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*: simplify checks for gz/bz2/xz magic

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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>
This commit is contained in:
Denys Vlasenko 2010-06-02 14:14:48 +02:00
parent abb154ba02
commit 26b6ccf340
3 changed files with 41 additions and 15 deletions
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19
archival/rpm2cpio.c
View File

@ -68,26 +68,31 @@ int rpm2cpio_main(int argc UNUSED_PARAM, char **argv)
#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 {

16
include/unarchive.h
View File

@ -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;

21
libbb/read.c
View File

@ -312,7 +312,11 @@ void* FAST_FUNC xmalloc_xopen_read_close(const char *filename, size_t *maxsz_p)
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 @@ void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/)
/* .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 @@ void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/)
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 @@ void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/)
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;
}
}