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

   1 /* vi: set sw=4 ts=4: */
   2 /* Copyright 2001 Glenn McGrath.
   3  *
   4  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   5  */
   6
   7 #include "libbb.h"
   8 #include "unarchive.h"
   9
  10 char FAST_FUNC get_header_ar(archive_handle_t *archive_handle)
  11 {
  12         int err;
  13         file_header_t *typed = archive_handle->file_header;
  14         union {
  15                 char raw[60];
  16                 struct {
  17                         char name[16];
  18                         char date[12];
  19                         char uid[6];
  20                         char gid[6];
  21                         char mode[8];
  22                         char size[10];
  23                         char magic[2];
  24                 } formatted;
  25         } ar;
  26 #if ENABLE_FEATURE_AR_LONG_FILENAMES
  27         static char *ar_long_names;
  28         static unsigned ar_long_name_size;
  29 #endif
  30
  31         /* dont use xread as we want to handle the error ourself */
  32         if (read(archive_handle->src_fd, ar.raw, 60) != 60) {
  33                 /* End Of File */
  34                 return EXIT_FAILURE;
  35         }
  36
  37         /* ar header starts on an even byte (2 byte aligned)
  38          * '\n' is used for padding
  39          */
  40         if (ar.raw[0] == '\n') {
  41                 /* fix up the header, we started reading 1 byte too early */
  42                 memmove(ar.raw, &ar.raw[1], 59);
  43                 ar.raw[59] = xread_char(archive_handle->src_fd);
  44                 archive_handle->offset++;
  45         }
  46         archive_handle->offset += 60;
  47
  48         /* align the headers based on the header magic */
  49         if (ar.formatted.magic[0] != '`' || ar.formatted.magic[1] != '\n')
  50                 bb_error_msg_and_die("invalid ar header");
  51
  52         /* FIXME: more thorough routine would be in order here */
  53         /* (we have something like that in tar) */
  54         /* but for now we are lax. This code works because */
  55         /* on misformatted numbers bb_strtou returns all-ones */
  56         typed->mode = err = bb_strtou(ar.formatted.mode, NULL, 8);
  57         if (err == -1) bb_error_msg_and_die("invalid ar header");
  58         typed->mtime = err = bb_strtou(ar.formatted.date, NULL, 10);
  59         if (err == -1) bb_error_msg_and_die("invalid ar header");
  60         typed->uid = err = bb_strtou(ar.formatted.uid, NULL, 10);
  61         if (err == -1) bb_error_msg_and_die("invalid ar header");
  62         typed->gid = err = bb_strtou(ar.formatted.gid, NULL, 10);
  63         if (err == -1) bb_error_msg_and_die("invalid ar header");
  64         typed->size = err = bb_strtou(ar.formatted.size, NULL, 10);
  65         if (err == -1) bb_error_msg_and_die("invalid ar header");
  66
  67         /* long filenames have '/' as the first character */
  68         if (ar.formatted.name[0] == '/') {
  69 #if ENABLE_FEATURE_AR_LONG_FILENAMES
  70                 unsigned long_offset;
  71
  72                 if (ar.formatted.name[1] == '/') {
  73                         /* If the second char is a '/' then this entries data section
  74                          * stores long filename for multiple entries, they are stored
  75                          * in static variable long_names for use in future entries */
  76                         ar_long_name_size = typed->size;
  77                         ar_long_names = xmalloc(ar_long_name_size);
  78                         xread(archive_handle->src_fd, ar_long_names, ar_long_name_size);
  79                         archive_handle->offset += ar_long_name_size;
  80                         /* This ar entries data section only contained filenames for other records
  81                          * they are stored in the static ar_long_names for future reference */
  82                         return get_header_ar(archive_handle); /* Return next header */
  83                 }
  84
  85                 if (ar.formatted.name[1] == ' ') {
  86                         /* This is the index of symbols in the file for compilers */
  87                         data_skip(archive_handle);
  88                         archive_handle->offset += typed->size;
  89                         return get_header_ar(archive_handle); /* Return next header */
  90                 }
  91
  92                 /* The number after the '/' indicates the offset in the ar data section
  93                  * (saved in variable long_name) that conatains the real filename */
  94                 long_offset = atoi(&ar.formatted.name[1]);
  95                 if (long_offset >= ar_long_name_size) {
  96                         bb_error_msg_and_die("can't resolve long filename");
  97                 }
  98                 typed->name = xstrdup(ar_long_names + long_offset);
  99 #else
 100                 bb_error_msg_and_die("long filenames not supported");
 101 #endif
 102         } else {
 103                 /* short filenames */
 104                 typed->name = xstrndup(ar.formatted.name, 16);
 105         }
 106
 107         typed->name[strcspn(typed->name, " /")] = '\0';
 108
 109         if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
 110                 archive_handle->action_header(typed);
 111 #if ENABLE_DPKG || ENABLE_DPKG_DEB
 112                 if (archive_handle->sub_archive) {
 113                         while (archive_handle->action_data_subarchive(archive_handle->sub_archive) == EXIT_SUCCESS)
 114                                 continue;
 115                 } else
 116 #endif
 117                         archive_handle->action_data(archive_handle);
 118         } else {
 119                 data_skip(archive_handle);
 120         }
 121
 122         archive_handle->offset += typed->size;
 123         /* Set the file pointer to the correct spot, we may have been reading a compressed file */
 124         lseek(archive_handle->src_fd, archive_handle->offset, SEEK_SET);
 125
 126         return EXIT_SUCCESS;
 127 }