archival/libunarchive/get_header_cpio.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
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <string.h>
  20 #include "unarchive.h"
  21 #include "libbb.h"
  22
  23 struct hardlinks {
  24         file_header_t *entry;
  25         int inode;
  26         struct hardlinks *next;
  27 };
  28
  29 file_header_t *get_header_cpio(FILE *src_stream)
  30 {
  31         file_header_t *cpio_entry = NULL;
  32         char cpio_header[110];
  33         int namesize;
  34         char dummy[16];
  35         int major, minor, nlink, inode;
  36         static struct hardlinks *saved_hardlinks = NULL;
  37         static int pending_hardlinks = 0;
  38
  39         if (pending_hardlinks) { /* Deal with any pending hardlinks */
  40                 struct hardlinks *tmp = saved_hardlinks, *oldtmp = NULL;
  41                 while (tmp) {
  42                         if (tmp->entry->link_name) { /* Found a hardlink ready to be extracted */
  43                                 cpio_entry = tmp->entry;
  44                                 if (oldtmp) oldtmp->next = tmp->next; /* Remove item from linked list */
  45                                 else saved_hardlinks = tmp->next;
  46                                 free(tmp);
  47                                 return (cpio_entry);
  48                         }
  49                         oldtmp = tmp;
  50                         tmp = tmp->next;
  51                 }
  52                 pending_hardlinks = 0; /* No more pending hardlinks, read next file entry */
  53         }
  54
  55         /* There can be padding before archive header */
  56         seek_sub_file(src_stream, (4 - (archive_offset % 4)) % 4);
  57         if (fread(cpio_header, 1, 110, src_stream) == 110) {
  58                 archive_offset += 110;
  59                 if (strncmp(cpio_header, "07070", 5) != 0) {
  60                         error_msg("Unsupported format or invalid magic");
  61                         return(NULL);
  62                 }
  63                 switch (cpio_header[5]) {
  64                         case '2': /* "crc" header format */
  65                                 /* Doesnt do the crc check yet */
  66                         case '1': /* "newc" header format */
  67                                 cpio_entry = (file_header_t *) xcalloc(1, sizeof(file_header_t));
  68                                 sscanf(cpio_header, "%6c%8x%8x%8x%8x%8x%8lx%8lx%16c%8x%8x%8x%8c",
  69                                         dummy, &inode, (unsigned int*)&cpio_entry->mode,
  70                                         (unsigned int*)&cpio_entry->uid, (unsigned int*)&cpio_entry->gid,
  71                                         &nlink, &cpio_entry->mtime, &cpio_entry->size,
  72                                         dummy, &major, &minor, &namesize, dummy);
  73
  74                                 cpio_entry->name = (char *) xcalloc(1, namesize);
  75                                 fread(cpio_entry->name, 1, namesize, src_stream); /* Read in filename */
  76                                 archive_offset += namesize;
  77                                 /* Skip padding before file contents */
  78                                 seek_sub_file(src_stream, (4 - (archive_offset % 4)) % 4);
  79                                 if (strcmp(cpio_entry->name, "TRAILER!!!") == 0) {
  80                                         printf("%d blocks\n", (int) (archive_offset % 512 ? (archive_offset / 512) + 1 : archive_offset / 512)); /* Always round up */
  81                                         if (saved_hardlinks) { /* Bummer - we still have unresolved hardlinks */
  82                                                 struct hardlinks *tmp = saved_hardlinks, *oldtmp = NULL;
  83                                                 while (tmp) {
  84                                                         error_msg("%s not created: cannot resolve hardlink", tmp->entry->name);
  85                                                         oldtmp = tmp;
  86                                                         tmp = tmp->next;
  87                                                         free (oldtmp->entry->name);
  88                                                         free (oldtmp->entry);
  89                                                         free (oldtmp);
  90                                                 }
  91                                                 saved_hardlinks = NULL;
  92                                                 pending_hardlinks = 0;
  93                                         }
  94                                         return(NULL);
  95                                 }
  96
  97                                 if (S_ISLNK(cpio_entry->mode)) {
  98                                         cpio_entry->link_name = (char *) xcalloc(1, cpio_entry->size + 1);
  99                                         fread(cpio_entry->link_name, 1, cpio_entry->size, src_stream);
 100                                         archive_offset += cpio_entry->size;
 101                                         cpio_entry->size = 0; /* Stop possiable seeks in future */
 102                                 }
 103                                 if (nlink > 1 && !S_ISDIR(cpio_entry->mode)) {
 104                                         if (cpio_entry->size == 0) { /* Put file on a linked list for later */
 105                                                 struct hardlinks *new = xmalloc(sizeof(struct hardlinks));
 106                                                 new->next = saved_hardlinks;
 107                                                 new->inode = inode;
 108                                                 new->entry = cpio_entry;
 109                                                 saved_hardlinks = new;
 110                                         return(get_header_cpio(src_stream)); /* Recurse to next file */
 111                                         } else { /* Found the file with data in */
 112                                                 struct hardlinks *tmp = saved_hardlinks;
 113                                                 pending_hardlinks = 1;
 114                                                 while (tmp) {
 115                                                         if (tmp->inode == inode) {
 116                                                                 tmp->entry->link_name = xstrdup(cpio_entry->name);
 117                                                                 nlink--;
 118                                                         }
 119                                                         tmp = tmp->next;
 120                                                 }
 121                                                 if (nlink > 1) error_msg("error resolving hardlink: did you create the archive with GNU cpio 2.0-2.2?");
 122                                         }
 123                                 }
 124                                 cpio_entry->device = (major << 8) | minor;
 125                                 break;
 126                         default:
 127                                 error_msg("Unsupported format");
 128                                 return(NULL);
 129                 }
 130                 if (ferror(src_stream) || feof(src_stream)) {
 131                         perror_msg("Stream error");
 132                         return(NULL);
 133                 }
 134         }
 135         return(cpio_entry);
 136 }
 137