146 lines
3.3 KiB
C++
146 lines
3.3 KiB
C++
/*
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* Copyright 2003-2021 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "FixString.hxx"
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#include "util/AllocatedArray.hxx"
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#include "util/CharUtil.hxx"
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#include "util/WritableBuffer.hxx"
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#include "util/StringView.hxx"
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#include "util/UTF8.hxx"
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#include <algorithm>
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#include <cassert>
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#include <stdlib.h>
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[[gnu::pure]]
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static const char *
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FindInvalidUTF8(const char *p, const char *const end) noexcept
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{
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while (p < end) {
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const size_t s = SequenceLengthUTF8(*p);
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if (p + s > end)
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/* partial sequence at end of string */
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return p;
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/* now call the other SequenceLengthUTF8() overload
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which also validates the continuations */
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const size_t t = SequenceLengthUTF8(p);
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if (t == 0)
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return p;
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assert(s == t);
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p += s;
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}
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return nullptr;
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}
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/**
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* Replace invalid sequences with the question mark.
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*/
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static AllocatedArray<char>
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patch_utf8(StringView src, const char *_invalid)
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{
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/* duplicate the string, and replace invalid bytes in that
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buffer */
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AllocatedArray<char> dest{src};
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char *const end = dest.data() + src.size;
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char *invalid = dest.data() + (_invalid - src.data);
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do {
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*invalid = '?';
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const char *__invalid = FindInvalidUTF8(invalid + 1, end);
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invalid = const_cast<char *>(__invalid);
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} while (invalid != nullptr);
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return dest;
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}
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static AllocatedArray<char>
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fix_utf8(StringView p)
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{
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/* check if the string is already valid UTF-8 */
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const char *invalid = FindInvalidUTF8(p.begin(), p.end());
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if (invalid == nullptr)
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return nullptr;
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/* no, broken - patch invalid sequences */
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return patch_utf8(p, invalid);
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}
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static const char *
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find_non_printable(StringView p)
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{
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for (const char &ch : p)
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if (IsNonPrintableASCII(ch))
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return &ch;
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return nullptr;
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}
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/**
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* Clears all non-printable characters, convert them to space.
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* Returns nullptr if nothing needs to be cleared.
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*/
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static AllocatedArray<char>
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clear_non_printable(StringView src)
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{
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const char *first = find_non_printable(src);
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if (first == nullptr)
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return nullptr;
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AllocatedArray<char> dest{src};
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for (size_t i = first - src.data; i < src.size; ++i)
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if (IsNonPrintableASCII(dest[i]))
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dest[i] = ' ';
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return dest;
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}
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[[gnu::pure]]
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static bool
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IsSafe(StringView s) noexcept
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{
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return std::all_of(s.begin(), s.end(),
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[](char ch){
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return IsASCII(ch) && IsPrintableASCII(ch);
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});
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}
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AllocatedArray<char>
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FixTagString(StringView p)
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{
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if (IsSafe(p))
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/* optimistic optimization for the common case */
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return nullptr;
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auto utf8 = fix_utf8(p);
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if (utf8 != nullptr)
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p = {utf8.data(), utf8.size()};
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auto cleared = clear_non_printable(p);
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if (cleared == nullptr)
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cleared = std::move(utf8);
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return cleared;
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}
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