or -1 on failure, such as being
+ called too late.
int gzsetparams(gzFile file, int level, int strategy);
The gzsetparams() function dynamically updates the compression
level or strategy. See the description of deflateInit2() for the
- meaning of these parameters.
+ meaning of these parameters. Previously provided data is flushed
+ before the parameter change.
- gzsetparams() returns Z_OK if successful, or Z_STREAM_ERROR if
- the file was not opened for writing.
+ gzsetparams() returns Z_OK if successful, Z_STREAM_ERROR if the
+ file was not opened for writing, Z_ERRNO if there is an error
+ writing the flushed data, or Z_MEM_ERROR if there is a memory al‐
+ location error.
int gzread(gzFile file, voidp buf, unsigned len);
- The gzread() function reads the given number of uncompressed
- bytes from the compressed file. If the input file was not in
- gzip format, gzread() copies the given number of bytes into the
- buffer.
-
- gzread() returns the number of uncompressed bytes actually read
- (0 for end of file, -1 for error).
+ Reads the given number of uncompressed bytes from the compressed
+ file. If the input file is not in gzip format, gzread() copies
+ the given number ofbytes into the buffer directly from the file.
+
+ After reaching the end of a gzip stream in the input, gzread()
+ will continue to read, looking for another gzip stream. Any num‐
+ ber of gzip streams may be concatenated in the input file, and
+ will all be decompressed by gzread(). If something other than a
+ gzip stream is encountered after a gzip stream, that remaining
+ trailing garbage is ignored (and no error is returned).
+
+ gzread() can be used to read a gzip file that is being concur‐
+ rently written. Upon reaching the end of the input, gzread()
+ will return with the available data. If the error code returned
+ by gzerror() is Z_OK or Z_BUF_ERROR, then gzclearerr() can be
+ used to clear the end of file indicator in order to permit
+ gzread() to be tried again. Z_OK indicates that a gzip stream
+ was completed on the last gzread(). Z_BUF_ERROR indicates that
+ the input file ended in the middle of a gzip stream. Note that
+ gzread() does not return -1 in the event of an incomplete gzip
+ stream. This error is deferred until gzclose(), which will re‐
+ turn Z_BUF_ERROR if the last gzread() ended in the middle of a
+ gzip stream. Alternatively, gzerror() can be used before
+ gzclose() to detect this case.
+
+ gzread() returns the number of uncompressed bytes actually read,
+ less than len for end of file, or -1 for error. If len is too
+ large to fit in an int, then nothing is read, -1 is returned, and
+ the error state is set to Z_STREAM_ERROR.
+
+ z_size_t gzfread(voidp buf, z_size_t size, z_size_t nitems, gzFile file);
+
+ Read up to nitems items of size size from file to buf, otherwise
+ operating as gzread() does. This duplicates the interface of
+ stdio's fread(3), with size_t request and return types. If the
+ library defines size_t, then z_size_t is identical to size_t. If
+ not, then z_size_t is an unsigned integer type that can contain a
+ pointer.
+
+ gzfread() returns the number of full items read of size size, or
+ zero if the end of the file was reached and a full item could not
+ be read, or if there was an error. gzerror() must be consulted
+ if zero is returned in order to determine if there was an error.
+ If the multiplication of size and nitems overflows, i.e. the
+ product does not fit in a z_size_t, then nothing is read, zero is
+ returned, and the error state is set to Z_STREAM_ERROR.
+
+ In the event that the end of file is reached and only a partial
+ item is available at the end, i.e. the remaining uncompressed
+ data length is not a multiple of size, then the final partial
+ item is nevetheless read into buf and the end-of-file flag is
+ set. The length of the partial item read is not provided, but
+ could be inferred from the result of gztell(). This behavior is
+ the same as the behavior of fread(3) implementations in common
+ libraries, but it prevents the direct use of gzfread() to read a
+ concurrently written file, resetting and retrying on end-of-file,
+ when size is not 1.
int gzwrite(gzFile file, voidpc buf, unsigned len);
The gzwrite() function writes the given number of uncompressed
bytes into the compressed file. gzwrite() returns the number of
- uncompressed bytes actually written (0 in case of error).
+ uncompressed bytes written or 0 in case of error.
+
+ z_size_t gzfwrite(voidpc buf, z_size_t size, z_size_t nitems, gzFile
+ file);
+
+ gzfwrite() writes nitems items of size size from buf to file, du‐
+ plicating the interface of stdio's fwrite(3), with size_t request
+ and return types. If the library defines size_t, then z_size_t
+ is identical to size_t. If not, then z_size_t is an unsigned in‐
+ teger type that can contain a pointer.
+
+ gzfwrite() returns the number of full items written of size size,
+ or zero if there was an error. If the multiplication of size and
+ nitems overflows, i.e. the product does not fit in a z_size_t,
+ then nothing is written, zero is returned, and the error state is
+ set to Z_STREAM_ERROR.
int gzprintf(gzFile file, const char *format, ...);
The gzprintf() function converts, formats, and writes the args to
the compressed file under control of the format string, as in
fprintf(3). gzprintf() returns the number of uncompressed bytes
- actually written (0 in case of error). The number of uncom-
- pressed bytes written is limited to 4095. The caller should make
- sure that this limit is not exceeded. If it is exceeded, then
- gzprintf() will return an error (0) with nothing written. In
- this case, there may also be a buffer overflow with unpredictable
- consequences, which is possible only if zlib was compiled with
- the insecure functions sprintf() or vsprintf() because the secure
- snprintf() or vsnprintf() functions were not available.
+ actually written, or a negative zlib error code in case of error.
+ The number of uncompressed bytes written is limited to 8191, or
+ one less than the buffer size given to gzbuffer(). The caller
+ should ensure that this limit is not exceeded. If it is ex‐
+ ceeded, then gzprintf() will return an error (0) with nothing
+ written. In this case, there may also be a buffer overflow with
+ unpredictable consequences, which is possible only if zlib was
+ compiled with the insecure functions sprintf() or vsprintf() be‐
+ cause the secure snprintf() or vsnprintf() functions were not
+ available. This can be determined using zlibCompileFlags().
int gzputs(gzFile file, const char *s);
- The gzputs() function writes the given null-terminated string to
- the compressed file, excluding the terminating null character.
+ The gzputs() function writes the given NUL-terminated string to
+ the compressed file, excluding the terminating NUL character.
gzputs() returns the number of characters written, or -1 in case
of error.
@@ -1220,9 +1616,15 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
The gzgets() function reads bytes from the compressed file until
len-1 characters are read, or a newline character is read and
transferred to buf, or an end-of-file condition is encountered.
- The string is then terminated with a null character.
+ If any characters are read or if len == 1, the string is termi‐
+ nated with a NUL character. If no characters are read due to an
+ end-of-file or len < 1, then the buffer is left untouched.
+
+ gzgets() returns buf, which is a NUL-terminated string, or it re‐
+ turns NULL for end-of-file or in case of error. If there was an
+ error, the contents at buf are indeterminate.
- gzgets() returns buf, or Z_NULL in case of error.
+ gzgets() returns buf, or NULL in case of error.
int gzputc(gzFile file, int c);
@@ -1234,26 +1636,37 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
The gzgetc() function reads one byte from the compressed file.
gzgetc() returns this byte or -1 in case of end of file or error.
-
- int gzungetc(int c, gzFile file)
-
- Push one character back onto the stream to be read again later.
- Only one character of push-back is allowed. gzungetc() returns
- the character pushed, or -1 on failure. gzungetc() will fail if
- a character has been pushed but not read yet, or if c is -1. The
- pushed character will be discarded if the stream is repositioned
- with gzseek() or gzrewind().
+ This is implemented as a macro for speed. As such, it does not
+ do all of the checking the other functions do. That is, it does
+ not check to see if file is NULL, nor whether the structure file
+ points to has been clobbered or not.
+
+ int gzungetc(int c, gzFile file);
+
+ Push one character back onto the stream to be read as the first
+ character on the next read. At least one character of push-back
+ is allowed. gzungetc() returns the character pushed, or -1 on
+ failure. gzungetc() will fail if c is -1, and may fail if a
+ character has been pushed but not read yet. If gzungetc() is
+ used immediately after gzopen() or gzdopen(), at least the output
+ buffer size of pushed characters is allowed. (See gzbuffer()
+ above.) The pushed character will be discarded if the stream is
+ repositioned with gzseek() or gzrewind().
int gzflush(gzFile file, int flush);
- The gzflush() function flushes all pending output into the com-
- pressed file. The parameter flush is as in the deflate() func-
+ The gzflush() function flushes all pending output into the com‐
+ pressed file. The parameter flush is as in the deflate() func‐
tion. The return value is the zlib error number (see function
- gzerror() below). gzflush() returns Z_OK if the flush parameter
- is Z_FINISH and all output could be flushed.
+ gzerror() below). gzflush() is only permitted when writing.
+
+ If the flush parameter is Z_FINISH, the remaining data is written
+ and the gzip stream is completed in the output. If gzwrite() is
+ called again, a new gzip stream will be started in the output.
+ gzread() is able to read such concatenated gzip streams.
gzflush() should be called only when strictly necessary because
- it can degrade compression.
+ it will degrade compression if called too often.
z_off_t gzseek(gzFile file, z_off_t offset, int whence);
@@ -1270,7 +1683,7 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
gzseek() returns the resulting offset location as measured in
bytes from the beginning of the uncompressed stream, or -1 in
case of error, in particular if the file is opened for writing
- and the new starting position would be before the current posi-
+ and the new starting position would be before the current posi‐
tion.
int gzrewind(gzFile file);
@@ -1283,47 +1696,113 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
z_off_t gztell(gzFile file);
The gztell() function returns the starting position for the next
- gzread() or gzwrite() on the given compressed file. This posi-
+ gzread() or gzwrite() on the given compressed file. This posi‐
tion represents a number of bytes in the uncompressed data
- stream.
+ stream, and is zero when starting, even if appending or reading a
+ gzip stream from the middle of a file using gzdopen().
gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR).
+ int gzeoffset(gzFile file);
+
+ Returns the current offset in the file being read or written.
+ This offset includes the count of bytes that precede the gzip
+ stream, for example when appending or when using gzdopen() for
+ reading. When reading, the offset does not include as yet unused
+ buffered input. This information can be used for a progress in‐
+ dicator. On error, gzoffset() returns -1.
+
int gzeof(gzFile file);
- The gzeof() function returns 1 when EOF has previously been de-
- tected reading the given input stream, otherwise zero.
+ Returns true (1) if the end-of-file indicator has been set while
+ reading, false (0) otherwise. Note that the end-of-file indica‐
+ tor is set only if the read tried to go past the end of the in‐
+ put, but came up short. Therefore just like feof(3), gzeof() may
+ return false even if there is no more data to read, in the event
+ that the last read request was for the exact number of bytes re‐
+ maining in the input file. This will happen if the input file
+ size is an exact multiple of the buffer size.
+
+ If gzeof() returns true, then the read functions will return no
+ more data, unless the end-of-file indicator is reset by
+ gzclearerr() and the input file has grown since the previous end
+ of file was detected.
int gzdirect(gzFile file);
- The gzdirect() function returns 1 if the file is being read di-
- rectly without compression; otherwise it returns 0.
+ Returns true (1) if file is being copied directly while reading,
+ or false (0) if file is a gzip stream being decompressed.
+
+ If the input file is empty, gzdirect() will return true, since
+ the input does not contain a gzip stream.
+
+ If gzdirect() is used immediately after gzopen() or gzdopen(), it
+ will cause buffers to be allocated to allow reading the file to
+ determine if it is a gzip file. Therefore if gzbuffer() is used,
+ it should be called before gzdirect().
+
+ When writing, gzdirect() returns true (1) if transparent writing
+ was requested ("wT" for the gzopen() mode), or false (0) other‐
+ wise. (Note: gzdirect() is not needed when writing. Transparent
+ writing must be explicitly requested, so the application already
+ knows the answer. When linking statically, using gzdirect() will
+ include all of the zlib code for gzip file reading and decompres‐
+ sion, which may not be desired.)
int gzclose(gzFile file);
- The gzclose() function flushes all pending output if necessary,
- closes the compressed file and deallocates all the (de)compres-
- sion state. The return value is the zlib error number (see func-
- tion gzerror() below).
+ Flushes all pending output if necessary, closes the compressed
+ file and deallocates the (de)compression state. Note that once
+ file is closed, you cannot call gzerror() with file, since its
+ structures have been deallocated. gzclose() must not be called
+ more than once on the same file, just as free(3) must not be
+ called more than once on the same allocation.
+
+ gzclose() will return Z_STREAM_ERROR if file is not valid,
+ Z_ERRNO on a file operation error, Z_MEM_ERROR if out of memory,
+ Z_BUF_ERROR if the last read ended in the middle of a gzip
+ stream, or Z_OK on success.
+
+ int gzclose_r(gzFile file);
+
+ int gzclose_w(gzFile file);
+
+ Same as gzclose(), but gzclose_r() is only for use when reading,
+ and gzclose_w() is only for use when writing or appending. The
+ advantage to using these instead of gzclose() is that they avoid
+ linking in zlib compression or decompression code that is not
+ used when only reading or only writing, respectively. If
+ gzclose() is used, then both compression and decompression code
+ will be included in the application when linking to a static zlib
+ library.
const char * gzerror(gzFile file, int *errnum);
- The gzerror() function returns the error message for the last er-
+ The gzerror() function returns the error message for the last er‐
ror which occurred on the given compressed file. errnum is set
- to the zlib error number. If an error occurred in the file sys-
+ to the zlib error number. If an error occurred in the file sys‐
tem and not in the compression library, errnum is set to Z_ERRNO
and the application may consult errno to get the exact error
code.
- void gzclearerr(gzFile file)
- Clears the error and end-of-file flags for file. This is analo-
+ The application must not modify the returned string. Future
+ calls to this function may invalidate the previously returned
+ string. If file is closed, then the string previously returned
+ by gzerror() will no longer be available.
+
+ gzerror() should be used to distinguish errors from end-of-file
+ for those functions above that do not distinguish those cases in
+ their return values.
+
+ void gzclearerr(gzFile file);
+ Clears the error and end-of-file flags for file. This is analo‐
gous to the clearerr() function in stdio. This is useful for
- continuing to read a gzip file that is being written concur-
+ continuing to read a gzip file that is being written concur‐
rently.
CHECKSUM FUNCTIONS
These functions are not related to compression but are exported anyway
- because they might be useful in applications using the compression li-
+ because they might be useful in applications using the compression li‐
brary.
uLong adler32(uLong adler, const Bytef *buf, uInt len);
@@ -1332,24 +1811,29 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
is NULL, this function returns the required initial value for the
checksum.
- An Adler-32 checksum is almost as reliable as a CRC32 but can be
+ An Adler-32 checksum is almost as reliable as a CRC-32 but can be
computed much faster. Usage example:
- uLong adler = adler32(0L, Z_NULL, 0);
+ uLong adler = adler32(0L, NULL, 0);
while (read_buffer(buffer, length) != EOF) {
adler = adler32(adler, buffer, length);
}
if (adler != original_adler) error();
- uLong adler32_combine(uLong adler1, uLong adler2, z_off_t len2)
+ uLong adler32_z(uLong adler, const Bytef *buf, z_size_t len);
+
+ The same as adler32(), but with a size_t length.
+
+ uLong adler32_combine(uLong adler1, uLong adler2, z_off_t len2);
The adler32_combine() function combines two Adler-32 checksums
into one. For two sequences of bytes, seq1 and seq2 with lengths
len1 and len2, Adler-32 checksums are calculated for each, adler1
and adler2. adler32_combine() returns the Adler-32 checksum of
seq1 and seq2 concatenated, requiring only adler1, adler2, and
- len2.
+ len2. Note that the z_off_t type (like off_t) is a signed inte‐
+ ger. If len2 is negative, the result has no meaning or utility.
uLong crc32(uLong crc, const Bytef *buf, uInt len);
@@ -1360,14 +1844,18 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
this function so it shouldn't be done by the application. Usage
example:
- uLong crc = crc32(0L, Z_NULL, 0);
+ uLong crc = crc32(0L, NULL, 0);
while (read_buffer(buffer, length) != EOF) {
crc = crc32(crc, buffer, length);
}
if (crc != original_crc) error();
- uLong crc32_combine(uLong crc1, uLong crc2, z_off_t len2)
+ uLong crc32_z(uLong adler , const, Bytef, *buf", z_size_t len);
+
+ The same as crc32(), but with a size_t length.
+
+ uLong crc32_combine(uLong crc1, uLong crc2, z_off_t len2);
The crc32_combine() function combines two CRC-32 check values
into one. For two sequences of bytes, seq1 and seq2 with lengths
@@ -1381,11 +1869,11 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
typedef struct z_stream_s {
Bytef *next_in; /* next input byte */
uInt avail_in; /* number of bytes available at next_in */
- off_t total_in; /* total nb of input bytes read so far */
+ off_t total_in; /* total number of input bytes read so far */
- Bytef *next_out; /* next output byte should be put there */
+ Bytef *next_out; /* next output byte will go here */
uInt avail_out; /* remaining free space at next_out */
- off_t total_out; /* total nb of bytes output so far */
+ off_t total_out; /* total number of bytes output so far */
char *msg; /* last error message, NULL if no error */
struct internal_state FAR *state; /* not visible by applications */
@@ -1394,8 +1882,9 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
free_func zfree; /* used to free the internal state */
voidpf opaque; /* private data object passed to zalloc and zfree*/
- int data_type; /* best guess about the data type: binary or text*/
- uLong adler; /* adler32 value of the uncompressed data */
+ int data_type; /* best guess about the data type: binary or text
+ for deflate, or the decoding state for inflate */
+ uLong adler; /* Adler-32 or CRC-32 value of the uncompressed data */
uLong reserved; /* reserved for future use */
} z_stream;
@@ -1410,12 +1899,12 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
uLong time; /* modification time */
int xflags; /*extra flags (not used when writing a gzip file)*/
int os; /* operating system */
- Bytef *extra; /* pointer to extra field or Z_NULL if none */
- uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
+ Bytef *extra; /* pointer to extra field or NULL if none */
+ uInt extra_len; /* extra field length (valid if extra != NULL) */
uInt extra_max; /* space at extra (only when reading header) */
- Bytef *name; /* pointer to zero-terminated file name or Z_NULL*/
+ Bytef *name; /* pointer to zero-terminated file name or NULL*/
uInt name_max; /* space at name (only when reading header) */
- Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
+ Bytef *comment; /* pointer to zero-terminated comment or NULL */
uInt comm_max; /* space at comment (only when reading header) */
int hcrc; /* true if there was or will be a header crc */
int done; /* true when done reading gzip header (not used
@@ -1431,37 +1920,41 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
compression library and must not be updated by the application.
The opaque value provided by the application will be passed as the first
- parameter for calls to zalloc() and zfree(). This can be useful for cus-
+ parameter for calls to zalloc() and zfree(). This can be useful for cus‐
tom memory management. The compression library attaches no meaning to
the opaque value.
- zalloc must return Z_NULL if there is not enough memory for the object.
- If zlib is used in a multi-threaded application, zalloc and zfree must be
- thread safe.
+ zalloc must return NULL if there is not enough memory for the object. If
+ zlib is used in a multi-threaded application, zalloc and zfree must be
+ thread safe. In that case, zlib is thread-safe. When zalloc and zfree
+ are NULL on entry to the initialization function, they are set to inter‐
+ nal routines that use the standard library functions malloc(3) and
+ free(3).
- On 16-bit systems, the functions zalloc and zfree must be able to allo-
+ On 16-bit systems, the functions zalloc and zfree must be able to allo‐
cate exactly 65536 bytes, but will not be required to allocate more than
this if the symbol MAXSEG_64K is defined (see <zconf.h>).
WARNING: On MSDOS, pointers returned by zalloc for objects of exactly
- 65536 bytes *must* have their offset normalized to zero. The default al-
+ 65536 bytes *must* have their offset normalized to zero. The default al‐
location function provided by this library ensures this (see zutil.c).
To reduce memory requirements and avoid any allocation of 64K objects, at
the expense of compression ratio, compile the library with -DMAX_WBITS=14
(see <zconf.h>).
The fields total_in and total_out can be used for statistics or progress
- reports. After compression, total_in holds the total size of the uncom-
+ reports. After compression, total_in holds the total size of the uncom‐
pressed data and may be saved for use in the decompressor (particularly
if the decompressor wants to decompress everything in a single step).
CONSTANTS
#define Z_NO_FLUSH 0
- #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
+ #define Z_PARTIAL_FLUSH 1
#define Z_SYNC_FLUSH 2
#define Z_FULL_FLUSH 3
#define Z_FINISH 4
- #define Z_BLOCK 5
+ #define Z_BLOCK 5
+ #define Z_TREES 6
/* Allowed flush values; see deflate() and inflate() below for details */
#define Z_OK 0
@@ -1495,7 +1988,7 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
#define Z_TEXT 1
#define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
#define Z_UNKNOWN 2
- /* Possible values of the data_type field (though see inflate()) */
+ /* Possible values of the data_type field for deflate() */
#define Z_DEFLATED 8
/* The deflate compression method
@@ -1517,13 +2010,14 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
int inflateInit_(z_stream strm, const char *version, int stream_size);
int deflateInit2_(z_stream strm, int level, int method, int windowBits,
- int memLevel, int strategy, const char *version, int stream_size)
+ int memLevel, int strategy, const char *version,
+ int stream_size);
int inflateInit2_(z_stream strm, int windowBits, const char *version, int
stream_size);
int inflateBackInit_(z_stream *strm, int windowBits, unsigned char FAR
- *window, const char *version, int stream_size)
+ *window, const char *version, int stream_size);
const char * zError(int err);
@@ -1553,4 +2047,4 @@ COMPRESS(3) BSD Library Functions Manual COMPRESS(3)
Jean-loup Gailly <jloup@gzip.org>
Mark Adler <madler@alumni.caltech.edu>
-BSD March 16, 2018 BSD
+BSD July 6, 2021 BSD
generated by cgit v1.2.3 (git 2.39.1) at 2024-04-26 08:25:54 +0000