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authorRob Landley <rob@landley.net>2014-02-08 13:37:57 -0600
committerRob Landley <rob@landley.net>2014-02-08 13:37:57 -0600
commitb34b237e6229344ce460e117eb442db9a32fe813 (patch)
treef829092b0df21cf62a1057bd828c47978a27aa0d /toys/pending/compress.c
parent5a2583ac4ff866caee57b465f429f75417c629ad (diff)
downloadtoybox-b34b237e6229344ce460e117eb442db9a32fe813.tar.gz
Nothing to see here, move along.
Diffstat (limited to 'toys/pending/compress.c')
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+/* compress.c - deflate/inflate code for zip, gzip, zlib, and raw
+ *
+ * Copyright 2014 Rob Landley <rob@landley.net>
+ *
+ * The inflate/deflate code lives here, so the various things that use it
+ * either live here or call these commands to pipe data through them.
+ *
+ * Divergence from posix: replace obsolete "compress" with mutiplexer.
+ *
+ * See RFCs 1950 (zlib), 1951 (deflate), and 1952 (gzip)
+ * LSB 4.1 has gzip, gunzip, and zcat
+ * TODO: zip -d DIR -x LIST -list -quiet -no overwrite -overwrite -p to stdout
+
+// Accept many different kinds of command line argument:
+
+USE_COMPRESS(NEWTOY(compress, "zglrcd9[-cd][!zglr]", TOYFLAG_USR|TOYFLAG_BIN))
+
+//zip unzip gzip gunzip zcat
+
+config COMPRESS
+ bool "compress"
+ default n
+ help
+ usage: compress [-zglrcd9] [FILE]
+
+ Compress or decompress file (or stdin) using "deflate" algorithm.
+
+ -c compress
+ -d decompress
+ -g gzip
+ -l zlib
+ -r raw (default)
+ -z zip
+*/
+
+#define FOR_compress
+#include "toys.h"
+
+GLOBALS(
+ // base offset and extra bits tables (length and distance)
+ char lenbits[29], distbits[30];
+ unsigned short lenbase[29], distbase[30];
+)
+
+// little endian bit buffer
+struct bitbuf {
+ int fd, pos, len, max;
+ char buf[];
+};
+
+struct bitbuf *get_bitbuf(int fd, int size)
+{
+ struct bitbuf *bb = xmalloc(sizeof(struct bitbuf)+size);
+
+ memset(bb, 0, sizeof(struct bitbuf));
+ bb->max = size;
+ bb->fd = fd;
+
+ return bb;
+}
+
+int get_bits(struct bitbuf *bb, int bits)
+{
+ int result = 0, offset = 0;
+
+ while (bits) {
+ int click = bb->pos >> 3, blow, blen;
+
+ // Load more data if buffer empty
+ if (click == bb->len) {
+ bb->len = read(bb->fd, bb->buf, bb->max);
+ if (bb->len < 1) perror_exit("inflate EOF");
+ bb->pos = click = 0;
+ }
+
+ // grab bits from next byte
+ blow = bb->pos & 7;
+ blen = 8-blow;
+ if (blen > bits) blen = bits;
+ result |= ((bb->buf[click] >> blow) & ((1<<blen)-1)) << offset;
+ offset += blen;
+ bits -= blen;
+ bb->pos += blen;
+ }
+
+ return result;
+}
+
+static int deflate(struct bitbuf *buf)
+{
+ return 0;
+}
+
+static void init_deflate(void)
+{
+ int i, n = 1;
+
+ // Calculate lenbits, lenbase, distbits, distbase
+ *TT.lenbase = 3;
+ for (i = 0; i<sizeof(TT.lenbits)-1; i++) {
+ if (i>4) {
+ if (!(i&3)) {
+ TT.lenbits[i]++;
+ n <<= 1;
+ }
+ if (i == 27) n--;
+ else TT.lenbits[i+1] = TT.lenbits[i];
+ }
+ TT.lenbase[i+1] = n + TT.lenbase[i];
+ }
+ n = 0;
+ for (i = 0; i<sizeof(TT.distbits); i++) {
+ TT.distbase[i] = 1<<n;
+ if (i) TT.distbase[i] += TT.distbase[i-1];
+ if (i>3 && !(i&1)) n++;
+ TT.distbits[i] = n;
+ }
+}
+
+// Return true/false whether we consumed a gzip header.
+static int is_gzip(struct bitbuf *bb)
+{
+ int flags;
+
+ // Confirm signature
+ if (get_bits(bb, 24) != 0x088b1f || (flags = get_bits(bb, 8)) > 31) return 0;
+ get_bits(bb, 6*8);
+
+ // Skip extra, name, comment, header CRC fields
+ if (flags & 4) get_bits(bb, 16);
+ if (flags & 8) while (get_bits(bb, 8));
+ if (flags & 16) while (get_bits(bb, 8));
+ if (flags & 2) get_bits(bb, 16);
+
+ return 1;
+}
+
+static void do_gzip(int fd, char *name)
+{
+ struct bitbuf *bb = get_bitbuf(fd, sizeof(toybuf));
+
+ printf("is_gzip=%d\n", is_gzip(bb));
+
+ // tail: crc32, len32
+
+ free(bb);
+}
+
+// Parse many different kinds of command line argument:
+
+void compress_main(void)
+{
+ // 31, 139, 8
+ // &2 = skip 2 bytes
+ init_deflate();
+
+ loopfiles(toys.optargs, do_gzip);
+}