e955c94ed3
Listing the "Blender Foundation" as copyright holder implied the Blender Foundation holds copyright to files which may include work from many developers. While keeping copyright on headers makes sense for isolated libraries, Blender's own code may be refactored or moved between files in a way that makes the per file copyright holders less meaningful. Copyright references to the "Blender Foundation" have been replaced with "Blender Authors", with the exception of `./extern/` since these this contains libraries which are more isolated, any changed to license headers there can be handled on a case-by-case basis. Some directories in `./intern/` have also been excluded: - `./intern/cycles/` it's own `AUTHORS` file is planned. - `./intern/opensubdiv/`. An "AUTHORS" file has been added, using the chromium projects authors file as a template. Design task: #110784 Ref !110783.
131 lines
3.0 KiB
C
131 lines
3.0 KiB
C
/* SPDX-FileCopyrightText: 2004-2021 Blender Authors
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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/** \file
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* \ingroup bli
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*/
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#include <string.h>
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#include "BLI_blenlib.h"
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#include "BLI_filereader.h"
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#include "BLI_mmap.h"
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#include "MEM_guardedalloc.h"
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/* This file implements both memory-backed and memory-mapped-file-backed reading. */
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typedef struct {
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FileReader reader;
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const char *data;
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BLI_mmap_file *mmap;
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size_t length;
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} MemoryReader;
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static ssize_t memory_read_raw(FileReader *reader, void *buffer, size_t size)
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{
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MemoryReader *mem = (MemoryReader *)reader;
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/* Don't read more bytes than there are available in the buffer. */
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size_t readsize = MIN2(size, (size_t)(mem->length - mem->reader.offset));
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memcpy(buffer, mem->data + mem->reader.offset, readsize);
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mem->reader.offset += readsize;
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return readsize;
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}
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static off64_t memory_seek(FileReader *reader, off64_t offset, int whence)
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{
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MemoryReader *mem = (MemoryReader *)reader;
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off64_t new_pos;
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if (whence == SEEK_CUR) {
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new_pos = mem->reader.offset + offset;
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}
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else if (whence == SEEK_SET) {
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new_pos = offset;
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}
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else if (whence == SEEK_END) {
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new_pos = mem->length + offset;
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}
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else {
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return -1;
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}
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if (new_pos < 0 || new_pos > mem->length) {
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return -1;
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}
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mem->reader.offset = new_pos;
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return mem->reader.offset;
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}
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static void memory_close_raw(FileReader *reader)
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{
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MEM_freeN(reader);
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}
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FileReader *BLI_filereader_new_memory(const void *data, size_t len)
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{
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MemoryReader *mem = MEM_callocN(sizeof(MemoryReader), __func__);
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mem->data = (const char *)data;
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mem->length = len;
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mem->reader.read = memory_read_raw;
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mem->reader.seek = memory_seek;
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mem->reader.close = memory_close_raw;
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return (FileReader *)mem;
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}
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/* Memory-mapped file reading.
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* By using `mmap()`, we can map a file so that it can be treated like normal memory,
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* meaning that we can just read from it with `memcpy()` etc.
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* This avoids system call overhead and can significantly speed up file loading.
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*/
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static ssize_t memory_read_mmap(FileReader *reader, void *buffer, size_t size)
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{
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MemoryReader *mem = (MemoryReader *)reader;
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/* Don't read more bytes than there are available in the buffer. */
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size_t readsize = MIN2(size, (size_t)(mem->length - mem->reader.offset));
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if (!BLI_mmap_read(mem->mmap, buffer, mem->reader.offset, readsize)) {
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return 0;
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}
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mem->reader.offset += readsize;
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return readsize;
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}
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static void memory_close_mmap(FileReader *reader)
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{
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MemoryReader *mem = (MemoryReader *)reader;
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BLI_mmap_free(mem->mmap);
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MEM_freeN(mem);
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}
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FileReader *BLI_filereader_new_mmap(int filedes)
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{
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BLI_mmap_file *mmap = BLI_mmap_open(filedes);
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if (mmap == NULL) {
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return NULL;
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}
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MemoryReader *mem = MEM_callocN(sizeof(MemoryReader), __func__);
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mem->mmap = mmap;
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mem->length = BLI_lseek(filedes, 0, SEEK_END);
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mem->reader.read = memory_read_mmap;
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mem->reader.seek = memory_seek;
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mem->reader.close = memory_close_mmap;
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return (FileReader *)mem;
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}
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