| Glenn L McGrath | 95ebf61 | 2001-10-25 14:18:08 +0000 | [diff] [blame^] | 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 | file_header_t *get_header_tar(FILE *tar_stream) |
| 24 | { |
| 25 | union { |
| 26 | unsigned char raw[512]; |
| 27 | struct { |
| 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 | } formated; |
| 46 | } tar; |
| 47 | file_header_t *tar_entry = NULL; |
| 48 | long sum = 0; |
| 49 | long i; |
| 50 | |
| 51 | if (archive_offset % 512 != 0) { |
| 52 | seek_sub_file(tar_stream, 512 - (archive_offset % 512)); |
| 53 | } |
| 54 | |
| 55 | if (fread(tar.raw, 1, 512, tar_stream) != 512) { |
| 56 | /* Unfortunatly its common for tar files to have all sorts of |
| 57 | * trailing garbage, fail silently */ |
| 58 | // error_msg("Couldnt read header"); |
| 59 | return(NULL); |
| 60 | } |
| 61 | archive_offset += 512; |
| 62 | |
| 63 | /* Check header has valid magic, unfortunately some tar files |
| 64 | * have empty (0'ed) tar entries at the end, which will |
| 65 | * cause this to fail, so fail silently for now |
| 66 | */ |
| 67 | if (strncmp(tar.formated.magic, "ustar", 5) != 0) { |
| 68 | return(NULL); |
| 69 | } |
| 70 | |
| 71 | /* Do checksum on headers */ |
| 72 | for (i = 0; i < 148 ; i++) { |
| 73 | sum += tar.raw[i]; |
| 74 | } |
| 75 | sum += ' ' * 8; |
| 76 | for (i = 156; i < 512 ; i++) { |
| 77 | sum += tar.raw[i]; |
| 78 | } |
| 79 | if (sum != strtol(tar.formated.chksum, NULL, 8)) { |
| 80 | error_msg("Invalid tar header checksum"); |
| 81 | return(NULL); |
| 82 | } |
| 83 | |
| 84 | /* convert to type'ed variables */ |
| 85 | tar_entry = xcalloc(1, sizeof(file_header_t)); |
| 86 | tar_entry->name = xstrdup(tar.formated.name); |
| 87 | |
| 88 | parse_mode(tar.formated.mode, &tar_entry->mode); |
| 89 | tar_entry->uid = strtol(tar.formated.uid, NULL, 8); |
| 90 | tar_entry->gid = strtol(tar.formated.gid, NULL, 8); |
| 91 | tar_entry->size = strtol(tar.formated.size, NULL, 8); |
| 92 | tar_entry->mtime = strtol(tar.formated.mtime, NULL, 8); |
| 93 | tar_entry->link_name = strlen(tar.formated.linkname) ? |
| 94 | xstrdup(tar.formated.linkname) : NULL; |
| 95 | tar_entry->device = (strtol(tar.formated.devmajor, NULL, 8) << 8) + |
| 96 | strtol(tar.formated.devminor, NULL, 8); |
| 97 | |
| 98 | return(tar_entry); |
| 99 | } |