tar: fix too eager autodetection, closes 11531

function                                             old     new   delta
is_suffixed_with                                       -      54     +54
tar_main                                            1006    1026     +20
open_transformer                                      92      79     -13
config_file_action                                   478     458     -20
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/2 up/down: 74/-33)             Total: 41 bytes

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

3 files changed, 11 insertions, 5 deletions

diff --git a/archival/libarchive/open_transformer.c b/archival/libarchive/open_transformer.c
index 9fefd4aad..4a4bf3916 100644
--- a/archival/libarchive/open_transformer.c
+++ b/archival/libarchive/open_transformer.c
@@ -278,8 +278,7 @@ static transformer_state_t *open_transformer(const char *fname, int fail_if_not_
 
         if (ENABLE_FEATURE_SEAMLESS_LZMA) {
                 /* .lzma has no header/signature, can only detect it by extension */
-                char *sfx = strrchr(fname, '.');
-                if (sfx && strcmp(sfx+1, "lzma") == 0) {
+                if (is_suffixed_with(fname, ".lzma")) {
                         xstate = xzalloc(sizeof(*xstate));
                         xstate->src_fd = fd;
                         xstate->xformer = unpack_lzma_stream;
diff --git a/archival/tar.c b/archival/tar.c
index 1c71f7f66..6950c271d 100644
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -1162,8 +1162,16 @@ int tar_main(int argc UNUSED_PARAM, char **argv)
                         tar_handle->seek = seek_by_read;
                 } else
                 if (ENABLE_FEATURE_TAR_AUTODETECT
+                 && ENABLE_FEATURE_SEAMLESS_LZMA
                  && flags == O_RDONLY
                  && !(opt & OPT_ANY_COMPRESS)
+                 && is_suffixed_with(tar_filename, ".lzma")
+                /* We do this only for .lzma files, they have no signature.
+                 * All other compression formats are recognized in
+                 * get_header_tar() when first tar block has invalid format.
+                 * Doing it here for all filenames would falsely trigger
+                 * on e.g. tarball with 1st file named "BZh5".
+                 */
                 ) {
                         tar_handle->src_fd = open_zipped(tar_filename, /*fail_if_not_compressed:*/ 0);
                         if (tar_handle->src_fd < 0)
diff --git a/modutils/modprobe.c b/modutils/modprobe.c
index 59f6d54f3..291e4cb90 100644
--- a/modutils/modprobe.c
+++ b/modutils/modprobe.c
@@ -245,7 +245,7 @@ static int FAST_FUNC config_file_action(const char *filename,
         parser_t *p;
         struct module_entry *m;
         int rc = TRUE;
-        const char *base, *ext;
+        const char *base;
 
         /* Skip files that begin with a "." */
         base = bb_basename(filename);
@@ -266,8 +266,7 @@ static int FAST_FUNC config_file_action(const char *filename,
          * "include FILE_NOT_ENDING_IN_CONF" must work too.
          */
         if (depth != 0) {
-                ext = strrchr(base, '.');
-                if (ext == NULL || strcmp(ext + 1, "conf"))
+                if (!is_suffixed_with(base, ".conf"))
                         goto error;
         }