Add zlib support

diff --git a/ChangeLog b/ChangeLog
index 710266822b4841b13e6b4699d4ddd8e5804bc948..05cc75e7104478fb520e0ba51e2c38329215cfb1 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2015-11-09  16:05  Christos Zoulas <christos@zoulas.com>
+
+       * Add zlib support if we have it.
+
 2015-11-05  11:22  Christos Zoulas <christos@zoulas.com>
 
        * PR/492: compression forking was broken with magic_buffer.

diff --git a/src/compress.c b/src/compress.c
index 5ff6af9846ea3d39f842c05195a4bb4a890addbb..ab1a4222bcf2dcf61f42f22082ccd38189e076de 100644 (file)
--- a/src/compress.c
+++ b/src/compress.c
@@ -35,7 +35,7 @@
 #include "file.h"
 
 #ifndef lint
-FILE_RCSID("@(#)$File: compress.c,v 1.80 2015/06/03 18:21:24 christos Exp $")
+FILE_RCSID("@(#)$File: compress.c,v 1.81 2015/11/05 16:21:06 christos Exp $")
 #endif
 
 #include "magic.h"
@@ -63,6 +63,7 @@ typedef void (*sig_t)(int);
 #if defined(HAVE_ZLIB_H) && defined(HAVE_LIBZ)
 #define BUILTIN_DECOMPRESS
 #include <zlib.h>
+#define ZLIBSUPPORT
 #endif
 #ifdef DEBUG
 #define DPRINTF(...)   fprintf(stderr, __VA_ARGS__)
@@ -70,28 +71,81 @@ typedef void (*sig_t)(int);
 #define DPRINTF(...)
 #endif
 
+#ifdef ZLIBSUPPORT
+/*
+ * The following python code is not really used because ZLIBSUPPORT is only
+ * defined if we have a built-in zlib, and the built-in zlib handles that.
+ */
+static const char zlibcode[] =
+    "import sys, zlib; sys.stdout.write(zlib.decompress(sys.stdin.read()))";
+
+static const char *zlib_args[] = { "python", "-c", zlibcode, NULL };
+
+static int
+zlibcmp(const unsigned char *buf)
+{
+       unsigned short x = 1;
+       unsigned char *s = (unsigned char *)&x;
+
+       if ((buf[0] & 0xf) != 8 || (buf[0] & 0x80) != 0)
+               return 1;
+       if (s[0] != 1)  /* endianness test */
+               x = buf[0] | (buf[1] << 8);
+       else
+               x = buf[1] | (buf[0] << 8);
+       if (x % 31)
+               return 1;
+       return 0;
+}
+#endif
+
+static const char *gzip_args[] = {
+       "gzip", "-cdq", NULL
+};
+static const char *uncompress_args[] = {
+       "uncompress", "-c", NULL
+};
+static const char *bzip2_args[] = {
+       "bzip2", "-cd", NULL
+};
+static const char *lzip_args[] = {
+       "lzip", "-cdq", NULL
+};
+static const char *xz_args[] = {
+       "xz", "-cd", NULL
+};
+static const char *lrzip_args[] = {
+       "lrzip", "-dqo-", NULL
+};
+static const char *lz4_args[] = {
+       "lz4", "-cd", NULL
+};
+
 private const struct {
-       const char magic[8];
+       const void *magic;
        size_t maglen;
-       const char *argv[3];
+       const char **argv;
        int silent;
 } compr[] = {
-       { "\037\235", 2, { "gzip", "-cdq", NULL }, 1 },         /* compressed */
+       { "\037\235",   2, gzip_args,   1 },            /* compressed */
        /* Uncompress can get stuck; so use gzip first if we have it
         * Idea from Damien Clark, thanks! */
-       { "\037\235", 2, { "uncompress", "-c", NULL }, 1 },     /* compressed */
-       { "\037\213", 2, { "gzip", "-cdq", NULL }, 1 },         /* gzipped */
-       { "\037\236", 2, { "gzip", "-cdq", NULL }, 1 },         /* frozen */
-       { "\037\240", 2, { "gzip", "-cdq", NULL }, 1 },         /* SCO LZH */
+       { "\037\235",   2, uncompress_args, 1,          /* compressed */
+       { "\037\213",   2, gzip_args,   1 },            /* gzipped */
+       { "\037\236",   2, gzip_args,   1 },            /* frozen */
+       { "\037\240",   2, gzip_args,   1 },            /* SCO LZH */
        /* the standard pack utilities do not accept standard input */
-       { "\037\036", 2, { "gzip", "-cdq", NULL }, 0 },         /* packed */
-       { "PK\3\4",   4, { "gzip", "-cdq", NULL }, 1 },         /* pkzipped, */
-                                           /* ...only first file examined */
-       { "BZh",      3, { "bzip2", "-cd", NULL }, 1 },         /* bzip2-ed */
-       { "LZIP",     4, { "lzip", "-cdq", NULL }, 1 },
-       { "\3757zXZ\0",6,{ "xz", "-cd", NULL }, 1 },            /* XZ Utils */
-       { "LRZI",     4, { "lrzip", "-dqo-", NULL }, 1 },       /* LRZIP */
-       { "\004\"M\030", 4, { "lz4", "-cd", NULL }, 1 },        /* LZ4 */
+       { "\037\036",   2, gzip_args,   0 },            /* packed */
+       { "PK\3\4",     4, gzip_args,   1 },            /* pkzipped, */
+       /* ...only first file examined */
+       { "BZh",        3, bzip2_args,  1 },            /* bzip2-ed */
+       { "LZIP",       4, lzip_args,   1 },            /* lzip-ed */
+       { "\3757zXZ\0", 6, xz_args,     1 },            /* XZ Utils */
+       { "LRZI",       4, lrzip_args,  1 },            /* LRZIP */
+       { "\004\"M\030",4, lz4_args,    1 },            /* LZ4 */
+#ifdef ZLIBSUPPORT
+       { zlibcmp,      0, zlib_args,   1 },            /* zlib */
+#endif
 };
 
 #define NODATA ((size_t)~0)
@@ -102,6 +156,8 @@ private size_t ncompr = sizeof(compr) / sizeof(compr[0]);
 private size_t uncompressbuf(struct magic_set *, int, size_t,
     const unsigned char *, unsigned char **, size_t);
 #ifdef BUILTIN_DECOMPRESS
+private size_t uncompresszlib(struct magic_set *, const unsigned char *,
+    unsigned char **, size_t, int);
 private size_t uncompressgzipped(struct magic_set *, const unsigned char *,
     unsigned char **, size_t);
 #endif
@@ -127,7 +183,15 @@ file_zmagic(struct magic_set *ms, int fd, const char *name,
        for (i = 0; i < ncompr; i++) {
                if (nbytes < compr[i].maglen)
                        continue;
-               if (memcmp(buf, compr[i].magic, compr[i].maglen) == 0 &&
+#ifdef ZLIBSUPPORT
+               if (compr[i].maglen == 0)
+                       rv = (CAST(int (*)(const unsigned char *),
+                           CCAST(void *, compr[i].magic)))(buf);
+               else
+#endif
+                       rv = memcmp(buf, compr[i].magic, compr[i].maglen);
+
+               if (rv == 0 &&
                    (nsz = uncompressbuf(ms, fd, i, buf, &newbuf,
                    nbytes)) != NODATA) {
                        ms->flags &= ~MAGIC_COMPRESS;
@@ -333,8 +397,6 @@ uncompressgzipped(struct magic_set *ms, const unsigned char *old,
 {
        unsigned char flg = old[3];
        size_t data_start = 10;
-       z_stream z;
-       int rc;
 
        if (flg & FEXTRA) {
                if (data_start+1 >= n)
@@ -356,14 +418,22 @@ uncompressgzipped(struct magic_set *ms, const unsigned char *old,
 
        if (data_start >= n)
                return 0;
+       return uncompresszlib(ms, old + data_start, newch, n - data_start, 0);
+}
+
+private size_t
+uncompresszlib(struct magic_set *ms, const unsigned char *old,
+       unsigned char **newch, size_t n, int zlib)
+{
+       int rc;
+       z_stream z;
+
        if ((*newch = CAST(unsigned char *, malloc(HOWMANY + 1))) == NULL) {
                return 0;
        }
-       
-       /* XXX: const castaway, via strchr */
-       z.next_in = (Bytef *)strchr((const char *)old + data_start,
-           old[data_start]);
-       z.avail_in = CAST(uint32_t, (n - data_start));
+
+       z.next_in = CCAST(Bytef *, old);
+       z.avail_in = CAST(uint32_t, n);
        z.next_out = *newch;
        z.avail_out = HOWMANY;
        z.zalloc = Z_NULL;
@@ -371,7 +441,7 @@ uncompressgzipped(struct magic_set *ms, const unsigned char *old,
        z.opaque = Z_NULL;
 
        /* LINTED bug in header macro */
-       rc = inflateInit2(&z, -15);
+       rc = zlib ? inflateInit(&z) : inflateInit2(&z, -15);
        if (rc != Z_OK) {
                file_error(ms, 0, "zlib: %s", z.msg);
                return 0;
@@ -405,6 +475,8 @@ uncompressbuf(struct magic_set *ms, int fd, size_t method,
         /* FIXME: This doesn't cope with bzip2 */
        if (method == 2)
                return uncompressgzipped(ms, old, newch, n);
+       if (compr[method].maglen == 0)
+               return uncompresszlib(ms, old, newch, n, 1);
 #endif
        (void)fflush(stdout);
        (void)fflush(stderr);