rpm2cpio: teach it to understand xz format

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

1 files changed, 24 insertions, 11 deletions

diff --git a/archival/rpm2cpio.c b/archival/rpm2cpio.c
index 4ed5b023b..598ec8670 100644
--- a/archival/rpm2cpio.c
+++ b/archival/rpm2cpio.c
@@ -68,22 +68,35 @@ int rpm2cpio_main(int argc UNUSED_PARAM, char **argv)
 #else
         /* BLOAT */
         {
-                unsigned char magic[2];
+                unsigned char magic[8];
                 IF_DESKTOP(long long) int FAST_FUNC (*unpack)(int src_fd, int dst_fd);
 
                 xread(rpm_fd, &magic, 2);
-                unpack = unpack_gz_stream;
-                if (magic[0] != 0x1f || magic[1] != 0x8b) {
-                        if (!ENABLE_FEATURE_SEAMLESS_BZ2
-                         || magic[0] != 'B' || magic[1] != 'Z'
-                        ) {
-                                bb_error_msg_and_die("invalid gzip"
-                                                IF_FEATURE_SEAMLESS_BZ2("/bzip2")
-                                                " magic");
-                        }
+                if (magic[0] == 0x1f && magic[1] == 0x8b) {
+                        unpack = unpack_gz_stream;
+                } else
+                if (ENABLE_FEATURE_SEAMLESS_BZ2
+                 && magic[0] == 'B' && magic[1] == 'Z'
+                ) {
                         unpack = unpack_bz2_stream;
+                } else
+                if (ENABLE_FEATURE_SEAMLESS_XZ
+                 && magic[0] == 0xfd && magic[1] == '7'
+                ) {
+                        /* .xz signature: 0xfd, '7', 'z', 'X', 'Z', 0x00 */
+                        /* More info at: http://tukaani.org/xz/xz-file-format.txt */
+                        xread(rpm_fd, magic + 2, 4);
+                        if (strcmp((char*)magic + 2, "zXZ") != 0)
+                                goto no_magic;
+                        xlseek(rpm_fd, -6, SEEK_CUR);
+                        unpack = unpack_xz_stream;
+                } else {
+ no_magic:
+                        bb_error_msg_and_die("no gzip"
+                                        IF_FEATURE_SEAMLESS_BZ2("/bzip2")
+                                        IF_FEATURE_SEAMLESS_XZ("/xz")
+                                        " magic");
                 }
-
                 if (unpack(rpm_fd, STDOUT_FILENO) < 0)
                         bb_error_msg_and_die("error unpacking");
         }