streamcpy.c
2.7 KB
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/* GNU Mailutils -- a suite of utilities for electronic mail
Copyright (C) 2009, 2010, 2011 Free Software Foundation, Inc.
This library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
This library 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with GNU Mailutils. If not, see <http://www.gnu.org/licenses/>. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdlib.h>
#include <mailutils/types.h>
#include <mailutils/alloc.h>
#include <mailutils/error.h>
#include <mailutils/errno.h>
#include <mailutils/stream.h>
#include <mailutils/sys/stream.h>
#define STREAMCPY_MIN_BUF_SIZE 2
#define STREAMCPY_MAX_BUF_SIZE 16384
/* Copy SIZE bytes from SRC to DST. If SIZE is 0, copy everything up to
EOF. */
int
mu_stream_copy (mu_stream_t dst, mu_stream_t src, mu_off_t size,
mu_off_t *pcsz)
{
int status;
size_t bufsize, n;
char *buf;
mu_off_t total = 0;
if (pcsz)
*pcsz = 0;
if (size == 0)
{
status = mu_stream_size (src, &size);
switch (status)
{
case 0:
break;
case ENOSYS:
size = 0;
break;
default:
return status;
}
if (size)
{
mu_off_t pos;
status = mu_stream_seek (src, 0, MU_SEEK_CUR, &pos);
switch (status)
{
case 0:
if (pos > size)
return ESPIPE;
size -= pos;
break;
case EACCES:
mu_stream_clearerr (src);
case ENOSYS:
size = 0;
break;
default:
return status;
}
}
}
bufsize = size;
if (!bufsize)
bufsize = STREAMCPY_MAX_BUF_SIZE;
for (; (buf = malloc (bufsize)) == NULL; bufsize >>= 1)
if (bufsize < STREAMCPY_MIN_BUF_SIZE)
return ENOMEM;
if (size)
while (size)
{
size_t rdsize = bufsize < size ? bufsize : size;
status = mu_stream_read (src, buf, rdsize, &n);
if (status)
break;
if (n == 0)
break;
status = mu_stream_write (dst, buf, n, NULL);
if (status)
break;
size -= n;
total += n;
}
else
while ((status = mu_stream_read (src, buf, bufsize, &n)) == 0
&& n > 0)
{
status = mu_stream_write (dst, buf, n, NULL);
if (status)
break;
total += n;
}
if (pcsz)
*pcsz = total;
/* FIXME: When EOF error code is implemented:
else if (total == 0)
status = EOF;
*/
free (buf);
return status;
}