/* keybox-file.c - File operations

 *  Copyright (C) 2001, 2003 Free Software Foundation, Inc.

 *

 * This file is part of GnuPG.

 *

 * GnuPG is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 3 of the License, or

 * (at your option) any later version.

 *

 * GnuPG is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, see <https://www.gnu.org/licenses/>.

 */

#include <config.h>

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <time.h>

#include "keybox-defs.h"

#define IMAGELEN_LIMIT (5*1024*1024)

#if !defined(HAVE_FTELLO) && !defined(ftello)

static off_t

ftello (FILE *stream)

{

  long int off;

  off = ftell (stream);

  if (off == -1)

    return (off_t)-1;

  return off;

}

#endif /* !defined(HAVE_FTELLO) && !defined(ftello) */

/* Read a block at the current position and return it in R_BLOB.

   R_BLOB may be NULL to simply skip the current block.  */

int

_keybox_read_blob (KEYBOXBLOB *r_blob, estream_t fp, int *skipped_deleted)

{

  unsigned char *image;

  size_t imagelen = 0;

  int c1, c2, c3, c4, type;

  int rc;

  off_t off;

  if (skipped_deleted)

    *skipped_deleted = 0;

 again:

  if (r_blob)

    *r_blob = NULL;

  off = es_ftello (fp);

  if (off == (off_t)-1)

    return gpg_error_from_syserror ();

  if ((c1 = es_getc (fp)) == EOF

      || (c2 = es_getc (fp)) == EOF

      || (c3 = es_getc (fp)) == EOF

      || (c4 = es_getc (fp)) == EOF

      || (type = es_getc (fp)) == EOF)

    {

      if ( c1 == EOF && !es_ferror (fp) )

        return -1; /* eof */

      if (!es_ferror (fp))

        return gpg_error (GPG_ERR_TOO_SHORT);

      return gpg_error_from_syserror ();

    }

  imagelen = ((unsigned int) c1 << 24) | (c2 << 16) | (c3 << 8 ) | c4;

  if (imagelen < 5)

    return gpg_error (GPG_ERR_TOO_SHORT);

  if (!type)

    {

      /* Special treatment for empty blobs. */

      if (es_fseek (fp, imagelen-5, SEEK_CUR))

        return gpg_error_from_syserror ();

      if (skipped_deleted)

        *skipped_deleted = 1;

      goto again;

    }

  if (imagelen > IMAGELEN_LIMIT) /* Sanity check. */

    {

      /* Seek forward so that the caller may choose to ignore this

         record.  */

      if (es_fseek (fp, imagelen-5, SEEK_CUR))

        return gpg_error_from_syserror ();

      return gpg_error (GPG_ERR_TOO_LARGE);

    }

  if (!r_blob)

    {

      /* This blob shall be skipped.  */

      if (es_fseek (fp, imagelen-5, SEEK_CUR))

        return gpg_error_from_syserror ();

      return 0;

    }

  image = xtrymalloc (imagelen);

  if (!image)

    return gpg_error_from_syserror ();

  image[0] = c1; image[1] = c2; image[2] = c3; image[3] = c4; image[4] = type;

  if (es_fread (image+5, imagelen-5, 1, fp) != 1)

    {

      gpg_error_t tmperr = gpg_error_from_syserror ();

      xfree (image);

      return tmperr;

    }

  rc = _keybox_new_blob (r_blob, image, imagelen, off);

  if (rc)

    xfree (image);

  return rc;

}

/* Write the block to the current file position */

int

_keybox_write_blob (KEYBOXBLOB blob, estream_t fp, FILE *outfp)

{

  const unsigned char *image;

  size_t length;

  image = _keybox_get_blob_image (blob, &length);

  if (length > IMAGELEN_LIMIT)

    return gpg_error (GPG_ERR_TOO_LARGE);

  if (fp)

    {

      if (es_fwrite (image, length, 1, fp) != 1)

        return gpg_error_from_syserror ();

    }

  else

    {

      if (fwrite (image, length, 1, outfp) != 1)

        return gpg_error_from_syserror ();

    }

  return 0;

}

/* Write a fresh header type blob. */

gpg_error_t

_keybox_write_header_blob (estream_t fp, int for_openpgp)

{

  unsigned char image[32];

  u32 val;

  memset (image, 0, sizeof image);

  /* Length of this blob. */

  image[3] = 32;

  image[4] = KEYBOX_BLOBTYPE_HEADER;

  image[5] = 1; /* Version */

  if (for_openpgp)

    image[7] = 0x02; /* OpenPGP data may be available.  */

  memcpy (image+8, "KBXf", 4);

  val = time (NULL);

  /* created_at and last maintenance run. */

  image[16]   = (val >> 24);

  image[16+1] = (val >> 16);

  image[16+2] = (val >>  8);

  image[16+3] = (val      );

  image[20]   = (val >> 24);

  image[20+1] = (val >> 16);

  image[20+2] = (val >>  8);

  image[20+3] = (val      );

  if (es_fwrite (image, 32, 1, fp) != 1)

    return gpg_error_from_syserror ();

  return 0;

}