*: 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>
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abb154ba02
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26b6ccf340
@ -68,26 +68,31 @@ int rpm2cpio_main(int argc UNUSED_PARAM, char **argv)
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#else
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/* BLOAT */
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{
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unsigned char magic[8];
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union {
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uint8_t b[4];
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uint16_t b16[2];
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uint32_t b32[1];
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} magic;
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IF_DESKTOP(long long) int FAST_FUNC (*unpack)(int src_fd, int dst_fd);
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xread(rpm_fd, &magic, 2);
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if (magic[0] == 0x1f && magic[1] == 0x8b) {
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xread(rpm_fd, magic.b16, sizeof(magic.b16));
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if (magic.b16[0] == GZIP_MAGIC) {
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unpack = unpack_gz_stream;
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} else
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if (ENABLE_FEATURE_SEAMLESS_BZ2
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&& magic[0] == 'B' && magic[1] == 'Z'
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&& magic.b16[0] == BZIP2_MAGIC
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) {
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unpack = unpack_bz2_stream;
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} else
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if (ENABLE_FEATURE_SEAMLESS_XZ
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&& magic[0] == 0xfd && magic[1] == '7'
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&& magic.b16[0] == XZ_MAGIC1
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) {
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/* .xz signature: 0xfd, '7', 'z', 'X', 'Z', 0x00 */
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/* More info at: http://tukaani.org/xz/xz-file-format.txt */
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xread(rpm_fd, magic + 2, 4);
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if (strcmp((char*)magic + 2, "zXZ") != 0)
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xread(rpm_fd, magic.b32, sizeof(magic.b32));
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if (magic.b32[0] != XZ_MAGIC2)
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goto no_magic;
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/* unpack_xz_stream wants fd at position 0 */
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xlseek(rpm_fd, -6, SEEK_CUR);
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unpack = unpack_xz_stream;
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} else {
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@ -4,6 +4,22 @@
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PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
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enum {
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#if BB_BIG_ENDIAN
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COMPRESS_MAGIC = 0x1f9d,
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GZIP_MAGIC = 0x1f8b,
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BZIP2_MAGIC = ('B'<<8) + 'Z',
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XZ_MAGIC1 = (0xfd<<8) + '7',
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XZ_MAGIC2 = ((((('z'<<8) + 'X')<<8) + 'Z')<<8) + 0,
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#else
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COMPRESS_MAGIC = 0x9d1f,
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GZIP_MAGIC = 0x8b1f,
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BZIP2_MAGIC = ('Z'<<8) + 'B',
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XZ_MAGIC1 = ('7'<<8) + 0xfd,
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XZ_MAGIC2 = (((((0<<8) + 'Z')<<8) + 'X')<<8) + 'z',
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#endif
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};
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typedef struct file_header_t {
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char *name;
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char *link_target;
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21
libbb/read.c
21
libbb/read.c
@ -312,7 +312,11 @@ void* FAST_FUNC xmalloc_xopen_read_close(const char *filename, size_t *maxsz_p)
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void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/)
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{
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const int fail_if_not_detected = 1;
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unsigned char magic[8];
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union {
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uint8_t b[4];
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uint16_t b16[2];
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uint32_t b32[1];
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} magic;
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int offset = -2;
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# if BB_MMU
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IF_DESKTOP(long long) int FAST_FUNC (*xformer)(int src_fd, int dst_fd);
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@ -324,9 +328,9 @@ void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/)
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/* .gz and .bz2 both have 2-byte signature, and their
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* unpack_XXX_stream wants this header skipped. */
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xread(fd, magic, 2);
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xread(fd, magic.b16, sizeof(magic.b16));
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if (ENABLE_FEATURE_SEAMLESS_GZ
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&& magic[0] == 0x1f && magic[1] == 0x8b
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&& magic.b16[0] == GZIP_MAGIC
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) {
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# if BB_MMU
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xformer = unpack_gz_stream;
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@ -336,7 +340,7 @@ void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/)
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goto found_magic;
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}
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if (ENABLE_FEATURE_SEAMLESS_BZ2
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&& magic[0] == 'B' && magic[1] == 'Z'
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&& magic.b16[0] == BZIP2_MAGIC
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) {
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# if BB_MMU
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xformer = unpack_bz2_stream;
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@ -346,19 +350,20 @@ void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/)
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goto found_magic;
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}
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if (ENABLE_FEATURE_SEAMLESS_XZ
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&& magic[0] == 0xfd && magic[1] == '7'
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&& magic.b16[0] == XZ_MAGIC1
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) {
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/* .xz signature: 0xfd, '7', 'z', 'X', 'Z', 0x00 */
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/* More info at: http://tukaani.org/xz/xz-file-format.txt */
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offset = -6;
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xread(fd, magic + 2, 4);
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if (strcmp((char*)magic + 2, "zXZ") == 0) {
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xread(fd, magic.b32, sizeof(magic.b32));
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if (magic.b32[0] == XZ_MAGIC2) {
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# if BB_MMU
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xformer = unpack_xz_stream;
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/* unpack_xz_stream wants fd at position 0 */
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xlseek(fd, offset, SEEK_CUR);
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# else
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xformer_prog = "unxz";
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# endif
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xlseek(fd, offset, SEEK_CUR);
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goto found_magic;
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}
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}
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