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
  57         /* Align header */
  58         data_align(archive_handle, 512);
  59
  60         if (archive_xread(archive_handle, tar.raw, 512) != 512) {
  61                 /* Assume end of file */
  62                 return(EXIT_FAILURE);
  63         }
  64         archive_handle->offset += 512;
  65
  66         /* If there is no filename its an empty header */
  67         if (tar.formated.name[0] == 0) {
  68                 return(EXIT_SUCCESS);
  69         }
  70
  71         /* Check header has valid magic, "ustar" is for the proper tar
  72          * 0's are for the old tar format
  73          */
  74         if (strncmp(tar.formated.magic, "ustar", 5) != 0) {
  75 #ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATABILITY
  76                 if (strncmp(tar.formated.magic, "\0\0\0\0\0", 5) != 0)
  77 #endif
  78                         bb_error_msg_and_die("Invalid tar magic");
  79         }
  80         /* Do checksum on headers */
  81         for (i =  0; i < 148 ; i++) {
  82                 sum += tar.raw[i];
  83         }
  84         sum += ' ' * 8;
  85         for (i =  156; i < 512 ; i++) {
  86                 sum += tar.raw[i];
  87         }
  88         if (sum != strtol(tar.formated.chksum, NULL, 8)) {
  89                 bb_error_msg("Invalid tar header checksum");
  90                 return(EXIT_FAILURE);
  91         }
  92
  93 #ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
  94         if (longname) {
  95                 file_header->name = longname;
  96                 longname = NULL;
  97         }
  98         else if (linkname) {
  99                 file_header->name = linkname;
 100                 linkname = NULL;
 101         } else
 102 #endif
 103         if (tar.formated.prefix[0] == 0) {
 104                 file_header->name = strdup(tar.formated.name);
 105         } else {
 106                 file_header->name = concat_path_file(tar.formated.prefix, tar.formated.name);
 107         }
 108
 109         file_header->mode = strtol(tar.formated.mode, NULL, 8);
 110         file_header->uid = strtol(tar.formated.uid, NULL, 8);
 111         file_header->gid = strtol(tar.formated.gid, NULL, 8);
 112         file_header->size = strtol(tar.formated.size, NULL, 8);
 113         file_header->mtime = strtol(tar.formated.mtime, NULL, 8);
 114         file_header->link_name = (tar.formated.linkname[0] != '\0') ?
 115             bb_xstrdup(tar.formated.linkname) : NULL;
 116         file_header->device = (dev_t) ((strtol(tar.formated.devmajor, NULL, 8) << 8) +
 117                                  strtol(tar.formated.devminor, NULL, 8));
 118
 119         /* Fix mode, used by the old format */
 120         switch (tar.formated.typeflag) {
 121 # ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATABILITY
 122         case 0:
 123         case '0':
 124                 if (last_char_is(file_header->name, '/')) {
 125                         file_header->mode |= S_IFDIR;
 126                 } else {
 127                         file_header->mode |= S_IFREG;
 128                 }
 129                 break;
 130         case '2':
 131                 file_header->mode |= S_IFLNK;
 132                 break;
 133         case '3':
 134                 file_header->mode |= S_IFCHR;
 135                 break;
 136         case '4':
 137                 file_header->mode |= S_IFBLK;
 138                 break;
 139         case '5':
 140                 file_header->mode |= S_IFDIR;
 141                 break;
 142         case '6':
 143                 file_header->mode |= S_IFIFO;
 144                 break;
 145 # endif
 146         /* hard links are detected as entries with 0 size, a link name,
 147          * and not being a symlink, hence we have nothing to do here */
 148         case '1':
 149                 file_header->mode |= ~S_IFLNK;
 150                 break;
 151 # ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
 152         case 'L': {
 153                         longname = xmalloc(file_header->size + 1);
 154                         archive_xread_all(archive_handle, longname, file_header->size);
 155                         longname[file_header->size] = '\0';
 156                         archive_handle->offset += file_header->size;
 157
 158                         return(get_header_tar(archive_handle));
 159                 }
 160         case 'K': {
 161                         linkname = xmalloc(file_header->size + 1);
 162                         archive_xread_all(archive_handle, linkname, file_header->size);
 163                         linkname[file_header->size] = '\0';
 164                         archive_handle->offset += file_header->size;
 165
 166                         file_header->name = linkname;
 167                         return(get_header_tar(archive_handle));
 168                 }
 169         case 'D':
 170         case 'M':
 171         case 'N':
 172         case 'S':
 173         case 'V':
 174                 bb_error_msg("Ignoring GNU extension type %c", tar.formated.typeflag);
 175 # endif
 176         }
 177
 178         if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
 179                 archive_handle->action_header(archive_handle->file_header);
 180                 archive_handle->flags |= ARCHIVE_EXTRACT_QUIET;
 181                 archive_handle->action_data(archive_handle);
 182                 archive_handle->passed = llist_add_to(archive_handle->passed, file_header->name);
 183         } else {
 184                 data_skip(archive_handle);
 185         }
 186         archive_handle->offset += file_header->size;
 187
 188         free(file_header->link_name);
 189
 190         return(EXIT_SUCCESS);
 191 }