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/* GNU Mailutils -- a suite of utilities for electronic mail
Copyright (C) 2009-2025 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 <string.h>
#include <mailutils/errno.h>
#include <mailutils/filter.h>
/* CRLF filter.
In decode mode, translates each \r\n to \n. Takes no arguments.
In encode mode, translates each \n to \r\n. If created with the
"-n" option, leaves each \r\n input sequence untranslated, thereby
"normalizing" the output (hence the option name).
*/
enum crlf_state
{
state_init,
state_cr
};
struct crlf_encoder_state
{
enum crlf_state cur;
enum crlf_state last;
};
/* Move min(isize,osize) bytes from iptr to optr, replacing each \n
with \r\n. If state->last is state_cr, any input \r\n sequences
remain untouched, otherwise \r is treated as a regular character. */
static enum mu_filter_result
_crlf_encoder (void *xd,
enum mu_filter_command cmd,
struct mu_filter_io *iobuf)
{
size_t i, j;
const unsigned char *iptr;
size_t isize;
char *optr;
size_t osize;
struct crlf_encoder_state *state = xd;
switch (cmd)
{
case mu_filter_init:
state->cur = state_init;
case mu_filter_done:
return mu_filter_ok;
default:
break;
}
iptr = (const unsigned char *) iobuf->input;
isize = iobuf->isize;
optr = iobuf->output;
osize = iobuf->osize;
for (i = j = 0; i < isize && j < osize; i++)
{
unsigned char c = *iptr++;
if (c == '\n')
{
if (state->cur == state_cr)
{
state->cur = state_init;
optr[j++] = c;
}
else if (j + 1 == osize)
{
if (i == 0)
{
iobuf->osize += 2;
return mu_filter_moreoutput;
}
break;
}
else
{
optr[j++] = '\r';
optr[j++] = '\n';
}
}
else if (c == '\r' && state->last == state_cr)
{
state->cur = state_cr;
optr[j++] = c;
}
else
{
state->cur = state_init;
optr[j++] = c;
}
}
iobuf->isize = i;
iobuf->osize = j;
return mu_filter_ok;
}
/* Move min(isize,osize) bytes from iptr to optr, replacing each \r\n
with \n. */
static enum mu_filter_result
_crlf_decoder (void *xd MU_ARG_UNUSED,
enum mu_filter_command cmd,
struct mu_filter_io *iobuf)
{
size_t i, j;
const unsigned char *iptr;
size_t isize;
char *optr;
size_t osize;
switch (cmd)
{
case mu_filter_init:
case mu_filter_done:
return mu_filter_ok;
default:
break;
}
iptr = (const unsigned char *) iobuf->input;
isize = iobuf->isize;
optr = iobuf->output;
osize = iobuf->osize;
for (i = j = 0; i < isize && j < osize; i++)
{
unsigned char c = *iptr++;
if (c == '\r')
{
if (i + 1 == isize)
break;
if (*iptr == '\n')
continue;
}
optr[j++] = c;
}
iobuf->isize = i;
iobuf->osize = j;
return mu_filter_ok;
}
static int
alloc_state (void **pret, int mode, int argc, const char **argv)
{
struct crlf_encoder_state *st;
switch (mode)
{
case MU_FILTER_ENCODE:
st = malloc (sizeof (*st));
if (!st)
return ENOMEM;
st->cur = state_init;
if (argc == 2 && strcmp (argv[1], "-n") == 0)
st->last = state_cr;
else
st->last = state_init;
*pret = st;
break;
case MU_FILTER_DECODE:
*pret = NULL;
}
return 0;
}
static struct _mu_filter_record _crlf_filter = {
"CRLF",
alloc_state,
_crlf_encoder,
_crlf_decoder
};
mu_filter_record_t mu_crlf_filter = &_crlf_filter;
/* For compatibility with previous versions */
static struct _mu_filter_record _rfc822_filter = {
"RFC822",
alloc_state,
_crlf_encoder,
_crlf_decoder
};
mu_filter_record_t mu_rfc822_filter = &_rfc822_filter;
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