zcat: complain if input is not compressed

function                                             old     new   delta
buffer_fill_and_print                                178     191     +13
varvalue                                             735     743      +8
bbunpack                                             747     755      +8
open_zipped                                           85      89      +4
xmalloc_open_zipped_read_close                        61      63      +2
get_addr_1                                           240     242      +2
fbsplash_main                                       1228    1230      +2
pstree_main                                          322     321      -1
builtin_type                                         121     119      -2
do_load                                              954     926     -28
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 7/3 up/down: 39/-31)              Total: 8 bytes

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

9 files changed, 17 insertions, 25 deletions

diff --git a/archival/bbunzip.c b/archival/bbunzip.c
index b3fb90f31..fce5ab9e1 100644
--- a/archival/bbunzip.c
+++ b/archival/bbunzip.c
@@ -72,7 +72,8 @@ int FAST_FUNC bbunpack(char **argv,
 					goto err;
 			} else {
 				/* "clever zcat" with FILE */
-				int fd = open_zipped(filename);
+				/* fail_if_not_compressed because zcat refuses uncompressed input */
+				int fd = open_zipped(filename, /*fail_if_not_compressed:*/ 1);
 				if (fd < 0)
 					goto err_name;
 				xmove_fd(fd, STDIN_FILENO);
@@ -80,7 +81,7 @@ int FAST_FUNC bbunpack(char **argv,
 		} else
 		if (option_mask32 & SEAMLESS_MAGIC) {
 			/* "clever zcat" on stdin */
-			if (setup_unzip_on_fd(STDIN_FILENO, /*fail_if_not_detected*/ 0))
+			if (setup_unzip_on_fd(STDIN_FILENO, /*fail_if_not_compressed*/ 1))
 				goto err;
 		}
 
diff --git a/archival/libarchive/get_header_tar.c b/archival/libarchive/get_header_tar.c
index 54d910431..ba43bb073 100644
--- a/archival/libarchive/get_header_tar.c
+++ b/archival/libarchive/get_header_tar.c
@@ -243,7 +243,7 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
 		 * or not first block (false positive, it's not .gz/.bz2!) */
 		if (lseek(archive_handle->src_fd, -i, SEEK_CUR) != 0)
 			goto err;
-		if (setup_unzip_on_fd(archive_handle->src_fd, /*fail_if_not_detected:*/ 0) != 0)
+		if (setup_unzip_on_fd(archive_handle->src_fd, /*fail_if_not_compressed:*/ 0) != 0)
  err:
 			bb_error_msg_and_die("invalid tar magic");
 		archive_handle->offset = 0;
diff --git a/archival/libarchive/open_transformer.c b/archival/libarchive/open_transformer.c
index 27854af21..198663041 100644
--- a/archival/libarchive/open_transformer.c
+++ b/archival/libarchive/open_transformer.c
@@ -118,7 +118,7 @@ void FAST_FUNC open_transformer(int fd, const char *transform_prog)
 /* Used by e.g. rpm which gives us a fd without filename,
  * thus we can't guess the format from filename's extension.
  */
-int FAST_FUNC setup_unzip_on_fd(int fd, int fail_if_not_detected)
+int FAST_FUNC setup_unzip_on_fd(int fd, int fail_if_not_compressed)
 {
 	union {
 		uint8_t b[4];
@@ -159,7 +159,7 @@ int FAST_FUNC setup_unzip_on_fd(int fd, int fail_if_not_detected)
 	}
 
 	/* No known magic seen */
-	if (fail_if_not_detected)
+	if (fail_if_not_compressed)
 		bb_error_msg_and_die("no gzip"
 			IF_FEATURE_SEAMLESS_BZ2("/bzip2")
 			IF_FEATURE_SEAMLESS_XZ("/xz")
@@ -180,7 +180,7 @@ int FAST_FUNC setup_unzip_on_fd(int fd, int fail_if_not_detected)
 	return 0;
 }
 
-int FAST_FUNC open_zipped(const char *fname)
+int FAST_FUNC open_zipped(const char *fname, int fail_if_not_compressed)
 {
 	int fd;
 
@@ -200,16 +200,7 @@ int FAST_FUNC open_zipped(const char *fname)
 	 || (ENABLE_FEATURE_SEAMLESS_BZ2)
 	 || (ENABLE_FEATURE_SEAMLESS_XZ)
 	) {
-		/*
-		 * Do we want to fail_if_not_detected?
-		 * In most cases, no: think "insmod non_compressed_module".
-		 * A case which would like to fail is "zcat uncompressed_file":
-		 * otherwise, it happily outputs uncompressed_file as-is,
-		 * which is, strictly speaking, not what is expected.
-		 * If this ever becomes a problem, we can add
-		 * fail_if_not_detected bool argument to open_zipped().
-		 */
-		setup_unzip_on_fd(fd, /*fail_if_not_detected:*/ 0);
+		setup_unzip_on_fd(fd, fail_if_not_compressed);
 	}
 
 	return fd;
@@ -222,7 +213,7 @@ void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_
 	int fd;
 	char *image;
 
-	fd = open_zipped(fname);
+	fd = open_zipped(fname, /*fail_if_not_compressed:*/ 0);
 	if (fd < 0)
 		return NULL;
 
diff --git a/archival/rpm.c b/archival/rpm.c
index 885eddd64..105394481 100644
--- a/archival/rpm.c
+++ b/archival/rpm.c
@@ -122,7 +122,7 @@ static void extract_cpio(int fd, const char *source_rpm)
 	archive_handle->src_fd = fd;
 	/*archive_handle->offset = 0; - init_handle() did it */
 
-	setup_unzip_on_fd(archive_handle->src_fd, /*fail_if_not_detected:*/ 1);
+	setup_unzip_on_fd(archive_handle->src_fd, /*fail_if_not_compressed:*/ 1);
 	while (get_header_cpio(archive_handle) == EXIT_SUCCESS)
 		continue;
 }
diff --git a/archival/rpm2cpio.c b/archival/rpm2cpio.c
index 61adde795..7057570f5 100644
--- a/archival/rpm2cpio.c
+++ b/archival/rpm2cpio.c
@@ -80,7 +80,7 @@ int rpm2cpio_main(int argc UNUSED_PARAM, char **argv)
 	//	signal(SIGCHLD, check_errors_in_children);
 
 	/* This works, but doesn't report uncompress errors (they happen in child) */
-	setup_unzip_on_fd(rpm_fd, /*fail_if_not_detected:*/ 1);
+	setup_unzip_on_fd(rpm_fd, /*fail_if_not_compressed:*/ 1);
 	if (bb_copyfd_eof(rpm_fd, STDOUT_FILENO) < 0)
 		bb_error_msg_and_die("error unpacking");
 
diff --git a/archival/tar.c b/archival/tar.c
index bd61abd57..aa02d3512 100644
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -1137,7 +1137,7 @@ int tar_main(int argc UNUSED_PARAM, char **argv)
 			 && flags == O_RDONLY
 			 && !(opt & OPT_ANY_COMPRESS)
 			) {
-				tar_handle->src_fd = open_zipped(tar_filename);
+				tar_handle->src_fd = open_zipped(tar_filename, /*fail_if_not_compressed:*/ 0);
 				if (tar_handle->src_fd < 0)
 					bb_perror_msg_and_die("can't open '%s'", tar_filename);
 			} else {
diff --git a/include/libbb.h b/include/libbb.h
index 64167bba3..96f33340e 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -736,12 +736,12 @@ extern void *xmalloc_xopen_read_close(const char *filename, size_t *maxsz_p) FAS
 
 #if SEAMLESS_COMPRESSION
 /* Autodetects gzip/bzip2 formats. fd may be in the middle of the file! */
-extern int setup_unzip_on_fd(int fd, int fail_if_not_detected) FAST_FUNC;
+extern int setup_unzip_on_fd(int fd, int fail_if_not_compressed) FAST_FUNC;
 /* Autodetects .gz etc */
-extern int open_zipped(const char *fname) FAST_FUNC;
+extern int open_zipped(const char *fname, int fail_if_not_compressed) FAST_FUNC;
 #else
 # define setup_unzip_on_fd(...) (0)
-# define open_zipped(fname)     open((fname), O_RDONLY);
+# define open_zipped(fname, fail_if_not_compressed)  open((fname), O_RDONLY);
 #endif
 extern void *xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p) FAST_FUNC RETURNS_MALLOC;
 
diff --git a/miscutils/fbsplash.c b/miscutils/fbsplash.c
index 12a77b70f..7b695b26f 100644
--- a/miscutils/fbsplash.c
+++ b/miscutils/fbsplash.c
@@ -353,7 +353,7 @@ static void fb_drawimage(void)
 	if (LONE_DASH(G.image_filename)) {
 		theme_file = stdin;
 	} else {
-		int fd = open_zipped(G.image_filename);
+		int fd = open_zipped(G.image_filename, /*fail_if_not_compressed:*/ 0);
 		if (fd < 0)
 			bb_simple_perror_msg_and_die(G.image_filename);
 		theme_file = xfdopen_for_read(fd);
diff --git a/miscutils/man.c b/miscutils/man.c
index 51baceb16..f046e24f3 100644
--- a/miscutils/man.c
+++ b/miscutils/man.c
@@ -102,7 +102,7 @@ static int run_pipe(const char *pager, char *man_filename, int man, int level)
 
  ordinary_manpage:
 	close(STDIN_FILENO);
-	open_zipped(man_filename); /* guaranteed to use fd 0 (STDIN_FILENO) */
+	open_zipped(man_filename, /*fail_if_not_compressed:*/ 0); /* guaranteed to use fd 0 (STDIN_FILENO) */
 	/* "2>&1" is added so that nroff errors are shown in pager too.
 	 * Otherwise it may show just empty screen */
 	cmd = xasprintf(