archival/libunarchive/get_header_tar.c

   1 /*
   2  *  This program is free software; you can redistribute it and/or modify
   3  *  it under the terms of the GNU General Public License as published by
   4  *  the Free Software Foundation; either version 2 of the License, or
   5  *  (at your option) any later version.
   6  *
   7  *  This program is distributed in the hope that it will be useful,
   8  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  *  GNU Library General Public License for more details.
  11  *
  12  *  You should have received a copy of the GNU General Public License
  13  *  along with this program; if not, write to the Free Software
  14  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  15  */
  16
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <string.h>
  20 #include "unarchive.h"
  21 #include "libbb.h"
  22
  23 #ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
  24 static char *longname = NULL;
  25 static char *linkname = NULL;
  26 #endif
  27
  28 extern char get_header_tar(archive_handle_t *archive_handle)
  29 {
  30         file_header_t *file_header = archive_handle->file_header;
  31         union {
  32                 /* ustar header, Posix 1003.1 */
  33                 unsigned char raw[512];
  34                 struct {
  35                         char name[100]; /*   0-99 */
  36                         char mode[8];   /* 100-107 */
  37                         char uid[8];    /* 108-115 */
  38                         char gid[8];    /* 116-123 */
  39                         char size[12];  /* 124-135 */
  40                         char mtime[12]; /* 136-147 */
  41                         char chksum[8]; /* 148-155 */
  42                         char typeflag;  /* 156-156 */
  43                         char linkname[100];     /* 157-256 */
  44                         char magic[6];  /* 257-262 */
  45                         char version[2];        /* 263-264 */
  46                         char uname[32]; /* 265-296 */
  47                         char gname[32]; /* 297-328 */
  48                         char devmajor[8];       /* 329-336 */
  49                         char devminor[8];       /* 337-344 */
  50                         char prefix[155];       /* 345-499 */
  51                         char padding[12];       /* 500-512 */
  52                 } formated;
  53         } tar;
  54         long sum = 0;
  55         long i;
  56         char *tmp;
  57
  58         /* Align header */
  59         data_align(archive_handle, 512);
  60
  61         if (archive_xread(archive_handle, tar.raw, 512) != 512) {
  62                 /* Assume end of file */
  63                 return(EXIT_FAILURE);
  64         }
  65         archive_handle->offset += 512;
  66
  67         /* If there is no filename its an empty header */
  68         if (tar.formated.name[0] == 0) {
  69                 return(EXIT_SUCCESS);
  70         }
  71
  72         /* Check header has valid magic, "ustar" is for the proper tar
  73          * 0's are for the old tar format
  74          */
  75         if (strncmp(tar.formated.magic, "ustar", 5) != 0) {
  76 #ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATABILITY
  77                 if (strncmp(tar.formated.magic, "\0\0\0\0\0", 5) != 0)
  78 #endif
  79                         bb_error_msg_and_die("Invalid tar magic");
  80         }
  81         /* Do checksum on headers */
  82         for (i =  0; i < 148 ; i++) {
  83                 sum += tar.raw[i];
  84         }
  85         sum += ' ' * 8;
  86         for (i =  156; i < 512 ; i++) {
  87                 sum += tar.raw[i];
  88         }
  89         if (sum != strtol(tar.formated.chksum, NULL, 8)) {
  90                 bb_error_msg("Invalid tar header checksum");
  91                 return(EXIT_FAILURE);
  92         }
  93
  94 #ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
  95         if (longname) {
  96                 file_header->name = longname;
  97                 longname = NULL;
  98         }
  99         else if (linkname) {
 100                 file_header->name = linkname;
 101                 linkname = NULL;
 102         } else
 103 #endif
 104         if (tar.formated.prefix[0] == 0) {
 105                 file_header->name = strdup(tar.formated.name);
 106         } else {
 107                 file_header->name = concat_path_file(tar.formated.prefix, tar.formated.name);
 108         }
 109
 110         file_header->mode = strtol(tar.formated.mode, NULL, 8);
 111         file_header->uid = strtol(tar.formated.uid, NULL, 8);
 112         file_header->gid = strtol(tar.formated.gid, NULL, 8);
 113         file_header->size = strtol(tar.formated.size, NULL, 8);
 114         file_header->mtime = strtol(tar.formated.mtime, NULL, 8);
 115         file_header->link_name = (tar.formated.linkname[0] != '\0') ?
 116             bb_xstrdup(tar.formated.linkname) : NULL;
 117         file_header->device = (dev_t) ((strtol(tar.formated.devmajor, NULL, 8) << 8) +
 118                                  strtol(tar.formated.devminor, NULL, 8));
 119
 120 #if defined CONFIG_FEATURE_TAR_OLDGNU_COMPATABILITY || defined CONFIG_FEATURE_TAR_GNU_EXTENSIONS
 121         /* Fix mode, used by the old format */
 122         switch (tar.formated.typeflag) {
 123 # ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATABILITY
 124         case 0:
 125         case '0':
 126                 if (last_char_is(file_header->name, '/')) {
 127                         file_header->mode |= S_IFDIR;
 128                 } else {
 129                         file_header->mode |= S_IFREG;
 130                 }
 131                 break;
 132         case '2':
 133                 file_header->mode |= S_IFLNK;
 134                 break;
 135         case '3':
 136                 file_header->mode |= S_IFCHR;
 137                 break;
 138         case '4':
 139                 file_header->mode |= S_IFBLK;
 140                 break;
 141         case '5':
 142                 file_header->mode |= S_IFDIR;
 143                 break;
 144         case '6':
 145                 file_header->mode |= S_IFIFO;
 146                 break;
 147 # endif
 148         /* hard links are detected as entries with 0 size, a link name,
 149          * and not being a symlink, hence we have nothing to do here */
 150         case '1':
 151                 file_header->mode |= ~S_IFLNK;
 152                 break;
 153 # ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
 154         case 'L': {
 155                         longname = xmalloc(file_header->size + 1);
 156                         archive_xread_all(archive_handle, longname, file_header->size);
 157                         longname[file_header->size] = '\0';
 158                         archive_handle->offset += file_header->size;
 159
 160                         return(get_header_tar(archive_handle));
 161                 }
 162         case 'K': {
 163                         linkname = xmalloc(file_header->size + 1);
 164                         archive_xread_all(archive_handle, linkname, file_header->size);
 165                         linkname[file_header->size] = '\0';
 166                         archive_handle->offset += file_header->size;
 167
 168                         file_header->name = linkname;
 169                         return(get_header_tar(archive_handle));
 170                 }
 171         case 'D':
 172         case 'M':
 173         case 'N':
 174         case 'S':
 175         case 'V':
 176                 bb_error_msg("Ignoring GNU extension type %c", tar.formated.typeflag);
 177 # endif
 178         }
 179 #endif
 180
 181         if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
 182                 archive_handle->action_header(archive_handle->file_header);
 183                 archive_handle->flags |= ARCHIVE_EXTRACT_QUIET;
 184                 archive_handle->action_data(archive_handle);
 185                 archive_handle->passed = llist_add_to(archive_handle->passed, archive_handle->file_header->name);
 186         } else {
 187                 data_skip(archive_handle);
 188         }
 189         archive_handle->offset += file_header->size;
 190
 191         return(EXIT_SUCCESS);
 192 }