release/src/router/busybox/archival/libarchive/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 source tree.
   5  */
   6
   7 #include "libbb.h"
   8 #include "bb_archive.h"
   9 #include "ar.h"
  10
  11 static unsigned read_num(const char *str, int base)
  12 {
  13         /* This code works because
  14          * on misformatted numbers bb_strtou returns all-ones */
  15         int err = bb_strtou(str, NULL, base);
  16         if (err == -1)
  17                 bb_error_msg_and_die("invalid ar header");
  18         return err;
  19 }
  20
  21 char FAST_FUNC get_header_ar(archive_handle_t *archive_handle)
  22 {
  23         file_header_t *typed = archive_handle->file_header;
  24         unsigned size;
  25         union {
  26                 char raw[60];
  27                 struct ar_header formatted;
  28         } ar;
  29 #if ENABLE_FEATURE_AR_LONG_FILENAMES
  30         static char *ar_long_names;
  31         static unsigned ar_long_name_size;
  32 #endif
  33
  34         /* dont use xread as we want to handle the error ourself */
  35         if (read(archive_handle->src_fd, ar.raw, 60) != 60) {
  36                 /* End Of File */
  37                 return EXIT_FAILURE;
  38         }
  39
  40         /* ar header starts on an even byte (2 byte aligned)
  41          * '\n' is used for padding
  42          */
  43         if (ar.raw[0] == '\n') {
  44                 /* fix up the header, we started reading 1 byte too early */
  45                 memmove(ar.raw, &ar.raw[1], 59);
  46                 ar.raw[59] = xread_char(archive_handle->src_fd);
  47                 archive_handle->offset++;
  48         }
  49         archive_handle->offset += 60;
  50
  51         if (ar.formatted.magic[0] != '`' || ar.formatted.magic[1] != '\n')
  52                 bb_error_msg_and_die("invalid ar header");
  53
  54         /* FIXME: more thorough routine would be in order here
  55          * (we have something like that in tar)
  56          * but for now we are lax. */
  57         ar.formatted.magic[0] = '\0'; /* else 4G-2 file will have size="4294967294`\n..." */
  58         typed->size = size = read_num(ar.formatted.size, 10);
  59
  60         /* special filenames have '/' as the first character */
  61         if (ar.formatted.name[0] == '/') {
  62                 if (ar.formatted.name[1] == ' ') {
  63                         /* This is the index of symbols in the file for compilers */
  64                         data_skip(archive_handle);
  65                         archive_handle->offset += size;
  66                         return get_header_ar(archive_handle); /* Return next header */
  67                 }
  68 #if ENABLE_FEATURE_AR_LONG_FILENAMES
  69                 if (ar.formatted.name[1] == '/') {
  70                         /* If the second char is a '/' then this entries data section
  71                          * stores long filename for multiple entries, they are stored
  72                          * in static variable long_names for use in future entries
  73                          */
  74                         ar_long_name_size = size;
  75                         free(ar_long_names);
  76                         ar_long_names = xmalloc(size);
  77                         xread(archive_handle->src_fd, ar_long_names, size);
  78                         archive_handle->offset += size;
  79                         /* Return next header */
  80                         return get_header_ar(archive_handle);
  81                 }
  82 #else
  83                 bb_error_msg_and_die("long filenames not supported");
  84 #endif
  85         }
  86         /* Only size is always present, the rest may be missing in
  87          * long filename pseudo file. Thus we decode the rest
  88          * after dealing with long filename pseudo file.
  89          */
  90         typed->mode = read_num(ar.formatted.mode, 8);
  91         typed->mtime = read_num(ar.formatted.date, 10);
  92         typed->uid = read_num(ar.formatted.uid, 10);
  93         typed->gid = read_num(ar.formatted.gid, 10);
  94
  95 #if ENABLE_FEATURE_AR_LONG_FILENAMES
  96         if (ar.formatted.name[0] == '/') {
  97                 unsigned long_offset;
  98
  99                 /* The number after the '/' indicates the offset in the ar data section
 100                  * (saved in ar_long_names) that conatains the real filename */
 101                 long_offset = read_num(&ar.formatted.name[1], 10);
 102                 if (long_offset >= ar_long_name_size) {
 103                         bb_error_msg_and_die("can't resolve long filename");
 104                 }
 105                 typed->name = xstrdup(ar_long_names + long_offset);
 106         } else
 107 #endif
 108         {
 109                 /* short filenames */
 110                 typed->name = xstrndup(ar.formatted.name, 16);
 111         }
 112
 113         typed->name[strcspn(typed->name, " /")] = '\0';
 114
 115         if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
 116                 archive_handle->action_header(typed);
 117 #if ENABLE_DPKG || ENABLE_DPKG_DEB
 118                 if (archive_handle->dpkg__sub_archive) {
 119                         while (archive_handle->dpkg__action_data_subarchive(archive_handle->dpkg__sub_archive) == EXIT_SUCCESS)
 120                                 continue;
 121                 } else
 122 #endif
 123                         archive_handle->action_data(archive_handle);
 124         } else {
 125                 data_skip(archive_handle);
 126         }
 127
 128         archive_handle->offset += typed->size;
 129         /* Set the file pointer to the correct spot, we may have been reading a compressed file */
 130         lseek(archive_handle->src_fd, archive_handle->offset, SEEK_SET);
 131
 132         return EXIT_SUCCESS;
 133 }