kbx/keybox-file.c

   1 /* keybox-file.c - file oeprations
   2  *      Copyright (C) 2001, 2003 Free Software Foundation, Inc.
   3  *
   4  * This file is part of GnuPG.
   5  *
   6  * GnuPG is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * GnuPG is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  19  */
  20
  21 #include <config.h>
  22 #include <stdlib.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <errno.h>
  26
  27 #include "keybox-defs.h"
  28
  29 /* Read a block at the current postion and return it in r_blob.
  30    r_blob may be NULL to simply skip the current block */
  31 int
  32 _keybox_read_blob (KEYBOXBLOB *r_blob, FILE *fp)
  33 {
  34   char *image;
  35   size_t imagelen = 0;
  36   int c1, c2, c3, c4, type;
  37   int rc;
  38   off_t off;
  39
  40  again:
  41   *r_blob = NULL;
  42   off = ftello (fp);
  43   if (off == (off_t)-1)
  44     return gpg_error (gpg_err_code_from_errno (errno));
  45
  46   if ((c1 = getc (fp)) == EOF
  47       || (c2 = getc (fp)) == EOF
  48       || (c3 = getc (fp)) == EOF
  49       || (c4 = getc (fp)) == EOF
  50       || (type = getc (fp)) == EOF)
  51     {
  52       if ( c1 == EOF && !ferror (fp) )
  53         return -1; /* eof */
  54       return gpg_error (gpg_err_code_from_errno (errno));
  55     }
  56
  57   imagelen = (c1 << 24) | (c2 << 16) | (c3 << 8 ) | c4;
  58   if (imagelen > 500000) /* sanity check */
  59     return gpg_error (GPG_ERR_TOO_LARGE);
  60
  61   if (imagelen < 5)
  62     return gpg_error (GPG_ERR_TOO_SHORT);
  63
  64   if (!type)
  65     {
  66       /* special treatment for empty blobs. */
  67       if (fseek (fp, imagelen-5, SEEK_CUR))
  68         return gpg_error (gpg_err_code_from_errno (errno));
  69       goto again;
  70     }
  71
  72   image = xtrymalloc (imagelen);
  73   if (!image)
  74     return gpg_error (gpg_err_code_from_errno (errno));
  75
  76   image[0] = c1; image[1] = c2; image[2] = c3; image[3] = c4; image[4] = type;
  77   if (fread (image+5, imagelen-5, 1, fp) != 1)
  78     {
  79       gpg_error_t tmperr = gpg_error (gpg_err_code_from_errno (errno));
  80       xfree (image);
  81       return tmperr;
  82     }
  83
  84   rc = r_blob? _keybox_new_blob (r_blob, image, imagelen, off) : 0;
  85   if (rc || !r_blob)
  86         xfree (image);
  87   return rc;
  88 }
  89
  90
  91 /* Write the block to the current file position */
  92 int
  93 _keybox_write_blob (KEYBOXBLOB blob, FILE *fp)
  94 {
  95   const char *image;
  96   size_t length;
  97
  98   image = _keybox_get_blob_image (blob, &length);
  99   if (fwrite (image, length, 1, fp) != 1)
 100     return gpg_error (gpg_err_code_from_errno (errno));
 101   return 0;
 102 }