c-escape.c
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/* GNU Mailutils -- a suite of utilities for electronic mail
Copyright (C) 2011-2012, 2014 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 of the License, 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 this library. If not, see
<http://www.gnu.org/licenses/>. */
/* A C-escape filter.
In encode mode, replaces control characters with their C escapes.
For example, newline (ASCII 10) becomes \n, horizontal tab (ASCII 9)
becomes \t etc.
In decode mode, the reverse operation is performed, i.e. each C escape
is replaced with the corresponding character. Unrecognized escape
sequences are copied verbatim.
FIXME: Only named escapes are supported.
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <mailutils/errno.h>
#include <mailutils/filter.h>
#include <mailutils/wordsplit.h>
#include <mailutils/cctype.h>
/* Move min(isize,osize) bytes from iptr to optr, replacing each
escapable control character with its escape sequence. */
static enum mu_filter_result
_c_escape_encoder (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 (mu_iscntrl (c))
{
int x;
x = mu_wordsplit_c_quote_char (c);
if (x == -1)
optr[j++] = c;
else if (j + 1 == osize)
{
if (i == 0)
{
iobuf->osize = 2;
return mu_filter_moreoutput;
}
break;
}
else
{
optr[j++] = '\\';
optr[j++] = x;
}
}
else
optr[j++] = c;
}
iobuf->isize = i;
iobuf->osize = j;
return mu_filter_ok;
}
/* Move min(isize,osize) bytes from iptr to optr, replacing each escape
sequence with its ASCII code. */
static enum mu_filter_result
_c_escape_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 == '\\')
{
int x;
if (i + 1 == isize)
break;
c = *iptr++;
i++;
x = mu_wordsplit_c_unquote_char (c);
optr[j++] = (x == -1) ? c : x;
}
else
optr[j++] = c;
}
iobuf->isize = i;
iobuf->osize = j;
return mu_filter_ok;
}
static struct _mu_filter_record _c_escape_filter = {
"C-escape",
NULL,
_c_escape_encoder,
_c_escape_decoder,
};
mu_filter_record_t mu_c_escape_filter = &_c_escape_filter;