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// Copyright (c) 2005-2022 Jay Berkenbilt
//
// This file is part of qpdf.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Versions of qpdf prior to version 7 were released under the terms
// of version 2.0 of the Artistic License. At your option, you may
// continue to consider qpdf to be licensed under those terms. Please
// see the manual for additional information.
#ifndef QPDF_INPUTSOURCE_HH
#define QPDF_INPUTSOURCE_HH
#include <qpdf/DLL.h>
#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
#include <qpdf/Types.h>
#include <memory>
#include <stdio.h>
#include <string>
// Remember to use QPDF_DLL_CLASS on anything derived from InputSource
// so it will work with dynamic_cast across the shared object
// boundary.
class QPDF_DLL_CLASS InputSource
{
public:
QPDF_DLL
InputSource() :
last_offset(0)
{
}
QPDF_DLL
virtual ~InputSource() = default;
class QPDF_DLL_CLASS Finder
{
public:
QPDF_DLL
Finder() = default;
QPDF_DLL
virtual ~Finder() = default;
virtual bool check() = 0;
};
QPDF_DLL
void setLastOffset(qpdf_offset_t);
QPDF_DLL
qpdf_offset_t getLastOffset() const;
QPDF_DLL
std::string readLine(size_t max_line_length);
// Find first or last occurrence of a sequence of characters
// starting within the range defined by offset and len such that,
// when the input source is positioned at the beginning of that
// sequence, finder.check() returns true. If len is 0, the search
// proceeds until EOF. If a qualifying pattern is found, these
// methods return true and leave the input source positioned
// wherever check() left it at the end of the matching pattern.
QPDF_DLL
bool findFirst(
char const* start_chars,
qpdf_offset_t offset,
size_t len,
Finder& finder);
QPDF_DLL
bool findLast(
char const* start_chars,
qpdf_offset_t offset,
size_t len,
Finder& finder);
virtual qpdf_offset_t findAndSkipNextEOL() = 0;
virtual std::string const& getName() const = 0;
virtual qpdf_offset_t tell() = 0;
virtual void seek(qpdf_offset_t offset, int whence) = 0;
virtual void rewind() = 0;
virtual size_t read(char* buffer, size_t length) = 0;
// Note: you can only unread the character you just read. The
// specific character is ignored by some implementations, and the
// implementation doesn't check this. Use of unreadCh is
// semantically equivalent to seek(-1, SEEK_CUR) but is much more
// efficient.
virtual void unreadCh(char ch) = 0;
// The following methods are for use by QPDFTokenizer
inline qpdf_offset_t fastTell();
inline bool fastRead(char&);
inline void fastUnread(bool);
inline void loadBuffer();
protected:
qpdf_offset_t last_offset;
private:
class QPDF_DLL_PRIVATE Members
{
friend class InputSource;
public:
QPDF_DLL
~Members() = default;
private:
Members() = default;
Members(Members const&) = delete;
};
std::shared_ptr<Members> m;
// State for fast... methods
static const qpdf_offset_t buf_size = 128;
char buffer[buf_size];
qpdf_offset_t buf_len = 0;
qpdf_offset_t buf_idx = 0;
qpdf_offset_t buf_start = 0;
};
inline void
InputSource::loadBuffer()
{
this->buf_idx = 0;
this->buf_len = qpdf_offset_t(read(this->buffer, this->buf_size));
// NB read sets last_offset
this->buf_start = this->last_offset;
}
inline qpdf_offset_t
InputSource::fastTell()
{
if (this->buf_len == 0) {
loadBuffer();
} else {
auto curr = tell();
if (curr < this->buf_start ||
curr >= (this->buf_start + this->buf_len)) {
loadBuffer();
} else {
this->last_offset = curr;
this->buf_idx = curr - this->buf_start;
}
}
return this->last_offset;
}
inline bool
InputSource::fastRead(char& ch)
{
// Before calling fastRead, fastTell must be called to prepare the buffer.
// Once reading is complete, fastUnread must be called to set the correct
// file position.
if (this->buf_idx < this->buf_len) {
ch = this->buffer[this->buf_idx];
++(this->buf_idx);
++(this->last_offset);
return true;
} else if (this->buf_len == 0) {
return false;
} else {
seek(this->buf_start + this->buf_len, SEEK_SET);
fastTell();
return fastRead(ch);
}
}
inline void
InputSource::fastUnread(bool back)
{
this->last_offset -= back ? 1 : 0;
seek(this->last_offset, SEEK_SET);
}
#endif // QPDF_INPUTSOURCE_HH
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