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168 lines
5.0 KiB
C++
168 lines
5.0 KiB
C++
// Copyright (c) 2005-2023 Jay Berkenbilt
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//
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// This file is part of qpdf.
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
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// in compliance with the License. You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software distributed under the License
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// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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// or implied. See the License for the specific language governing permissions and limitations under
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// the License.
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//
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// Versions of qpdf prior to version 7 were released under the terms of version 2.0 of the Artistic
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// License. At your option, you may continue to consider qpdf to be licensed under those terms.
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// Please see the manual for additional information.
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#ifndef QPDF_INPUTSOURCE_HH
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#define QPDF_INPUTSOURCE_HH
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#include <qpdf/DLL.h>
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#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
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#include <qpdf/Types.h>
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#include <cstdio>
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#include <memory>
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#include <string>
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// Remember to use QPDF_DLL_CLASS on anything derived from InputSource so it will work with
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// dynamic_cast across the shared object boundary.
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class QPDF_DLL_CLASS InputSource
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{
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public:
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QPDF_DLL
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InputSource()
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{
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}
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QPDF_DLL
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virtual ~InputSource() = default;
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class QPDF_DLL_CLASS Finder
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{
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public:
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QPDF_DLL
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Finder() = default;
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QPDF_DLL
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virtual ~Finder() = default;
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virtual bool check() = 0;
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};
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QPDF_DLL
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void setLastOffset(qpdf_offset_t);
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QPDF_DLL
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qpdf_offset_t getLastOffset() const;
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QPDF_DLL
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std::string readLine(size_t max_line_length);
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// Find first or last occurrence of a sequence of characters starting within the range defined
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// by offset and len such that, when the input source is positioned at the beginning of that
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// sequence, finder.check() returns true. If len is 0, the search proceeds until EOF. If a
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// qualifying pattern is found, these methods return true and leave the input source positioned
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// wherever check() left it at the end of the matching pattern.
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QPDF_DLL
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bool findFirst(char const* start_chars, qpdf_offset_t offset, size_t len, Finder& finder);
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QPDF_DLL
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bool findLast(char const* start_chars, qpdf_offset_t offset, size_t len, Finder& finder);
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virtual qpdf_offset_t findAndSkipNextEOL() = 0;
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virtual std::string const& getName() const = 0;
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virtual qpdf_offset_t tell() = 0;
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virtual void seek(qpdf_offset_t offset, int whence) = 0;
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virtual void rewind() = 0;
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virtual size_t read(char* buffer, size_t length) = 0;
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// Note: you can only unread the character you just read. The specific character is ignored by
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// some implementations, and the implementation doesn't check this. Use of unreadCh is
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// semantically equivalent to seek(-1, SEEK_CUR) but is much more efficient.
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virtual void unreadCh(char ch) = 0;
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// The following methods are for use by QPDFTokenizer
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inline qpdf_offset_t fastTell();
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inline bool fastRead(char&);
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inline void fastUnread(bool);
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inline void loadBuffer();
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protected:
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qpdf_offset_t last_offset{0};
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private:
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class QPDF_DLL_PRIVATE Members
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{
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friend class InputSource;
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public:
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QPDF_DLL
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~Members() = default;
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private:
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Members() = default;
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Members(Members const&) = delete;
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};
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std::shared_ptr<Members> m;
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// State for fast... methods
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static const qpdf_offset_t buf_size = 128;
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char buffer[buf_size];
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qpdf_offset_t buf_len = 0;
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qpdf_offset_t buf_idx = 0;
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qpdf_offset_t buf_start = 0;
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};
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inline void
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InputSource::loadBuffer()
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{
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this->buf_idx = 0;
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this->buf_len = qpdf_offset_t(read(this->buffer, this->buf_size));
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// NB read sets last_offset
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this->buf_start = this->last_offset;
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}
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inline qpdf_offset_t
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InputSource::fastTell()
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{
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if (this->buf_len == 0) {
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loadBuffer();
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} else {
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auto curr = tell();
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if (curr < this->buf_start || curr >= (this->buf_start + this->buf_len)) {
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loadBuffer();
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} else {
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this->last_offset = curr;
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this->buf_idx = curr - this->buf_start;
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}
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}
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return this->last_offset;
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}
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inline bool
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InputSource::fastRead(char& ch)
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{
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// Before calling fastRead, fastTell must be called to prepare the buffer. Once reading is
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// complete, fastUnread must be called to set the correct file position.
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if (this->buf_idx < this->buf_len) {
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ch = this->buffer[this->buf_idx];
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++(this->buf_idx);
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++(this->last_offset);
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return true;
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} else if (this->buf_len == 0) {
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return false;
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} else {
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seek(this->buf_start + this->buf_len, SEEK_SET);
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fastTell();
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return fastRead(ch);
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}
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}
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inline void
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InputSource::fastUnread(bool back)
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{
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this->last_offset -= back ? 1 : 0;
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seek(this->last_offset, SEEK_SET);
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}
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#endif // QPDF_INPUTSOURCE_HH
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