--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/include/mupdf/fitz/stream.h	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,646 @@
+// Copyright (C) 2004-2021 Artifex Software, Inc.
+//
+// This file is part of MuPDF.
+//
+// MuPDF is free software: you can redistribute it and/or modify it under the
+// terms of the GNU Affero General Public License as published by the Free
+// Software Foundation, either version 3 of the License, or (at your option)
+// any later version.
+//
+// MuPDF 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 Affero General Public License for more
+// details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
+//
+// Alternative licensing terms are available from the licensor.
+// For commercial licensing, see <https://www.artifex.com/> or contact
+// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
+// CA 94129, USA, for further information.
+
+#ifndef MUPDF_FITZ_STREAM_H
+#define MUPDF_FITZ_STREAM_H
+
+#include "mupdf/fitz/system.h"
+#include "mupdf/fitz/context.h"
+#include "mupdf/fitz/buffer.h"
+
+/**
+	Return true if the named file exists and is readable.
+*/
+int fz_file_exists(fz_context *ctx, const char *path);
+
+/**
+	fz_stream is a buffered reader capable of seeking in both
+	directions.
+
+	Streams are reference counted, so references must be dropped
+	by a call to fz_drop_stream.
+
+	Only the data between rp and wp is valid.
+*/
+typedef struct fz_stream fz_stream;
+
+/**
+	Open the named file and wrap it in a stream.
+
+	filename: Path to a file. On non-Windows machines the filename
+	should be exactly as it would be passed to fopen(2). On Windows
+	machines, the path should be UTF-8 encoded so that non-ASCII
+	characters can be represented. Other platforms do the encoding
+	as standard anyway (and in most cases, particularly for MacOS
+	and Linux, the encoding they use is UTF-8 anyway).
+*/
+fz_stream *fz_open_file(fz_context *ctx, const char *filename);
+
+/**
+	Do the same as fz_open_file, but delete the file upon close.
+*/
+fz_stream *fz_open_file_autodelete(fz_context *ctx, const char *filename);
+
+/**
+	Open the named file and wrap it in a stream.
+
+	Does the same as fz_open_file, but in the event the file
+	does not open, it will return NULL rather than throw an
+	exception.
+*/
+fz_stream *fz_try_open_file(fz_context *ctx, const char *name);
+
+#ifdef _WIN32
+/**
+	Open the named file and wrap it in a stream.
+
+	This function is only available when compiling for Win32.
+
+	filename: Wide character path to the file as it would be given
+	to _wfopen().
+*/
+fz_stream *fz_open_file_w(fz_context *ctx, const wchar_t *filename);
+#endif /* _WIN32 */
+
+/**
+	Return the filename (UTF-8 encoded) from which a stream was opened.
+
+	Returns NULL if the filename is not available (or the stream was
+	opened from a source other than a file).
+*/
+const char *fz_stream_filename(fz_context *ctx, fz_stream *stm);
+
+/**
+	Open a block of memory as a stream.
+
+	data: Pointer to start of data block. Ownership of the data
+	block is NOT passed in.
+
+	len: Number of bytes in data block.
+
+	Returns pointer to newly created stream. May throw exceptions on
+	failure to allocate.
+*/
+fz_stream *fz_open_memory(fz_context *ctx, const unsigned char *data, size_t len);
+
+/**
+	Open a buffer as a stream.
+
+	buf: The buffer to open. Ownership of the buffer is NOT passed
+	in (this function takes its own reference).
+
+	Returns pointer to newly created stream. May throw exceptions on
+	failure to allocate.
+*/
+fz_stream *fz_open_buffer(fz_context *ctx, fz_buffer *buf);
+
+/**
+	Attach a filter to a stream that will store any
+	characters read from the stream into the supplied buffer.
+
+	chain: The underlying stream to leech from.
+
+	buf: The buffer into which the read data should be appended.
+	The buffer will be resized as required.
+
+	Returns pointer to newly created stream. May throw exceptions on
+	failure to allocate.
+*/
+fz_stream *fz_open_leecher(fz_context *ctx, fz_stream *chain, fz_buffer *buf);
+
+/**
+	Increments the reference count for a stream. Returns the same
+	pointer.
+
+	Never throws exceptions.
+*/
+fz_stream *fz_keep_stream(fz_context *ctx, fz_stream *stm);
+
+/**
+	Decrements the reference count for a stream.
+
+	When the reference count for the stream hits zero, frees the
+	storage used for the fz_stream itself, and (usually)
+	releases the underlying resources that the stream is based upon
+	(depends on the method used to open the stream initially).
+*/
+void fz_drop_stream(fz_context *ctx, fz_stream *stm);
+
+/**
+	return the current reading position within a stream
+*/
+int64_t fz_tell(fz_context *ctx, fz_stream *stm);
+
+/**
+	Seek within a stream.
+
+	stm: The stream to seek within.
+
+	offset: The offset to seek to.
+
+	whence: From where the offset is measured (see fseek).
+	SEEK_SET - start of stream.
+	SEEK_CUR - current position.
+	SEEK_END - end of stream.
+
+*/
+void fz_seek(fz_context *ctx, fz_stream *stm, int64_t offset, int whence);
+
+/**
+	Read from a stream into a given data block.
+
+	stm: The stream to read from.
+
+	data: The data block to read into.
+
+	len: The length of the data block (in bytes).
+
+	Returns the number of bytes read. May throw exceptions.
+*/
+size_t fz_read(fz_context *ctx, fz_stream *stm, unsigned char *data, size_t len);
+
+/**
+	Read from a stream discarding data.
+
+	stm: The stream to read from.
+
+	len: The number of bytes to read.
+
+	Returns the number of bytes read. May throw exceptions.
+*/
+size_t fz_skip(fz_context *ctx, fz_stream *stm, size_t len);
+
+/**
+	Read all of a stream into a buffer.
+
+	stm: The stream to read from
+
+	initial: Suggested initial size for the buffer.
+
+	Returns a buffer created from reading from the stream. May throw
+	exceptions on failure to allocate.
+*/
+fz_buffer *fz_read_all(fz_context *ctx, fz_stream *stm, size_t initial);
+
+/**
+	Read all the contents of a file into a buffer.
+*/
+fz_buffer *fz_read_file(fz_context *ctx, const char *filename);
+
+/**
+	Read all the contents of a file into a buffer.
+
+	Returns NULL if the file does not exist, otherwise
+	behaves exactly as fz_read_file.
+*/
+fz_buffer *fz_try_read_file(fz_context *ctx, const char *filename);
+
+/**
+	fz_read_[u]int(16|24|32|64)(_le)?
+
+	Read a 16/32/64 bit signed/unsigned integer from stream,
+	in big or little-endian byte orders.
+
+	Throws an exception if EOF is encountered.
+*/
+uint16_t fz_read_uint16(fz_context *ctx, fz_stream *stm);
+uint32_t fz_read_uint24(fz_context *ctx, fz_stream *stm);
+uint32_t fz_read_uint32(fz_context *ctx, fz_stream *stm);
+uint64_t fz_read_uint64(fz_context *ctx, fz_stream *stm);
+
+uint16_t fz_read_uint16_le(fz_context *ctx, fz_stream *stm);
+uint32_t fz_read_uint24_le(fz_context *ctx, fz_stream *stm);
+uint32_t fz_read_uint32_le(fz_context *ctx, fz_stream *stm);
+uint64_t fz_read_uint64_le(fz_context *ctx, fz_stream *stm);
+
+int16_t fz_read_int16(fz_context *ctx, fz_stream *stm);
+int32_t fz_read_int32(fz_context *ctx, fz_stream *stm);
+int64_t fz_read_int64(fz_context *ctx, fz_stream *stm);
+
+int16_t fz_read_int16_le(fz_context *ctx, fz_stream *stm);
+int32_t fz_read_int32_le(fz_context *ctx, fz_stream *stm);
+int64_t fz_read_int64_le(fz_context *ctx, fz_stream *stm);
+
+float fz_read_float_le(fz_context *ctx, fz_stream *stm);
+float fz_read_float(fz_context *ctx, fz_stream *stm);
+
+/**
+	Read a null terminated string from the stream into
+	a buffer of a given length. The buffer will be null terminated.
+	Throws on failure (including the failure to fit the entire
+	string including the terminator into the buffer).
+*/
+void fz_read_string(fz_context *ctx, fz_stream *stm, char *buffer, int len);
+
+/**
+	Read a utf-8 rune from a stream.
+
+	In the event of encountering badly formatted utf-8 codes
+	(such as a leading code with an unexpected number of following
+	codes) no error/exception is given, but undefined values may be
+	returned.
+*/
+int fz_read_rune(fz_context *ctx, fz_stream *in);
+
+/**
+	Read a utf-16 rune from a stream. (little endian and
+	big endian respectively).
+
+	In the event of encountering badly formatted utf-16 codes
+	(mismatched surrogates) no error/exception is given, but
+	undefined values may be returned.
+*/
+int fz_read_utf16_le(fz_context *ctx, fz_stream *stm);
+int fz_read_utf16_be(fz_context *ctx, fz_stream *stm);
+
+/**
+	A function type for use when implementing
+	fz_streams. The supplied function of this type is called
+	whenever data is required, and the current buffer is empty.
+
+	stm: The stream to operate on.
+
+	max: a hint as to the maximum number of bytes that the caller
+	needs to be ready immediately. Can safely be ignored.
+
+	Returns -1 if there is no more data in the stream. Otherwise,
+	the function should find its internal state using stm->state,
+	refill its buffer, update stm->rp and stm->wp to point to the
+	start and end of the new data respectively, and then
+	"return *stm->rp++".
+*/
+typedef int (fz_stream_next_fn)(fz_context *ctx, fz_stream *stm, size_t max);
+
+/**
+	A function type for use when implementing
+	fz_streams. The supplied function of this type is called
+	when the stream is dropped, to release the stream specific
+	state information.
+
+	state: The stream state to release.
+*/
+typedef void (fz_stream_drop_fn)(fz_context *ctx, void *state);
+
+/**
+	A function type for use when implementing
+	fz_streams. The supplied function of this type is called when
+	fz_seek is requested, and the arguments are as defined for
+	fz_seek.
+
+	The stream can find it's private state in stm->state.
+*/
+typedef void (fz_stream_seek_fn)(fz_context *ctx, fz_stream *stm, int64_t offset, int whence);
+
+struct fz_stream
+{
+	int refs;
+	int error;
+	int eof;
+	int progressive;
+	int64_t pos;
+	int avail;
+	int bits;
+	unsigned char *rp, *wp;
+	void *state;
+	fz_stream_next_fn *next;
+	fz_stream_drop_fn *drop;
+	fz_stream_seek_fn *seek;
+};
+
+/**
+	Create a new stream object with the given
+	internal state and function pointers.
+
+	state: Internal state (opaque to everything but implementation).
+
+	next: Should provide the next set of bytes (up to max) of stream
+	data. Return the number of bytes read, or EOF when there is no
+	more data.
+
+	drop: Should clean up and free the internal state. May not
+	throw exceptions.
+*/
+fz_stream *fz_new_stream(fz_context *ctx, void *state, fz_stream_next_fn *next, fz_stream_drop_fn *drop);
+
+/**
+	Attempt to read a stream into a buffer. If truncated
+	is NULL behaves as fz_read_all, sets a truncated flag in case of
+	error.
+
+	stm: The stream to read from.
+
+	initial: Suggested initial size for the buffer.
+
+	truncated: Flag to store success/failure indication in.
+
+	worst_case: 0 for unknown, otherwise an upper bound for the
+	size of the stream.
+
+	Returns a buffer created from reading from the stream.
+*/
+fz_buffer *fz_read_best(fz_context *ctx, fz_stream *stm, size_t initial, int *truncated, size_t worst_case);
+
+/**
+	Read a line from stream into the buffer until either a
+	terminating newline or EOF, which it replaces with a null byte
+	('\0').
+
+	Returns buf on success, and NULL when end of file occurs while
+	no characters have been read.
+*/
+char *fz_read_line(fz_context *ctx, fz_stream *stm, char *buf, size_t max);
+
+/**
+	Skip over a given string in a stream. Return 0 if successfully
+	skipped, non-zero otherwise. As many characters will be skipped
+	over as matched in the string.
+*/
+int fz_skip_string(fz_context *ctx, fz_stream *stm, const char *str);
+
+/**
+	Skip over whitespace (bytes <= 32) in a stream.
+*/
+void fz_skip_space(fz_context *ctx, fz_stream *stm);
+
+/**
+	Ask how many bytes are available immediately from
+	a given stream.
+
+	stm: The stream to read from.
+
+	max: A hint for the underlying stream; the maximum number of
+	bytes that we are sure we will want to read. If you do not know
+	this number, give 1.
+
+	Returns the number of bytes immediately available between the
+	read and write pointers. This number is guaranteed only to be 0
+	if we have hit EOF. The number of bytes returned here need have
+	no relation to max (could be larger, could be smaller).
+*/
+static inline size_t fz_available(fz_context *ctx, fz_stream *stm, size_t max)
+{
+	size_t len = stm->wp - stm->rp;
+	int c = EOF;
+
+	if (len)
+		return len;
+	if (stm->eof)
+		return 0;
+
+	fz_try(ctx)
+		c = stm->next(ctx, stm, max);
+	fz_catch(ctx)
+	{
+		fz_rethrow_if(ctx, FZ_ERROR_TRYLATER);
+		fz_report_error(ctx);
+		fz_warn(ctx, "read error; treating as end of file");
+		stm->error = 1;
+		c = EOF;
+	}
+	if (c == EOF)
+	{
+		stm->eof = 1;
+		return 0;
+	}
+	stm->rp--;
+	return stm->wp - stm->rp;
+}
+
+/**
+	Read the next byte from a stream.
+
+	stm: The stream t read from.
+
+	Returns -1 for end of stream, or the next byte. May
+	throw exceptions.
+*/
+static inline int fz_read_byte(fz_context *ctx, fz_stream *stm)
+{
+	int c = EOF;
+
+	if (stm->rp != stm->wp)
+		return *stm->rp++;
+	if (stm->eof)
+		return EOF;
+	fz_try(ctx)
+		c = stm->next(ctx, stm, 1);
+	fz_catch(ctx)
+	{
+		fz_rethrow_if(ctx, FZ_ERROR_TRYLATER);
+		fz_report_error(ctx);
+		fz_warn(ctx, "read error; treating as end of file");
+		stm->error = 1;
+		c = EOF;
+	}
+	if (c == EOF)
+		stm->eof = 1;
+	return c;
+}
+
+/**
+	Peek at the next byte in a stream.
+
+	stm: The stream to peek at.
+
+	Returns -1 for EOF, or the next byte that will be read.
+*/
+static inline int fz_peek_byte(fz_context *ctx, fz_stream *stm)
+{
+	int c = EOF;
+
+	if (stm->rp != stm->wp)
+		return *stm->rp;
+	if (stm->eof)
+		return EOF;
+
+	fz_try(ctx)
+	{
+		c = stm->next(ctx, stm, 1);
+		if (c != EOF)
+			stm->rp--;
+	}
+	fz_catch(ctx)
+	{
+		fz_rethrow_if(ctx, FZ_ERROR_TRYLATER);
+		fz_report_error(ctx);
+		fz_warn(ctx, "read error; treating as end of file");
+		stm->error = 1;
+		c = EOF;
+	}
+	if (c == EOF)
+		stm->eof = 1;
+	return c;
+}
+
+/**
+	Unread the single last byte successfully
+	read from a stream. Do not call this without having
+	successfully read a byte.
+
+	stm: The stream to operate upon.
+*/
+static inline void fz_unread_byte(fz_context *ctx FZ_UNUSED, fz_stream *stm)
+{
+	stm->rp--;
+}
+
+/**
+	Query if the stream has reached EOF (during normal bytewise
+	reading).
+
+	See fz_is_eof_bits for the equivalent function for bitwise
+	reading.
+*/
+static inline int fz_is_eof(fz_context *ctx, fz_stream *stm)
+{
+	if (stm->rp == stm->wp)
+	{
+		if (stm->eof)
+			return 1;
+		return fz_peek_byte(ctx, stm) == EOF;
+	}
+	return 0;
+}
+
+/**
+	Read the next n bits from a stream (assumed to
+	be packed most significant bit first).
+
+	stm: The stream to read from.
+
+	n: The number of bits to read, between 1 and 8*sizeof(int)
+	inclusive.
+
+	Returns -1 for EOF, or the required number of bits.
+*/
+static inline unsigned int fz_read_bits(fz_context *ctx, fz_stream *stm, int n)
+{
+	int x;
+
+	if (n <= stm->avail)
+	{
+		stm->avail -= n;
+		x = (stm->bits >> stm->avail) & ((1 << n) - 1);
+	}
+	else
+	{
+		x = stm->bits & ((1 << stm->avail) - 1);
+		n -= stm->avail;
+		stm->avail = 0;
+
+		while (n > 8)
+		{
+			x = (x << 8) | fz_read_byte(ctx, stm);
+			n -= 8;
+		}
+
+		if (n > 0)
+		{
+			stm->bits = fz_read_byte(ctx, stm);
+			stm->avail = 8 - n;
+			x = (x << n) | (stm->bits >> stm->avail);
+		}
+	}
+
+	return x;
+}
+
+/**
+	Read the next n bits from a stream (assumed to
+	be packed least significant bit first).
+
+	stm: The stream to read from.
+
+	n: The number of bits to read, between 1 and 8*sizeof(int)
+	inclusive.
+
+	Returns (unsigned int)-1 for EOF, or the required number of bits.
+*/
+static inline unsigned int fz_read_rbits(fz_context *ctx, fz_stream *stm, int n)
+{
+	int x;
+
+	if (n <= stm->avail)
+	{
+		x = stm->bits & ((1 << n) - 1);
+		stm->avail -= n;
+		stm->bits = stm->bits >> n;
+	}
+	else
+	{
+		unsigned int used = 0;
+
+		x = stm->bits & ((1 << stm->avail) - 1);
+		n -= stm->avail;
+		used = stm->avail;
+		stm->avail = 0;
+
+		while (n > 8)
+		{
+			x = (fz_read_byte(ctx, stm) << used) | x;
+			n -= 8;
+			used += 8;
+		}
+
+		if (n > 0)
+		{
+			stm->bits = fz_read_byte(ctx, stm);
+			x = ((stm->bits & ((1 << n) - 1)) << used) | x;
+			stm->avail = 8 - n;
+			stm->bits = stm->bits >> n;
+		}
+	}
+
+	return x;
+}
+
+/**
+	Called after reading bits to tell the stream
+	that we are about to return to reading bytewise. Resyncs
+	the stream to whole byte boundaries.
+*/
+static inline void fz_sync_bits(fz_context *ctx FZ_UNUSED, fz_stream *stm)
+{
+	stm->avail = 0;
+}
+
+/**
+	Query if the stream has reached EOF (during bitwise
+	reading).
+
+	See fz_is_eof for the equivalent function for bytewise
+	reading.
+*/
+static inline int fz_is_eof_bits(fz_context *ctx, fz_stream *stm)
+{
+	return fz_is_eof(ctx, stm) && (stm->avail == 0 || stm->bits == EOF);
+}
+
+/* Implementation details: subject to change. */
+
+/**
+	Create a stream from a FILE * that will not be closed
+	when the stream is dropped.
+*/
+fz_stream *fz_open_file_ptr_no_close(fz_context *ctx, FILE *file);
+
+#endif