--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/extract/src/buffer.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,508 @@
+#include "extract/buffer.h"
+#include "extract/alloc.h"
+
+#include "outf.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* TODO: Check whether the whole complexity of the cache is actually justified. */
+
+struct extract_buffer_t
+{
+	/* First member must be extract_buffer_cache_t - required by inline
+	implementations of extract_buffer_read() and extract_buffer_write(). */
+	extract_buffer_cache_t   cache;
+	extract_alloc_t         *alloc;
+	void                    *handle;
+	extract_buffer_fn_read  *fn_read;
+	extract_buffer_fn_write *fn_write;
+	extract_buffer_fn_cache *fn_cache;
+	extract_buffer_fn_close *fn_close;
+	size_t                   pos;    /* Does not include bytes currently read/written to cache. */
+};
+
+
+extract_alloc_t *extract_buffer_alloc(extract_buffer_t* buffer)
+{
+	return buffer->alloc;
+}
+
+
+int extract_buffer_open(extract_alloc_t          *alloc,
+			void                     *handle,
+			extract_buffer_fn_read   *fn_read,
+			extract_buffer_fn_write  *fn_write,
+			extract_buffer_fn_cache  *fn_cache,
+			extract_buffer_fn_close  *fn_close,
+			extract_buffer_t        **o_buffer)
+{
+	extract_buffer_t *buffer;
+
+	if (extract_malloc(alloc, &buffer, sizeof(*buffer)))
+		return -1;
+
+	buffer->alloc = alloc;
+	buffer->handle = handle;
+	buffer->fn_read = fn_read;
+	buffer->fn_write = fn_write;
+	buffer->fn_cache = fn_cache;
+	buffer->fn_close = fn_close;
+	buffer->cache.cache = NULL;
+	buffer->cache.numbytes = 0;
+	buffer->cache.pos = 0;
+	buffer->pos = 0;
+
+	*o_buffer = buffer;
+
+	return 0;
+}
+
+
+size_t extract_buffer_pos(extract_buffer_t *buffer)
+{
+	size_t ret = buffer->pos;
+
+	if (buffer->cache.cache)
+		ret += buffer->cache.pos;
+
+	return ret;
+}
+
+
+/* Send contents of cache to fn_write() using a loop to cope with short
+writes. Returns with *o_actual containing the number of bytes successfully
+sent, and buffer->cache.{cache,numbytes,pos} all set to zero.
+
+If we return zero but *actual is less than original buffer->cache.numbytes,
+then fn_write returned EOF. */
+static int cache_flush(extract_buffer_t *buffer, size_t *o_actual)
+{
+	int e = -1;
+	size_t p = 0;
+
+	assert(buffer->cache.pos <= buffer->cache.numbytes);
+
+	while (p != buffer->cache.pos)
+	{
+		size_t actual;
+		if (buffer->fn_write(
+			buffer->handle,
+			(char*) buffer->cache.cache + p,
+			buffer->cache.pos - p,
+			&actual
+			)) goto end;
+		buffer->pos += actual;
+		p += actual;
+		if (actual == 0)
+		{
+			/* EOF while flushing cache. We set <pos> to the
+			 * number of bytes in data..+numbytes that we know
+			 * have been successfully handled by buffer->fn_write().
+			 * This can be negative if we failed to flush
+			 * earlier data. */
+			outf("*** buffer->fn_write() EOF\n");
+			e = 0;
+			goto end;
+		}
+	}
+	outfx("cache flush, buffer->pos=%i p=buffer->cache.pos=%i\n",
+		buffer->pos, p);
+	buffer->cache.cache = NULL;
+	buffer->cache.numbytes = 0;
+	buffer->cache.pos = 0;
+
+	e = 0;
+end:
+	*o_actual = p;
+
+	return e;
+}
+
+int extract_buffer_close(extract_buffer_t **p_buffer)
+{
+	extract_buffer_t *buffer = *p_buffer;
+	int e = -1;
+
+	if (buffer == NULL)
+		return 0;
+
+	if (buffer->cache.cache && buffer->fn_write)
+	{
+		/* Flush cache. */
+		size_t cache_bytes = buffer->cache.pos;
+		size_t actual;
+		if (cache_flush(buffer, &actual)) goto end;
+		if (actual != cache_bytes)
+		{
+			e = 1;
+			goto end;
+		}
+	}
+
+	if (buffer->fn_close)
+		buffer->fn_close(buffer->handle);
+
+	e = 0;
+end:
+	extract_free(buffer->alloc, &buffer);
+	*p_buffer = NULL;
+
+	return e;
+}
+
+static int simple_cache(void *handle, void **o_cache, size_t *o_numbytes)
+{
+	/* Indicate EOF. */
+	(void) handle;
+	*o_cache = NULL;
+	*o_numbytes = 0;
+
+	return 0;
+}
+
+int extract_buffer_open_simple(extract_alloc_t           *alloc,
+				const void               *data,
+				size_t                    numbytes,
+				void                     *handle,
+				extract_buffer_fn_close  *fn_close,
+				extract_buffer_t        **o_buffer)
+{
+	extract_buffer_t *buffer;
+
+	if (extract_malloc(alloc, &buffer, sizeof(*buffer)))
+		return -1;
+
+	/* We need cast away the const here. data[] will be written-to if caller
+	uses us as a write buffer. */
+	buffer->alloc = alloc;
+	buffer->cache.cache = (void*) data;
+	buffer->cache.numbytes = numbytes;
+	buffer->cache.pos = 0;
+	buffer->handle = handle;
+	buffer->fn_read = NULL;
+	buffer->fn_write = NULL;
+	buffer->fn_cache = simple_cache;
+	buffer->fn_close = fn_close;
+	*o_buffer = buffer;
+
+	return 0;
+}
+
+
+/* Implementation of extract_buffer_file*. */
+
+static int file_read(void *handle, void *data, size_t numbytes, size_t *o_actual)
+{
+	FILE   *file = handle;
+	size_t  n    = fread(data, 1, numbytes, file);
+
+	outfx("file=%p numbytes=%i => n=%zi", file, numbytes, n);
+	assert(o_actual); /* We are called by other extract_buffer fns, not by user code. */
+
+	*o_actual = n;
+	if (n == 0 && ferror(file))
+	{
+		errno = EIO;
+		return -1;
+	}
+
+	return 0;
+}
+
+static int file_write(void *handle, const void *data, size_t numbytes, size_t *o_actual)
+{
+	FILE   *file = handle;
+	size_t  n    = fwrite(data, 1 /*size*/, numbytes /*nmemb*/, file);
+
+	outfx("file=%p numbytes=%i => n=%zi", file, numbytes, n);
+	assert(o_actual); /* We are called by other extract_buffer fns, not by user code. */
+
+	*o_actual = n;
+	if (n == 0 && ferror(file))
+	{
+		errno = EIO;
+		return -1;
+	}
+
+	return 0;
+}
+
+static void file_close(void *handle)
+{
+	FILE *file = handle;
+
+	if (file)
+		fclose(file);
+}
+
+int extract_buffer_open_file(extract_alloc_t *alloc, const char *path, int writable, extract_buffer_t **o_buffer)
+{
+	int   e    = -1;
+	FILE *file = fopen(path, (writable) ? "wb" : "rb");
+
+	if (!file)
+	{
+		outf("failed to open '%s': %s", path, strerror(errno));
+		goto end;
+	}
+
+	if (extract_buffer_open(alloc,
+				file /*handle*/,
+				writable ? NULL : file_read,
+				writable ? file_write : NULL,
+				NULL /*fn_cache*/,
+				file_close,
+				o_buffer)) goto end;
+
+	e = 0;
+end:
+
+	if (e)
+	{
+		if (file)
+			fclose(file);
+		*o_buffer = NULL;
+	}
+
+	return e;
+}
+
+
+/* Support for read/write. */
+
+/* Called by extract_buffer_read() if not enough space in buffer->cache. */
+int extract_buffer_read_internal(extract_buffer_t *buffer,
+				void              *destination,
+				size_t             numbytes,
+				size_t            *o_actual)
+{
+	int    e   = -1;
+	size_t pos = 0;    /* Number of bytes read so far. */
+
+	/* In each iteration we either read from cache, or use buffer->fn_read()
+	directly or repopulate the cache. */
+	while (pos != numbytes)
+	{
+		size_t n = buffer->cache.numbytes - buffer->cache.pos;
+		if (n)
+		{
+			/* There is data in cache. */
+			if (n > numbytes - pos) n = numbytes - pos;
+			memcpy((char *)destination + pos, (char *)buffer->cache.cache + buffer->cache.pos, n);
+			pos += n;
+			buffer->cache.pos += n;
+		}
+		/* No data in the cache - do we use fn_read or fn_cache ? */
+		else if (buffer->fn_read &&
+				(buffer->fn_cache == NULL ||
+					(buffer->cache.numbytes && numbytes - pos > buffer->cache.numbytes / 2)))
+		{
+			/* Either there is no cache, or this read is large
+			 * compared to previously-returned cache size, so
+			 * let's ignore buffer->fn_cache and use
+			 * buffer->fn_read() directly instead. */
+			/* Carry on looping in case of short read. */
+			size_t actual;
+			outfx("using buffer->fn_read() directly for numbytes-pos=%i\n", numbytes-pos);
+			if (buffer->fn_read(buffer->handle, (char*) destination + pos, numbytes - pos, &actual))
+				goto end;
+			if (actual == 0)
+				break; /* EOF. */
+			pos += actual;
+			buffer->pos += actual;
+		}
+		else
+		{
+			/* Repopulate cache. */
+			outfx("using buffer->fn_cache() for buffer->cache.numbytes=%i\n", buffer->cache.numbytes);
+			if (buffer->fn_cache(buffer->handle, &buffer->cache.cache, &buffer->cache.numbytes))
+				goto end;
+			buffer->pos += buffer->cache.pos;
+			buffer->cache.pos = 0;
+			if (buffer->cache.numbytes == 0)
+				break; /* EOF. */
+		}
+	}
+
+	e = 0;
+end:
+
+	if (o_actual)
+		*o_actual = pos;
+	if (e == 0 && pos != numbytes)
+		return +1; /* EOF. */
+
+	return e;
+}
+
+
+int extract_buffer_write_internal(extract_buffer_t *buffer,
+                                  const void       *source,
+                                  size_t            numbytes,
+                                  size_t           *o_actual)
+{
+	int    e   = -1;
+	size_t pos = 0;    /* Number of bytes written so far. */
+
+	if (buffer->fn_write == NULL)
+	{
+		errno = EINVAL;
+		return -1;
+	}
+
+	/* In each iteration we either write to cache, or use buffer->fn_write()
+	directly or flush the cache. */
+	while (pos != numbytes)
+	{
+		size_t n = buffer->cache.numbytes - buffer->cache.pos;
+		outfx("numbytes=%i pos=%i. buffer->cache.numbytes=%i buffer->cache.pos=%i\n",
+			numbytes, pos, buffer->cache.numbytes, buffer->cache.pos);
+		if (n)
+		{
+			/* There is space in cache for writing. */
+			if (n > numbytes - pos)
+				n = numbytes - pos;
+			outfx("writing to cache: numbytes=%i n=%i\n", numbytes, n);
+			memcpy((char*) buffer->cache.cache + buffer->cache.pos, (char*) source + pos, n);
+			pos += n;
+			buffer->cache.pos += n;
+		}
+		else
+		{
+			/* No space left in cache. */
+			outfx("cache empty. pos=%i. buffer->cache.numbytes=%i buffer->cache.pos=%i\n",
+				pos, buffer->cache.numbytes, buffer->cache.pos);
+			{
+				/* Flush the cache. */
+				size_t actual;
+				size_t b = buffer->cache.numbytes;
+				ptrdiff_t delta;
+				int ee = cache_flush(buffer, &actual);
+				assert(actual <= b);
+				delta = actual - b;
+				pos += delta;
+				buffer->pos += delta;
+				if (delta)
+				{
+					/* We have only partially flushed the cache. This
+					 * is not recoverable. <pos> will be the number of
+					 * bytes in source..+numbytes that have been
+					 * successfully flushed, and could be negative
+					 * if we failed to flush earlier data. */
+					outf("failed to flush. actual=%li delta=%li\n", (long) actual, (long) delta);
+					e = 0;
+					goto end;
+				}
+				if (ee) goto end;
+			}
+
+			if (buffer->fn_cache == NULL ||
+				(buffer->cache.numbytes && numbytes - pos > buffer->cache.numbytes / 2))
+			{
+				/* Either there is no cache, or this write is large
+				 * compared to previously-returned cache size, so let's
+				 * ignore the cache and call buffer->fn_write()
+				 * directly instead. Carry on looping in case of short
+				 * write. */
+				size_t actual;
+				if (buffer->fn_write(buffer->handle, (char*) source + pos, numbytes - pos, &actual))
+					goto end;
+				if (actual == 0)
+					break; /* EOF. */
+				outfx("direct write numbytes-pos=%i actual=%i buffer->pos=%i => %i\n",
+					numbytes-pos, actual, buffer->pos, buffer->pos + actual);
+				pos += actual;
+				buffer->pos += actual;
+			}
+			else
+			{
+				/* Repopulate cache. */
+				outfx("repopulating cache buffer->pos=%i", buffer->pos);
+				if (buffer->fn_cache(buffer->handle, &buffer->cache.cache, &buffer->cache.numbytes))
+					goto end;
+				buffer->cache.pos = 0;
+				if (buffer->cache.numbytes == 0)
+					break;    /* EOF. */
+			}
+		}
+	}
+
+	e = 0;
+end:
+
+	if (o_actual)
+		*o_actual = pos;
+	if (e == 0 && pos != numbytes)
+		e = +1; /* EOF. */
+
+	return e;
+}
+
+
+static int expanding_memory_buffer_write(void *handle, const void *source, size_t numbytes, size_t *o_actual)
+{
+	/* We realloc our memory region as required. For efficiency, we also use
+	 * any currently-unused region of our memory buffer as an extract_buffer
+	 * cache. So we can be called either to 'flush the cache' (in which case we
+	 * don't actually copy any data) or to accept data from somewhere else (in
+	 * which case we need to increase the size of our memory region. */
+	extract_buffer_expanding_t *ebe = handle;
+	if ((char *)source >= ebe->data && (char *)source < ebe->data + ebe->alloc_size)
+	{
+		/* Source is inside our memory region so we are being called by
+		 * extract_buffer_write_internal() to re-populate the cache. We don't
+		 * actually have to copy anything. */
+		assert((size_t) ((char *)source - ebe->data) == ebe->data_size);
+		assert((size_t) ((char *)source - ebe->data + numbytes) <= ebe->alloc_size);
+		ebe->data_size += numbytes;
+	}
+	else
+	{
+		/* Data is external, so copy into our buffer. We will have already been
+		called to flush the cache. */
+		if (extract_realloc2(ebe->buffer->alloc, &ebe->data, ebe->alloc_size, ebe->data_size + numbytes))
+			return -1;
+		ebe->alloc_size = ebe->data_size + numbytes;
+		memcpy(ebe->data + ebe->data_size, source, numbytes);
+		ebe->data_size += numbytes;
+	}
+	*o_actual = numbytes;
+
+	return 0;
+}
+
+static int expanding_memory_buffer_cache(void *handle, void **o_cache, size_t *o_numbytes)
+{
+	extract_buffer_expanding_t *ebe   = handle;
+	size_t                      delta = 4096;
+
+	if (extract_realloc2(ebe->buffer->alloc, &ebe->data, ebe->alloc_size, ebe->data_size + delta))
+		return -1;
+
+	ebe->alloc_size = ebe->data_size + delta;
+	*o_cache = ebe->data + ebe->data_size;
+	*o_numbytes = delta;
+
+	return 0;
+}
+
+int extract_buffer_expanding_create(extract_alloc_t *alloc, extract_buffer_expanding_t *ebe)
+{
+	ebe->data = NULL;
+	ebe->data_size = 0;
+	ebe->alloc_size = 0;
+	if (extract_buffer_open(alloc,
+				ebe,
+				NULL /*fn_read*/,
+				expanding_memory_buffer_write,
+				expanding_memory_buffer_cache,
+				NULL /*fn_close*/,
+				&ebe->buffer))
+		return -1;
+
+	return 0;
+}