Aegisub/aegisub/libaegisub/common/charset_conv.cpp

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// Copyright (c) 2010, Thomas Goyne <plorkyeran@aegisub.org>
//
// Permission to use, copy, modify, and distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
//
// $Id$
/// @file charset_conv.cpp
/// @brief Wrapper for libiconv to present a more C++-friendly API
/// @ingroup libaegisub
#ifndef LAGI_PRE
#include <assert.h>
#include <map>
#endif
#include "../config.h"
#include <libaegisub/charset_conv.h>
#include <iconv.h>
// Check if we can use advanced fallback capabilities added in GNU's iconv
// implementation
#if !defined(_LIBICONV_VERSION) || _LIBICONV_VERSION < 0x010A || defined(LIBICONV_PLUG)
#define ICONV_POSIX
#endif
#ifdef AGI_ICONV_CONST
#define ICONV_CONST_CAST(a) a
#else
#define ICONV_CONST_CAST(a) const_cast<char **>(a)
#endif
static const iconv_t iconv_invalid = (iconv_t)-1;
static const size_t iconv_failed = (size_t)-1;
namespace {
struct ltstr {
bool operator()(const char* s1, const char* s2) const {
return strcmp(s1, s2) < 0;
}
};
}
/// @brief Map a user-friendly encoding name to the real encoding name
static const char* GetRealEncodingName(const char* name) {
static std::map<const char*, const char*, ltstr> prettyNames;
if (prettyNames.empty()) {
# define ADD(pretty, real) prettyNames[pretty] = real
# include <libaegisub/charsets.def>
# undef ADD
}
std::map<const char*, const char*, ltstr>::iterator real = prettyNames.find(name);
if (real != prettyNames.end()) {
return real->second;
}
return name;
}
namespace agi {
namespace charset {
#ifdef ICONV_POSIX
class IconvWrapper::Converter {
public:
Converter(bool, const char*) { }
size_t operator()(iconv_t cd, const char** inbuf, size_t* inbytesleft, char** outbuf, size_t* outbytesleft) {
return iconv(cd, ICONV_CONST_CAST(inbuf), inbytesleft, outbuf, outbytesleft);
}
};
#else
class IconvWrapper::Converter : public iconv_fallbacks {
private:
bool subst;
char invalidRep[4];
size_t invalidRepSize;
static void fallback(
unsigned int code,
void (*callback) (const char *buf, size_t buflen, void* callback_arg),
void *callback_arg,
void *convPtr)
{
// At some point in the future, this should probably switch to a real mapping
// For now, there's just three cases: BOM to nothing, '\' to itself
// (for Shift-JIS, which does not have \) and everything else to '?'
if (code == 0xFEFF) return;
if (code == 0x5C) callback("\\", 1, callback_arg);
else {
Converter *self = static_cast<Converter *>(convPtr);
callback(self->invalidRep, self->invalidRepSize, callback_arg);
}
}
public:
Converter(bool subst, const char* targetEnc)
: subst(subst)
{
data = this;
mb_to_uc_fallback = NULL;
mb_to_wc_fallback = NULL;
uc_to_mb_fallback = fallback;
wc_to_mb_fallback = NULL;
char sbuff[] = "?";
const char* src = sbuff;
char* dst = invalidRep;
size_t dstLen = 4;
size_t srcLen = 1;
iconv_t cd = iconv_open(GetRealEncodingName(targetEnc), "UTF-8");
assert(cd != iconv_invalid);
size_t res = iconv(cd, ICONV_CONST_CAST(&src), &srcLen, &dst, &dstLen);
assert(res != iconv_failed);
assert(srcLen == 0);
iconv_close(cd);
invalidRepSize = 4 - dstLen;
}
size_t operator()(iconv_t cd, const char** inbuf, size_t* inbytesleft, char** outbuf, size_t* outbytesleft) {
size_t res = iconv(cd, ICONV_CONST_CAST(inbuf), inbytesleft, outbuf, outbytesleft);
if (!subst) return res;
// Save original errno so we can return it rather than the result from iconvctl
int err = errno;
// Some characters in the input string do not exist in the output encoding
if (res == iconv_failed && err == EILSEQ) {
// first try transliteration only
int transliterate = 1;
iconvctl(cd, ICONV_SET_TRANSLITERATE, &transliterate);
res = iconv(cd, ICONV_CONST_CAST(inbuf), inbytesleft, outbuf, outbytesleft);
err = errno;
transliterate = 0;
iconvctl(cd, ICONV_SET_TRANSLITERATE, &transliterate);
}
if (res == iconv_failed && err == EILSEQ) {
// Conversion still failed with transliteration enabled, so try our substitution
iconvctl(cd, ICONV_SET_FALLBACKS, this);
res = iconv(cd, ICONV_CONST_CAST(inbuf), inbytesleft, outbuf, outbytesleft);
err = errno;
iconvctl(cd, ICONV_SET_FALLBACKS, NULL);
}
if (res == iconv_failed && err == E2BIG && *outbytesleft == 0) {
// Check for E2BIG false positives
char buff[4];
size_t buffsize = 4;
char* out = buff;
const char* in = *inbuf;
size_t insize = *inbytesleft;
iconvctl(cd, ICONV_SET_FALLBACKS, this);
res = iconv(cd, ICONV_CONST_CAST(&in), &insize, &out, &buffsize);
// If no bytes of the output buffer were used, the original
// conversion may have been successful
if (buffsize == 4) {
err = errno;
}
else {
res = iconv_failed;
}
iconvctl(cd, ICONV_SET_FALLBACKS, NULL);
}
errno = err;
return res;
}
};
#endif
// Calculate the size of NUL in the given character set
static size_t NulSize(const char* encoding) {
// We need a character set to convert from with a known encoding of NUL
// UTF-8 seems like the obvious choice
iconv_t cd = iconv_open(GetRealEncodingName(encoding), "UTF-8");
assert(cd != iconv_invalid);
char dbuff[4];
char sbuff[] = "";
char* dst = dbuff;
const char* src = sbuff;
size_t dstLen = sizeof(dbuff);
size_t srcLen = 1;
size_t ret = iconv(cd, ICONV_CONST_CAST(&src), &srcLen, &dst, &dstLen);
assert(ret != iconv_failed);
assert(dst - dbuff > 0);
iconv_close(cd);
return dst - dbuff;
}
IconvWrapper::IconvWrapper(const char* sourceEncoding, const char* destEncoding, bool enableSubst)
: toNulLen(0)
, fromNulLen(0)
, conv(NULL)
{
cd = iconv_open(GetRealEncodingName(destEncoding), GetRealEncodingName(sourceEncoding));
if (cd == iconv_invalid) {
throw UnsupportedConversion(std::string("Cannot convert from ") + sourceEncoding + " to " + destEncoding);
}
// These need to be set only after we verify that the source and des
// charsets are valid
toNulLen = NulSize(destEncoding);
fromNulLen = NulSize(sourceEncoding);
conv.reset(new Converter(enableSubst, destEncoding));
}
IconvWrapper::~IconvWrapper() {
if (cd != iconv_invalid) iconv_close(cd);
}
std::string IconvWrapper::Convert(std::string const& source) {
std::string dest;
Convert(source, dest);
return dest;
}
void IconvWrapper::Convert(std::string const& source, std::string &dest) {
/// @todo Investigate if it's worth using ropes to avoid having to convert
/// everything twice. It probably isn't.
size_t len = RequiredBufferSize(source);
dest.resize(len);
// This is technically invalid as C++03 does not require that strings use
// a single contiguous block of memory. However, no implementation has ever
// not done so and C++0x does require that it be contiguous
Convert(source.data(), source.size(), &dest[0], len);
}
size_t IconvWrapper::Convert(const char* source, size_t sourceSize, char *dest, size_t destSize) {
if (sourceSize == (size_t)-1) {
sourceSize = SrcStrLen(source);
}
size_t res = (*conv)(cd, &source, &sourceSize, &dest, &destSize);
if (res == iconv_failed) {
switch (errno) {
case E2BIG:
throw BufferTooSmall(
"Destination buffer was not large enough to fit converted "
"string.");
case EINVAL:
throw BadInput(
"One or more characters in the input string were not valid "
"characters in the given input encoding");
case EILSEQ:
throw BadOutput(
"One or more characters could not be converted to the "
"selected target encoding and the version of iconv "
"Aegisub was built with does not have useful fallbacks. "
"For best results, please build Aegisub using a recent "
"version of GNU iconv.");
default:
throw ConversionFailure("An unknown conversion failure occured");
}
}
return res;
}
size_t IconvWrapper::Convert(const char** source, size_t* sourceSize, char** dest, size_t* destSize) {
return (*conv)(cd, source, sourceSize, dest, destSize);
}
size_t IconvWrapper::RequiredBufferSize(std::string const& str) {
return RequiredBufferSize(str.data(), str.size());
}
size_t IconvWrapper::RequiredBufferSize(const char* src, size_t srcLen) {
char buff[512];
size_t charsWritten = 0;
size_t res;
do {
char* dst = buff;
size_t dstSize = sizeof(buff);
res = (*conv)(cd, &src, &srcLen, &dst, &dstSize);
charsWritten += dst - buff;
} while (res == iconv_failed && errno == E2BIG);
if (res == iconv_failed) {
switch (errno) {
case EINVAL:
throw BadInput(
"One or more characters in the input string were not valid "
"characters in the given input encoding");
case EILSEQ:
throw BadOutput(
"One or more characters could not be converted to the "
"selected target encoding and the version of iconv "
"Aegisub was built with does not have useful fallbacks. "
"For best results, please build Aegisub using a recent "
"version of GNU iconv.");
default:
throw ConversionFailure("An unknown conversion failure occured");
}
}
return charsWritten;
}
static size_t mbstrlen(const char* str, size_t nulLen) {
const char *ptr;
switch (nulLen) {
case 1:
return strlen(str);
case 2:
for (ptr = str; *reinterpret_cast<const uint16_t *>(ptr) != 0; ptr += 2) ;
return ptr - str;
case 4:
for (ptr = str; *reinterpret_cast<const uint32_t *>(ptr) != 0; ptr += 4) ;
return ptr - str;
default:
return (size_t)-1;
}
}
size_t IconvWrapper::SrcStrLen(const char* str) {
return mbstrlen(str, fromNulLen);
}
size_t IconvWrapper::DstStrLen(const char* str) {
return mbstrlen(str, toNulLen);
}
}
}