1 files changed, 158 insertions, 0 deletions
diff --git a/toys/pending/compress.c b/toys/pending/compress.c
new file mode 100644
index 00000000..24729dc5
--- /dev/null
+++ b/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);
+}