60 lines
1.3 KiB
C
60 lines
1.3 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*/
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#include "libbb.h"
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#include "unarchive.h" /* for external decl of check_header_gzip_or_die */
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void check_header_gzip_or_die(int src_fd)
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{
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union {
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unsigned char raw[8];
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struct {
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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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} formatted;
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} header;
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xread(src_fd, header.raw, 8);
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/* Check the compression method */
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if (header.formatted.method != 8) {
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bb_error_msg_and_die("unknown compression method %d",
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header.formatted.method);
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}
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if (header.formatted.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) + (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.formatted.flags & 0x08) {
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/* bit 3 set: original file name present */
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while (xread_char(src_fd) != 0);
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}
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/* Discard file comment if any */
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if (header.formatted.flags & 0x10) {
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/* bit 4 set: file comment present */
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while (xread_char(src_fd) != 0);
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}
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/* Read the header checksum */
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if (header.formatted.flags & 0x02) {
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xread_char(src_fd);
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xread_char(src_fd);
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}
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}
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