preparatory cleanups for seamless uncompression improvements

unpack_gz_stream_with_info: fix buggy error check
man: fix possible accesses past the end of a string
move seamless uncompression helpers from read_printf.c to open_transformer.c

function                                             old     new   delta
show_manpage                                         153     212     +59
unpack_gz_stream_with_info                           520     539     +19

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

1 files changed, 140 insertions, 0 deletions

diff --git a/archival/libarchive/open_transformer.c b/archival/libarchive/open_transformer.c
index aa8c102..743ffee 100644
--- a/archival/libarchive/open_transformer.c
+++ b/archival/libarchive/open_transformer.c
@@ -6,6 +6,16 @@
 #include "libbb.h"
 #include "bb_archive.h"
 
+#define ZIPPED (ENABLE_FEATURE_SEAMLESS_LZMA \
+	|| ENABLE_FEATURE_SEAMLESS_BZ2 \
+	|| ENABLE_FEATURE_SEAMLESS_GZ \
+	/* || ENABLE_FEATURE_SEAMLESS_Z */ \
+)
+
+#if ZIPPED
+# include "bb_archive.h"
+#endif
+
 /* transformer(), more than meets the eye */
 /*
  * On MMU machine, the transform_prog is removed by macro magic
@@ -52,3 +62,133 @@ void FAST_FUNC open_transformer(int fd,
 	close(fd_pipe.wr); /* don't want to write to the child */
 	xmove_fd(fd_pipe.rd, fd);
 }
+
+
+/* Used by e.g. rpm which gives us a fd without filename,
+ * thus we can't guess the format from filename's extension.
+ */
+#if ZIPPED
+void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/)
+{
+	const int fail_if_not_detected = 1;
+	union {
+		uint8_t b[4];
+		uint16_t b16[2];
+		uint32_t b32[1];
+	} magic;
+	int offset = -2;
+# if BB_MMU
+	IF_DESKTOP(long long) int FAST_FUNC (*xformer)(int src_fd, int dst_fd);
+	enum { xformer_prog = 0 };
+# else
+	enum { xformer = 0 };
+	const char *xformer_prog;
+# endif
+
+	/* .gz and .bz2 both have 2-byte signature, and their
+	 * unpack_XXX_stream wants this header skipped. */
+	xread(fd, magic.b16, sizeof(magic.b16[0]));
+	if (ENABLE_FEATURE_SEAMLESS_GZ
+	 && magic.b16[0] == GZIP_MAGIC
+	) {
+# if BB_MMU
+		xformer = unpack_gz_stream;
+# else
+		xformer_prog = "gunzip";
+# endif
+		goto found_magic;
+	}
+	if (ENABLE_FEATURE_SEAMLESS_BZ2
+	 && magic.b16[0] == BZIP2_MAGIC
+	) {
+# if BB_MMU
+		xformer = unpack_bz2_stream;
+# else
+		xformer_prog = "bunzip2";
+# endif
+		goto found_magic;
+	}
+	if (ENABLE_FEATURE_SEAMLESS_XZ
+	 && magic.b16[0] == XZ_MAGIC1
+	) {
+		offset = -6;
+		xread(fd, magic.b32, sizeof(magic.b32[0]));
+		if (magic.b32[0] == XZ_MAGIC2) {
+# if BB_MMU
+			xformer = unpack_xz_stream;
+			/* unpack_xz_stream wants fd at position 6, no need to seek */
+			//xlseek(fd, offset, SEEK_CUR);
+# else
+			xformer_prog = "unxz";
+# endif
+			goto found_magic;
+		}
+	}
+
+	/* No known magic seen */
+	if (fail_if_not_detected)
+		bb_error_msg_and_die("no gzip"
+			IF_FEATURE_SEAMLESS_BZ2("/bzip2")
+			IF_FEATURE_SEAMLESS_XZ("/xz")
+			" magic");
+	xlseek(fd, offset, SEEK_CUR);
+	return;
+
+ found_magic:
+# if !BB_MMU
+	/* NOMMU version of open_transformer execs
+	 * an external unzipper that wants
+	 * file position at the start of the file */
+	xlseek(fd, offset, SEEK_CUR);
+# endif
+	open_transformer(fd, xformer, xformer_prog);
+}
+#endif /* ZIPPED */
+
+int FAST_FUNC open_zipped(const char *fname)
+{
+#if !ZIPPED
+	return open(fname, O_RDONLY);
+#else
+	char *sfx;
+	int fd;
+
+	fd = open(fname, O_RDONLY);
+	if (fd < 0)
+		return fd;
+
+	sfx = strrchr(fname, '.');
+	if (sfx) {
+		sfx++;
+		if (ENABLE_FEATURE_SEAMLESS_LZMA && strcmp(sfx, "lzma") == 0)
+			/* .lzma has no header/signature, just trust it */
+			open_transformer(fd, unpack_lzma_stream, "unlzma");
+		else
+		if ((ENABLE_FEATURE_SEAMLESS_GZ && strcmp(sfx, "gz") == 0)
+		 || (ENABLE_FEATURE_SEAMLESS_BZ2 && strcmp(sfx, "bz2") == 0)
+		 || (ENABLE_FEATURE_SEAMLESS_XZ && strcmp(sfx, "xz") == 0)
+		) {
+			setup_unzip_on_fd(fd /*, fail_if_not_detected: 1*/);
+		}
+	}
+
+	return fd;
+#endif
+}
+
+void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p)
+{
+	int fd;
+	char *image;
+
+	fd = open_zipped(fname);
+	if (fd < 0)
+		return NULL;
+
+	image = xmalloc_read(fd, maxsz_p);
+	if (!image)
+		bb_perror_msg("read error from '%s'", fname);
+	close(fd);
+
+	return image;
+}