u-tools/apps/busybox/archival/libunarchive/get_header_tar_gz.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   4  */
   5
   6 #include "libbb.h"
   7 #include "unarchive.h"
   8
   9 char FAST_FUNC get_header_tar_gz(archive_handle_t *archive_handle)
  10 {
  11 #if BB_MMU
  12         unsigned char magic[2];
  13 #endif
  14
  15         /* Can't lseek over pipes */
  16         archive_handle->seek = seek_by_read;
  17
  18         /* Check gzip magic only if open_transformer will invoke unpack_gz_stream (MMU case).
  19          * Otherwise, it will invoke an external helper "gunzip -cf" (NOMMU case) which will
  20          * need the header. */
  21 #if BB_MMU
  22         xread(archive_handle->src_fd, &magic, 2);
  23         /* Can skip this check, but error message will be less clear */
  24         if ((magic[0] != 0x1f) || (magic[1] != 0x8b)) {
  25                 bb_error_msg_and_die("invalid gzip magic");
  26         }
  27 #endif
  28
  29         open_transformer(archive_handle->src_fd, unpack_gz_stream, "gunzip");
  30         archive_handle->offset = 0;
  31         while (get_header_tar(archive_handle) == EXIT_SUCCESS)
  32                 continue;
  33
  34         /* Can only do one file at a time */
  35         return EXIT_FAILURE;
  36 }