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