libarchive: fix xmalloc_open_zipped_read_close() on NOMMU

The somewhat new "unpack in memory" code was broken
for xmalloc_open_zipped_read_close() on NOMMU: we seek back
over signature, but then expect it to be already consumed.
Stop seeking back in this case.

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

5 files changed, 23 insertions, 28 deletions

diff --git a/archival/bbunzip.c b/archival/bbunzip.c
index b4f754e0b..07ef8617e 100644
--- a/archival/bbunzip.c
+++ b/archival/bbunzip.c
@@ -121,7 +121,7 @@ int FAST_FUNC bbunpack(char **argv,
 
                 if (!(option_mask32 & SEAMLESS_MAGIC)) {
                         init_transformer_state(&xstate);
-                        xstate.check_signature = 1;
+                        xstate.signature_skipped = 0;
                         /*xstate.src_fd = STDIN_FILENO; - already is */
                         xstate.dst_fd = STDOUT_FILENO;
                         status = unpacker(&xstate);
diff --git a/archival/libarchive/decompress_gunzip.c b/archival/libarchive/decompress_gunzip.c
index 20e4d9ac5..c7fa5b526 100644
--- a/archival/libarchive/decompress_gunzip.c
+++ b/archival/libarchive/decompress_gunzip.c
@@ -1201,7 +1201,7 @@ unpack_gz_stream(transformer_state_t *xstate)
         if (check_signature16(xstate, GZIP_MAGIC))
                 return -1;
 #else
-        if (xstate->check_signature) {
+        if (!xstate->signature_skipped) {
                 uint16_t magic2;
 
                 if (full_read(xstate->src_fd, &magic2, 2) != 2) {
@@ -1210,7 +1210,7 @@ unpack_gz_stream(transformer_state_t *xstate)
                         return -1;
                 }
                 if (magic2 == COMPRESS_MAGIC) {
-                        xstate->check_signature = 0;
+                        xstate->signature_skipped = 2;
                         return unpack_Z_stream(xstate);
                 }
                 if (magic2 != GZIP_MAGIC)
diff --git a/archival/libarchive/decompress_unxz.c b/archival/libarchive/decompress_unxz.c
index 1f408abfd..cd32cc745 100644
--- a/archival/libarchive/decompress_unxz.c
+++ b/archival/libarchive/decompress_unxz.c
@@ -55,7 +55,7 @@ unpack_xz_stream(transformer_state_t *xstate)
         iobuf.out = membuf + BUFSIZ;
         iobuf.out_size = BUFSIZ;
 
-        if (!xstate || xstate->check_signature == 0) {
+        if (!xstate || xstate->signature_skipped) {
                 /* Preload XZ file signature */
                 strcpy((char*)membuf, HEADER_MAGIC);
                 iobuf.in_size = HEADER_MAGIC_SIZE;
diff --git a/archival/libarchive/open_transformer.c b/archival/libarchive/open_transformer.c
index be536a3d7..d93c8366f 100644
--- a/archival/libarchive/open_transformer.c
+++ b/archival/libarchive/open_transformer.c
@@ -13,16 +13,13 @@ void FAST_FUNC init_transformer_state(transformer_state_t *xstate)
 
 int FAST_FUNC check_signature16(transformer_state_t *xstate, unsigned magic16)
 {
-        if (xstate->check_signature) {
+        if (!xstate->signature_skipped) {
                 uint16_t magic2;
                 if (full_read(xstate->src_fd, &magic2, 2) != 2 || magic2 != magic16) {
                         bb_error_msg("invalid magic");
-#if 0 /* possible future extension */
-                        if (xstate->check_signature > 1)
-                                xfunc_die();
-#endif
                         return -1;
                 }
+                xstate->signature_skipped = 2;
         }
         return 0;
 }
@@ -102,7 +99,7 @@ void check_errors_in_children(int signo)
 /* transformer(), more than meets the eye */
 #if BB_MMU
 void FAST_FUNC fork_transformer(int fd,
-        int check_signature,
+        int signature_skipped,
         IF_DESKTOP(long long) int FAST_FUNC (*transformer)(transformer_state_t *xstate)
 )
 #else
@@ -123,7 +120,7 @@ void FAST_FUNC fork_transformer(int fd, const char *transform_prog)
                         IF_DESKTOP(long long) int r;
                         transformer_state_t xstate;
                         init_transformer_state(&xstate);
-                        xstate.check_signature = check_signature;
+                        xstate.signature_skipped = signature_skipped;
                         xstate.src_fd = fd;
                         xstate.dst_fd = fd_pipe.wr;
                         r = transformer(&xstate);
@@ -168,12 +165,11 @@ static transformer_state_t *setup_transformer_on_fd(int fd, int fail_if_not_comp
                 uint16_t b16[2];
                 uint32_t b32[1];
         } magic;
-        int offset;
         transformer_state_t *xstate;
 
-        offset = -2;
         xstate = xzalloc(sizeof(*xstate));
         xstate->src_fd = fd;
+        xstate->signature_skipped = 2;
 
         /* .gz and .bz2 both have 2-byte signature, and their
          * unpack_XXX_stream wants this header skipped. */
@@ -202,7 +198,7 @@ static transformer_state_t *setup_transformer_on_fd(int fd, int fail_if_not_comp
         if (ENABLE_FEATURE_SEAMLESS_XZ
          && magic.b16[0] == XZ_MAGIC1
         ) {
-                offset = -6;
+                xstate->signature_skipped = 6;
                 xread(fd, magic.b32, sizeof(magic.b32[0]));
                 if (magic.b32[0] == XZ_MAGIC2) {
                         xstate->xformer = unpack_xz_stream;
@@ -226,16 +222,7 @@ static transformer_state_t *setup_transformer_on_fd(int fd, int fail_if_not_comp
 //      USE_FOR_NOMMU(xstate->xformer_prog = "cat";)
         /* fall through to seeking bck over bytes we read earlier */
 
- USE_FOR_NOMMU(found_magic:)
-        /* NOMMU version of fork_transformer execs
-         * an external unzipper that wants
-         * file position at the start of the file.
-         */
-        xlseek(fd, offset, SEEK_CUR);
-
- USE_FOR_MMU(found_magic:)
-        /* In MMU case, if magic was found, seeking back is not necessary */
-
+ found_magic:
         return xstate;
 }
 
@@ -254,6 +241,12 @@ int FAST_FUNC setup_unzip_on_fd(int fd, int fail_if_not_compressed)
 # if BB_MMU
         fork_transformer_with_no_sig(xstate->src_fd, xstate->xformer);
 # else
+        /* NOMMU version of fork_transformer execs
+         * an external unzipper that wants
+         * file position at the start of the file.
+         */
+        xlseek(fd, - xstate->signature_skipped, SEEK_CUR);
+        xstate->signature_skipped = 0;
         fork_transformer_with_sig(xstate->src_fd, xstate->xformer, xstate->xformer_prog);
 # endif
         free(xstate);
@@ -300,6 +293,8 @@ int FAST_FUNC open_zipped(const char *fname, int fail_if_not_compressed)
 # if BB_MMU
                 fork_transformer_with_no_sig(xstate->src_fd, xstate->xformer);
 # else
+                xlseek(fd, - xstate->signature_skipped, SEEK_CUR);
+                xstate->signature_skipped = 0;
                 fork_transformer_with_sig(xstate->src_fd, xstate->xformer, xstate->xformer_prog);
 # endif
         }
diff --git a/include/bb_archive.h b/include/bb_archive.h
index 10969b567..2b9c5f04c 100644
--- a/include/bb_archive.h
+++ b/include/bb_archive.h
@@ -211,7 +211,7 @@ void dealloc_bunzip(bunzip_data *bd) FAST_FUNC;
 
 /* Meaning and direction (input/output) of the fields are transformer-specific */
 typedef struct transformer_state_t {
-        smallint check_signature; /* most often referenced member */
+        smallint signature_skipped; /* most often referenced member */
 
         IF_DESKTOP(long long) int FAST_FUNC (*xformer)(struct transformer_state_t *xstate);
         USE_FOR_NOMMU(const char *xformer_prog;)
@@ -252,11 +252,11 @@ int bbunpack(char **argv,
 void check_errors_in_children(int signo);
 #if BB_MMU
 void fork_transformer(int fd,
-        int check_signature,
+        int signature_skipped,
         IF_DESKTOP(long long) int FAST_FUNC (*transformer)(transformer_state_t *xstate)
 ) FAST_FUNC;
-#define fork_transformer_with_sig(fd, transformer, transform_prog) fork_transformer((fd), 1, (transformer))
-#define fork_transformer_with_no_sig(fd, transformer)              fork_transformer((fd), 0, (transformer))
+#define fork_transformer_with_sig(fd, transformer, transform_prog) fork_transformer((fd), 0, (transformer))
+#define fork_transformer_with_no_sig(fd, transformer)              fork_transformer((fd), 1, (transformer))
 #else
 void fork_transformer(int fd, const char *transform_prog) FAST_FUNC;
 #define fork_transformer_with_sig(fd, transformer, transform_prog) fork_transformer((fd), (transform_prog))