wimboot/wimboot-2.7.3/src/cpio.c

   1 /*
   2  * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  17  * 02110-1301, USA.
  18  */
  19
  20 /**
  21  * @file
  22  *
  23  * CPIO archives
  24  *
  25  */
  26
  27 #include <stdint.h>
  28 #include <stddef.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include "wimboot.h"
  33 #include "cpio.h"
  34
  35 /**
  36  * Align CPIO length to nearest dword
  37  *
  38  * @v len               Length
  39  * @ret len             Aligned length
  40  */
  41 static size_t cpio_align ( size_t len ) {
  42         return ( ( len + 0x03 ) & ~0x03 );
  43 }
  44
  45 /**
  46  * Parse CPIO field value
  47  *
  48  * @v field             ASCII field
  49  * @ret value           Field value
  50  */
  51 static unsigned long cpio_value ( const char *field ) {
  52         char buf[9];
  53
  54         memcpy ( buf, field, ( sizeof ( buf ) - 1 ) );
  55         buf[ sizeof ( buf ) - 1 ] = '\0';
  56         return strtoul ( buf, NULL, 16 );
  57 }
  58
  59 /**
  60  * Extract files from CPIO archive
  61  *
  62  * @v data              CPIO archive
  63  * @v len               Maximum length of CPIO archive
  64  * @v file              File handler
  65  * @ret rc              Return status code
  66  */
  67 int cpio_extract ( void *data, size_t len,
  68                    int ( * file ) ( const char *name, void *data,
  69                                     size_t len ) ) {
  70         const struct cpio_header *cpio;
  71         const uint32_t *pad;
  72         const char *file_name;
  73         void *file_data;
  74         size_t file_name_len;
  75         size_t file_len;
  76         size_t cpio_len;
  77         int rc;
  78
  79         while ( 1 ) {
  80
  81                 /* Skip over any padding */
  82                 while ( len >= sizeof ( *pad ) ) {
  83                         pad = data;
  84                         if ( *pad )
  85                                 break;
  86                         data += sizeof ( *pad );
  87                         len -= sizeof ( *pad );
  88                 }
  89
  90                 /* Stop if we have reached the end of the archive */
  91                 if ( ! len )
  92                         return 0;
  93
  94                 /* Sanity check */
  95                 if ( len < sizeof ( *cpio ) ) {
  96                         DBG ( "Truncated CPIO header\n" );
  97                         return -1;
  98                 }
  99                 cpio = data;
 100
 101                 /* Check magic */
 102                 if ( memcmp ( cpio->c_magic, CPIO_MAGIC,
 103                               sizeof ( cpio->c_magic ) ) != 0 ) {
 104                         DBG ( "Bad CPIO magic\n" );
 105                         return -1;
 106                 }
 107
 108                 /* Extract file parameters */
 109                 file_name = ( ( void * ) ( cpio + 1 ) );
 110                 file_name_len = cpio_value ( cpio->c_namesize );
 111                 file_data = ( data + cpio_align ( sizeof ( *cpio ) +
 112                                                   file_name_len ) );
 113                 file_len = cpio_value ( cpio->c_filesize );
 114                 cpio_len = ( file_data + file_len - data );
 115                 if ( cpio_len < len )
 116                         cpio_len = cpio_align ( cpio_len );
 117                 if ( cpio_len > len ) {
 118                         DBG ( "Truncated CPIO file\n" );
 119                         return -1;
 120                 }
 121
 122                 /* If we reach the trailer, we're done */
 123                 if ( strcmp ( file_name, CPIO_TRAILER ) == 0 )
 124                         return 0;
 125
 126                 /* Process file */
 127                 if ( ( rc = file ( file_name, file_data, file_len ) ) != 0 )
 128                         return rc;
 129
 130                 /* Move to next file */
 131                 data += cpio_len;
 132                 len -= cpio_len;
 133         }
 134 }