libbb/untar.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  * NOTE: This is used by deb_extract to avoid calling the whole tar applet.
  17  * Its functionality should be merged with tar to avoid duplication
  18  */
  19
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include "libbb.h"
  24
  25 extern char *untar(FILE *src_tar_file, FILE *output, const int untar_function,
  26         const char *argument, const char *file_prefix)
  27 {
  28         typedef struct raw_tar_header {
  29         char name[100];               /*   0-99 */
  30         char mode[8];                 /* 100-107 */
  31         char uid[8];                  /* 108-115 */
  32         char gid[8];                  /* 116-123 */
  33         char size[12];                /* 124-135 */
  34         char mtime[12];               /* 136-147 */
  35         char chksum[8];               /* 148-155 */
  36         char typeflag;                /* 156-156 */
  37         char linkname[100];           /* 157-256 */
  38         char magic[6];                /* 257-262 */
  39         char version[2];              /* 263-264 */
  40         char uname[32];               /* 265-296 */
  41         char gname[32];               /* 297-328 */
  42         char devmajor[8];             /* 329-336 */
  43         char devminor[8];             /* 337-344 */
  44         char prefix[155];             /* 345-499 */
  45         char padding[12];             /* 500-512 */
  46         } raw_tar_header_t;
  47
  48         raw_tar_header_t raw_tar_header;
  49         unsigned char *temp = (unsigned char *) &raw_tar_header;
  50         long i;
  51         long next_header_offset = 0;
  52         long uncompressed_count = 0;
  53         size_t size;
  54         mode_t mode;
  55
  56         while (fread((char *) &raw_tar_header, 1, 512, src_tar_file) == 512) {
  57                 long sum = 0;
  58                 char *dir = NULL;
  59
  60                 if (ferror(src_tar_file) || feof(src_tar_file)) {
  61                         perror_msg("untar: ");
  62                         break;
  63                 }
  64
  65                 uncompressed_count += 512;
  66
  67                 /* Check header has valid magic */
  68                 if (strncmp(raw_tar_header.magic, "ustar", 5) != 0) {
  69 /*
  70  * FIXME, Need HELP with this
  71  *
  72  * This has to fail silently or it incorrectly reports errors when called from
  73  * deb_extract.
  74  * The problem is deb_extract decompresses the .gz file in a child process and
  75  * untar reads from the child proccess. The child process finishes and exits,
  76  * but fread reads 0's from the src_tar_file even though the child
  77  * closed its handle.
  78  */
  79 //                      error_msg("Invalid tar magic");
  80                         break;
  81                 }
  82
  83                 /* Do checksum on headers */
  84         for (i =  0; i < 148 ; i++) {
  85                         sum += temp[i];
  86                 }
  87         sum += ' ' * 8;
  88                 for (i =  156; i < 512 ; i++) {
  89                         sum += temp[i];
  90                 }
  91         if (sum != strtol(raw_tar_header.chksum, NULL, 8)) {
  92                         error_msg("Invalid tar header checksum");
  93                         break;
  94                 }
  95
  96                 /* convert to type'ed variables */
  97         size = strtol(raw_tar_header.size, NULL, 8);
  98                 parse_mode(raw_tar_header.mode, &mode);
  99
 100                 /* start of next header is at */
 101                 next_header_offset = uncompressed_count + size;
 102                 if (size % 512 != 0) {
 103                         next_header_offset += (512 - size % 512);
 104                 }
 105
 106                 /* If an exclude list is specified check current file against list
 107                 if (*exclude_list != NULL) {
 108                         i = 0;
 109                         while (exclude_list[i] != 0) {
 110                                 if (strncmp(exclude_list[i], raw_tar_header.name, strlen(raw_tar_header.name)) == 0) {
 111                                         break;
 112                                 }
 113                                 i++;
 114                         }
 115                 if (exclude_list[i] != 0) {
 116                                 continue;
 117                         }
 118                 } */
 119
 120                 if (untar_function & (extract_contents | extract_verbose_extract | extract_contents_to_file)) {
 121                         fprintf(output, "%s\n", raw_tar_header.name);
 122                 }
 123
 124                 /* extract files */
 125                 if (untar_function & (extract_extract | extract_verbose_extract | extract_control)) {
 126                         dir = concat_path_file(argument, raw_tar_header.name);
 127                         create_path(dir, 0777);
 128                 }
 129
 130                 switch (raw_tar_header.typeflag ) {
 131                         case '0':
 132                         case '\0':
 133                                 /* If the name ends in a '/' then assume it is
 134                                  * supposed to be a directory, and fall through
 135                                  */
 136                                 if (raw_tar_header.name[strlen(raw_tar_header.name)-1] != '/') {
 137                                         switch (untar_function) {
 138                                                 case (extract_extract):
 139                                                 case (extract_verbose_extract):
 140                                                 case (extract_control): {
 141                                                                 FILE *dst_file = NULL;
 142                                                                 char *full_name;
 143
 144                                                                 if (file_prefix != NULL) {
 145                                                                         char *file_name = NULL, *file_extension = NULL;
 146
 147                                                                         file_extension = xmalloc(strlen(raw_tar_header.name) + 1);
 148                                                                         file_extension = strrchr(raw_tar_header.name, '/');
 149                                                                         file_extension++;
 150                                                                         file_name = xmalloc(strlen(file_prefix) + strlen(file_extension) + 2);
 151                                                                         strcpy(file_name, file_prefix);
 152                                                                         strcat(file_name, ".");
 153                                                                         strcat(file_name, file_extension);
 154
 155                                                                         full_name = concat_path_file(strndup(dir, strlen(dir) - strlen(strrchr(dir, '/'))), file_name);
 156                                                                 } else {
 157                                                                         full_name = xstrdup(dir);
 158                                                                 }
 159                                                                 dst_file = wfopen(full_name, "w");
 160                                                                 copy_file_chunk(src_tar_file, dst_file, (unsigned long long) size);
 161                                                                 uncompressed_count += size;
 162                                                                 fclose(dst_file);
 163                                                                 chmod(full_name, mode);
 164                                                         }
 165                                                         break;
 166                                                 case (extract_info):
 167                                                         if (strstr(raw_tar_header.name, argument) != NULL) {
 168                                                                 copy_file_chunk(src_tar_file, stdout, (unsigned long long) size);
 169                                                                 uncompressed_count += size;
 170                                                         }
 171                                                         break;
 172                                                 case (extract_field):
 173                                                         if (strstr(raw_tar_header.name, "./control") != NULL) {
 174                                                                 return(read_text_file_to_buffer(src_tar_file));
 175                                                         }
 176                                                         break;
 177                                         }
 178                                         break;
 179                                 }
 180                         case '5':
 181                                 if (untar_function & (extract_extract | extract_verbose_extract | extract_control)) {
 182                                         if (create_path(dir, mode) != TRUE) {
 183                                                 free(dir);
 184                                                 perror_msg("%s: Cannot mkdir", raw_tar_header.name);
 185                                                 return NULL;
 186                                         }
 187                                 }
 188                                 break;
 189                         case '1':
 190                                 if (untar_function & (extract_extract | extract_verbose_extract | extract_control)) {
 191                                         if (link(raw_tar_header.linkname, raw_tar_header.name) < 0) {
 192                                                 free(dir);
 193                                                 perror_msg("%s: Cannot create hard link to '%s'", raw_tar_header.name, raw_tar_header.linkname);
 194                                                 return NULL;
 195                                         }
 196                                 }
 197                                 break;
 198                         case '2':
 199                                 if (untar_function & (extract_extract | extract_verbose_extract | extract_control)) {
 200                                         if (symlink(raw_tar_header.linkname, raw_tar_header.name) < 0) {
 201                                                 free(dir);
 202                                                 perror_msg("%s: Cannot create symlink to '%s'", raw_tar_header.name, raw_tar_header.linkname);
 203                                                 return NULL;
 204                                         }
 205                                 }
 206                                 break;
 207                         case '3':
 208                         case '4':
 209                         case '6':
 210 //                              if (tarExtractSpecial( &header, extractFlag, tostdoutFlag)==FALSE)
 211 //                                      errorFlag=TRUE;
 212 //                              break;
 213                         default:
 214                                 error_msg("Unknown file type '%c' in tar file", raw_tar_header.typeflag);
 215                                 free(dir);
 216                                 return NULL;
 217                 }
 218
 219                 /*
 220                  * Seek to start of next block, cant use fseek as unzip() does support it
 221                  */
 222                 while (uncompressed_count < next_header_offset) {
 223                         if (fgetc(src_tar_file) == EOF) {
 224                                 break;
 225                         }
 226                         uncompressed_count++;
 227                 }
 228
 229 //              free(dir);
 230         }
 231         return NULL;
 232 }