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/*
* Copyright (C) 2003-2014 The Music Player Daemon Project
* http://www.musicpd.org
*
* 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include "TagString.hxx"
#include "util/Alloc.hxx"
#include "util/WritableBuffer.hxx"
#include "util/UTF8.hxx"
#include <assert.h>
#include <string.h>
#include <stdlib.h>
gcc_pure
static const char *
FindInvalidUTF8(const char *p, const char *const end)
{
while (p < end) {
const size_t s = SequenceLengthUTF8(*p);
if (p + s > end)
/* partial sequence at end of string */
return p;
/* now call the other SequenceLengthUTF8() overload
which also validates the continuations */
const size_t t = SequenceLengthUTF8(p);
assert(s == t);
if (t == 0)
return p;
p += s;
}
return nullptr;
}
/**
* Replace invalid sequences with the question mark.
*/
static WritableBuffer<char>
patch_utf8(const char *src, size_t length, const char *_invalid)
{
/* duplicate the string, and replace invalid bytes in that
buffer */
char *dest = (char *)xmemdup(src, length);
char *const end = dest + length;
char *invalid = dest + (_invalid - src);
do {
*invalid = '?';
const char *__invalid = FindInvalidUTF8(invalid + 1, end);
invalid = const_cast<char *>(__invalid);
} while (invalid != nullptr);
return { dest, length };
}
static WritableBuffer<char>
fix_utf8(const char *str, size_t length)
{
/* check if the string is already valid UTF-8 */
const char *invalid = FindInvalidUTF8(str, str + length);
if (invalid == nullptr)
return nullptr;
/* no, broken - patch invalid sequences */
return patch_utf8(str, length, invalid);
}
static bool
char_is_non_printable(unsigned char ch)
{
return ch < 0x20;
}
static const char *
find_non_printable(const char *p, size_t length)
{
for (size_t i = 0; i < length; ++i)
if (char_is_non_printable(p[i]))
return p + i;
return nullptr;
}
/**
* Clears all non-printable characters, convert them to space.
* Returns nullptr if nothing needs to be cleared.
*/
static WritableBuffer<char>
clear_non_printable(const char *p, size_t length)
{
const char *first = find_non_printable(p, length);
if (first == nullptr)
return nullptr;
char *dest = (char *)xmemdup(p, length);
for (size_t i = first - p; i < length; ++i)
if (char_is_non_printable(dest[i]))
dest[i] = ' ';
return { dest, length };
}
WritableBuffer<char>
FixTagString(const char *p, size_t length)
{
auto utf8 = fix_utf8(p, length);
if (!utf8.IsNull()) {
p = utf8.data;
length = utf8.size;
}
WritableBuffer<char> cleared = clear_non_printable(p, length);
if (cleared.IsNull())
cleared = utf8;
else
free(utf8.data);
return cleared;
}
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