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 /*
  26  * stdout can be redircted to FILE *output
  27  * If const char *file_prefix isnt NULL is prepended to all the extracted filenames.
  28  * The purpose of const char *argument depends on the value of const int untar_function
  29  */
  30
  31 extern char *untar(FILE *src_tar_file, FILE *output, const int untar_function,
  32         const char *argument, const char *file_prefix)
  33 {
  34         typedef struct raw_tar_header {
  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         } raw_tar_header_t;
  53
  54         raw_tar_header_t raw_tar_header;
  55         unsigned char *temp = (unsigned char *) &raw_tar_header;
  56         long i;
  57         long next_header_offset = 0;
  58         long uncompressed_count = 0;
  59         size_t size;
  60         mode_t mode;
  61
  62         while (fread((char *) &raw_tar_header, 1, 512, src_tar_file) == 512) {
  63                 long sum = 0;
  64
  65                 if (ferror(src_tar_file) || feof(src_tar_file)) {
  66                         perror_msg("untar: ");
  67                         break;
  68                 }
  69
  70                 uncompressed_count += 512;
  71
  72                 /* Check header has valid magic */
  73                 if (strncmp(raw_tar_header.magic, "ustar", 5) != 0) {
  74 /*
  75  * FIXME, Need HELP with this
  76  *
  77  * This has to fail silently or it incorrectly reports errors when called from
  78  * deb_extract.
  79  * The problem is deb_extract decompresses the .gz file in a child process and
  80  * untar reads from the child proccess. The child process finishes and exits,
  81  * but fread reads 0's from the src_tar_file even though the child
  82  * closed its handle.
  83  */
  84 //                      error_msg("Invalid tar magic");
  85                         break;
  86                 }
  87
  88                 /* Do checksum on headers */
  89         for (i =  0; i < 148 ; i++) {
  90                         sum += temp[i];
  91                 }
  92         sum += ' ' * 8;
  93                 for (i =  156; i < 512 ; i++) {
  94                         sum += temp[i];
  95                 }
  96         if (sum != strtol(raw_tar_header.chksum, NULL, 8)) {
  97                         error_msg("Invalid tar header checksum");
  98                         break;
  99                 }
 100
 101                 /* convert to type'ed variables */
 102         size = strtol(raw_tar_header.size, NULL, 8);
 103                 parse_mode(raw_tar_header.mode, &mode);
 104
 105                 /* start of next header is at */
 106                 next_header_offset = uncompressed_count + size;
 107                 if (size % 512 != 0) {
 108                         next_header_offset += (512 - size % 512);
 109                 }
 110
 111                 /* If an exclude list is specified check current file against list */
 112 #if 0
 113                 if (*exclude_list != NULL) {
 114                         i = 0;
 115                         while (exclude_list[i] != 0) {
 116                                 if (strncmp(exclude_list[i], raw_tar_header.name, strlen(raw_tar_header.name)) == 0) {
 117                                         break;
 118                                 }
 119                                 i++;
 120                         }
 121                 if (exclude_list[i] != 0) {
 122                                 continue;
 123                         }
 124                 }
 125 #endif
 126                 if (untar_function & (extract_contents | extract_verbose_extract | extract_contents_to_file)) {
 127                         fprintf(output, "%s\n", raw_tar_header.name);
 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                                 int name_length = strlen(raw_tar_header.name);
 137                                 if (raw_tar_header.name[name_length - 1] != '/') {
 138                                         switch (untar_function) {
 139                                                 case (extract_extract):
 140                                                 case (extract_verbose_extract):
 141                                                 case (extract_control): {
 142                                                                 FILE *dst_file = NULL;
 143                                                                 char *full_name;
 144
 145                                                                 if (file_prefix != NULL) {
 146                                                                         full_name = xmalloc(strlen(argument) + strlen(file_prefix) + name_length + 3);
 147                                                                         sprintf(full_name, "%s/%s.%s", argument, file_prefix, strrchr(raw_tar_header.name, '/') + 1);
 148                                                                 } else {
 149                                                                         full_name = concat_path_file(argument, raw_tar_header.name);
 150                                                                 }
 151                                                                 dst_file = wfopen(full_name, "w");
 152                                                                 copy_file_chunk(src_tar_file, dst_file, (unsigned long long) size);
 153                                                                 uncompressed_count += size;
 154                                                                 fclose(dst_file);
 155                                                                 chmod(full_name, mode);
 156                                                                 free(full_name);
 157                                                         }
 158                                                         break;
 159                                                 case (extract_info):
 160                                                         if (strstr(raw_tar_header.name, argument) != NULL) {
 161                                                                 copy_file_chunk(src_tar_file, stdout, (unsigned long long) size);
 162                                                                 uncompressed_count += size;
 163                                                         }
 164                                                         break;
 165                                                 case (extract_field):
 166                                                         if (strstr(raw_tar_header.name, "./control") != NULL) {
 167                                                                 return(read_text_file_to_buffer(src_tar_file));
 168                                                         }
 169                                                         break;
 170                                         }
 171                                         break;
 172                                 }
 173                         }
 174                         case '5':
 175                                 if (untar_function & (extract_extract | extract_verbose_extract | extract_control)) {
 176                                         int ret;
 177                                         char *dir;
 178                                         dir = concat_path_file(argument, raw_tar_header.name);
 179                                         ret = create_path(dir, mode);
 180                                         free(dir);
 181                                         if (ret == FALSE) {
 182                                                 perror_msg("%s: Cannot mkdir", raw_tar_header.name);
 183                                                 return NULL;
 184                                         }
 185                                         chmod(dir, mode);
 186                                 }
 187                                 break;
 188                         case '1':
 189                                 if (untar_function & (extract_extract | extract_verbose_extract | extract_control)) {
 190                                         if (link(raw_tar_header.linkname, raw_tar_header.name) < 0) {
 191                                                 perror_msg("%s: Cannot create hard link to '%s'", raw_tar_header.name, raw_tar_header.linkname);
 192                                                 return NULL;
 193                                         }
 194                                 }
 195                                 break;
 196                         case '2':
 197                                 if (untar_function & (extract_extract | extract_verbose_extract | extract_control)) {
 198                                         if (symlink(raw_tar_header.linkname, raw_tar_header.name) < 0) {
 199                                                 perror_msg("%s: Cannot create symlink to '%s'", raw_tar_header.name, raw_tar_header.linkname);
 200                                                 return NULL;
 201                                         }
 202                                 }
 203                                 break;
 204                         case '3':
 205                         case '4':
 206                         case '6':
 207 //                              if (tarExtractSpecial( &header, extractFlag, tostdoutFlag)==FALSE)
 208 //                                      errorFlag=TRUE;
 209 //                              break;
 210                         default:
 211                                 error_msg("Unknown file type '%c' in tar file", raw_tar_header.typeflag);
 212                                 return NULL;
 213                 }
 214                 /*
 215                  * Seek to start of next block, cant use fseek as unzip() does support it
 216                  */
 217                 while (uncompressed_count < next_header_offset) {
 218                         if (fgetc(src_tar_file) == EOF) {
 219                                 break;
 220                         }
 221                         uncompressed_count++;
 222                 }
 223         }
 224         return NULL;
 225 }