76 lines
1.5 KiB
C
76 lines
1.5 KiB
C
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#include <stdlib.h>
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#include <unistd.h>
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#include "libbb.h"
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extern void check_header_gzip(int src_fd)
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{
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union {
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unsigned char raw[10];
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struct {
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unsigned char magic[2];
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unsigned char method;
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unsigned char flags;
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unsigned int mtime;
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unsigned char xtra_flags;
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unsigned char os_flags;
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} formated;
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} header;
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xread_all(src_fd, header.raw, 10);
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/* Magic header for gzip files, 1F 8B = \037\213 */
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if ((header.formated.magic[0] != 0x1F)
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|| (header.formated.magic[1] != 0x8b)) {
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error_msg_and_die("Invalid gzip magic");
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}
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/* Check the compression method */
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if (header.formated.method != 8) {
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error_msg_and_die("Unknown compression method %d",
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header.formated.method);
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}
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if (header.formated.flags & 0x04) {
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/* bit 2 set: extra field present */
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unsigned char extra_short;
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extra_short = xread_char(src_fd);
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extra_short += xread_char(src_fd) << 8;
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while (extra_short > 0) {
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/* Ignore extra field */
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xread_char(src_fd);
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extra_short--;
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}
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}
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/* Discard original name if any */
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if (header.formated.flags & 0x08) {
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/* bit 3 set: original file name present */
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char tmp;
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do {
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read(src_fd, &tmp, 1);
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} while (tmp != 0);
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}
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/* Discard file comment if any */
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if (header.formated.flags & 0x10) {
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/* bit 4 set: file comment present */
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char tmp;
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do {
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read(src_fd, &tmp, 1);
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} while (tmp != 0);
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}
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/* Read the header checksum */
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if (header.formated.flags & 0x02) {
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char tmp;
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read(src_fd, &tmp, 1);
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read(src_fd, &tmp, 1);
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}
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return;
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}
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