zcat: if seamless uncompressors are defined, autodetect file's format

function                                             old     new   delta
bbunpack                                             526     622     +96
packed_usage                                       29335   29341      +6
gunzip_main                                           64      67      +3

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/archival/bbunzip.c b/archival/bbunzip.c
index 46f99cf781fb7444cd9f41d205c788d086e497ce..54dc2f5f1c3198ae8d64d00e2b517d73d0b3d387 100644 (file)
--- a/archival/bbunzip.c
+++ b/archival/bbunzip.c
@@ -14,6 +14,7 @@ enum {
        OPT_VERBOSE    = 1 << 2,
        OPT_DECOMPRESS = 1 << 3,
        OPT_TEST       = 1 << 4,
+       SEAMLESS_MAGIC = (1 << 31) * SEAMLESS_COMPRESSION,
 };
 
 static
@@ -39,7 +40,7 @@ int FAST_FUNC bbunpack(char **argv,
 )
 {
        struct stat stat_buf;
-       IF_DESKTOP(long long) int status;
+       IF_DESKTOP(long long) int status = 0;
        char *filename, *new_name;
        smallint exitcode = 0;
        transformer_aux_data_t aux;
@@ -54,14 +55,23 @@ int FAST_FUNC bbunpack(char **argv,
 
                /* Open src */
                if (filename) {
-                       if (stat(filename, &stat_buf) != 0) {
-                               bb_simple_perror_msg(filename);
+                       if (!(option_mask32 & SEAMLESS_MAGIC)) {
+                               if (stat(filename, &stat_buf) != 0) {
+ err_name:
+                                       bb_simple_perror_msg(filename);
  err:
-                               exitcode = 1;
-                               goto free_name;
+                                       exitcode = 1;
+                                       goto free_name;
+                               }
+                               if (open_to_or_warn(STDIN_FILENO, filename, O_RDONLY, 0))
+                                       goto err;
+                       } else {
+                               /* "clever zcat" */
+                               int fd = open_zipped(filename);
+                               if (fd < 0)
+                                       goto err_name;
+                               xmove_fd(fd, STDIN_FILENO);
                        }
-                       if (open_to_or_warn(STDIN_FILENO, filename, O_RDONLY, 0))
-                               goto err;
                }
 
                /* Special cases: test, stdout */
@@ -98,11 +108,23 @@ int FAST_FUNC bbunpack(char **argv,
                                        "use -f to force it");
                }
 
-               init_transformer_aux_data(&aux);
-               aux.check_signature = 1;
-               status = unpacker(&aux);
-               if (status < 0)
-                       exitcode = 1;
+               if (!(option_mask32 & SEAMLESS_MAGIC)) {
+                       init_transformer_aux_data(&aux);
+                       aux.check_signature = 1;
+                       status = unpacker(&aux);
+                       if (status < 0)
+                               exitcode = 1;
+               } else {
+                       /* "clever zcat" */
+                       if (!filename) {
+                               if (setup_unzip_on_fd(STDIN_FILENO, /*fail_if_not_detected*/ 0))
+                                       goto err;
+                       }
+                       if (bb_copyfd_eof(STDIN_FILENO, STDOUT_FILENO) < 0) {
+                               /* Disk full, tty closed, etc. No point in continuing */
+                               xfunc_die();
+                       }
+               }
 
                if (!(option_mask32 & OPT_STDOUT))
                        xclose(STDOUT_FILENO); /* with error check! */
@@ -294,9 +316,13 @@ int gunzip_main(int argc UNUSED_PARAM, char **argv)
 {
        getopt32(argv, "cfvdtn");
        argv += optind;
-       /* if called as zcat */
+
+       /* If called as zcat...
+        * Normally, "zcat" is just "gunzip -c".
+        * But if seamless magic is enabled, then we are much more clever.
+        */
        if (applet_name[1] == 'c')
-               option_mask32 |= OPT_STDOUT;
+               option_mask32 |= OPT_STDOUT | SEAMLESS_MAGIC;
 
        return bbunpack(argv, unpack_gunzip, make_new_name_gunzip, /*unused:*/ NULL);
 }