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authorGlenn L McGrath2002-09-25 02:47:48 +0000
committerGlenn L McGrath2002-09-25 02:47:48 +0000
commit7ca04f328e22fcbee4659d73f9a72dfdf1dd6a23 (patch)
treef38c7ef4317eea28c6abdb0adbbb286fe041711e /archival/libunarchive/check_header_gzip.c
parentecfa290cfd4953598e6d91989bd66ac16e135f84 (diff)
downloadbusybox-7ca04f328e22fcbee4659d73f9a72dfdf1dd6a23.zip
busybox-7ca04f328e22fcbee4659d73f9a72dfdf1dd6a23.tar.gz
New common unarchive code.
Diffstat (limited to 'archival/libunarchive/check_header_gzip.c')
-rw-r--r--archival/libunarchive/check_header_gzip.c75
1 files changed, 75 insertions, 0 deletions
diff --git a/archival/libunarchive/check_header_gzip.c b/archival/libunarchive/check_header_gzip.c
new file mode 100644
index 0000000..508d309
--- /dev/null
+++ b/archival/libunarchive/check_header_gzip.c
@@ -0,0 +1,75 @@
+#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;
+}