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, int untar_function, char *base_path)
  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                         break;
  61                 }
  62
  63                 uncompressed_count += 512;
  64
  65                 /* Check header has valid magic */
  66                 if (strncmp(raw_tar_header.magic, "ustar", 5) != 0) {
  67 /*
  68  * FIXME, Need HELP with this
  69  *
  70  * This has to fail silently or it incorrectly reports errors when called from
  71  * deb_extract.
  72  * The problem is deb_extract decompresses the .gz file in a child process and
  73  * untar reads from the child proccess. The child process finishes and exits,
  74  * but fread reads 0's from the src_tar_file even though the child
  75  * closed its handle.
  76  */
  77 //                      error_msg("Invalid tar magic");
  78                         break;
  79                 }
  80
  81                 /* Do checksum on headers */
  82         for (i =  0; i < 148 ; i++) {
  83                         sum += temp[i];
  84                 }
  85         sum += ' ' * 8;
  86                 for (i =  156; i < 512 ; i++) {
  87                         sum += temp[i];
  88                 }
  89         if (sum != strtol(raw_tar_header.chksum, NULL, 8)) {
  90                         error_msg("Invalid tar header checksum");
  91                         break;
  92                 }
  93
  94                 /* convert to type'ed variables */
  95         size = strtol(raw_tar_header.size, NULL, 8);
  96                 parse_mode(raw_tar_header.mode, &mode);
  97
  98                 /* start of next header is at */
  99                 next_header_offset = uncompressed_count + size;
 100                 if (size % 512 != 0) {
 101                         next_header_offset += (512 - size % 512);
 102                 }
 103
 104                 /*
 105                  * seek to start of control file, return length
 106                  *
 107                 if (dpkg_untar_function & dpkg_untar_seek_control) {
 108                         if ((raw_tar_header.typeflag == '0') || (raw_tar_header.typeflag == '\0')) {
 109                                 char *tar_filename;
 110
 111                                 tar_filename = strrchr(raw_tar_header.name, '/');
 112                                 if (tar_filename == NULL) {
 113                                         tar_filename = strdup(raw_tar_header.name);
 114                                 } else {
 115                                         tar_filename++;
 116                                 }
 117
 118                                 if (strcmp(tar_filename, "control") == 0) {
 119                                         return(size);
 120                                 }
 121                         }
 122
 123                 }
 124 */
 125                 if (untar_function & (extract_contents | extract_verbose_extract)) {
 126                         printf("%s\n", raw_tar_header.name);
 127                 }
 128
 129                 /* extract files */
 130                 if (base_path != NULL) {
 131                         dir = xmalloc(strlen(raw_tar_header.name) + strlen(base_path) + 2);
 132                         sprintf(dir, "%s/%s", base_path, raw_tar_header.name);
 133                         create_path(dir, 0777);
 134                 }
 135                 switch (raw_tar_header.typeflag ) {
 136                         case '0':
 137                         case '\0':
 138                                 /* If the name ends in a '/' then assume it is
 139                                  * supposed to be a directory, and fall through
 140                                  */
 141                                 if (raw_tar_header.name[strlen(raw_tar_header.name)-1] != '/') {
 142                                         switch (untar_function) {
 143                                                 case (extract_extract): {
 144                                                                 FILE *dst_file = wfopen(dir, "w");
 145                                                                 copy_file_chunk(src_tar_file, dst_file, size);
 146                                                                 fclose(dst_file);
 147                                                         }
 148                                                         break;
 149                                                 default: {
 150                                                                 int remaining = size;
 151                                                                 while (remaining-- > 0) {
 152                                                                         fgetc(src_tar_file);
 153                                                                 }
 154                                                         }
 155                                         }
 156                                         uncompressed_count += size;
 157                                         break;
 158                                 }
 159                         case '5':
 160                                 if (untar_function & extract_extract) {
 161                                         if (create_path(dir, mode) != TRUE) {
 162                                                 free(dir);
 163                                                 perror_msg("%s: Cannot mkdir", raw_tar_header.name);
 164                                                 return(EXIT_FAILURE);
 165                                         }
 166                                 }
 167                                 break;
 168                         case '1':
 169                                 if (untar_function & extract_extract) {
 170                                         if (link(raw_tar_header.linkname, raw_tar_header.name) < 0) {
 171                                                 free(dir);
 172                                                 perror_msg("%s: Cannot create hard link to '%s'", raw_tar_header.name, raw_tar_header.linkname);
 173                                                 return(EXIT_FAILURE);
 174                                         }
 175                                 }
 176                                 break;
 177                         case '2':
 178                                 if (untar_function & extract_extract) {
 179                                         if (symlink(raw_tar_header.linkname, raw_tar_header.name) < 0) {
 180                                                 free(dir);
 181                                                 perror_msg("%s: Cannot create symlink to '%s'", raw_tar_header.name, raw_tar_header.linkname);
 182                                                 return(EXIT_FAILURE);
 183                                         }
 184                                 }
 185                                 break;
 186                         case '3':
 187                         case '4':
 188                         case '6':
 189 //                              if (tarExtractSpecial( &header, extractFlag, tostdoutFlag)==FALSE)
 190 //                                      errorFlag=TRUE;
 191 //                              break;
 192                         default:
 193                                 error_msg("Unknown file type '%c' in tar file", raw_tar_header.typeflag);
 194                                 free(dir);
 195                                 return(EXIT_FAILURE);
 196                 }
 197 //              free(dir);
 198         }
 199         return(EXIT_SUCCESS);
 200 }