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/*
* Copyright 2003-2020 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 "FixString.hxx"
#include "util/Alloc.hxx"
#include "util/CharUtil.hxx"
#include "util/WritableBuffer.hxx"
#include "util/StringView.hxx"
#include "util/UTF8.hxx"
#include <algorithm>
#include <cassert>
#include <stdlib.h>
gcc_pure
static const char *
FindInvalidUTF8(const char *p, const char *const end) noexcept
{
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);
if (t == 0)
return p;
assert(s == t);
p += s;
}
return nullptr;
}
/**
* Replace invalid sequences with the question mark.
*/
static WritableBuffer<char>
patch_utf8(StringView src, const char *_invalid)
{
/* duplicate the string, and replace invalid bytes in that
buffer */
char *dest = (char *)xmemdup(src.data, src.size);
char *const end = dest + src.size;
char *invalid = dest + (_invalid - src.data);
do {
*invalid = '?';
const char *__invalid = FindInvalidUTF8(invalid + 1, end);
invalid = const_cast<char *>(__invalid);
} while (invalid != nullptr);
return { dest, src.size };
}
static WritableBuffer<char>
fix_utf8(StringView p)
{
/* check if the string is already valid UTF-8 */
const char *invalid = FindInvalidUTF8(p.begin(), p.end());
if (invalid == nullptr)
return nullptr;
/* no, broken - patch invalid sequences */
return patch_utf8(p, invalid);
}
static const char *
find_non_printable(StringView p)
{
for (const char &ch : p)
if (IsNonPrintableASCII(ch))
return &ch;
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(StringView src)
{
const char *first = find_non_printable(src);
if (first == nullptr)
return nullptr;
char *dest = (char *)xmemdup(src.data, src.size);
for (size_t i = first - src.data; i < src.size; ++i)
if (IsNonPrintableASCII(dest[i]))
dest[i] = ' ';
return { dest, src.size };
}
gcc_pure
static bool
IsSafe(StringView s) noexcept
{
return std::all_of(s.begin(), s.end(),
[](char ch){
return IsASCII(ch) && IsPrintableASCII(ch);
});
}
WritableBuffer<char>
FixTagString(StringView p)
{
if (IsSafe(p))
/* optimistic optimization for the common case */
return nullptr;
auto utf8 = fix_utf8(p);
if (!utf8.IsNull())
p = {utf8.data, utf8.size};
WritableBuffer<char> cleared = clear_non_printable(p);
if (cleared.IsNull())
cleared = utf8;
else
free(utf8.data);
return cleared;
}
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