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mpv/misc/charset_conv.c

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/*
* This file is part of mpv.
*
* Based on code taken from libass (ISC license), which was originally part
* of MPlayer (GPL).
* Copyright (C) 2006 Evgeniy Stepanov <eugeni.stepanov@gmail.com>
*
* mpv 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.
*
* mpv 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 mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <errno.h>
#include <strings.h>
#include <assert.h>
#include "config.h"
#include "common/msg.h"
#if HAVE_ENCA
#include <enca.h>
#endif
#if HAVE_LIBGUESS
#include <libguess.h>
#endif
#if HAVE_UCHARDET
#include <uchardet.h>
#endif
#if HAVE_ICONV
#include <iconv.h>
#endif
#include "charset_conv.h"
bool mp_charset_is_utf8(const char *user_cp)
{
return user_cp && (strcasecmp(user_cp, "utf8") == 0 ||
strcasecmp(user_cp, "utf-8") == 0);
}
bool mp_charset_is_utf16(const char *user_cp)
{
bstr s = bstr0(user_cp);
return bstr_case_startswith(s, bstr0("utf16")) ||
bstr_case_startswith(s, bstr0("utf-16"));
}
// Split the string on ':' into components.
// out_arr is at least max entries long.
// Return number of out_arr entries filled.
static int split_colon(const char *user_cp, int max, bstr *out_arr)
{
if (!user_cp || max < 1)
return 0;
int count = 0;
while (1) {
const char *next = strchr(user_cp, ':');
if (next && max - count > 1) {
out_arr[count++] = (bstr){(char *)user_cp, next - user_cp};
user_cp = next + 1;
} else {
out_arr[count++] = (bstr){(char *)user_cp, strlen(user_cp)};
break;
}
}
return count;
}
// Returns true if user_cp implies that calling mp_charset_guess() on the
// input data is required to determine the real codepage. This is the case
// if user_cp is not a real iconv codepage, but a magic value that requests
// for example ENCA charset auto-detection.
bool mp_charset_requires_guess(const char *user_cp)
{
bstr res[2] = {{0}};
int r = split_colon(user_cp, 2, res);
// Note that "utf8" is the UTF-8 codepage, while "utf8:..." specifies UTF-8
// by default, plus a codepage that is used if the input is not UTF-8.
return bstrcasecmp0(res[0], "enca") == 0 ||
bstrcasecmp0(res[0], "uchardet") == 0 ||
bstrcasecmp0(res[0], "auto") == 0 ||
bstrcasecmp0(res[0], "guess") == 0 ||
(r > 1 && bstrcasecmp0(res[0], "utf-8") == 0) ||
(r > 1 && bstrcasecmp0(res[0], "utf8") == 0);
}
static const char *const utf_bom[3] = {"\xEF\xBB\xBF", "\xFF\xFE", "\xFE\xFF"};
static const char *const utf_enc[3] = {"utf-8", "utf-16le", "utf-16be"};
static const char *ms_bom_guess(bstr buf)
{
for (int n = 0; n < 3; n++) {
if (bstr_startswith0(buf, utf_bom[n]))
return utf_enc[n];
}
return NULL;
}
#if HAVE_ENCA
static const char *enca_guess(struct mp_log *log, bstr buf, const char *language)
{
// Do our own UTF-8 detection, because ENCA seems to get it wrong sometimes
// (suggested by divVerent). Explicitly allow cut-off UTF-8.
if (bstr_validate_utf8(buf) > -8)
return "UTF-8";
if (!language || !language[0])
language = "__"; // neutral language
const char *detected_cp = NULL;
EncaAnalyser analyser = enca_analyser_alloc(language);
if (analyser) {
enca_set_termination_strictness(analyser, 0);
EncaEncoding enc = enca_analyse_const(analyser, buf.start, buf.len);
const char *tmp = enca_charset_name(enc.charset, ENCA_NAME_STYLE_ICONV);
if (tmp && enc.charset != ENCA_CS_UNKNOWN)
detected_cp = tmp;
enca_analyser_free(analyser);
} else {
mp_err(log, "ENCA doesn't know language '%s'\n", language);
size_t langcnt;
const char **languages = enca_get_languages(&langcnt);
mp_err(log, "ENCA supported languages:");
for (int i = 0; i < langcnt; i++)
mp_err(log, " %s", languages[i]);
mp_err(log, "\n");
free(languages);
}
return detected_cp;
}
#endif
#if HAVE_LIBGUESS
static const char *libguess_guess(struct mp_log *log, bstr buf,
const char *language)
{
if (!language || !language[0] || strcmp(language, "help") == 0) {
mp_err(log, "libguess needs a language: "
"japanese taiwanese chinese korean russian arabic turkish "
"greek hebrew polish baltic\n");
return NULL;
}
return libguess_determine_encoding(buf.start, buf.len, language);
}
#endif
#if HAVE_UCHARDET
static const char *mp_uchardet(void *talloc_ctx, struct mp_log *log, bstr buf)
{
uchardet_t det = uchardet_new();
if (!det)
return NULL;
if (uchardet_handle_data(det, buf.start, buf.len) != 0) {
uchardet_delete(det);
return NULL;
}
uchardet_data_end(det);
char *res = talloc_strdup(talloc_ctx, uchardet_get_charset(det));
if (res && !res[0])
res = NULL;
if (res) {
iconv_t icdsc = iconv_open("UTF-8", res);
if (icdsc == (iconv_t)(-1)) {
mp_warn(log, "Charset detected as %s, but not supported by iconv.\n",
res);
res = NULL;
} else {
iconv_close(icdsc);
}
}
if (!res && bstr_validate_utf8(buf) >= 0)
res = "utf-8";
uchardet_delete(det);
return res;
}
#endif
// Runs charset auto-detection on the input buffer, and returns the result.
// If auto-detection fails, NULL is returned.
// If user_cp doesn't refer to any known auto-detection (for example because
// it's a real iconv codepage), user_cp is returned without even looking at
// the buf data.
// The return value may (but doesn't have to) be allocated under talloc_ctx.
const char *mp_charset_guess(void *talloc_ctx, struct mp_log *log, bstr buf,
const char *user_cp, int flags)
{
if (!mp_charset_requires_guess(user_cp))
return user_cp;
bool use_auto = strcasecmp(user_cp, "auto") == 0;
if (use_auto) {
#if HAVE_UCHARDET
user_cp = "uchardet";
#elif HAVE_ENCA
user_cp = "enca";
#else
user_cp = "UTF-8:UTF-8-BROKEN";
#endif
}
bstr params[3] = {{0}};
split_colon(user_cp, 3, params);
bstr type = params[0];
char lang[100];
snprintf(lang, sizeof(lang), "%.*s", BSTR_P(params[1]));
const char *fallback = params[2].start; // last item, already 0-terminated
const char *res = NULL;
if (use_auto) {
res = ms_bom_guess(buf);
if (res)
type = bstr0("auto");
}
#if HAVE_ENCA
if (bstrcasecmp0(type, "enca") == 0)
res = enca_guess(log, buf, lang);
#endif
#if HAVE_LIBGUESS
if (bstrcasecmp0(type, "guess") == 0)
res = libguess_guess(log, buf, lang);
#endif
#if HAVE_UCHARDET
if (bstrcasecmp0(type, "uchardet") == 0)
res = mp_uchardet(talloc_ctx, log, buf);
#endif
if (bstrcasecmp0(type, "utf8") == 0 || bstrcasecmp0(type, "utf-8") == 0) {
if (!fallback)
fallback = params[1].start; // must be already 0-terminated
int r = bstr_validate_utf8(buf);
if (r >= 0 || (r > -8 && (flags & MP_ICONV_ALLOW_CUTOFF)))
res = "utf-8";
}
if (res) {
mp_dbg(log, "%.*s detected charset: '%s'\n", BSTR_P(type), res);
} else {
res = fallback;
mp_dbg(log, "Detection with %.*s failed: fallback to %s\n",
BSTR_P(type), res && res[0] ? res : "broken UTF-8/Latin1");
}
if (!res && !(flags & MP_STRICT_UTF8))
res = "UTF-8-BROKEN";
mp_verbose(log, "Using charset '%s'.\n", res);
return res;
}
// Use iconv to convert buf to UTF-8.
// Returns buf.start==NULL on error. Returns buf if cp is NULL, or if there is
// obviously no conversion required (e.g. if cp is "UTF-8").
// Returns a newly allocated buffer if conversion is done and succeeds. The
// buffer will be terminated with 0 for convenience (the terminating 0 is not
// included in the returned length).
// Free the returned buffer with talloc_free().
// buf: input data
// cp: iconv codepage (or NULL)
// flags: combination of MP_ICONV_* flags
// returns: buf (no conversion), .start==NULL (error), or allocated buffer
bstr mp_iconv_to_utf8(struct mp_log *log, bstr buf, const char *cp, int flags)
{
#if HAVE_ICONV
if (!cp || !cp[0] || mp_charset_is_utf8(cp))
return buf;
if (strcasecmp(cp, "ASCII") == 0)
return buf;
if (strcasecmp(cp, "UTF-8-BROKEN") == 0)
return bstr_sanitize_utf8_latin1(NULL, buf);
iconv_t icdsc;
if ((icdsc = iconv_open("UTF-8", cp)) == (iconv_t) (-1)) {
if (flags & MP_ICONV_VERBOSE)
mp_err(log, "Error opening iconv with codepage '%s'\n", cp);
goto failure;
}
size_t size = buf.len;
size_t osize = size;
size_t ileft = size;
size_t oleft = size - 1;
char *outbuf = talloc_size(NULL, osize);
char *ip = buf.start;
char *op = outbuf;
while (1) {
int clear = 0;
size_t rc;
if (ileft)
rc = iconv(icdsc, &ip, &ileft, &op, &oleft);
else {
clear = 1; // clear the conversion state and leave
rc = iconv(icdsc, NULL, NULL, &op, &oleft);
}
if (rc == (size_t) (-1)) {
if (errno == E2BIG) {
size_t offset = op - outbuf;
outbuf = talloc_realloc_size(NULL, outbuf, osize + size);
op = outbuf + offset;
osize += size;
oleft += size;
} else {
if (errno == EINVAL && (flags & MP_ICONV_ALLOW_CUTOFF)) {
// This is intended for cases where the input buffer is cut
// at a random byte position. If this happens in the middle
// of the buffer, it should still be an error. We say it's
// fine if the error is within 10 bytes of the end.
if (ileft <= 10)
break;
}
if (flags & MP_ICONV_VERBOSE) {
mp_err(log, "Error recoding text with codepage '%s'\n", cp);
}
talloc_free(outbuf);
iconv_close(icdsc);
goto failure;
}
} else if (clear)
break;
}
iconv_close(icdsc);
outbuf[osize - oleft - 1] = 0;
return (bstr){outbuf, osize - oleft - 1};
#endif
failure:
return (bstr){0};
}
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