Conversion between different character encodings. More...

#include "config.h"
#include <errno.h>
#include <iconv.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include "mutt/lib.h"
#include "email/lib.h"
#include "lib.h"

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Functions
size_t	mutt_convert_file_to (FILE fp, const char fromcode, struct Slist const const tocodes, int tocode, struct Content *info)
	Change the encoding of a file.

size_t	mutt_convert_file_from_to (FILE fp, const struct Slist fromcodes, const struct Slist tocodes, char fromcode, char tocode, struct Content info)
	Convert a file between encodings.

Detailed Description

Conversion between different character encodings.

Authors

Michal Siedlaczek
Richard Russon

Copyright: This program 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.

This program 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 http://www.gnu.org/licenses/.

Definition in file convert.c.

Function Documentation

◆ mutt_convert_file_to()

size_t mutt_convert_file_to	(	FILE *	fp,
		const char *	fromcode,
		struct Slist const *const	tocodes,
		int *	tocode,
		struct Content *	info
	)

Change the encoding of a file.

Parameters

[in]	fp	File to convert
[in]	fromcode	Original encoding
[in]	tocodes	List of target encodings
[out]	tocode	Chosen encoding
[out]	info	Encoding information

Return values

-1	Error, no conversion was possible
>0	Success, number of bytes converted

Find the best charset conversion of the file from fromcode into one of the tocodes. If successful, set *tocode and Content *info and return the number of characters converted inexactly.

We convert via UTF-8 in order to avoid the condition -1(EINVAL), which would otherwise prevent us from knowing the number of inexact conversions. Where the candidate target charset is UTF-8 we avoid doing the second conversion because iconv_open("UTF-8", "UTF-8") fails with some libraries.

We assume that the output from iconv is never more than 4 times as long as the input for any pair of charsets we might be interested in.

Definition at line 64 of file convert.c.

{
  char bufi[256] = { 0 };
  char bufu[512] = { 0 };
  char bufo[4 * sizeof(bufi)] = { 0 };
  size_t rc;
 
  const iconv_t cd1 = mutt_ch_iconv_open("utf-8", fromcode, MUTT_ICONV_NO_FLAGS);
  if (!iconv_t_valid(cd1))
    return -1;
 
  int ncodes = tocodes->count;
  iconv_t *cd = mutt_mem_calloc(ncodes, sizeof(iconv_t));
  size_t *score = mutt_mem_calloc(ncodes, sizeof(size_t));
  struct ContentState *states = mutt_mem_calloc(ncodes, sizeof(struct ContentState));
  struct Content *infos = mutt_mem_calloc(ncodes, sizeof(struct Content));
 
  struct ListNode *np = NULL;
  int ni = 0;
  STAILQ_FOREACH(np, &tocodes->head, entries)
  {
    if (!mutt_istr_equal(np->data, "utf-8"))
    {
      cd[ni] = mutt_ch_iconv_open(np->data, "utf-8", MUTT_ICONV_NO_FLAGS);
    }
    else
    {
      /* Special case for conversion to UTF-8 */
      cd[ni] = ICONV_T_INVALID;
      score[ni] = ICONV_ILLEGAL_SEQ;
    }
    ni += 1;
  }
 
  rewind(fp);
  size_t ibl = 0;
  while (true)
  {
    /* Try to fill input buffer */
    size_t n = fread(bufi + ibl, 1, sizeof(bufi) - ibl, fp);
    ibl += n;
 
    /* Convert to UTF-8 */
    const char *ib = bufi;
    char *ob = bufu;
    size_t obl = sizeof(bufu);
    n = iconv(cd1, (ICONV_CONST char **) ((ibl != 0) ? &ib : 0), &ibl, &ob, &obl);
    if ((n == ICONV_ILLEGAL_SEQ) && (((errno != EINVAL) && (errno != E2BIG)) || (ib == bufi)))
    {
      rc = ICONV_ILLEGAL_SEQ;
      break;
    }
    const size_t ubl1 = ob - bufu;
 
    /* Convert from UTF-8 */
    for (int i = 0; i < ncodes; i++)
    {
      if (iconv_t_valid(cd[i]) && (score[i] != ICONV_ILLEGAL_SEQ))
      {
        const char *ub = bufu;
        size_t ubl = ubl1;
        ob = bufo;
        obl = sizeof(bufo);
        n = iconv(cd[i], (ICONV_CONST char **) ((ibl || ubl) ? &ub : 0), &ubl, &ob, &obl);
        if (n == ICONV_ILLEGAL_SEQ)
        {
          score[i] = ICONV_ILLEGAL_SEQ;
        }
        else
        {
          score[i] += n;
          mutt_update_content_info(&infos[i], &states[i], bufo, ob - bufo);
        }
      }
      else if (!iconv_t_valid(cd[i]) && (score[i] == ICONV_ILLEGAL_SEQ))
      {
        /* Special case for conversion to UTF-8 */
        mutt_update_content_info(&infos[i], &states[i], bufu, ubl1);
      }
    }
 
    if (ibl)
    {
      /* Save unused input */
      memmove(bufi, ib, ibl);
    }
    else if (!ubl1 && (ib < bufi + sizeof(bufi)))
    {
      rc = 0;
      break;
    }
  }
 
  if (rc == 0)
  {
    /* Find best score */
    rc = ICONV_ILLEGAL_SEQ;
    for (int i = 0; i < ncodes; i++)
    {
      if (!iconv_t_valid(cd[i]) && (score[i] == ICONV_ILLEGAL_SEQ))
      {
        /* Special case for conversion to UTF-8 */
        *tocode = i;
        rc = 0;
        break;
      }
      else if (!iconv_t_valid(cd[i]) || (score[i] == ICONV_ILLEGAL_SEQ))
      {
        continue;
      }
      else if ((rc == ICONV_ILLEGAL_SEQ) || (score[i] < rc))
      {
        *tocode = i;
        rc = score[i];
        if (rc == 0)
          break;
      }
    }
    if (rc != ICONV_ILLEGAL_SEQ)
    {
      memcpy(info, &infos[*tocode], sizeof(struct Content));
      mutt_update_content_info(info, &states[*tocode], 0, 0); /* EOF */
    }
  }
 
  FREE(&cd);
  FREE(&infos);
  FREE(&score);
  FREE(&states);
 
  return rc;
}

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◆ mutt_convert_file_from_to()

size_t mutt_convert_file_from_to	(	FILE *	fp,
		const struct Slist *	fromcodes,
		const struct Slist *	tocodes,
		char **	fromcode,
		char **	tocode,
		struct Content *	info
	)

Convert a file between encodings.