tar: optional autodetection of gz/bz2 compressed tarballs.

+130 bytes. Closes bug 992.

diff --git a/archival/Config.in b/archival/Config.in
index 160c54d..6f803f4 100644 (file)
--- a/archival/Config.in
+++ b/archival/Config.in
@@ -166,6 +166,14 @@ config FEATURE_TAR_CREATE
          If you enable this option you'll be able to create
          tar archives using the `-c' option.
 
+config FEATURE_TAR_GZIP
+       bool "Enable -z option"
+       default y
+       depends on TAR
+       help
+         If you enable this option tar will be able to call gzip,
+         when creating or extracting tar gziped archives.
+
 config FEATURE_TAR_BZIP2
        bool "Enable -j option to handle .tar.bz2 files"
        default n
@@ -182,29 +190,29 @@ config FEATURE_TAR_LZMA
          If you enable this option you'll be able to extract
          archives compressed with lzma.
 
-config FEATURE_TAR_FROM
-       bool "Enable -X (exclude from) and -T (include from) options)"
+config FEATURE_TAR_COMPRESS
+       bool "Enable -Z option"
        default n
        depends on TAR
        help
-         If you enable this option you'll be able to specify
-         a list of files to include or exclude from an archive.
+         If you enable this option tar will be able to call uncompress,
+         when extracting .tar.Z archives.
 
-config FEATURE_TAR_GZIP
-       bool "Enable -z option"
-       default y
-       depends on TAR
+config FEATURE_TAR_AUTODETECT
+       bool "Let tar autodetect gz/bz2 compresses tarballs"
+       default n
+       depends on FEATURE_TAR_GZIP || FEATURE_TAR_BZIP2
        help
-         If you enable this option tar will be able to call gzip,
-         when creating or extracting tar gziped archives.
+         With this option tar can automatically detect gzip/bzip2 compressed
+         tarballs. Currently it works only on seekable streams.
 
-config FEATURE_TAR_COMPRESS
-       bool "Enable -Z option"
+config FEATURE_TAR_FROM
+       bool "Enable -X (exclude from) and -T (include from) options)"
        default n
        depends on TAR
        help
-         If you enable this option tar will be able to call uncompress,
-         when extracting .tar.Z archives.
+         If you enable this option you'll be able to specify
+         a list of files to include or exclude from an archive.
 
 config FEATURE_TAR_OLDGNU_COMPATIBILITY
        bool "Enable support for old tar header format"

diff --git a/archival/libunarchive/get_header_tar.c b/archival/libunarchive/get_header_tar.c
index 893cd5b..54c8f76 100644 (file)
--- a/archival/libunarchive/get_header_tar.c
+++ b/archival/libunarchive/get_header_tar.c
@@ -46,6 +46,9 @@ void BUG_tar_header_size(void);
 char get_header_tar(archive_handle_t *archive_handle)
 {
        static smallint end;
+#if ENABLE_FEATURE_TAR_AUTODETECT
+       static smallint not_first;
+#endif
 
        file_header_t *file_header = archive_handle->file_header;
        struct {
@@ -115,7 +118,7 @@ char get_header_tar(archive_handle_t *archive_handle)
                         * Read until the end to empty the pipe from gz or bz2
                         */
                        while (full_read(archive_handle->src_fd, &tar, 512) == 512)
-                               /* repeat */;
+                               continue;
                        return EXIT_FAILURE;
                }
                end = 1;
@@ -123,16 +126,49 @@ char get_header_tar(archive_handle_t *archive_handle)
        }
        end = 0;
 
-       /* Check header has valid magic, "ustar" is for the proper tar
-        * 0's are for the old tar format
-        */
-       if (strncmp(tar.magic, "ustar", 5) != 0) {
-#if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
-               if (memcmp(tar.magic, "\0\0\0\0", 5) != 0)
+       /* Check header has valid magic, "ustar" is for the proper tar,
+        * five NULs are for the old tar format  */
+       if (strncmp(tar.magic, "ustar", 5) != 0
+        && (!ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
+            || memcmp(tar.magic, "\0\0\0\0", 5) != 0)
+       ) {
+#if ENABLE_FEATURE_TAR_AUTODETECT
+               char (*get_header_ptr)(archive_handle_t *);
+
+               /* tar gz/bz autodetect: check for gz/bz2 magic.
+                * If it is the very first block, and we see the magic,
+                * we can switch to get_header_tar_gz/bz2/lzma().
+                * Needs seekable fd. I wish recv(MSG_PEEK) would work
+                * on any fd... */
+               if (not_first)
+                       goto err;
+#if ENABLE_FEATURE_TAR_GZIP
+               if (tar.name[0] == 0x1f && tar.name[1] == 0x8b) { /* gzip */
+                       get_header_ptr = get_header_tar_gz;
+               } else
 #endif
-                       bb_error_msg_and_die("invalid tar magic");
+#if ENABLE_FEATURE_TAR_BZIP2
+               if (tar.name[0] == 'B' && tar.name[1] == 'Z'
+                && tar.name[2] == 'h' && isdigit(tar.name[3])
+               ) { /* bzip2 */
+                       get_header_ptr = get_header_tar_bz2;
+               } else
+#endif
+                       goto err;
+               if (lseek(archive_handle->src_fd, -512, SEEK_CUR) != 0)
+                       goto err;
+               while (get_header_ptr(archive_handle) == EXIT_SUCCESS)
+                       continue;
+               return EXIT_FAILURE;
+ err:
+#endif /* FEATURE_TAR_AUTODETECT */
+               bb_error_msg_and_die("invalid tar magic");
        }
 
+#if ENABLE_FEATURE_TAR_AUTODETECT
+       not_first = 1;
+#endif
+
        /* Do checksum on headers.
         * POSIX says that checksum is done on unsigned bytes, but
         * Sun and HP-UX gets it wrong... more details in

diff --git a/archival/tar.c b/archival/tar.c
index 4ec454b..e790f28 100644 (file)
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -33,8 +33,17 @@
 #define FNM_LEADING_DIR 0
 #endif
 
+
 #define block_buf bb_common_bufsiz1
 
+
+#if !ENABLE_FEATURE_TAR_GZIP && !ENABLE_FEATURE_TAR_BZIP2
+/* Do not pass gzip flag to writeTarFile() */
+#define writeTarFile(tar_fd, verboseFlag, dereferenceFlag, include, exclude, gzip) \
+       writeTarFile(tar_fd, verboseFlag, dereferenceFlag, include, exclude)
+#endif
+
+
 #if ENABLE_FEATURE_TAR_CREATE
 
 /* Tar file constants  */
@@ -514,18 +523,23 @@ static int writeTarFile(const int tar_fd, const int verboseFlag,
        if (fstat(tbInfo.tarFd, &tbInfo.statBuf) < 0)
                bb_perror_msg_and_die("cannot stat tar file");
 
-       if ((ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2) && gzip) {
-// On Linux, vfork never unpauses parent early, although standard
-// allows for that. Do we want to waste bytes checking for it?
+#if ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2
+       if (gzip) {
+#if ENABLE_FEATURE_TAR_GZIP && ENABLE_FEATURE_TAR_BZIP2
+               const char *zip_exec = (gzip == 1) ? "gzip" : "bzip2";
+#elif ENABLE_FEATURE_TAR_GZIP
+               const char *zip_exec = "gzip";
+#else /* only ENABLE_FEATURE_TAR_BZIP2 */
+               const char *zip_exec = "bzip2";
+#endif
+       // On Linux, vfork never unpauses parent early, although standard
+       // allows for that. Do we want to waste bytes checking for it?
 #define WAIT_FOR_CHILD 0
-
                volatile int vfork_exec_errno = 0;
 #if WAIT_FOR_CHILD
                struct fd_pair gzipStatusPipe;
 #endif
                struct fd_pair gzipDataPipe;
-               const char *zip_exec = (gzip == 1) ? "gzip" : "bzip2";
-
                xpiped_pair(gzipDataPipe);
 #if WAIT_FOR_CHILD
                xpiped_pair(gzipStatusPipe);
@@ -584,6 +598,7 @@ static int writeTarFile(const int tar_fd, const int verboseFlag,
                        bb_perror_msg_and_die("cannot exec %s", zip_exec);
                }
        }
+#endif
 
        tbInfo.excludeList = exclude;
 
@@ -934,11 +949,13 @@ int tar_main(int argc, char **argv)
 
        /* create an archive */
        if (opt & OPT_CREATE) {
+#if ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2
                int zipMode = 0;
-               if (ENABLE_FEATURE_TAR_GZIP && get_header_ptr == get_header_tar_gz)
+               if (ENABLE_FEATURE_TAR_GZIP && (opt & OPT_GZIP))
                        zipMode = 1;
-               if (ENABLE_FEATURE_TAR_BZIP2 && get_header_ptr == get_header_tar_bz2)
+               if (ENABLE_FEATURE_TAR_BZIP2 && (opt & OPT_BZIP2))
                        zipMode = 2;
+#endif
                /* NB: writeTarFile() closes tar_handle->src_fd */
                return writeTarFile(tar_handle->src_fd, verboseFlag, opt & OPT_DEREFERENCE,
                                tar_handle->accept,
@@ -946,7 +963,7 @@ int tar_main(int argc, char **argv)
        }
 
        while (get_header_ptr(tar_handle) == EXIT_SUCCESS)
-               /* nothing */;
+               continue;
 
        /* Check that every file that should have been extracted was */
        while (tar_handle->accept) {