*: simplify checks for gz/bz2/xz magic
function old new delta
send_tree 360 355 -5
rpm2cpio_main 249 220 -29
setup_unzip_on_fd 150 118 -32
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-66) Total: -66 bytes
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/archival/rpm2cpio.c b/archival/rpm2cpio.c
index 598ec86..1c67dcc 100644
--- a/archival/rpm2cpio.c
+++ b/archival/rpm2cpio.c
@@ -68,26 +68,31 @@
#else
/* BLOAT */
{
- unsigned char magic[8];
+ union {
+ uint8_t b[4];
+ uint16_t b16[2];
+ uint32_t b32[1];
+ } magic;
IF_DESKTOP(long long) int FAST_FUNC (*unpack)(int src_fd, int dst_fd);
- xread(rpm_fd, &magic, 2);
- if (magic[0] == 0x1f && magic[1] == 0x8b) {
+ xread(rpm_fd, magic.b16, sizeof(magic.b16));
+ if (magic.b16[0] == GZIP_MAGIC) {
unpack = unpack_gz_stream;
} else
if (ENABLE_FEATURE_SEAMLESS_BZ2
- && magic[0] == 'B' && magic[1] == 'Z'
+ && magic.b16[0] == BZIP2_MAGIC
) {
unpack = unpack_bz2_stream;
} else
if (ENABLE_FEATURE_SEAMLESS_XZ
- && magic[0] == 0xfd && magic[1] == '7'
+ && magic.b16[0] == XZ_MAGIC1
) {
/* .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)
+ xread(rpm_fd, magic.b32, sizeof(magic.b32));
+ if (magic.b32[0] != XZ_MAGIC2)
goto no_magic;
+ /* unpack_xz_stream wants fd at position 0 */
xlseek(rpm_fd, -6, SEEK_CUR);
unpack = unpack_xz_stream;
} else {
diff --git a/include/unarchive.h b/include/unarchive.h
index aa7ecec..8009de2 100644
--- a/include/unarchive.h
+++ b/include/unarchive.h
@@ -4,6 +4,22 @@
PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
+enum {
+#if BB_BIG_ENDIAN
+ COMPRESS_MAGIC = 0x1f9d,
+ GZIP_MAGIC = 0x1f8b,
+ BZIP2_MAGIC = ('B'<<8) + 'Z',
+ XZ_MAGIC1 = (0xfd<<8) + '7',
+ XZ_MAGIC2 = ((((('z'<<8) + 'X')<<8) + 'Z')<<8) + 0,
+#else
+ COMPRESS_MAGIC = 0x9d1f,
+ GZIP_MAGIC = 0x8b1f,
+ BZIP2_MAGIC = ('Z'<<8) + 'B',
+ XZ_MAGIC1 = ('7'<<8) + 0xfd,
+ XZ_MAGIC2 = (((((0<<8) + 'Z')<<8) + 'X')<<8) + 'z',
+#endif
+};
+
typedef struct file_header_t {
char *name;
char *link_target;
diff --git a/libbb/read.c b/libbb/read.c
index cd6bbeb..b1eb3f2 100644
--- a/libbb/read.c
+++ b/libbb/read.c
@@ -312,7 +312,11 @@
void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/)
{
const int fail_if_not_detected = 1;
- unsigned char magic[8];
+ 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);
@@ -324,9 +328,9 @@
/* .gz and .bz2 both have 2-byte signature, and their
* unpack_XXX_stream wants this header skipped. */
- xread(fd, magic, 2);
+ xread(fd, magic.b16, sizeof(magic.b16));
if (ENABLE_FEATURE_SEAMLESS_GZ
- && magic[0] == 0x1f && magic[1] == 0x8b
+ && magic.b16[0] == GZIP_MAGIC
) {
# if BB_MMU
xformer = unpack_gz_stream;
@@ -336,7 +340,7 @@
goto found_magic;
}
if (ENABLE_FEATURE_SEAMLESS_BZ2
- && magic[0] == 'B' && magic[1] == 'Z'
+ && magic.b16[0] == BZIP2_MAGIC
) {
# if BB_MMU
xformer = unpack_bz2_stream;
@@ -346,19 +350,20 @@
goto found_magic;
}
if (ENABLE_FEATURE_SEAMLESS_XZ
- && magic[0] == 0xfd && magic[1] == '7'
+ && magic.b16[0] == XZ_MAGIC1
) {
/* .xz signature: 0xfd, '7', 'z', 'X', 'Z', 0x00 */
/* More info at: http://tukaani.org/xz/xz-file-format.txt */
offset = -6;
- xread(fd, magic + 2, 4);
- if (strcmp((char*)magic + 2, "zXZ") == 0) {
+ xread(fd, magic.b32, sizeof(magic.b32));
+ if (magic.b32[0] == XZ_MAGIC2) {
# if BB_MMU
xformer = unpack_xz_stream;
+ /* unpack_xz_stream wants fd at position 0 */
+ xlseek(fd, offset, SEEK_CUR);
# else
xformer_prog = "unxz";
# endif
- xlseek(fd, offset, SEEK_CUR);
goto found_magic;
}
}