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