gpgme/gpgme/data.c

/* data.c
 *	Copyright (C) 2000 Werner Koch (dd9jn)
 *      Copyright (C) 2001, 2002 g10 Code GmbH
 *
 * This file is part of GPGME.
 *
 * GPGME 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 2 of the License, or
 * (at your option) any later version.
 *
 * GPGME 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "util.h"
#include "context.h"
#include "ops.h"
#include "io.h"

/* When expanding an internal buffer, always extend it by ALLOC_CHUNK
   bytes at a time.  */
#define ALLOC_CHUNK 1024


/**
 * gpgme_data_new:
 * @r_dh: returns the new data object 
 * 
 * Create a new data object without any content. 
 * 
 * Return value: An error value or 0 on success
 **/
GpgmeError
gpgme_data_new (GpgmeData *r_dh)
{
  GpgmeData dh;

  if (!r_dh)
    return mk_error (Invalid_Value);
  *r_dh = NULL;

  dh = xtrycalloc (1, sizeof *dh);
  if (!dh)
    return mk_error (Out_Of_Core);

  dh->mode = GPGME_DATA_MODE_INOUT; 

  *r_dh = dh;
  return 0;
}


/**
 * gpgme_data_new_from_mem:
 * @r_dh:   Returns a new data object.
 * @buffer: Initialize with this.
 * @size: Size of the buffer
 * @copy: Flag wether a copy of the buffer should be used.
 * 
 * Create a new data object and initialize with data from the memory.
 * A @copy with value %TRUE creates a copy of the memory, a value of
 * %FALSE uses the original memory of @buffer and the caller has to
 * make sure that this buffer is valid until gpgme_data_release() is
 * called.
 * 
 * Return value: An error value or 0 for success.
 **/
GpgmeError
gpgme_data_new_from_mem (GpgmeData *r_dh, const char *buffer, size_t size,
			 int copy)
{
  GpgmeData dh;
  GpgmeError err;

  if (!r_dh)
    return mk_error (Invalid_Value);
  *r_dh = NULL;
  if (!buffer)
    return mk_error (Invalid_Value);

  err = gpgme_data_new (&dh);
  if (err)
    return err;

  dh->type = GPGME_DATA_TYPE_MEM;
  dh->len = size;
  if (!copy)
    dh->data = buffer;
  else
    {
      dh->private_buffer = xtrymalloc (size);
      if (!dh->private_buffer)
	{
	  gpgme_data_release (dh);
	  return mk_error (Out_Of_Core);
	}
      dh->private_len = size;
      memcpy (dh->private_buffer, buffer, size);
      dh->data = dh->private_buffer;
      dh->writepos = size;
    }

  *r_dh = dh;
  return 0;
}


/**
 * gpgme_data_new_with_read_cb:
 * @r_dh: returns the new data object
 * @read_cb: callback function
 * @read_cb_value: value passed to the callback function
 * 
 * Create a new data object which is a wrapper around the callback function.
 * The callback function is defined as:
 * <literal>
 * typedef int (*read_cb) (void *cb_value,
 *                         char *buffer,
 *                         size_t count,
 *                         size_t *nread);
 * </literal>
 *
 * The callback should return a maximium of @count bytes in @buffer
 * and the number actually read in @nread.  It may return 0 in @nread
 * if there are no bytes currently available.  To indicate EOF the
 * function should return with an error code of %-1 and set @nread to
 * 0.  The callback may support passing %NULL for @buffer and @nread
 * and %0 for count as an indication to reset its internal read
 * pointer.
 *
 * Return value: An error value or 0 for success.
 **/
GpgmeError
gpgme_data_new_with_read_cb (GpgmeData *r_dh,
			     int (*read_cb) (void *,char *, size_t ,size_t *),
			     void *read_cb_value)
{
  GpgmeData dh;
  GpgmeError err;

  if (!r_dh)
    return mk_error (Invalid_Value);
  *r_dh = NULL;

  if (!read_cb)
    return mk_error (Invalid_Value);

  err = gpgme_data_new (&dh);
  if (err)
    return err;

  dh->type = GPGME_DATA_TYPE_CB;
  dh->mode = GPGME_DATA_MODE_OUT;
  dh->read_cb = read_cb;
  dh->read_cb_value = read_cb_value;
    
  *r_dh = dh;
  return 0;
}


/**
 * gpgme_data_new_from_file:
 * @r_dh: returns the new data object
 * @fname: filename
 * @copy: Flag, whether the file should be copied.
 * 
 * Create a new data object and initialize it with the content of 
 * the file @file.  If @copy is %True the file is immediately read in
 * and closed.  @copy of %False is not yet supportted.
 * 
 * Return value: An error code or 0 on success. If the error code is
 * %GPGME_File_Error, the OS error code is held in %errno.
 **/
GpgmeError
gpgme_data_new_from_file (GpgmeData *r_dh, const char *fname, int copy)
{
  GpgmeData dh;
  GpgmeError err;
  struct stat st;
  FILE *fp;

  if (!r_dh)
    return mk_error (Invalid_Value);
  *r_dh = NULL;
  if (!fname)
    return mk_error (Invalid_Value);

  /* We only support copy for now.  In future we might want to honor
     the copy flag and just store a file pointer.  */
  if (!copy)
    return mk_error (Not_Implemented);

  err = gpgme_data_new (&dh);
  if (err)
    return err;

  fp = fopen (fname, "rb");
  if (!fp)
    {
      int save_errno = errno;
      gpgme_data_release (dh);
      errno = save_errno;
      return mk_error (File_Error);
    }

  if (fstat(fileno(fp), &st))
    {
      int save_errno = errno;
      fclose (fp);
      gpgme_data_release (dh);
      errno = save_errno;
      return mk_error (File_Error);
    }

  /* We should check the length of the file and don't allow for too
     large files.  */
  dh->private_buffer = xtrymalloc (st.st_size);
  if (!dh->private_buffer)
    {
      fclose (fp);
      gpgme_data_release (dh);
      return mk_error (Out_Of_Core);
    }
  dh->private_len = st.st_size;

  while (fread (dh->private_buffer, dh->private_len, 1, fp) < 1
	 && ferror (fp) && errno == EINTR);

  if (ferror (fp))
    {
      int save_errno = errno;
      fclose (fp);
      gpgme_data_release (dh);
      errno = save_errno;
      return mk_error (File_Error);
    }

  fclose (fp);

  dh->type = GPGME_DATA_TYPE_MEM;
  dh->len = dh->private_len;
  dh->data = dh->private_buffer;
  dh->writepos = dh->len;
    
  *r_dh = dh;
  return 0;
}


/**
 * gpgme_data_new_from_filepart:
 * @r_dh: returns the new data object
 * @fname: filename
 * @fp: filepointer
 * @offset: Start reading at this offset
 * @length: Read this many bytes 
 * 
 * Create a new data object and initialize it with @length bytes
 * starting at @offset of @file or @fp.  Either a filename or an open
 * filepointer may be given.
 *
 *
 * Return value: An error code or 0 on success. If the error code is
 * %GPGME_File_Error, the OS error code is held in %errno.
 **/
GpgmeError
gpgme_data_new_from_filepart (GpgmeData *r_dh, const char *fname, FILE *fp,
			      off_t offset, size_t length)
{
  GpgmeData dh;
  GpgmeError err;
  int save_errno = 0;

  if (!r_dh)
    return mk_error (Invalid_Value);
  *r_dh = NULL;

  if ((fname && fp) || (!fname && !fp))
    return mk_error (Invalid_Value);

  err = gpgme_data_new (&dh);
  if (err)
    return err;

  if (!length)
    goto out;

  if (fname)
    {
      fp = fopen (fname, "rb");
      if (!fp)
	{
	  err = mk_error (File_Error);
	  goto out;
	}
    }

  if (fseek (fp, (long) offset, SEEK_SET))
    {
      err = mk_error (File_Error);
      goto out;
    }

  dh->private_buffer = xtrymalloc (length);
  if (!dh->private_buffer)
    {
      err = mk_error (Out_Of_Core);
      goto out;
    }
  dh->private_len = length;
  
  while (fread (dh->private_buffer, dh->private_len, 1, fp) < 1
	 && ferror (fp) && errno == EINTR);

  if (ferror (fp))
    {
      err = mk_error (File_Error);
      goto out;
    }
      
  dh->type = GPGME_DATA_TYPE_MEM;
  dh->len = dh->private_len;
  dh->data = dh->private_buffer;
  dh->writepos = dh->len;

 out:
  if (err)
    save_errno = errno;

  if (fname && fp)
    fclose (fp);

  if (err)
    {
      gpgme_data_release (dh);
      errno = save_errno;
    }
  else
    *r_dh = dh;
  return err;
}


/**
 * gpgme_data_release:
 * @dh: Data object 
 * 
 * Release the data object @dh.  @dh may be NULL in which case nothing
 * happens.
 **/
void
gpgme_data_release (GpgmeData dh)
{
  if (dh)
    {
      xfree (dh->private_buffer); 
      xfree (dh);
    }
}


/*
 * Release the data object @dh.  @dh may be NULL in which case nothing
 * happens.
 * 
 * Return value: An allocated memory object with the content of the
 * data object.  The function makes sure that the returned string can
 * safely be accessed using the string fucntions.
 **/
char *
_gpgme_data_release_and_return_string (GpgmeData dh)
{
  char *val = NULL;

  if (dh)
    {
      if (_gpgme_data_append (dh, "", 1)) /* append EOS */
	xfree (dh->private_buffer );
      else
	{
	  val = dh->private_buffer;
	  if (!val && dh->data)
	    {
	      val = xtrymalloc (dh->len);
	      if (val)
		memcpy (val, dh->data, dh->len);
            }
        }
      xfree (dh);
    }
  return val;
}


/**
 * gpgme_data_release_and_get_mem:
 * @dh: the data object
 * @r_len: returns the length of the memory
 * 
 * Release the data object @dh and return its content and the length
 * of that content.  The caller has to free this data.  @dh maybe NULL
 * in which case NULL is returned.  If there is not enough memory for
 * allocating the return value, NULL is returned and the object is
 * released.
 * 
 * Return value: a pointer to an allocated buffer of length @r_len.
 **/
char *
gpgme_data_release_and_get_mem (GpgmeData dh, size_t *r_len)
{
  char *val = NULL;

  if (r_len)
    *r_len = 0;
  if (dh)
    {
      size_t len = dh->len;
      val = dh->private_buffer;
      if (!val && dh->data)
	{
	  val = xtrymalloc (len);
	  if (val)
	    memcpy (val, dh->data, len);
        }
      xfree (dh);
      if (val && r_len)
	*r_len = len;
    }
  return val;
}


/**
 * gpgme_data_get_type:
 * @dh: the data object
 * 
 * Get the type of the data object.
 * Data types are prefixed with %GPGME_DATA_TYPE_
 * 
 * Return value: the data type
 **/
GpgmeDataType
gpgme_data_get_type (GpgmeData dh)
{
  if (!dh || (!dh->data && !dh->read_cb))
    return GPGME_DATA_TYPE_NONE;

  return dh->type;
}

/* Get the current encoding meta information. */
GpgmeDataEncoding
gpgme_data_get_encoding (GpgmeData dh)
{
  return dh? dh->encoding : GPGME_DATA_ENCODING_NONE;
}

/* Set the encoding meta information for DB to ENC */
GpgmeError
gpgme_data_set_encoding (GpgmeData dh, GpgmeDataEncoding enc)
{
  if (!dh)
    return GPGME_Invalid_Value;
  if (enc < 0 || enc > GPGME_DATA_ENCODING_ARMOR)
    return GPGME_Invalid_Value;
  dh->encoding = enc;
  return 0;
}

void 
_gpgme_data_set_mode (GpgmeData dh, GpgmeDataMode mode)
{
  assert (dh);
  dh->mode = mode;
}


GpgmeDataMode
_gpgme_data_get_mode (GpgmeData dh)
{
  assert (dh);
  return dh->mode;
}


/**
 * gpgme_data_rewind:
 * @dh: the data object 
 * 
 * Prepare the data object in a way, that a gpgme_data_read() does start
 * at the beginning of the data.  This has to be done for all types
 * of data objects.
 * 
 * Return value: An error code or 0 on success
 **/
GpgmeError
gpgme_data_rewind (GpgmeData dh)
{
  if (!dh)
    return mk_error (Invalid_Value);

  switch (dh->type)
    {
    case GPGME_DATA_TYPE_NONE:
    case GPGME_DATA_TYPE_MEM:
      dh->readpos = 0;
      return 0;

    case GPGME_DATA_TYPE_CB:
      dh->len = dh->readpos = 0;
      dh->read_cb_eof = 0;
      if (dh->read_cb (dh->read_cb_value, NULL, 0, NULL))
	return mk_error (Not_Implemented);
      return 0;

    default:
      return mk_error (General_Error);
    }
}

/**
 * gpgme_data_read:
 * @dh: the data object
 * @buffer: A buffer 
 * @length: The length of that bufer
 * @nread: Returns the number of bytes actually read.
 * 
 * Copy data from the current read position (which may be set by
 * gpgme_data_rewind()) to the supplied @buffer, max. @length bytes
 * are copied and the actual number of bytes are returned in @nread.
 * If there are no more bytes available %GPGME_EOF is returned and @nread
 * is set to 0.
 *
 * With a @buffer of NULL, the function does only return the number of
 * bytes available and does not move the read pointer.  This does only
 * work for certain data types, all other will respond with an
 * %GPGME_Invalid_Type.
 * 
 * Return value: An error code or 0 on success, EOF is indcated by the
 * error code GPGME_EOF.
 **/
GpgmeError
gpgme_data_read (GpgmeData dh, void *buffer, size_t length, size_t *nread)
{
  size_t nbytes;

  if (!dh)
    return mk_error (Invalid_Value);
  
  switch (dh->type)
    {
    case GPGME_DATA_TYPE_MEM:
      nbytes = dh->len - dh->readpos;
      if (!nbytes)
	{
	  *nread = 0;
	  return mk_error(EOF);
        }

      if (!buffer)
	*nread = nbytes;
      else
	{
	  if (nbytes > length)
	    nbytes = length;
	  memcpy (buffer, dh->data + dh->readpos, nbytes);
	  *nread = nbytes;
	  dh->readpos += nbytes;
        }
      return 0;
    
    case GPGME_DATA_TYPE_CB:
      if (!buffer)
	{
	  *nread = 0;
	  return mk_error (Invalid_Type);
        }
      nbytes = dh->len - dh->readpos;
      if (nbytes)
	{
	  /* We have unread data - return this.  */
	  if (nbytes > length)
	    nbytes = length;
	  memcpy (buffer, dh->data + dh->readpos, nbytes);
	  *nread = nbytes;
	  dh->readpos += nbytes;
        }
      else
	{
	  /* Get the data from the callback.  */
	  if (!dh->read_cb || dh->read_cb_eof)
	    { 
	      *nread = 0;
	      return mk_error (EOF);
            }
	  if (dh->read_cb (dh->read_cb_value, buffer, length, nread))
	    {
	      *nread = 0;
	      dh->read_cb_eof = 1;
	      return mk_error (EOF);
	    }
        }
      return 0;
      
    default:
      return mk_error (General_Error);
    }
} 


GpgmeError
_gpgme_data_unread (GpgmeData dh, const char *buffer, size_t length)
{
   if (!dh)
     return mk_error (Invalid_Value);

   if (dh->type == GPGME_DATA_TYPE_MEM)
     {
       /* Check that we don't unread more than we have yet read.  */
       if (dh->readpos < length)
	 return mk_error (Invalid_Value);
       /* No need to use the buffer for this data type.  */
       dh->readpos -= length;
     }
   else
     return mk_error (General_Error);

   return 0;
}


/* 
 * This function does make sense when we know that it contains no nil chars.
 */
char *
_gpgme_data_get_as_string (GpgmeData dh)
{
  char *val = NULL;

  if (dh)
    {
      val = xtrymalloc (dh->len+1);
      if (val)
	{
	  memcpy (val, dh->data, dh->len);
	  val[dh->len] = 0;
        }
    }
  return val;
}


/**
 * gpgme_data_write:
 * @dh: the context
 * @buffer: data to be written to the data object
 * @length: length of this data
 * 
 * Write the content of @buffer to the data object @dh at the current write
 * position. 
 * 
 * Return value: 0 on success or an error code
 **/
GpgmeError
gpgme_data_write (GpgmeData dh, const void *buffer, size_t length)
{
  if (!dh || !buffer)
    return mk_error (Invalid_Value);
      
  return _gpgme_data_append (dh, (const char *)buffer, length );
}


GpgmeError
_gpgme_data_append (GpgmeData dh, const char *buffer, size_t length)
{
  assert (dh);

  if (dh->type == GPGME_DATA_TYPE_NONE)
    {
      /* Convert it to a mem data type.  */
      assert (!dh->private_buffer);
      dh->type = GPGME_DATA_TYPE_MEM;
      dh->private_len = length < ALLOC_CHUNK? ALLOC_CHUNK : length;
      dh->private_buffer = xtrymalloc (dh->private_len);
      if (!dh->private_buffer)
	{
	  dh->private_len = 0;
	  return mk_error (Out_Of_Core);
        }
      dh->writepos = 0;
      dh->data = dh->private_buffer;
    }
  else if (dh->type != GPGME_DATA_TYPE_MEM)
    return mk_error (Invalid_Type);
    
  if (dh->mode != GPGME_DATA_MODE_INOUT 
      && dh->mode != GPGME_DATA_MODE_IN)
    return mk_error (Invalid_Mode);

  if (!dh->private_buffer)
    {
      /* We have to copy it now.  */
      assert (dh->data);
      dh->private_len = dh->len+length;
      if (dh->private_len < ALLOC_CHUNK)
	dh->private_len = ALLOC_CHUNK;
      dh->private_buffer = xtrymalloc (dh->private_len);
      if (!dh->private_buffer)
	{
	  dh->private_len = 0;
	  return mk_error (Out_Of_Core);
        }
      memcpy (dh->private_buffer, dh->data, dh->len);
      dh->writepos = dh->len;
      dh->data = dh->private_buffer;
    }

    /* Allocate more memory if needed.  */
  if (dh->writepos + length > dh->private_len)
    {
      char *p;
      size_t newlen = dh->private_len
	+ (length < ALLOC_CHUNK? ALLOC_CHUNK : length);
      p = xtryrealloc (dh->private_buffer, newlen);
      if (!p) 
	return mk_error (Out_Of_Core);
      dh->private_buffer = p;
      dh->private_len = newlen;
      dh->data = dh->private_buffer;
      assert (!(dh->writepos + length > dh->private_len));
    }

  memcpy (dh->private_buffer + dh->writepos, buffer, length);
  dh->writepos += length;
  dh->len += length;

  return 0;
}


GpgmeError
_gpgme_data_append_string (GpgmeData dh, const char *s)
{
  return _gpgme_data_append (dh, s, s ? strlen(s) : 0);
}


GpgmeError
_gpgme_data_append_for_xml (GpgmeData dh,
			    const char *buffer, size_t len)
{
  const char *text, *s;
  size_t n;
  int rc = 0; 
       
  if (!dh || !buffer)
    return mk_error (Invalid_Value);

  do
    {
      for (text=NULL, s = buffer, n = len; n && !text; s++, n--)
	{
	  if (*s == '<') 
	    text = "&lt;";
	  else if (*s == '>')
	    text = "&gt;";  /* Not sure whether this is really needed.  */
	  else if (*s == '&')
	    text = "&amp;";
	  else if (!*s)
	    text = "&#00;";
        }
      if (text)
	{
	  s--;
	  n++;
        }
      if (s != buffer) 
	rc = _gpgme_data_append (dh, buffer, s-buffer);
      if (!rc && text)
	{
	  rc = _gpgme_data_append_string (dh, text);
	  s++;
	  n--;
        }
      buffer = s;
      len = n;
    }
  while (!rc && len);
  return rc;
}


/*
 * Append a string to DATA and convert it so that the result will be 
 * valid XML. 
 */
GpgmeError
_gpgme_data_append_string_for_xml (GpgmeData dh, const char *string)
{
  return _gpgme_data_append_for_xml (dh, string, strlen (string));
}


static int
hextobyte(const byte *s)
{
  int c;

  if (*s >= '0' && *s <= '9')
    c = 16 * (*s - '0');
  else if (*s >= 'A' && *s <= 'F')
    c = 16 * (10 + *s - 'A');
  else if (*s >= 'a' && *s <= 'f')
    c = 16 * (10 + *s - 'a');
  else
    return -1;
  s++;
  if (*s >= '0' && *s <= '9')
    c += *s - '0';
  else if (*s >= 'A' && *s <= 'F')
    c += 10 + *s - 'A';
  else if (*s >= 'a' && *s <= 'f')
    c += 10 + *s - 'a';
  else
    return -1;
  return c;
}

/* 
 * Append a string with percent style (%XX) escape characters as XML.
 */
GpgmeError
_gpgme_data_append_percentstring_for_xml (GpgmeData dh, const char *string)
{
  const byte *s;
  byte *buf, *d;
  int val;
  GpgmeError err;

  d = buf = xtrymalloc (strlen (string));
  for (s = string; *s; s++)
    {
      if (*s == '%' && (val = hextobyte (s+1)) != -1)
	{
	  *d++ = val;
	  s += 2;
        }
      else
	*d++ = *s;
    }

  err = _gpgme_data_append_for_xml (dh, buf, d - buf);
  xfree (buf);
  return err;
}

/* Functions to support the wait interface.  */

void
_gpgme_data_inbound_handler (void *opaque, int fd)
{
  GpgmeData dh = opaque;
  GpgmeError err;
  int nread;
  char buf[200];

  assert (_gpgme_data_get_mode (dh) == GPGME_DATA_MODE_IN);

  nread = _gpgme_io_read (fd, buf, 200);
  if (nread < 0)
    {
      DEBUG3 ("read_mem_data: read failed on fd %d (n=%d): %s",
	      fd, nread, strerror (errno) );
      _gpgme_io_close (fd);	/* XXX ??? */
      return;
    }
  else if (!nread)
    {
      _gpgme_io_close (fd);
      return; /* eof */
    }
  /* We could improve this with a GpgmeData function which takes
   * the read function or provides a memory area for writing to it.
   */
    
  err = _gpgme_data_append (dh, buf, nread);
  if (err)
    {
      DEBUG1 ("_gpgme_append_data failed: %s\n",
	      gpgme_strerror(err));
      /* Fixme: we should close the pipe or read it to /dev/null in
       * this case. Returnin EOF is not sufficient */
      _gpgme_io_close (fd);	/* XXX ??? */
      return;
    }

  return;
}

static int
write_mem_data (GpgmeData dh, int fd)
{
  size_t nbytes;
  int nwritten; 

  nbytes = dh->len - dh->readpos;
  if (!nbytes)
    {
      return 1;
    }
    
  /* FIXME: Arggg, the pipe blocks on large write request, although
   * select told us that it is okay to write - need to figure out
   * why this happens?  Stevens says nothing about this problem (or
   * is it my Linux kernel 2.4.0test1)
   * To avoid that we have set the pipe to nonblocking.
   */

  nwritten = _gpgme_io_write (fd, dh->data+dh->readpos, nbytes);
  if (nwritten == -1 && errno == EAGAIN)
    return 0;
  if (nwritten < 1)
    {
      DEBUG3 ("write_mem_data(%d): write failed (n=%d): %s",
	      fd, nwritten, strerror (errno));
      return 1;
    }

  dh->readpos += nwritten;
  return 0;
}

static int
write_cb_data (GpgmeData dh, int fd)
{
  size_t nbytes;
  int  err, nwritten; 
  char buffer[512];

  err = gpgme_data_read (dh, buffer, DIM(buffer), &nbytes);
  if (err == GPGME_EOF)
    {
      return 1;
    }
    
  nwritten = _gpgme_io_write (fd, buffer, nbytes);
  if (nwritten == -1 && errno == EAGAIN )
    return 0;
  if (nwritten < 1)
    {
      DEBUG3 ("write_cb_data(%d): write failed (n=%d): %s",
	      fd, nwritten, strerror (errno));
      return 1;
    }

  if (nwritten < nbytes)
    {
      /* ugly, ugly: It does currently only for for MEM type data */
      if (_gpgme_data_unread (dh, buffer + nwritten, nbytes - nwritten))
	DEBUG1 ("wite_cb_data: unread of %d bytes failed\n",
		nbytes - nwritten);
      return 1;
    }
  
  return 0;
}

void
_gpgme_data_outbound_handler (void *opaque, int fd)
{
  GpgmeData dh = opaque;

  assert (_gpgme_data_get_mode (dh) == GPGME_DATA_MODE_OUT);
  switch (gpgme_data_get_type (dh))
    {
    case GPGME_DATA_TYPE_MEM:
      if (write_mem_data (dh, fd))
	_gpgme_io_close (fd);
      break;
    case GPGME_DATA_TYPE_CB:
      if (write_cb_data (dh, fd))
	_gpgme_io_close (fd);
      break;
    default:
      assert (0);
    }
}