D5799 macOS platform fix attempt 2

This reverts commit edfcaf0abd.

build_files/cmake/Modules/FindZstd.cmake

@@ -0,0 +1,66 @@
+# - Find Zstd library
+# Find the native Zstd includes and library
+# This module defines
+#  ZSTD_INCLUDE_DIRS, where to find zstd.h, Set when
+#                     ZSTD_INCLUDE_DIR is found.
+#  ZSTD_LIBRARIES, libraries to link against to use Zstd.
+#  ZSTD_ROOT_DIR, The base directory to search for Zstd.
+#                 This can also be an environment variable.
+#  ZSTD_FOUND, If false, do not try to use Zstd.
+#
+# also defined, but not for general use are
+#  ZSTD_LIBRARY, where to find the Zstd library.
+
+#=============================================================================
+# Copyright 2019 Blender Foundation.
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file Copyright.txt for details.
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+#=============================================================================
+
+# If ZSTD_ROOT_DIR was defined in the environment, use it.
+IF(NOT ZSTD_ROOT_DIR AND NOT $ENV{ZSTD_ROOT_DIR} STREQUAL "")
+  SET(ZSTD_ROOT_DIR $ENV{ZSTD_ROOT_DIR})
+ENDIF()
+
+SET(_zstd_SEARCH_DIRS
+  ${ZSTD_ROOT_DIR}
+)
+
+FIND_PATH(ZSTD_INCLUDE_DIR
+  NAMES
+    zstd.h
+  HINTS
+    ${_zstd_SEARCH_DIRS}
+  PATH_SUFFIXES
+    include
+)
+
+FIND_LIBRARY(ZSTD_LIBRARY
+  NAMES
+    zstd
+  HINTS
+    ${_zstd_SEARCH_DIRS}
+  PATH_SUFFIXES
+    lib64 lib
+  )
+
+# handle the QUIETLY and REQUIRED arguments and set ZSTD_FOUND to TRUE if
+# all listed variables are TRUE
+INCLUDE(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(Zstd DEFAULT_MSG
+    ZSTD_LIBRARY ZSTD_INCLUDE_DIR)
+
+IF(ZSTD_FOUND)
+  SET(ZSTD_LIBRARIES ${ZSTD_LIBRARY})
+  SET(ZSTD_INCLUDE_DIRS ${ZSTD_INCLUDE_DIR})
+ENDIF()
+
+MARK_AS_ADVANCED(
+  ZSTD_INCLUDE_DIR
+  ZSTD_LIBRARY
+)

build_files/cmake/platform/platform_apple.cmake

@@ -441,6 +441,9 @@ if(WITH_HARU)
   endif()
 endif()
 
+set(ZSTD_ROOT_DIR ${LIBDIR}/zstd)
+find_package(Zstd REQUIRED)
+
 if(EXISTS ${LIBDIR})
   without_system_libs_end()
 endif()

build_files/cmake/platform/platform_unix.cmake

@@ -99,6 +99,7 @@ endif()
 find_package_wrapper(JPEG REQUIRED)
 find_package_wrapper(PNG REQUIRED)
 find_package_wrapper(ZLIB REQUIRED)
+find_package_wrapper(Zstd REQUIRED)
 find_package_wrapper(Freetype REQUIRED)
 
 if(WITH_PYTHON)

build_files/cmake/platform/platform_win32.cmake

@@ -873,3 +873,6 @@ if(WITH_HARU)
     set(WITH_HARU OFF)
   endif()
 endif()
+
+set(ZSTD_INCLUDE_DIRS ${LIBDIR}/zstd/include)
+set(ZSTD_LIBRARIES ${LIBDIR}/zstd/lib/zstd_static.lib)

source/blender/blenlib/BLI_fileops.h

@@ -154,18 +154,17 @@ bool BLI_file_is_writable(const char *file) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL
 bool BLI_file_touch(const char *file) ATTR_NONNULL();
 bool BLI_file_alias_target(const char *filepath, char *r_targetpath) ATTR_WARN_UNUSED_RESULT;
 
-#if 0 /* UNUSED */
-int BLI_file_gzip(const char *from, const char *to) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL();
-#endif
-char *BLI_file_ungzip_to_mem(const char *from_file, int *r_size) ATTR_WARN_UNUSED_RESULT
-    ATTR_NONNULL();
-size_t BLI_gzip_mem_to_file_at_pos(void *buf,
-                                   size_t len,
-                                   FILE *file,
-                                   size_t gz_stream_offset,
-                                   int compression_level) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL();
-size_t BLI_ungzip_file_to_mem_at_pos(void *buf, size_t len, FILE *file, size_t gz_stream_offset)
+bool BLI_file_magic_is_gzip(const char header[4]);
+
+size_t BLI_file_zstd_from_mem_at_pos(void *buf,
+                                     size_t len,
+                                     FILE *file,
+                                     size_t file_offset,
+                                     int compression_level) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL();
+size_t BLI_file_unzstd_to_mem_at_pos(void *buf, size_t len, FILE *file, size_t file_offset)
     ATTR_WARN_UNUSED_RESULT ATTR_NONNULL();
+bool BLI_file_magic_is_zstd(const char header[4]);
+
 size_t BLI_file_descriptor_size(int file) ATTR_WARN_UNUSED_RESULT;
 size_t BLI_file_size(const char *path) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL();
 

source/blender/blenlib/BLI_filereader.h

@@ -0,0 +1,81 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup bli
+ * \brief Wrapper for reading from various sources (e.g. raw files, compressed files, memory...).
+ */
+
+#pragma once
+
+#ifdef WIN32
+#  include "BLI_winstuff.h"
+#else
+#  include <sys/types.h>
+#endif
+
+#include "BLI_compiler_attrs.h"
+#include "BLI_utildefines.h"
+
+#if defined(_MSC_VER) || defined(__APPLE__) || defined(__HAIKU__) || defined(__NetBSD__)
+typedef int64_t off64_t;
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct FileReader;
+
+typedef ssize_t (*FileReaderReadFn)(struct FileReader *reader, void *buffer, size_t size);
+typedef off64_t (*FileReaderSeekFn)(struct FileReader *reader, off64_t offset, int whence);
+typedef void (*FileReaderCloseFn)(struct FileReader *reader);
+
+/* General structure for all FileReaders, implementations add custom fields at the end. */
+typedef struct FileReader {
+  FileReaderReadFn read;
+  FileReaderSeekFn seek;
+  FileReaderCloseFn close;
+
+  off64_t offset;
+} FileReader;
+
+/* Functions for opening the various types of FileReader.
+ * They either succeed and return a valid FileReader, or fail and return NULL.
+ *
+ * If a FileReader is created, it has to be cleaned up and freed by calling
+ * its close() function unless another FileReader has taken ownership - for example,
+ * Zstd and Gzip take over the base FileReader and will clean it up when their clean() is called.
+ */
+
+/* Create FileReader from raw file descriptor. */
+FileReader *BLI_filereader_new_file(int filedes) ATTR_WARN_UNUSED_RESULT;
+/* Create FileReader from raw file descriptor using memory-mapped IO. */
+FileReader *BLI_filereader_new_mmap(int filedes) ATTR_WARN_UNUSED_RESULT;
+/* Create FileReader from a region of memory. */
+FileReader *BLI_filereader_new_memory(const void *data, size_t len) ATTR_WARN_UNUSED_RESULT
+    ATTR_NONNULL();
+/* Create FileReader from applying Zstd decompression on an underlying file. */
+FileReader *BLI_filereader_new_zstd(FileReader *base) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL();
+/* Create FileReader from applying Gzip decompression on an underlying file. */
+FileReader *BLI_filereader_new_gzip(FileReader *base) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL();
+
+#ifdef __cplusplus
+}
+#endif

source/blender/blenlib/CMakeLists.txt

@@ -31,6 +31,7 @@ set(INC
 
 set(INC_SYS
   ${ZLIB_INCLUDE_DIRS}
+  ${ZSTD_INCLUDE_DIRS}
   ${FREETYPE_INCLUDE_DIRS}
   ${GMP_INCLUDE_DIRS}
 )
@@ -75,6 +76,10 @@ set(SRC
   intern/endian_switch.c
   intern/expr_pylike_eval.c
   intern/fileops.c
+  intern/filereader_file.c
+  intern/filereader_gzip.c
+  intern/filereader_memory.c
+  intern/filereader_zstd.c
   intern/fnmatch.c
   intern/freetypefont.c
   intern/gsqueue.c
@@ -194,6 +199,7 @@ set(SRC
   BLI_enumerable_thread_specific.hh
   BLI_expr_pylike_eval.h
   BLI_fileops.h
+  BLI_filereader.h
   BLI_fileops_types.h
   BLI_float2.hh
   BLI_float3.hh
@@ -323,6 +329,7 @@ set(LIB
 
   ${FREETYPE_LIBRARY}
   ${ZLIB_LIBRARIES}
+  ${ZSTD_LIBRARIES}
 )
 
 if(WITH_MEM_VALGRIND)

source/blender/blenlib/intern/fileops.c

@@ -31,6 +31,7 @@
 #include <errno.h>
 
 #include "zlib.h"
+#include "zstd.h"
 
 #ifdef WIN32
 #  include "BLI_fileops_types.h"
@@ -61,199 +62,123 @@
 #include "BLI_sys_types.h" /* for intptr_t support */
 #include "BLI_utildefines.h"
 
-#if 0 /* UNUSED */
-/* gzip the file in from and write it to "to".
- * return -1 if zlib fails, -2 if the originating file does not exist
- * NOTE: will remove the "from" file
- */
-int BLI_file_gzip(const char *from, const char *to)
+size_t BLI_file_zstd_from_mem_at_pos(
+    void *buf, size_t len, FILE *file, size_t file_offset, int compression_level)
 {
-  char buffer[10240];
-  int file;
-  int readsize = 0;
-  int rval = 0, err;
-  gzFile gzfile;
+  fseek(file, file_offset, SEEK_SET);
 
-  /* level 1 is very close to 3 (the default) in terms of file size,
-   * but about twice as fast, best use for speedy saving - campbell */
-  gzfile = BLI_gzopen(to, "wb1");
-  if (gzfile == NULL) {
-    return -1;
-  }
-  file = BLI_open(from, O_BINARY | O_RDONLY, 0);
-  if (file == -1) {
-    return -2;
-  }
+  ZSTD_CCtx *ctx = ZSTD_createCCtx();
+  ZSTD_CCtx_setParameter(ctx, ZSTD_c_compressionLevel, compression_level);
 
-  while (1) {
-    readsize = read(file, buffer, sizeof(buffer));
+  ZSTD_inBuffer input = {buf, len, 0};
 
-    if (readsize < 0) {
-      rval = -2; /* error happened in reading */
-      fprintf(stderr, "Error reading file %s: %s.\n", from, strerror(errno));
+  size_t out_len = ZSTD_CStreamOutSize();
+  void *out_buf = MEM_mallocN(out_len, __func__);
+  size_t total_written = 0;
+
+  /* Compress block and write it out until the input has been consumed. */
+  while (input.pos < input.size) {
+    ZSTD_outBuffer output = {out_buf, out_len, 0};
+    size_t ret = ZSTD_compressStream2(ctx, &output, &input, ZSTD_e_continue);
+    if (ZSTD_isError(ret)) {
       break;
     }
-    else if (readsize == 0) {
-      break; /* done reading */
-    }
-
-    if (gzwrite(gzfile, buffer, readsize) <= 0) {
-      rval = -1; /* error happened in writing */
-      fprintf(stderr, "Error writing gz file %s: %s.\n", to, gzerror(gzfile, &err));
+    if (fwrite(out_buf, 1, output.pos, file) != output.pos) {
       break;
     }
+    total_written += output.pos;
   }
 
-  gzclose(gzfile);
-  close(file);
-
-  return rval;
-}
-#endif
-
-/* gzip the file in from_file and write it to memory to_mem, at most size bytes.
- * return the unzipped size
- */
-char *BLI_file_ungzip_to_mem(const char *from_file, int *r_size)
-{
-  gzFile gzfile;
-  int readsize, size, alloc_size = 0;
-  char *mem = NULL;
-  const int chunk_size = 512 * 1024;
-
-  size = 0;
-
-  gzfile = BLI_gzopen(from_file, "rb");
-  for (;;) {
-    if (mem == NULL) {
-      mem = MEM_callocN(chunk_size, "BLI_ungzip_to_mem");
-      alloc_size = chunk_size;
-    }
-    else {
-      mem = MEM_reallocN(mem, size + chunk_size);
-      alloc_size += chunk_size;
-    }
-
-    readsize = gzread(gzfile, mem + size, chunk_size);
-    if (readsize > 0) {
-      size += readsize;
-    }
-    else {
+  /* Finalize the Zstd frame. */
+  size_t ret = 1;
+  while (ret != 0) {
+    ZSTD_outBuffer output = {out_buf, out_len, 0};
+    ret = ZSTD_compressStream2(ctx, &output, &input, ZSTD_e_end);
+    if (ZSTD_isError(ret)) {
       break;
     }
+    if (fwrite(out_buf, 1, output.pos, file) != output.pos) {
+      break;
+    }
+    total_written += output.pos;
   }
 
-  gzclose(gzfile);
+  MEM_freeN(out_buf);
+  ZSTD_freeCCtx(ctx);
 
-  if (size == 0) {
-    MEM_freeN(mem);
-    mem = NULL;
-  }
-  else if (alloc_size != size) {
-    mem = MEM_reallocN(mem, size);
-  }
-
-  *r_size = size;
-
-  return mem;
+  return ZSTD_isError(ret) ? 0 : total_written;
 }
 
-#define CHUNK (256 * 1024)
-
-/* gzip byte array from memory and write it to file at certain position.
- * return size of gzip stream.
- */
-size_t BLI_gzip_mem_to_file_at_pos(
-    void *buf, size_t len, FILE *file, size_t gz_stream_offset, int compression_level)
+size_t BLI_file_unzstd_to_mem_at_pos(void *buf, size_t len, FILE *file, size_t file_offset)
 {
-  int ret, flush;
-  unsigned have;
-  z_stream strm;
-  unsigned char out[CHUNK];
+  fseek(file, file_offset, SEEK_SET);
 
-  BLI_fseek(file, gz_stream_offset, 0);
+  ZSTD_DCtx *ctx = ZSTD_createDCtx();
 
-  strm.zalloc = Z_NULL;
-  strm.zfree = Z_NULL;
-  strm.opaque = Z_NULL;
-  ret = deflateInit(&strm, compression_level);
-  if (ret != Z_OK) {
-    return 0;
-  }
+  size_t in_len = ZSTD_DStreamInSize();
+  void *in_buf = MEM_mallocN(in_len, __func__);
+  ZSTD_inBuffer input = {in_buf, in_len, 0};
 
-  strm.avail_in = len;
-  strm.next_in = (Bytef *)buf;
-  flush = Z_FINISH;
+  ZSTD_outBuffer output = {buf, len, 0};
 
-  do {
-    strm.avail_out = CHUNK;
-    strm.next_out = out;
-    ret = deflate(&strm, flush);
-    if (ret == Z_STREAM_ERROR) {
-      return 0;
-    }
-    have = CHUNK - strm.avail_out;
-    if (fwrite(out, 1, have, file) != have || ferror(file)) {
-      deflateEnd(&strm);
-      return 0;
-    }
-  } while (strm.avail_out == 0);
-
-  if (strm.avail_in != 0 || ret != Z_STREAM_END) {
-    return 0;
-  }
-
-  deflateEnd(&strm);
-  return (size_t)strm.total_out;
-}
-
-/* read and decompress gzip stream from file at certain position to buffer.
- * return size of decompressed data.
- */
-size_t BLI_ungzip_file_to_mem_at_pos(void *buf, size_t len, FILE *file, size_t gz_stream_offset)
-{
-  int ret;
-  z_stream strm;
-  size_t chunk = 256 * 1024;
-  unsigned char in[CHUNK];
-
-  BLI_fseek(file, gz_stream_offset, 0);
-
-  strm.zalloc = Z_NULL;
-  strm.zfree = Z_NULL;
-  strm.opaque = Z_NULL;
-  strm.avail_in = 0;
-  strm.next_in = Z_NULL;
-  ret = inflateInit(&strm);
-  if (ret != Z_OK) {
-    return 0;
-  }
-
-  do {
-    strm.avail_in = fread(in, 1, chunk, file);
-    strm.next_in = in;
-    if (ferror(file)) {
-      inflateEnd(&strm);
-      return 0;
+  size_t ret = 0;
+  /* Read and decompress chunks of input data until we have enough output. */
+  while (output.pos < output.size && !ZSTD_isError(ret)) {
+    input.size = fread(in_buf, 1, in_len, file);
+    if (input.size == 0) {
+      break;
     }
 
-    do {
-      strm.avail_out = len;
-      strm.next_out = (Bytef *)buf + strm.total_out;
+    /* Consume input data until we run out or have enough output. */
+    input.pos = 0;
+    while (input.pos < input.size && output.pos < output.size) {
+      ret = ZSTD_decompressStream(ctx, &output, &input);
 
-      ret = inflate(&strm, Z_NO_FLUSH);
-      if (ret == Z_STREAM_ERROR) {
-        return 0;
+      if (ZSTD_isError(ret)) {
+        break;
       }
-    } while (strm.avail_out == 0);
+    }
+  }
 
-  } while (ret != Z_STREAM_END);
+  MEM_freeN(in_buf);
+  ZSTD_freeDCtx(ctx);
 
-  inflateEnd(&strm);
-  return (size_t)strm.total_out;
+  return ZSTD_isError(ret) ? 0 : output.pos;
 }
 
-#undef CHUNK
+bool BLI_file_magic_is_gzip(const char header[4])
+{
+  /* GZIP itself starts with the magic bytes 0x1f 0x8b.
+   * The third byte indicates the compression method, which is 0x08 for DEFLATE. */
+  return header[0] == 0x1f && header[1] == 0x8b && header[2] == 0x08;
+}
+
+bool BLI_file_magic_is_zstd(const char header[4])
+{
+  /* ZSTD files consist of concatenated frames, each either a Zstd frame or a skippable frame.
+   * Both types of frames start with a magic number: 0xFD2FB528 for Zstd frames and 0x184D2A5*
+   * for skippable frames, with the * being anything from 0 to F.
+   *
+   * To check whether a file is Zstd-compressed, we just check whether the first frame matches
+   * either. Seeking through the file until a Zstd frame is found would make things more
+   * complicated and the probability of a false positive is rather low anyways.
+   *
+   * Note that LZ4 uses a compatible format, so even though its compressed frames have a
+   * different magic number, a valid LZ4 file might also start with a skippable frame matching
+   * the second check here.
+   *
+   * For more details, see https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md
+   */
+
+  uint32_t magic = *((uint32_t *)header);
+  if (magic == 0xFD2FB528) {
+    return true;
+  }
+  if ((magic >> 4) == 0x184D2A5) {
+    return true;
+  }
+  return false;
+}
 
 /**
  * Returns true if the file with the specified name can be written.

source/blender/blenlib/intern/filereader_file.c

@@ -0,0 +1,80 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004-2021 Blender Foundation
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup bli
+ */
+
+#ifndef WIN32
+#  include <unistd.h> /* for read close */
+#else
+#  include "BLI_winstuff.h"
+#  include "winsock2.h"
+#  include <io.h> /* for open close read */
+#endif
+
+#include "BLI_blenlib.h"
+#include "BLI_filereader.h"
+
+#include "MEM_guardedalloc.h"
+
+typedef struct {
+  FileReader reader;
+
+  int filedes;
+} RawFileReader;
+
+static ssize_t file_read(FileReader *reader, void *buffer, size_t size)
+{
+  RawFileReader *rawfile = (RawFileReader *)reader;
+  ssize_t readsize = read(rawfile->filedes, buffer, size);
+
+  if (readsize >= 0) {
+    rawfile->reader.offset += readsize;
+  }
+
+  return readsize;
+}
+
+static off64_t file_seek(FileReader *reader, off64_t offset, int whence)
+{
+  RawFileReader *rawfile = (RawFileReader *)reader;
+  rawfile->reader.offset = BLI_lseek(rawfile->filedes, offset, whence);
+  return rawfile->reader.offset;
+}
+
+static void file_close(FileReader *reader)
+{
+  RawFileReader *rawfile = (RawFileReader *)reader;
+  close(rawfile->filedes);
+  MEM_freeN(rawfile);
+}
+
+FileReader *BLI_filereader_new_file(int filedes)
+{
+  RawFileReader *rawfile = MEM_callocN(sizeof(RawFileReader), __func__);
+
+  rawfile->filedes = filedes;
+
+  rawfile->reader.read = file_read;
+  rawfile->reader.seek = file_seek;
+  rawfile->reader.close = file_close;
+
+  return (FileReader *)rawfile;
+}

source/blender/blenlib/intern/filereader_gzip.c

@@ -0,0 +1,108 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004-2021 Blender Foundation
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup bli
+ */
+
+#include <zlib.h>
+
+#include "BLI_blenlib.h"
+#include "BLI_filereader.h"
+
+#include "MEM_guardedalloc.h"
+
+typedef struct {
+  FileReader reader;
+
+  FileReader *base;
+
+  z_stream strm;
+
+  void *in_buf;
+  size_t in_size;
+} GzipReader;
+
+static ssize_t gzip_read(FileReader *reader, void *buffer, size_t size)
+{
+  GzipReader *gzip = (GzipReader *)reader;
+
+  gzip->strm.avail_out = size;
+  gzip->strm.next_out = buffer;
+
+  while (gzip->strm.avail_out > 0) {
+    if (gzip->strm.avail_in == 0) {
+      /* Ran out of buffered input data, read some more. */
+      size_t readsize = gzip->base->read(gzip->base, gzip->in_buf, gzip->in_size);
+
+      if (readsize > 0) {
+        /* We got some data, so mark the buffer as refilled. */
+        gzip->strm.avail_in = readsize;
+        gzip->strm.next_in = gzip->in_buf;
+      }
+      else {
+        /* The underlying file is EOF, so return as much as we can. */
+        break;
+      }
+    }
+
+    int ret = inflate(&gzip->strm, Z_NO_FLUSH);
+
+    if (ret != Z_OK && ret != Z_BUF_ERROR) {
+      break;
+    }
+  }
+
+  ssize_t read_len = size - gzip->strm.avail_out;
+  gzip->reader.offset += read_len;
+  return read_len;
+}
+
+static void gzip_close(FileReader *reader)
+{
+  GzipReader *gzip = (GzipReader *)reader;
+
+  if (inflateEnd(&gzip->strm) != Z_OK) {
+    printf("close gzip stream error\n");
+  }
+  MEM_freeN((void *)gzip->in_buf);
+
+  gzip->base->close(gzip->base);
+  MEM_freeN(gzip);
+}
+
+FileReader *BLI_filereader_new_gzip(FileReader *base)
+{
+  GzipReader *gzip = MEM_callocN(sizeof(GzipReader), __func__);
+  gzip->base = base;
+
+  if (inflateInit2(&gzip->strm, 16 + MAX_WBITS) != Z_OK) {
+    MEM_freeN(gzip);
+    return NULL;
+  }
+
+  gzip->in_size = 256 * 2014;
+  gzip->in_buf = MEM_mallocN(gzip->in_size, "gzip in buf");
+
+  gzip->reader.read = gzip_read;
+  gzip->reader.seek = NULL;
+  gzip->reader.close = gzip_close;
+
+  return (FileReader *)gzip;
+}

source/blender/blenlib/intern/filereader_memory.c

@@ -0,0 +1,145 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004-2021 Blender Foundation
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup bli
+ */
+
+#include <string.h>
+
+#include "BLI_blenlib.h"
+#include "BLI_filereader.h"
+#include "BLI_mmap.h"
+
+#include "MEM_guardedalloc.h"
+
+/* This file implements both memory-backed and memory-mapped-file-backed reading. */
+typedef struct {
+  FileReader reader;
+
+  const char *data;
+  BLI_mmap_file *mmap;
+  size_t length;
+} MemoryReader;
+
+static ssize_t memory_read_raw(FileReader *reader, void *buffer, size_t size)
+{
+  MemoryReader *mem = (MemoryReader *)reader;
+
+  /* Don't read more bytes than there are available in the buffer. */
+  size_t readsize = MIN2(size, (size_t)(mem->length - mem->reader.offset));
+
+  memcpy(buffer, mem->data + mem->reader.offset, readsize);
+  mem->reader.offset += readsize;
+
+  return readsize;
+}
+
+static off64_t memory_seek(FileReader *reader, off64_t offset, int whence)
+{
+  MemoryReader *mem = (MemoryReader *)reader;
+
+  off64_t new_pos;
+  if (whence == SEEK_CUR) {
+    new_pos = mem->reader.offset + offset;
+  }
+  else if (whence == SEEK_SET) {
+    new_pos = offset;
+  }
+  else if (whence == SEEK_END) {
+    new_pos = mem->length + offset;
+  }
+  else {
+    return -1;
+  }
+
+  if (new_pos < 0 || new_pos > mem->length) {
+    return -1;
+  }
+
+  mem->reader.offset = new_pos;
+  return mem->reader.offset;
+}
+
+static void memory_close_raw(FileReader *reader)
+{
+  MEM_freeN(reader);
+}
+
+FileReader *BLI_filereader_new_memory(const void *data, size_t len)
+{
+  MemoryReader *mem = MEM_callocN(sizeof(MemoryReader), __func__);
+
+  mem->data = (const char *)data;
+  mem->length = len;
+
+  mem->reader.read = memory_read_raw;
+  mem->reader.seek = memory_seek;
+  mem->reader.close = memory_close_raw;
+
+  return (FileReader *)mem;
+}
+
+/* Memory-mapped file reading.
+ * By using `mmap()`, we can map a file so that it can be treated like normal memory,
+ * meaning that we can just read from it with `memcpy()` etc.
+ * This avoids system call overhead and can significantly speed up file loading.
+ */
+
+static ssize_t memory_read_mmap(FileReader *reader, void *buffer, size_t size)
+{
+  MemoryReader *mem = (MemoryReader *)reader;
+
+  /* Don't read more bytes than there are available in the buffer. */
+  size_t readsize = MIN2(size, (size_t)(mem->length - mem->reader.offset));
+
+  if (!BLI_mmap_read(mem->mmap, buffer, mem->reader.offset, readsize)) {
+    return 0;
+  }
+
+  mem->reader.offset += readsize;
+
+  return readsize;
+}
+
+static void memory_close_mmap(FileReader *reader)
+{
+  MemoryReader *mem = (MemoryReader *)reader;
+  BLI_mmap_free(mem->mmap);
+  MEM_freeN(mem);
+}
+
+FileReader *BLI_filereader_new_mmap(int filedes)
+{
+  BLI_mmap_file *mmap = BLI_mmap_open(filedes);
+  if (mmap == NULL) {
+    return NULL;
+  }
+
+  MemoryReader *mem = MEM_callocN(sizeof(MemoryReader), __func__);
+
+  mem->mmap = mmap;
+  mem->length = BLI_lseek(filedes, 0, SEEK_END);
+
+  mem->reader.read = memory_read_mmap;
+  mem->reader.seek = memory_seek;
+  mem->reader.close = memory_close_mmap;
+
+  return (FileReader *)mem;
+}

source/blender/blenlib/intern/filereader_zstd.c

@@ -0,0 +1,335 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2021 Blender Foundation
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup bli
+ */
+
+#include <string.h>
+#include <zstd.h>
+
+#include "BLI_blenlib.h"
+#include "BLI_endian_switch.h"
+#include "BLI_filereader.h"
+#include "BLI_math_base.h"
+
+#include "MEM_guardedalloc.h"
+
+typedef struct {
+  FileReader reader;
+
+  FileReader *base;
+
+  ZSTD_DCtx *ctx;
+  ZSTD_inBuffer in_buf;
+  size_t in_buf_max_size;
+
+  struct {
+    int num_frames;
+    size_t *compressed_ofs;
+    size_t *uncompressed_ofs;
+
+    char *cached_content;
+    int cached_frame;
+  } seek;
+} ZstdReader;
+
+static bool zstd_read_u32(FileReader *base, uint32_t *val)
+{
+  if (base->read(base, val, sizeof(uint32_t)) != sizeof(uint32_t)) {
+    return false;
+  }
+#ifdef __BIG_ENDIAN__
+  BLI_endian_switch_uint32(val);
+#endif
+  return true;
+}
+
+static bool zstd_read_seek_table(ZstdReader *zstd)
+{
+  FileReader *base = zstd->base;
+
+  /* The seek table frame is at the end of the file, so seek there
+   * and verify that there is enough data. */
+  if (base->seek(base, -4, SEEK_END) < 13) {
+    return false;
+  }
+  uint32_t magic;
+  if (!zstd_read_u32(base, &magic) || magic != 0x8F92EAB1) {
+    return false;
+  }
+
+  uint8_t flags;
+  if (base->seek(base, -5, SEEK_END) < 0 || base->read(base, &flags, 1) != 1) {
+    return false;
+  }
+  /* Bit 7 indicates checksums. Bits 5 and 6 must be zero. */
+  bool has_checksums = (flags & 0x80);
+  if (flags & 0x60) {
+    return false;
+  }
+
+  uint32_t num_frames;
+  if (base->seek(base, -9, SEEK_END) < 0 || !zstd_read_u32(base, &num_frames)) {
+    return false;
+  }
+
+  /* Each frame has either 2 or 3 uint32_t, and after that we have
+   * num_frames, flags and magic for another 9 bytes. */
+  uint32_t expected_frame_length = num_frames * (has_checksums ? 12 : 8) + 9;
+  /* The frame starts with another magic number and its length, but these
+   * two fields are not included when counting length. */
+  off64_t frame_start_ofs = 8 + expected_frame_length;
+  /* Sanity check: Before the start of the seek table frame,
+   * there must be num_frames frames, each of which at least 8 bytes long. */
+  off64_t seek_frame_start = base->seek(base, -frame_start_ofs, SEEK_END);
+  if (seek_frame_start < num_frames * 8) {
+    return false;
+  }
+
+  if (!zstd_read_u32(base, &magic) || magic != 0x184D2A5E) {
+    return false;
+  }
+
+  uint32_t frame_length;
+  if (!zstd_read_u32(base, &frame_length) || frame_length != expected_frame_length) {
+    return false;
+  }
+
+  zstd->seek.num_frames = num_frames;
+  zstd->seek.compressed_ofs = MEM_malloc_arrayN(num_frames + 1, sizeof(size_t), __func__);
+  zstd->seek.uncompressed_ofs = MEM_malloc_arrayN(num_frames + 1, sizeof(size_t), __func__);
+
+  size_t compressed_ofs = 0;
+  size_t uncompressed_ofs = 0;
+  for (int i = 0; i < num_frames; i++) {
+    uint32_t compressed_size, uncompressed_size;
+    if (!zstd_read_u32(base, &compressed_size) || !zstd_read_u32(base, &uncompressed_size)) {
+      break;
+    }
+    if (has_checksums && base->seek(base, 4, SEEK_CUR) < 0) {
+      break;
+    }
+    zstd->seek.compressed_ofs[i] = compressed_ofs;
+    zstd->seek.uncompressed_ofs[i] = uncompressed_ofs;
+    compressed_ofs += compressed_size;
+    uncompressed_ofs += uncompressed_size;
+  }
+  zstd->seek.compressed_ofs[num_frames] = compressed_ofs;
+  zstd->seek.uncompressed_ofs[num_frames] = uncompressed_ofs;
+
+  /* Seek to the end of the previous frame for the following BHead frame detection. */
+  if (seek_frame_start != compressed_ofs || base->seek(base, seek_frame_start, SEEK_SET) < 0) {
+    MEM_freeN(zstd->seek.compressed_ofs);
+    MEM_freeN(zstd->seek.uncompressed_ofs);
+    memset(&zstd->seek, 0, sizeof(zstd->seek));
+    return false;
+  }
+
+  zstd->seek.cached_frame = -1;
+
+  return true;
+}
+
+/* Find out which frame contains the given position in the uncompressed stream.
+ * Basically just bisection. */
+static int zstd_frame_from_pos(ZstdReader *zstd, size_t pos)
+{
+  int low = 0, high = zstd->seek.num_frames;
+
+  if (pos >= zstd->seek.uncompressed_ofs[zstd->seek.num_frames]) {
+    return -1;
+  }
+
+  while (low + 1 < high) {
+    int mid = low + ((high - low) >> 1);
+    if (zstd->seek.uncompressed_ofs[mid] <= pos) {
+      low = mid;
+    }
+    else {
+      high = mid;
+    }
+  }
+
+  return low;
+}
+
+/* Ensure that the currently loaded frame is the correct one. */
+static const char *zstd_ensure_cache(ZstdReader *zstd, int frame)
+{
+  if (zstd->seek.cached_frame == frame) {
+    /* Cached frame matches, so just return it. */
+    return zstd->seek.cached_content;
+  }
+
+  /* Cached frame doesn't match, so discard it and cache the wanted one onstead. */
+  MEM_SAFE_FREE(zstd->seek.cached_content);
+
+  size_t compressed_size = zstd->seek.compressed_ofs[frame + 1] - zstd->seek.compressed_ofs[frame];
+  size_t uncompressed_size = zstd->seek.uncompressed_ofs[frame + 1] -
+                             zstd->seek.uncompressed_ofs[frame];
+
+  char *uncompressed_data = MEM_mallocN(uncompressed_size, __func__);
+  char *compressed_data = MEM_mallocN(compressed_size, __func__);
+  if (zstd->base->seek(zstd->base, zstd->seek.compressed_ofs[frame], SEEK_SET) < 0 ||
+      zstd->base->read(zstd->base, compressed_data, compressed_size) < compressed_size) {
+    MEM_freeN(compressed_data);
+    MEM_freeN(uncompressed_data);
+    return NULL;
+  }
+
+  size_t res = ZSTD_decompressDCtx(
+      zstd->ctx, uncompressed_data, uncompressed_size, compressed_data, compressed_size);
+  MEM_freeN(compressed_data);
+  if (ZSTD_isError(res) || res < uncompressed_size) {
+    MEM_freeN(uncompressed_data);
+    return NULL;
+  }
+
+  zstd->seek.cached_frame = frame;
+  zstd->seek.cached_content = uncompressed_data;
+  return uncompressed_data;
+}
+
+static ssize_t zstd_read_seekable(FileReader *reader, void *buffer, size_t size)
+{
+  ZstdReader *zstd = (ZstdReader *)reader;
+
+  size_t end_offset = zstd->reader.offset + size, read_len = 0;
+  while (zstd->reader.offset < end_offset) {
+    int frame = zstd_frame_from_pos(zstd, zstd->reader.offset);
+    if (frame < 0) {
+      /* EOF is reached, so return as much as we can. */
+      break;
+    }
+
+    const char *framedata = zstd_ensure_cache(zstd, frame);
+    if (framedata == NULL) {
+      /* Error while reading the frame, so return as much as we can. */
+      break;
+    }
+
+    size_t frame_end_offset = min_zz(zstd->seek.uncompressed_ofs[frame + 1], end_offset);
+    size_t frame_read_len = frame_end_offset - zstd->reader.offset;
+
+    size_t offset_in_frame = zstd->reader.offset - zstd->seek.uncompressed_ofs[frame];
+    memcpy((char *)buffer + read_len, framedata + offset_in_frame, frame_read_len);
+    read_len += frame_read_len;
+    zstd->reader.offset = frame_end_offset;
+  }
+
+  return read_len;
+}
+
+static off64_t zstd_seek(FileReader *reader, off64_t offset, int whence)
+{
+  ZstdReader *zstd = (ZstdReader *)reader;
+  off64_t new_pos;
+  if (whence == SEEK_SET) {
+    new_pos = offset;
+  }
+  else if (whence == SEEK_END) {
+    new_pos = zstd->seek.uncompressed_ofs[zstd->seek.num_frames] + offset;
+  }
+  else {
+    new_pos = zstd->reader.offset + offset;
+  }
+
+  if (new_pos < 0 || new_pos > zstd->seek.uncompressed_ofs[zstd->seek.num_frames]) {
+    return -1;
+  }
+  zstd->reader.offset = new_pos;
+  return zstd->reader.offset;
+}
+
+static ssize_t zstd_read(FileReader *reader, void *buffer, size_t size)
+{
+  ZstdReader *zstd = (ZstdReader *)reader;
+  ZSTD_outBuffer output = {buffer, size, 0};
+
+  while (output.pos < output.size) {
+    if (zstd->in_buf.pos == zstd->in_buf.size) {
+      /* Ran out of buffered input data, read some more. */
+      zstd->in_buf.pos = 0;
+      ssize_t readsize = zstd->base->read(
+          zstd->base, (char *)zstd->in_buf.src, zstd->in_buf_max_size);
+
+      if (readsize > 0) {
+        /* We got some data, so mark the buffer as refilled. */
+        zstd->in_buf.size = readsize;
+      }
+      else {
+        /* The underlying file is EOF, so return as much as we can. */
+        break;
+      }
+    }
+
+    if (ZSTD_isError(ZSTD_decompressStream(zstd->ctx, &output, &zstd->in_buf))) {
+      break;
+    }
+  }
+
+  zstd->reader.offset += output.pos;
+  return output.pos;
+}
+
+static void zstd_close(FileReader *reader)
+{
+  ZstdReader *zstd = (ZstdReader *)reader;
+
+  ZSTD_freeDCtx(zstd->ctx);
+  if (zstd->reader.seek) {
+    MEM_freeN(zstd->seek.uncompressed_ofs);
+    MEM_freeN(zstd->seek.compressed_ofs);
+    MEM_freeN(zstd->seek.cached_content);
+  }
+  else {
+    MEM_freeN((void *)zstd->in_buf.src);
+  }
+
+  zstd->base->close(zstd->base);
+  MEM_freeN(zstd);
+}
+
+FileReader *BLI_filereader_new_zstd(FileReader *base)
+{
+  ZstdReader *zstd = MEM_callocN(sizeof(ZstdReader), __func__);
+
+  zstd->ctx = ZSTD_createDCtx();
+  zstd->base = base;
+
+  if (zstd_read_seek_table(zstd)) {
+    zstd->reader.read = zstd_read_seekable;
+    zstd->reader.seek = zstd_seek;
+  }
+  else {
+    zstd->reader.read = zstd_read;
+    zstd->reader.seek = NULL;
+
+    zstd->in_buf_max_size = ZSTD_DStreamInSize();
+    zstd->in_buf.src = MEM_mallocN(zstd->in_buf_max_size, "zstd in buf");
+    zstd->in_buf.size = zstd->in_buf_max_size;
+    /* This signals that the buffer has run out,
+     * which will make the read function refill it on the first call. */
+    zstd->in_buf.pos = zstd->in_buf_max_size;
+  }
+  zstd->reader.close = zstd_close;
+
+  return (FileReader *)zstd;
+}

source/blender/blenloader/BLO_undofile.h

@@ -24,6 +24,8 @@
  * \ingroup blenloader
  */
 
+#include "BLI_filereader.h"
+
 struct GHash;
 struct Scene;
 
@@ -65,6 +67,16 @@ typedef struct MemFileUndoData {
   size_t undo_size;
 } MemFileUndoData;
 
+/* FileReader-compatible wrapper for reading MemFiles */
+typedef struct {
+  FileReader reader;
+
+  MemFile *memfile;
+  int undo_direction;
+
+  bool memchunk_identical;
+} UndoReader;
+
 /* actually only used writefile.c */
 
 void BLO_memfile_write_init(MemFileWriteData *mem_data,
@@ -84,3 +96,5 @@ extern struct Main *BLO_memfile_main_get(struct MemFile *memfile,
                                          struct Main *bmain,
                                          struct Scene **r_scene);
 extern bool BLO_memfile_write_file(struct MemFile *memfile, const char *filename);
+
+FileReader *BLO_memfile_new_filereader(MemFile *memfile, int undo_direction);

source/blender/blenloader/CMakeLists.txt

@@ -42,7 +42,7 @@ set(INC
 )
 
 set(INC_SYS
-  ${ZLIB_INCLUDE_DIRS}
+  ${ZSTD_INCLUDE_DIRS}
 )
 
 set(SRC

source/blender/blenloader/intern/readfile.c

@@ -21,8 +21,6 @@
  * \ingroup blenloader
  */
 
-#include "zlib.h"
-
 #include <ctype.h> /* for isdigit. */
 #include <fcntl.h> /* for open flags (O_BINARY, O_RDONLY). */
 #include <limits.h>
@@ -71,7 +69,6 @@
 #include "BLI_math.h"
 #include "BLI_memarena.h"
 #include "BLI_mempool.h"
-#include "BLI_mmap.h"
 #include "BLI_threads.h"
 
 #include "PIL_time.h"
@@ -788,7 +785,7 @@ static BHeadN *get_bhead(FileData *fd)
        */
       if (fd->flags & FD_FLAGS_FILE_POINTSIZE_IS_4) {
         bhead4.code = DATA;
-        readsize = fd->read(fd, &bhead4, sizeof(bhead4), NULL);
+        readsize = fd->file->read(fd->file, &bhead4, sizeof(bhead4));
 
         if (readsize == sizeof(bhead4) || bhead4.code == ENDB) {
           if (fd->flags & FD_FLAGS_SWITCH_ENDIAN) {
@@ -811,7 +808,7 @@ static BHeadN *get_bhead(FileData *fd)
       }
       else {
         bhead8.code = DATA;
-        readsize = fd->read(fd, &bhead8, sizeof(bhead8), NULL);
+        readsize = fd->file->read(fd->file, &bhead8, sizeof(bhead8));
 
         if (readsize == sizeof(bhead8) || bhead8.code == ENDB) {
           if (fd->flags & FD_FLAGS_SWITCH_ENDIAN) {
@@ -845,22 +842,22 @@ static BHeadN *get_bhead(FileData *fd)
         /* pass */
       }
 #ifdef USE_BHEAD_READ_ON_DEMAND
-      else if (fd->seek != NULL && BHEAD_USE_READ_ON_DEMAND(&bhead)) {
+      else if (fd->file->seek != NULL && BHEAD_USE_READ_ON_DEMAND(&bhead)) {
         /* Delay reading bhead content. */
         new_bhead = MEM_mallocN(sizeof(BHeadN), "new_bhead");
         if (new_bhead) {
           new_bhead->next = new_bhead->prev = NULL;
-          new_bhead->file_offset = fd->file_offset;
+          new_bhead->file_offset = fd->file->offset;
           new_bhead->has_data = false;
           new_bhead->is_memchunk_identical = false;
           new_bhead->bhead = bhead;
-          off64_t seek_new = fd->seek(fd, bhead.len, SEEK_CUR);
+          off64_t seek_new = fd->file->seek(fd->file, bhead.len, SEEK_CUR);
           if (seek_new == -1) {
             fd->is_eof = true;
             MEM_freeN(new_bhead);
             new_bhead = NULL;
           }
-          BLI_assert(fd->file_offset == seek_new);
+          BLI_assert(fd->file->offset == seek_new);
         }
         else {
           fd->is_eof = true;
@@ -878,14 +875,17 @@ static BHeadN *get_bhead(FileData *fd)
           new_bhead->is_memchunk_identical = false;
           new_bhead->bhead = bhead;
 
-          readsize = fd->read(
-              fd, new_bhead + 1, (size_t)bhead.len, &new_bhead->is_memchunk_identical);
+          readsize = fd->file->read(fd->file, new_bhead + 1, (size_t)bhead.len);
 
-          if (readsize != (ssize_t)bhead.len) {
+          if (readsize != bhead.len) {
             fd->is_eof = true;
             MEM_freeN(new_bhead);
             new_bhead = NULL;
           }
+
+          if (fd->flags & FD_FLAGS_IS_MEMFILE) {
+            new_bhead->is_memchunk_identical = ((UndoReader *)fd->file)->memchunk_identical;
+          }
         }
         else {
           fd->is_eof = true;
@@ -964,17 +964,19 @@ static bool blo_bhead_read_data(FileData *fd, BHead *thisblock, void *buf)
   bool success = true;
   BHeadN *new_bhead = BHEADN_FROM_BHEAD(thisblock);
   BLI_assert(new_bhead->has_data == false && new_bhead->file_offset != 0);
-  off64_t offset_backup = fd->file_offset;
-  if (UNLIKELY(fd->seek(fd, new_bhead->file_offset, SEEK_SET) == -1)) {
+  off64_t offset_backup = fd->file->offset;
+  if (UNLIKELY(fd->file->seek(fd->file, new_bhead->file_offset, SEEK_SET) == -1)) {
     success = false;
   }
   else {
-    if (fd->read(fd, buf, (size_t)new_bhead->bhead.len, &new_bhead->is_memchunk_identical) !=
-        (ssize_t)new_bhead->bhead.len) {
+    if (fd->file->read(fd->file, buf, (size_t)new_bhead->bhead.len) != new_bhead->bhead.len) {
       success = false;
     }
+    if (fd->flags & FD_FLAGS_IS_MEMFILE) {
+      new_bhead->is_memchunk_identical = ((UndoReader *)fd->file)->memchunk_identical;
+    }
   }
-  if (fd->seek(fd, offset_backup, SEEK_SET) == -1) {
+  if (fd->file->seek(fd->file, offset_backup, SEEK_SET) == -1) {
     success = false;
   }
   return success;
@@ -1017,7 +1019,7 @@ static void decode_blender_header(FileData *fd)
   ssize_t readsize;
 
   /* read in the header data */
-  readsize = fd->read(fd, header, sizeof(header), NULL);
+  readsize = fd->file->read(fd->file, header, sizeof(header));
 
   if (readsize == sizeof(header) && STREQLEN(header, "BLENDER", 7) && ELEM(header[7], '_', '-') &&
       ELEM(header[8], 'v', 'V') &&
@@ -1147,210 +1149,12 @@ static int *read_file_thumbnail(FileData *fd)
 
 /** \} */
 
-/* -------------------------------------------------------------------- */
-/** \name File Data API
- * \{ */
-
-/* Regular file reading. */
-
-static ssize_t fd_read_data_from_file(FileData *filedata,
-                                      void *buffer,
-                                      size_t size,
-                                      bool *UNUSED(r_is_memchunck_identical))
-{
-  ssize_t readsize = read(filedata->filedes, buffer, size);
-
-  if (readsize < 0) {
-    readsize = EOF;
-  }
-  else {
-    filedata->file_offset += readsize;
-  }
-
-  return readsize;
-}
-
-static off64_t fd_seek_data_from_file(FileData *filedata, off64_t offset, int whence)
-{
-  filedata->file_offset = BLI_lseek(filedata->filedes, offset, whence);
-  return filedata->file_offset;
-}
-
-/* GZip file reading. */
-
-static ssize_t fd_read_gzip_from_file(FileData *filedata,
-                                      void *buffer,
-                                      size_t size,
-                                      bool *UNUSED(r_is_memchunck_identical))
-{
-  BLI_assert(size <= INT_MAX);
-
-  ssize_t readsize = gzread(filedata->gzfiledes, buffer, (uint)size);
-
-  if (readsize < 0) {
-    readsize = EOF;
-  }
-  else {
-    filedata->file_offset += readsize;
-  }
-
-  return readsize;
-}
-
-/* Memory reading. */
-
-static ssize_t fd_read_from_memory(FileData *filedata,
-                                   void *buffer,
-                                   size_t size,
-                                   bool *UNUSED(r_is_memchunck_identical))
-{
-  /* don't read more bytes than there are available in the buffer */
-  ssize_t readsize = (ssize_t)MIN2(size, filedata->buffersize - (size_t)filedata->file_offset);
-
-  memcpy(buffer, filedata->buffer + filedata->file_offset, (size_t)readsize);
-  filedata->file_offset += readsize;
-
-  return readsize;
-}
-
-/* Memory-mapped file reading.
- * By using mmap(), we can map a file so that it can be treated like normal memory,
- * meaning that we can just read from it with memcpy() etc.
- * This avoids system call overhead and can significantly speed up file loading.
- */
-
-static ssize_t fd_read_from_mmap(FileData *filedata,
-                                 void *buffer,
-                                 size_t size,
-                                 bool *UNUSED(r_is_memchunck_identical))
-{
-  /* don't read more bytes than there are available in the buffer */
-  size_t readsize = MIN2(size, (size_t)(filedata->buffersize - filedata->file_offset));
-
-  if (!BLI_mmap_read(filedata->mmap_file, buffer, filedata->file_offset, readsize)) {
-    return 0;
-  }
-
-  filedata->file_offset += readsize;
-
-  return readsize;
-}
-
-static off64_t fd_seek_from_mmap(FileData *filedata, off64_t offset, int whence)
-{
-  off64_t new_pos;
-  if (whence == SEEK_CUR) {
-    new_pos = filedata->file_offset + offset;
-  }
-  else if (whence == SEEK_SET) {
-    new_pos = offset;
-  }
-  else if (whence == SEEK_END) {
-    new_pos = filedata->buffersize + offset;
-  }
-  else {
-    return -1;
-  }
-
-  if (new_pos < 0 || new_pos > filedata->buffersize) {
-    return -1;
-  }
-
-  filedata->file_offset = new_pos;
-  return filedata->file_offset;
-}
-
-/* MemFile reading. */
-
-static ssize_t fd_read_from_memfile(FileData *filedata,
-                                    void *buffer,
-                                    size_t size,
-                                    bool *r_is_memchunck_identical)
-{
-  static size_t seek = SIZE_MAX; /* the current position */
-  static size_t offset = 0;      /* size of previous chunks */
-  static MemFileChunk *chunk = NULL;
-  size_t chunkoffset, readsize, totread;
-
-  if (r_is_memchunck_identical != NULL) {
-    *r_is_memchunck_identical = true;
-  }
-
-  if (size == 0) {
-    return 0;
-  }
-
-  if (seek != (size_t)filedata->file_offset) {
-    chunk = filedata->memfile->chunks.first;
-    seek = 0;
-
-    while (chunk) {
-      if (seek + chunk->size > (size_t)filedata->file_offset) {
-        break;
-      }
-      seek += chunk->size;
-      chunk = chunk->next;
-    }
-    offset = seek;
-    seek = (size_t)filedata->file_offset;
-  }
-
-  if (chunk) {
-    totread = 0;
-
-    do {
-      /* first check if it's on the end if current chunk */
-      if (seek - offset == chunk->size) {
-        offset += chunk->size;
-        chunk = chunk->next;
-      }
-
-      /* debug, should never happen */
-      if (chunk == NULL) {
-        CLOG_ERROR(&LOG, "Illegal read, got a NULL chunk");
-        return 0;
-      }
-
-      chunkoffset = seek - offset;
-      readsize = size - totread;
-
-      /* data can be spread over multiple chunks, so clamp size
-       * to within this chunk, and then it will read further in
-       * the next chunk */
-      if (chunkoffset + readsize > chunk->size) {
-        readsize = chunk->size - chunkoffset;
-      }
-
-      memcpy(POINTER_OFFSET(buffer, totread), chunk->buf + chunkoffset, readsize);
-      totread += readsize;
-      filedata->file_offset += readsize;
-      seek += readsize;
-      if (r_is_memchunck_identical != NULL) {
-        /* `is_identical` of current chunk represents whether it changed compared to previous undo
-         * step. this is fine in redo case, but not in undo case, where we need an extra flag
-         * defined when saving the next (future) step after the one we want to restore, as we are
-         * supposed to 'come from' that future undo step, and not the one before current one. */
-        *r_is_memchunck_identical &= filedata->undo_direction == STEP_REDO ?
-                                         chunk->is_identical :
-                                         chunk->is_identical_future;
-      }
-    } while (totread < size);
-
-    return (ssize_t)totread;
-  }
-
-  return 0;
-}
-
 static FileData *filedata_new(BlendFileReadReport *reports)
 {
   BLI_assert(reports != NULL);
 
   FileData *fd = MEM_callocN(sizeof(FileData), "FileData");
 
-  fd->filedes = -1;
-  fd->gzfiledes = NULL;
-
   fd->memsdna = DNA_sdna_current_get();
 
   fd->datamap = oldnewmap_new();
@@ -1387,78 +1191,66 @@ static FileData *blo_decode_and_check(FileData *fd, ReportList *reports)
 
 static FileData *blo_filedata_from_file_descriptor(const char *filepath,
                                                    BlendFileReadReport *reports,
-                                                   int file)
+                                                   int filedes)
 {
-  FileDataReadFn *read_fn = NULL;
-  FileDataSeekFn *seek_fn = NULL; /* Optional. */
-  size_t buffersize = 0;
-  BLI_mmap_file *mmap_file = NULL;
-
-  gzFile gzfile = (gzFile)Z_NULL;
-
   char header[7];
+  FileReader *rawfile = BLI_filereader_new_file(filedes);
+  FileReader *file = NULL;
 
-  /* Regular file. */
   errno = 0;
-  if (read(file, header, sizeof(header)) != sizeof(header)) {
+  /* If opening the file failed or we can't read the header, give up. */
+  if (rawfile == NULL || rawfile->read(rawfile, header, sizeof(header)) != sizeof(header)) {
     BKE_reportf(reports->reports,
                 RPT_WARNING,
                 "Unable to read '%s': %s",
                 filepath,
                 errno ? strerror(errno) : TIP_("insufficient content"));
+    if (rawfile) {
+      rawfile->close(rawfile);
+    }
+    else {
+      close(filedes);
+    }
     return NULL;
   }
 
-  /* Regular file. */
+  /* Rewind the file after reading the header. */
+  rawfile->seek(rawfile, 0, SEEK_SET);
+
+  /* Check if we have a regular file. */
   if (memcmp(header, "BLENDER", sizeof(header)) == 0) {
-    read_fn = fd_read_data_from_file;
-    seek_fn = fd_seek_data_from_file;
-
-    mmap_file = BLI_mmap_open(file);
-    if (mmap_file != NULL) {
-      read_fn = fd_read_from_mmap;
-      seek_fn = fd_seek_from_mmap;
-      buffersize = BLI_lseek(file, 0, SEEK_END);
+    /* Try opening the file with memory-mapped IO. */
+    file = BLI_filereader_new_mmap(filedes);
+    if (file == NULL) {
+      /* mmap failed, so just keep using rawfile. */
+      file = rawfile;
+      rawfile = NULL;
+    }
+  }
+  else if (BLI_file_magic_is_gzip(header)) {
+    file = BLI_filereader_new_gzip(rawfile);
+    if (file != NULL) {
+      rawfile = NULL; /* The Gzip FileReader takes ownership of `rawfile`. */
+    }
+  }
+  else if (BLI_file_magic_is_zstd(header)) {
+    file = BLI_filereader_new_zstd(rawfile);
+    if (file != NULL) {
+      rawfile = NULL; /* The Zstd FileReader takes ownership of `rawfile`. */
     }
   }
 
-  BLI_lseek(file, 0, SEEK_SET);
-
-  /* Gzip file. */
-  errno = 0;
-  if ((read_fn == NULL) &&
-      /* Check header magic. */
-      (header[0] == 0x1f && header[1] == 0x8b)) {
-    gzfile = BLI_gzopen(filepath, "rb");
-    if (gzfile == (gzFile)Z_NULL) {
-      BKE_reportf(reports->reports,
-                  RPT_WARNING,
-                  "Unable to open '%s': %s",
-                  filepath,
-                  errno ? strerror(errno) : TIP_("unknown error reading file"));
-      return NULL;
-    }
-
-    /* 'seek_fn' is too slow for gzip, don't set it. */
-    read_fn = fd_read_gzip_from_file;
-    /* Caller must close. */
-    file = -1;
+  /* Clean up `rawfile` if it wasn't taken over. */
+  if (rawfile != NULL) {
+    rawfile->close(rawfile);
   }
-
-  if (read_fn == NULL) {
+  if (file == NULL) {
     BKE_reportf(reports->reports, RPT_WARNING, "Unrecognized file format '%s'", filepath);
     return NULL;
   }
 
   FileData *fd = filedata_new(reports);
-
-  fd->filedes = file;
-  fd->gzfiledes = gzfile;
-
-  fd->read = read_fn;
-  fd->seek = seek_fn;
-  fd->mmap_file = mmap_file;
-  fd->buffersize = buffersize;
+  fd->file = file;
 
   return fd;
 }
@@ -1475,11 +1267,7 @@ static FileData *blo_filedata_from_file_open(const char *filepath, BlendFileRead
                 errno ? strerror(errno) : TIP_("unknown error reading file"));
     return NULL;
   }
-  FileData *fd = blo_filedata_from_file_descriptor(filepath, reports, file);
-  if ((fd == NULL) || (fd->filedes == -1)) {
-    close(file);
-  }
-  return fd;
+  return blo_filedata_from_file_descriptor(filepath, reports, file);
 }
 
 /* cannot be called with relative paths anymore! */
@@ -1513,50 +1301,6 @@ static FileData *blo_filedata_from_file_minimal(const char *filepath)
   return NULL;
 }
 
-static ssize_t fd_read_gzip_from_memory(FileData *filedata,
-                                        void *buffer,
-                                        size_t size,
-                                        bool *UNUSED(r_is_memchunck_identical))
-{
-  int err;
-
-  filedata->strm.next_out = (Bytef *)buffer;
-  filedata->strm.avail_out = (uint)size;
-
-  /* Inflate another chunk. */
-  err = inflate(&filedata->strm, Z_SYNC_FLUSH);
-
-  if (err == Z_STREAM_END) {
-    return 0;
-  }
-  if (err != Z_OK) {
-    CLOG_ERROR(&LOG, "ZLib error (code %d)", err);
-    return 0;
-  }
-
-  filedata->file_offset += size;
-
-  return (ssize_t)size;
-}
-
-static int fd_read_gzip_from_memory_init(FileData *fd)
-{
-
-  fd->strm.next_in = (Bytef *)fd->buffer;
-  fd->strm.avail_in = fd->buffersize;
-  fd->strm.total_out = 0;
-  fd->strm.zalloc = Z_NULL;
-  fd->strm.zfree = Z_NULL;
-
-  if (inflateInit2(&fd->strm, (16 + MAX_WBITS)) != Z_OK) {
-    return 0;
-  }
-
-  fd->read = fd_read_gzip_from_memory;
-
-  return 1;
-}
-
 FileData *blo_filedata_from_memory(const void *mem, int memsize, BlendFileReadReport *reports)
 {
   if (!mem || memsize < SIZEOFBLENDERHEADER) {
@@ -1565,24 +1309,24 @@ FileData *blo_filedata_from_memory(const void *mem, int memsize, BlendFileReadRe
     return NULL;
   }
 
+  FileReader *mem_file = BLI_filereader_new_memory(mem, memsize);
+  FileReader *file = mem_file;
+
+  if (BLI_file_magic_is_gzip(mem)) {
+    file = BLI_filereader_new_gzip(mem_file);
+  }
+  else if (BLI_file_magic_is_zstd(mem)) {
+    file = BLI_filereader_new_zstd(mem_file);
+  }
+
+  if (file == NULL) {
+    /* Compression initialization failed. */
+    mem_file->close(mem_file);
+    return NULL;
+  }
+
   FileData *fd = filedata_new(reports);
-  const char *cp = mem;
-
-  fd->buffer = mem;
-  fd->buffersize = memsize;
-
-  /* test if gzip */
-  if (cp[0] == 0x1f && cp[1] == 0x8b) {
-    if (0 == fd_read_gzip_from_memory_init(fd)) {
-      blo_filedata_free(fd);
-      return NULL;
-    }
-  }
-  else {
-    fd->read = fd_read_from_memory;
-  }
-
-  fd->flags |= FD_FLAGS_NOT_MY_BUFFER;
+  fd->file = file;
 
   return blo_decode_and_check(fd, reports->reports);
 }
@@ -1597,11 +1341,9 @@ FileData *blo_filedata_from_memfile(MemFile *memfile,
   }
 
   FileData *fd = filedata_new(reports);
-  fd->memfile = memfile;
+  fd->file = BLO_memfile_new_filereader(memfile, params->undo_direction);
   fd->undo_direction = params->undo_direction;
-
-  fd->read = fd_read_from_memfile;
-  fd->flags |= FD_FLAGS_NOT_MY_BUFFER;
+  fd->flags |= FD_FLAGS_IS_MEMFILE;
 
   return blo_decode_and_check(fd, reports->reports);
 }
@@ -1609,30 +1351,7 @@ FileData *blo_filedata_from_memfile(MemFile *memfile,
 void blo_filedata_free(FileData *fd)
 {
   if (fd) {
-    if (fd->filedes != -1) {
-      close(fd->filedes);
-    }
-
-    if (fd->gzfiledes != NULL) {
-      gzclose(fd->gzfiledes);
-    }
-
-    if (fd->strm.next_in) {
-      int err = inflateEnd(&fd->strm);
-      if (err != Z_OK) {
-        CLOG_ERROR(&LOG, "Close gzip stream error (code %d)", err);
-      }
-    }
-
-    if (fd->buffer && !(fd->flags & FD_FLAGS_NOT_MY_BUFFER)) {
-      MEM_freeN((void *)fd->buffer);
-      fd->buffer = NULL;
-    }
-
-    if (fd->mmap_file) {
-      BLI_mmap_free(fd->mmap_file);
-      fd->mmap_file = NULL;
-    }
+    fd->file->close(fd->file);
 
     /* Free all BHeadN data blocks */
 #ifndef NDEBUG
@@ -1640,7 +1359,7 @@ void blo_filedata_free(FileData *fd)
 #else
     /* Sanity check we're not keeping memory we don't need. */
     LISTBASE_FOREACH_MUTABLE (BHeadN *, new_bhead, &fd->bhead_list) {
-      if (fd->seek != NULL && BHEAD_USE_READ_ON_DEMAND(&new_bhead->bhead)) {
+      if (fd->file->seek != NULL && BHEAD_USE_READ_ON_DEMAND(&new_bhead->bhead)) {
         BLI_assert(new_bhead->has_data == 0);
       }
       MEM_freeN(new_bhead);
@@ -2096,7 +1815,7 @@ static void blo_cache_storage_entry_clear_in_old(ID *UNUSED(id),
 
 void blo_cache_storage_init(FileData *fd, Main *bmain)
 {
-  if (fd->memfile != NULL) {
+  if (fd->flags & FD_FLAGS_IS_MEMFILE) {
     BLI_assert(fd->cache_storage == NULL);
     fd->cache_storage = MEM_mallocN(sizeof(*fd->cache_storage), __func__);
     fd->cache_storage->memarena = BLI_memarena_new(BLI_MEMARENA_STD_BUFSIZE, __func__);
@@ -2261,7 +1980,7 @@ static void *read_struct(FileData *fd, BHead *bh, const char *blockname)
  * undo since DNA must match. */
 static const void *peek_struct_undo(FileData *fd, BHead *bhead)
 {
-  BLI_assert(fd->memfile != NULL);
+  BLI_assert(fd->flags & FD_FLAGS_IS_MEMFILE);
   UNUSED_VARS_NDEBUG(fd);
   return (bhead->len) ? (const void *)(bhead + 1) : NULL;
 }
@@ -3679,7 +3398,7 @@ static BHead *read_libblock(FileData *fd,
    * When datablocks are changed but still exist, we restore them at the old
    * address and inherit recalc flags for the dependency graph. */
   ID *id_old = NULL;
-  if (fd->memfile != NULL) {
+  if (fd->flags & FD_FLAGS_IS_MEMFILE) {
     if (read_libblock_undo_restore(fd, main, bhead, tag, &id_old)) {
       if (r_id) {
         *r_id = id_old;
@@ -3980,13 +3699,14 @@ static void lib_link_all(FileData *fd, Main *bmain)
       continue;
     }
 
-    if (fd->memfile != NULL && GS(id->name) == ID_WM) {
+    if ((fd->flags & FD_FLAGS_IS_MEMFILE) && GS(id->name) == ID_WM) {
       /* No load UI for undo memfiles.
        * Only WM currently, SCR needs it still (see below), and so does WS? */
       continue;
     }
 
-    if (fd->memfile != NULL && do_partial_undo && (id->tag & LIB_TAG_UNDO_OLD_ID_REUSED) != 0) {
+    if ((fd->flags & FD_FLAGS_IS_MEMFILE) && do_partial_undo &&
+        (id->tag & LIB_TAG_UNDO_OLD_ID_REUSED) != 0) {
       /* This ID has been re-used from 'old' bmain. Since it was therefore unchanged across
        * current undo step, and old IDs re-use their old memory address, we do not need to liblink
        * it at all. */
@@ -4165,7 +3885,7 @@ BlendFileData *blo_read_file_internal(FileData *fd, const char *filepath)
   BlendFileData *bfd;
   ListBase mainlist = {NULL, NULL};
 
-  if (fd->memfile != NULL) {
+  if (fd->flags & FD_FLAGS_IS_MEMFILE) {
     CLOG_INFO(&LOG_UNDO, 2, "UNDO: read step");
   }
 
@@ -4256,7 +3976,7 @@ BlendFileData *blo_read_file_internal(FileData *fd, const char *filepath)
   }
 
   /* do before read_libraries, but skip undo case */
-  if (fd->memfile == NULL) {
+  if ((fd->flags & FD_FLAGS_IS_MEMFILE) == 0) {
     if ((fd->skip_flags & BLO_READ_SKIP_DATA) == 0) {
       do_versions(fd, NULL, bfd->main);
     }
@@ -4278,7 +3998,7 @@ BlendFileData *blo_read_file_internal(FileData *fd, const char *filepath)
     fd->reports->duration.libraries = PIL_check_seconds_timer() - fd->reports->duration.libraries;
 
     /* Skip in undo case. */
-    if (fd->memfile == NULL) {
+    if ((fd->flags & FD_FLAGS_IS_MEMFILE) == 0) {
       /* Note that we can't recompute user-counts at this point in undo case, we play too much with
        * IDs from different memory realms, and Main database is not in a fully valid state yet.
        */
@@ -4311,7 +4031,7 @@ BlendFileData *blo_read_file_internal(FileData *fd, const char *filepath)
 
     /* Now that all our data-blocks are loaded,
      * we can re-generate overrides from their references. */
-    if (fd->memfile == NULL) {
+    if ((fd->flags & FD_FLAGS_IS_MEMFILE) == 0) {
       /* Do not apply in undo case! */
       fd->reports->duration.lib_overrides = PIL_check_seconds_timer();
 
@@ -4391,7 +4111,7 @@ static void sort_bhead_old_map(FileData *fd)
 static BHead *find_previous_lib(FileData *fd, BHead *bhead)
 {
   /* Skip library data-blocks in undo, see comment in read_libblock. */
-  if (fd->memfile) {
+  if (fd->flags & FD_FLAGS_IS_MEMFILE) {
     return NULL;
   }
 
@@ -5850,7 +5570,7 @@ void BLO_read_pointer_array(BlendDataReader *reader, void **ptr_p)
 
 bool BLO_read_data_is_undo(BlendDataReader *reader)
 {
-  return reader->fd->memfile != NULL;
+  return (reader->fd->flags & FD_FLAGS_IS_MEMFILE);
 }
 
 void BLO_read_data_globmap_add(BlendDataReader *reader, void *oldaddr, void *newaddr)
@@ -5870,7 +5590,7 @@ BlendFileReadReport *BLO_read_data_reports(BlendDataReader *reader)
 
 bool BLO_read_lib_is_undo(BlendLibReader *reader)
 {
-  return reader->fd->memfile != NULL;
+  return (reader->fd->flags & FD_FLAGS_IS_MEMFILE);
 }
 
 Main *BLO_read_lib_get_main(BlendLibReader *reader)

source/blender/blenloader/intern/readfile.h

@@ -28,10 +28,10 @@
 #  include "BLI_winstuff.h"
 #endif
 
+#include "BLI_filereader.h"
 #include "DNA_sdna_types.h"
 #include "DNA_space_types.h"
 #include "DNA_windowmanager_types.h" /* for ReportType */
-#include "zlib.h"
 
 struct BLI_mmap_file;
 struct BLOCacheStorage;
@@ -50,7 +50,7 @@ enum eFileDataFlag {
   FD_FLAGS_FILE_POINTSIZE_IS_4 = 1 << 1,
   FD_FLAGS_POINTSIZE_DIFFERS = 1 << 2,
   FD_FLAGS_FILE_OK = 1 << 3,
-  FD_FLAGS_NOT_MY_BUFFER = 1 << 4,
+  FD_FLAGS_IS_MEMFILE = 1 << 4,
   /* XXX Unused in practice (checked once but never set). */
   FD_FLAGS_NOT_MY_LIBMAP = 1 << 5,
 };
@@ -60,44 +60,18 @@ enum eFileDataFlag {
 #  pragma GCC poison off_t
 #endif
 
-#if defined(_MSC_VER) || defined(__APPLE__) || defined(__HAIKU__) || defined(__NetBSD__)
-typedef int64_t off64_t;
-#endif
-
-typedef ssize_t(FileDataReadFn)(struct FileData *filedata,
-                                void *buffer,
-                                size_t size,
-                                bool *r_is_memchunk_identical);
-typedef off64_t(FileDataSeekFn)(struct FileData *filedata, off64_t offset, int whence);
-
 typedef struct FileData {
   /** Linked list of BHeadN's. */
   ListBase bhead_list;
   enum eFileDataFlag flags;
   bool is_eof;
-  size_t buffersize;
-  off64_t file_offset;
 
-  FileDataReadFn *read;
-  FileDataSeekFn *seek;
+  FileReader *file;
 
-  /** Regular file reading. */
-  int filedes;
-
-  /** Variables needed for reading from memory / stream / memory-mapped files. */
-  const char *buffer;
-  struct BLI_mmap_file *mmap_file;
-  /** Variables needed for reading from memfile (undo). */
-  struct MemFile *memfile;
   /** Whether we are undoing (< 0) or redoing (> 0), used to choose which 'unchanged' flag to use
    * to detect unchanged data from memfile. */
   int undo_direction; /* eUndoStepDir */
 
-  /** Variables needed for reading from file. */
-  gzFile gzfiledes;
-  /** Gzip stream for memory decompression. */
-  z_stream strm;
-
   /** Now only in use for library appending. */
   char relabase[FILE_MAX];
 

source/blender/blenloader/intern/undofile.c

@@ -48,6 +48,7 @@
 
 #include "BKE_lib_id.h"
 #include "BKE_main.h"
+#include "BKE_undo_system.h"
 
 /* keep last */
 #include "BLI_strict_flags.h"
@@ -273,3 +274,97 @@ bool BLO_memfile_write_file(struct MemFile *memfile, const char *filename)
   }
   return true;
 }
+
+static ssize_t undo_read(FileReader *reader, void *buffer, size_t size)
+{
+  UndoReader *undo = (UndoReader *)reader;
+
+  static size_t seek = SIZE_MAX; /* The current position. */
+  static size_t offset = 0;      /* Size of previous chunks. */
+  static MemFileChunk *chunk = NULL;
+  size_t chunkoffset, readsize, totread;
+
+  undo->memchunk_identical = true;
+
+  if (size == 0) {
+    return 0;
+  }
+
+  if (seek != (size_t)undo->reader.offset) {
+    chunk = undo->memfile->chunks.first;
+    seek = 0;
+
+    while (chunk) {
+      if (seek + chunk->size > (size_t)undo->reader.offset) {
+        break;
+      }
+      seek += chunk->size;
+      chunk = chunk->next;
+    }
+    offset = seek;
+    seek = (size_t)undo->reader.offset;
+  }
+
+  if (chunk) {
+    totread = 0;
+
+    do {
+      /* First check if it's on the end if current chunk. */
+      if (seek - offset == chunk->size) {
+        offset += chunk->size;
+        chunk = chunk->next;
+      }
+
+      /* Debug, should never happen. */
+      if (chunk == NULL) {
+        printf("illegal read, chunk zero\n");
+        return 0;
+      }
+
+      chunkoffset = seek - offset;
+      readsize = size - totread;
+
+      /* Data can be spread over multiple chunks, so clamp size
+       * to within this chunk, and then it will read further in
+       * the next chunk. */
+      if (chunkoffset + readsize > chunk->size) {
+        readsize = chunk->size - chunkoffset;
+      }
+
+      memcpy(POINTER_OFFSET(buffer, totread), chunk->buf + chunkoffset, readsize);
+      totread += readsize;
+      undo->reader.offset += (off64_t)readsize;
+      seek += readsize;
+
+      /* `is_identical` of current chunk represents whether it changed compared to previous undo
+       * step. this is fine in redo case, but not in undo case, where we need an extra flag
+       * defined when saving the next (future) step after the one we want to restore, as we are
+       * supposed to 'come from' that future undo step, and not the one before current one. */
+      undo->memchunk_identical &= undo->undo_direction == STEP_REDO ? chunk->is_identical :
+                                                                      chunk->is_identical_future;
+    } while (totread < size);
+
+    return (ssize_t)totread;
+  }
+
+  return 0;
+}
+
+static void undo_close(FileReader *reader)
+{
+  MEM_freeN(reader);
+}
+
+FileReader *BLO_memfile_new_filereader(MemFile *memfile, int undo_direction)
+{
+  UndoReader *undo = MEM_callocN(sizeof(UndoReader), __func__);
+
+  undo->memfile = memfile;
+  undo->undo_direction = undo_direction;
+
+  undo->reader.read = undo_read;
+  undo->reader.seek = NULL;
+  undo->reader.close = undo_close;
+
+  return (FileReader *)undo;
+}

source/blender/blenloader/intern/versioning_250.c

@@ -23,8 +23,7 @@
 #else
 #  include "BLI_winstuff.h"
 #  include "winsock2.h"
-#  include <io.h>   /* for open close read */
-#  include <zlib.h> /* odd include order-issue */
+#  include <io.h> /* for open close read */
 #endif
 
 /* allow readfile to use deprecated functionality */

source/blender/blenloader/intern/versioning_legacy.c

@@ -28,8 +28,7 @@
 #else
 #  include "BLI_winstuff.h"
 #  include "winsock2.h"
-#  include <io.h>   /* for open close read */
-#  include <zlib.h> /* odd include order-issue */
+#  include <io.h> /* for open close read */
 #endif
 
 /* allow readfile to use deprecated functionality */

source/blender/blenloader/intern/writefile.c

@@ -83,7 +83,6 @@
 #  include "BLI_winstuff.h"
 #  include "winsock2.h"
 #  include <io.h>
-#  include <zlib.h> /* odd include order-issue */
 #else
 #  include <unistd.h> /* FreeBSD, for write() and close(). */
 #endif
@@ -101,7 +100,12 @@
 #include "BLI_bitmap.h"
 #include "BLI_blenlib.h"
 #include "BLI_endian_defines.h"
+#include "BLI_endian_switch.h"
+#include "BLI_link_utils.h"
+#include "BLI_linklist.h"
+#include "BLI_math_base.h"
 #include "BLI_mempool.h"
+#include "BLI_threads.h"
 #include "MEM_guardedalloc.h" /* MEM_freeN */
 
 #include "BKE_blender_version.h"
@@ -129,14 +133,21 @@
 
 #include <errno.h>
 
+#include <zstd.h>
+
 /* Make preferences read-only. */
 #define U (*((const UserDef *)&U))
 
 /* ********* my write, buffered writing with minimum size chunks ************ */
 
 /* Use optimal allocation since blocks of this size are kept in memory for undo. */
-#define MYWRITE_BUFFER_SIZE (MEM_SIZE_OPTIMAL(1 << 17)) /* 128kb */
-#define MYWRITE_MAX_CHUNK (MEM_SIZE_OPTIMAL(1 << 15))   /* ~32kb */
+#define MEM_BUFFER_SIZE (MEM_SIZE_OPTIMAL(1 << 17)) /* 128kb */
+#define MEM_CHUNK_SIZE (MEM_SIZE_OPTIMAL(1 << 15))  /* ~32kb */
+
+#define ZSTD_BUFFER_SIZE (1 << 21) /* 2mb */
+#define ZSTD_CHUNK_SIZE (1 << 20)  /* 1mb */
+
+#define ZSTD_COMPRESSION_LEVEL 3
 
 /** Use if we want to store how many bytes have been written to the file. */
 // #define USE_WRITE_DATA_LEN
@@ -147,9 +158,16 @@
 
 typedef enum {
   WW_WRAP_NONE = 1,
-  WW_WRAP_ZLIB,
+  WW_WRAP_ZSTD,
 } eWriteWrapType;
 
+typedef struct ZstdFrame {
+  struct ZstdFrame *next, *prev;
+
+  uint32_t compressed_size;
+  uint32_t uncompressed_size;
+} ZstdFrame;
+
 typedef struct WriteWrap WriteWrap;
 struct WriteWrap {
   /* callbacks */
@@ -161,15 +179,23 @@ struct WriteWrap {
   bool use_buf;
 
   /* internal */
-  union {
-    int file_handle;
-    gzFile gz_handle;
-  } _user_data;
+  int file_handle;
+  struct {
+    ListBase threadpool;
+    ListBase tasks;
+    ThreadMutex mutex;
+    ThreadCondition condition;
+    int next_frame;
+    int num_frames;
+
+    int level;
+    ListBase frames;
+
+    bool write_error;
+  } zstd;
 };
 
 /* none */
-#define FILE_HANDLE(ww) (ww)->_user_data.file_handle
-
 static bool ww_open_none(WriteWrap *ww, const char *filepath)
 {
   int file;
@@ -177,7 +203,7 @@ static bool ww_open_none(WriteWrap *ww, const char *filepath)
   file = BLI_open(filepath, O_BINARY + O_WRONLY + O_CREAT + O_TRUNC, 0666);
 
   if (file != -1) {
-    FILE_HANDLE(ww) = file;
+    ww->file_handle = file;
     return true;
   }
 
@@ -185,39 +211,170 @@ static bool ww_open_none(WriteWrap *ww, const char *filepath)
 }
 static bool ww_close_none(WriteWrap *ww)
 {
-  return (close(FILE_HANDLE(ww)) != -1);
+  return (close(ww->file_handle) != -1);
 }
 static size_t ww_write_none(WriteWrap *ww, const char *buf, size_t buf_len)
 {
-  return write(FILE_HANDLE(ww), buf, buf_len);
+  return write(ww->file_handle, buf, buf_len);
 }
-#undef FILE_HANDLE
 
-/* zlib */
-#define FILE_HANDLE(ww) (ww)->_user_data.gz_handle
+/* zstd */
 
-static bool ww_open_zlib(WriteWrap *ww, const char *filepath)
+typedef struct {
+  struct ZstdWriteBlockTask *next, *prev;
+  void *data;
+  size_t size;
+  int frame_number;
+  WriteWrap *ww;
+} ZstdWriteBlockTask;
+
+static void *zstd_write_task(void *userdata)
 {
-  gzFile file;
+  ZstdWriteBlockTask *task = userdata;
+  WriteWrap *ww = task->ww;
 
-  file = BLI_gzopen(filepath, "wb1");
+  size_t out_buf_len = ZSTD_compressBound(task->size);
+  void *out_buf = MEM_mallocN(out_buf_len, "Zstd out buffer");
+  size_t out_size = ZSTD_compress(
+      out_buf, out_buf_len, task->data, task->size, ZSTD_COMPRESSION_LEVEL);
 
-  if (file != Z_NULL) {
-    FILE_HANDLE(ww) = file;
-    return true;
+  MEM_freeN(task->data);
+
+  BLI_mutex_lock(&ww->zstd.mutex);
+
+  while (ww->zstd.next_frame != task->frame_number) {
+    BLI_condition_wait(&ww->zstd.condition, &ww->zstd.mutex);
   }
 
-  return false;
+  if (ZSTD_isError(out_size)) {
+    ww->zstd.write_error = true;
+  }
+  else {
+    if (ww_write_none(ww, out_buf, out_size) == out_size) {
+      ZstdFrame *frameinfo = MEM_mallocN(sizeof(ZstdFrame), "zstd frameinfo");
+      frameinfo->uncompressed_size = task->size;
+      frameinfo->compressed_size = out_size;
+      BLI_addtail(&ww->zstd.frames, frameinfo);
+    }
+    else {
+      ww->zstd.write_error = true;
+    }
+  }
+
+  ww->zstd.next_frame++;
+
+  BLI_mutex_unlock(&ww->zstd.mutex);
+  BLI_condition_notify_all(&ww->zstd.condition);
+
+  MEM_freeN(out_buf);
+  return NULL;
 }
-static bool ww_close_zlib(WriteWrap *ww)
+
+static bool ww_open_zstd(WriteWrap *ww, const char *filepath)
 {
-  return (gzclose(FILE_HANDLE(ww)) == Z_OK);
+  if (!ww_open_none(ww, filepath)) {
+    return false;
+  }
+
+  /* Leave one thread open for the main writing logic, unless we only have one HW thread. */
+  int num_threads = max_ii(1, BLI_system_thread_count() - 1);
+  BLI_threadpool_init(&ww->zstd.threadpool, zstd_write_task, num_threads);
+  BLI_mutex_init(&ww->zstd.mutex);
+  BLI_condition_init(&ww->zstd.condition);
+
+  return true;
 }
-static size_t ww_write_zlib(WriteWrap *ww, const char *buf, size_t buf_len)
+
+static void zstd_write_u32_le(WriteWrap *ww, uint32_t val)
 {
-  return gzwrite(FILE_HANDLE(ww), buf, buf_len);
+#ifdef __BIG_ENDIAN__
+  BLI_endian_switch_uint32(&val);
+#endif
+  ww_write_none(ww, (char *)&val, sizeof(uint32_t));
+}
+
+/* In order to implement efficient seeking when reading the .blend, we append
+ * a skippable frame that encodes information about the other frames present
+ * in the file.
+ * The format here follows the upstream spec for seekable files:
+ * https://github.com/facebook/zstd/blob/master/contrib/seekable_format/zstd_seekable_compression_format.md
+ * If this information is not present in a file (e.g. if it was compressed
+ * with external tools), it can still be opened in Blender, but seeking will
+ * not be supported, so more memory might be needed. */
+static void zstd_write_seekable_frames(WriteWrap *ww)
+{
+  /* Write seek table header (magic number and frame size). */
+  zstd_write_u32_le(ww, 0x184D2A5E);
+
+  /* The actual frame number might not match ww->zstd.num_frames if there was a write error. */
+  const uint32_t num_frames = BLI_listbase_count(&ww->zstd.frames);
+  /* Each frame consists of two u32, so 8 bytes each.
+   * After the frames, a footer containing two u32 and one byte (9 bytes total) is written. */
+  const uint32_t frame_size = num_frames * 8 + 9;
+  zstd_write_u32_le(ww, frame_size);
+
+  /* Write seek table entries. */
+  LISTBASE_FOREACH (ZstdFrame *, frame, &ww->zstd.frames) {
+    zstd_write_u32_le(ww, frame->compressed_size);
+    zstd_write_u32_le(ww, frame->uncompressed_size);
+  }
+
+  /* Write seek table footer (number of frames, option flags and second magic number). */
+  zstd_write_u32_le(ww, num_frames);
+  const char flags = 0; /* We don't store checksums for each frame. */
+  ww_write_none(ww, &flags, 1);
+  zstd_write_u32_le(ww, 0x8F92EAB1);
+}
+
+static bool ww_close_zstd(WriteWrap *ww)
+{
+  BLI_threadpool_end(&ww->zstd.threadpool);
+  BLI_freelistN(&ww->zstd.tasks);
+
+  BLI_mutex_end(&ww->zstd.mutex);
+  BLI_condition_end(&ww->zstd.condition);
+
+  zstd_write_seekable_frames(ww);
+  BLI_freelistN(&ww->zstd.frames);
+
+  return ww_close_none(ww) && !ww->zstd.write_error;
+}
+
+static size_t ww_write_zstd(WriteWrap *ww, const char *buf, size_t buf_len)
+{
+  if (ww->zstd.write_error) {
+    return 0;
+  }
+
+  ZstdWriteBlockTask *task = MEM_mallocN(sizeof(ZstdWriteBlockTask), __func__);
+  task->data = MEM_mallocN(buf_len, __func__);
+  memcpy(task->data, buf, buf_len);
+  task->size = buf_len;
+  task->frame_number = ww->zstd.num_frames++;
+  task->ww = ww;
+
+  BLI_mutex_lock(&ww->zstd.mutex);
+  BLI_addtail(&ww->zstd.tasks, task);
+
+  /* If there's a free worker thread, just push the block into that thread.
+   * Otherwise, we wait for the earliest thread to finish.
+   * We look up the earliest thread while holding the mutex, but release it
+   * before joining the thread to prevent a deadlock. */
+  ZstdWriteBlockTask *first_task = ww->zstd.tasks.first;
+  BLI_mutex_unlock(&ww->zstd.mutex);
+  if (!BLI_available_threads(&ww->zstd.threadpool)) {
+    BLI_threadpool_remove(&ww->zstd.threadpool, first_task);
+
+    /* If the task list was empty before we pushed our task, there should
+     * always be a free thread. */
+    BLI_assert(first_task != task);
+    BLI_remlink(&ww->zstd.tasks, first_task);
+    MEM_freeN(first_task);
+  }
+  BLI_threadpool_insert(&ww->zstd.threadpool, task);
+
+  return buf_len;
 }
-#undef FILE_HANDLE
 
 /* --- end compression types --- */
 
@@ -226,11 +383,11 @@ static void ww_handle_init(eWriteWrapType ww_type, WriteWrap *r_ww)
   memset(r_ww, 0, sizeof(*r_ww));
 
   switch (ww_type) {
-    case WW_WRAP_ZLIB: {
-      r_ww->open = ww_open_zlib;
-      r_ww->close = ww_close_zlib;
-      r_ww->write = ww_write_zlib;
-      r_ww->use_buf = false;
+    case WW_WRAP_ZSTD: {
+      r_ww->open = ww_open_zstd;
+      r_ww->close = ww_close_zstd;
+      r_ww->write = ww_write_zstd;
+      r_ww->use_buf = true;
       break;
     }
     default: {
@@ -252,10 +409,17 @@ static void ww_handle_init(eWriteWrapType ww_type, WriteWrap *r_ww)
 typedef struct {
   const struct SDNA *sdna;
 
-  /** Use for file and memory writing (fixed size of #MYWRITE_BUFFER_SIZE). */
-  uchar *buf;
-  /** Number of bytes used in #WriteData.buf (flushed when exceeded). */
-  size_t buf_used_len;
+  struct {
+    /** Use for file and memory writing (size stored in max_size). */
+    uchar *buf;
+    /** Number of bytes used in #WriteData.buf (flushed when exceeded). */
+    size_t used_len;
+
+    /** Maximum size of the buffer. */
+    size_t max_size;
+    /** Threshold above which writes get their own chunk. */
+    size_t chunk_size;
+  } buffer;
 
 #ifdef USE_WRITE_DATA_LEN
   /** Total number of bytes written. */
@@ -271,7 +435,7 @@ typedef struct {
   bool use_memfile;
 
   /**
-   * Wrap writing, so we can use zlib or
+   * Wrap writing, so we can use zstd or
    * other compression types later, see: G_FILE_COMPRESS
    * Will be NULL for UNDO.
    */
@@ -291,7 +455,15 @@ static WriteData *writedata_new(WriteWrap *ww)
   wd->ww = ww;
 
   if ((ww == NULL) || (ww->use_buf)) {
-    wd->buf = MEM_mallocN(MYWRITE_BUFFER_SIZE, "wd->buf");
+    if (ww == NULL) {
+      wd->buffer.max_size = MEM_BUFFER_SIZE;
+      wd->buffer.chunk_size = MEM_CHUNK_SIZE;
+    }
+    else {
+      wd->buffer.max_size = ZSTD_BUFFER_SIZE;
+      wd->buffer.chunk_size = ZSTD_CHUNK_SIZE;
+    }
+    wd->buffer.buf = MEM_mallocN(wd->buffer.max_size, "wd->buffer.buf");
   }
 
   return wd;
@@ -325,8 +497,8 @@ static void writedata_do_write(WriteData *wd, const void *mem, size_t memlen)
 
 static void writedata_free(WriteData *wd)
 {
-  if (wd->buf) {
-    MEM_freeN(wd->buf);
+  if (wd->buffer.buf) {
+    MEM_freeN(wd->buffer.buf);
   }
   MEM_freeN(wd);
 }
@@ -343,9 +515,9 @@ static void writedata_free(WriteData *wd)
  */
 static void mywrite_flush(WriteData *wd)
 {
-  if (wd->buf_used_len != 0) {
-    writedata_do_write(wd, wd->buf, wd->buf_used_len);
-    wd->buf_used_len = 0;
+  if (wd->buffer.used_len != 0) {
+    writedata_do_write(wd, wd->buffer.buf, wd->buffer.used_len);
+    wd->buffer.used_len = 0;
   }
 }
 
@@ -369,20 +541,20 @@ static void mywrite(WriteData *wd, const void *adr, size_t len)
   wd->write_len += len;
 #endif
 
-  if (wd->buf == NULL) {
+  if (wd->buffer.buf == NULL) {
     writedata_do_write(wd, adr, len);
   }
   else {
     /* if we have a single big chunk, write existing data in
      * buffer and write out big chunk in smaller pieces */
-    if (len > MYWRITE_MAX_CHUNK) {
-      if (wd->buf_used_len != 0) {
-        writedata_do_write(wd, wd->buf, wd->buf_used_len);
-        wd->buf_used_len = 0;
+    if (len > wd->buffer.chunk_size) {
+      if (wd->buffer.used_len != 0) {
+        writedata_do_write(wd, wd->buffer.buf, wd->buffer.used_len);
+        wd->buffer.used_len = 0;
       }
 
       do {
-        size_t writelen = MIN2(len, MYWRITE_MAX_CHUNK);
+        size_t writelen = MIN2(len, wd->buffer.chunk_size);
         writedata_do_write(wd, adr, writelen);
         adr = (const char *)adr + writelen;
         len -= writelen;
@@ -392,14 +564,14 @@ static void mywrite(WriteData *wd, const void *adr, size_t len)
     }
 
     /* if data would overflow buffer, write out the buffer */
-    if (len + wd->buf_used_len > MYWRITE_BUFFER_SIZE - 1) {
-      writedata_do_write(wd, wd->buf, wd->buf_used_len);
-      wd->buf_used_len = 0;
+    if (len + wd->buffer.used_len > wd->buffer.max_size - 1) {
+      writedata_do_write(wd, wd->buffer.buf, wd->buffer.used_len);
+      wd->buffer.used_len = 0;
     }
 
     /* append data at end of buffer */
-    memcpy(&wd->buf[wd->buf_used_len], adr, len);
-    wd->buf_used_len += len;
+    memcpy(&wd->buffer.buf[wd->buffer.used_len], adr, len);
+    wd->buffer.used_len += len;
   }
 }
 
@@ -430,9 +602,9 @@ static WriteData *mywrite_begin(WriteWrap *ww, MemFile *compare, MemFile *curren
  */
 static bool mywrite_end(WriteData *wd)
 {
-  if (wd->buf_used_len != 0) {
-    writedata_do_write(wd, wd->buf, wd->buf_used_len);
-    wd->buf_used_len = 0;
+  if (wd->buffer.used_len != 0) {
+    writedata_do_write(wd, wd->buffer.buf, wd->buffer.used_len);
+    wd->buffer.used_len = 0;
   }
 
   if (wd->use_memfile) {
@@ -1150,7 +1322,6 @@ bool BLO_write_file(Main *mainvar,
                     ReportList *reports)
 {
   char tempname[FILE_MAX + 1];
-  eWriteWrapType ww_type;
   WriteWrap ww;
 
   eBLO_WritePathRemap remap_mode = params->remap_mode;
@@ -1172,14 +1343,7 @@ bool BLO_write_file(Main *mainvar,
   /* open temporary file, so we preserve the original in case we crash */
   BLI_snprintf(tempname, sizeof(tempname), "%s@", filepath);
 
-  if (write_flags & G_FILE_COMPRESS) {
-    ww_type = WW_WRAP_ZLIB;
-  }
-  else {
-    ww_type = WW_WRAP_NONE;
-  }
-
-  ww_handle_init(ww_type, &ww);
+  ww_handle_init((write_flags & G_FILE_COMPRESS) ? WW_WRAP_ZSTD : WW_WRAP_NONE, &ww);
 
   if (ww.open(&ww, tempname) == false) {
     BKE_reportf(

source/blender/sequencer/intern/image_cache.c

@@ -102,7 +102,7 @@
 /* <cache type>-<resolution X>x<resolution Y>-<rendersize>%(<view_id>)-<frame no>.dcf */
 #define DCACHE_FNAME_FORMAT "%d-%dx%d-%d%%(%d)-%d.dcf"
 #define DCACHE_IMAGES_PER_FILE 100
-#define DCACHE_CURRENT_VERSION 1
+#define DCACHE_CURRENT_VERSION 2
 #define COLORSPACE_NAME_MAX 64 /* XXX: defined in imb intern */
 
 typedef struct DiskCacheHeaderEntry {
@@ -496,24 +496,34 @@ static size_t deflate_imbuf_to_file(ImBuf *ibuf,
                                     int level,
                                     DiskCacheHeaderEntry *header_entry)
 {
-  if (ibuf->rect) {
-    return BLI_gzip_mem_to_file_at_pos(
-        ibuf->rect, header_entry->size_raw, file, header_entry->offset, level);
+  void *data = (ibuf->rect != NULL) ? (void *)ibuf->rect : (void *)ibuf->rect_float;
+
+  /* Apply compression if wanted, otherwise just write directly to the file. */
+  if (level > 0) {
+    return BLI_file_zstd_from_mem_at_pos(
+        data, header_entry->size_raw, file, header_entry->offset, level);
   }
 
-  return BLI_gzip_mem_to_file_at_pos(
-      ibuf->rect_float, header_entry->size_raw, file, header_entry->offset, level);
+  fseek(file, header_entry->offset, SEEK_SET);
+  return fwrite(data, 1, header_entry->size_raw, file);
 }
 
 static size_t inflate_file_to_imbuf(ImBuf *ibuf, FILE *file, DiskCacheHeaderEntry *header_entry)
 {
-  if (ibuf->rect) {
-    return BLI_ungzip_file_to_mem_at_pos(
-        ibuf->rect, header_entry->size_raw, file, header_entry->offset);
+  void *data = (ibuf->rect != NULL) ? (void *)ibuf->rect : (void *)ibuf->rect_float;
+  char header[4];
+  fseek(file, header_entry->offset, SEEK_SET);
+  if (fread(header, 1, sizeof(header), file) != sizeof(header)) {
+    return 0;
   }
 
-  return BLI_ungzip_file_to_mem_at_pos(
-      ibuf->rect_float, header_entry->size_raw, file, header_entry->offset);
+  /* Check if the data is compressed or raw. */
+  if (BLI_file_magic_is_zstd(header)) {
+    return BLI_file_unzstd_to_mem_at_pos(data, header_entry->size_raw, file, header_entry->offset);
+  }
+
+  fseek(file, header_entry->offset, SEEK_SET);
+  return fread(data, 1, header_entry->size_raw, file);
 }
 
 static bool seq_disk_cache_read_header(FILE *file, DiskCacheHeader *header)

source/blender/windowmanager/CMakeLists.txt

@@ -48,10 +48,6 @@ set(INC
   ${CMAKE_BINARY_DIR}/source/blender/makesdna/intern
 )
 
-set(INC_SYS
-  ${ZLIB_INCLUDE_DIRS}
-)
-
 set(SRC
   intern/wm.c
   intern/wm_cursors.c

source/blender/windowmanager/intern/wm_files.c

@@ -28,11 +28,10 @@
  * winsock stuff.
  */
 #include <errno.h>
+#include <fcntl.h> /* for open flags (O_BINARY, O_RDONLY). */
 #include <stddef.h>
 #include <string.h>
 
-#include "zlib.h" /* wm_read_exotic() */
-
 #ifdef WIN32
 /* Need to include windows.h so _WIN32_IE is defined. */
 #  include <windows.h>
@@ -51,6 +50,7 @@
 
 #include "BLI_blenlib.h"
 #include "BLI_fileops_types.h"
+#include "BLI_filereader.h"
 #include "BLI_linklist.h"
 #include "BLI_math.h"
 #include "BLI_system.h"
@@ -481,53 +481,64 @@ static void wm_init_userdef(Main *bmain)
 /* intended to check for non-blender formats but for now it only reads blends */
 static int wm_read_exotic(const char *name)
 {
-  int len;
-  gzFile gzfile;
-  char header[7];
-  int retval;
-
   /* make sure we're not trying to read a directory.... */
 
-  len = strlen(name);
-  if (len > 0 && ELEM(name[len - 1], '/', '\\')) {
-    retval = BKE_READ_EXOTIC_FAIL_PATH;
+  int namelen = strlen(name);
+  if (namelen > 0 && ELEM(name[namelen - 1], '/', '\\')) {
+    return BKE_READ_EXOTIC_FAIL_PATH;
+  }
+
+  /* open the file. */
+  const int filedes = BLI_open(name, O_BINARY | O_RDONLY, 0);
+  if (filedes == -1) {
+    return BKE_READ_EXOTIC_FAIL_OPEN;
+  }
+
+  FileReader *rawfile = BLI_filereader_new_file(filedes);
+  if (rawfile == NULL) {
+    return BKE_READ_EXOTIC_FAIL_OPEN;
+  }
+
+  /* read the header (7 bytes are enough to identify all known types). */
+  char header[7];
+  if (rawfile->read(rawfile, header, sizeof(header)) != sizeof(header)) {
+    rawfile->close(rawfile);
+    return BKE_READ_EXOTIC_FAIL_FORMAT;
+  }
+  rawfile->seek(rawfile, 0, SEEK_SET);
+
+  /* check for uncompressed .blend */
+  if (STREQLEN(header, "BLENDER", 7)) {
+    rawfile->close(rawfile);
+    return BKE_READ_EXOTIC_OK_BLEND;
+  }
+
+  /* check for compressed .blend */
+  FileReader *compressed_file = NULL;
+  if (BLI_file_magic_is_gzip(header)) {
+    /* In earlier versions of Blender (before 3.0), compressed files used Gzip instead of Zstd.
+     * While these files will no longer be written, there still needs to be reading support. */
+    compressed_file = BLI_filereader_new_gzip(rawfile);
+  }
+  else if (BLI_file_magic_is_zstd(header)) {
+    compressed_file = BLI_filereader_new_zstd(rawfile);
+  }
+
+  /* If a compression signature matches, try decompressing the start and check if it's a .blend */
+  if (compressed_file != NULL) {
+    size_t len = compressed_file->read(compressed_file, header, sizeof(header));
+    compressed_file->close(compressed_file);
+    if (len == sizeof(header) && STREQLEN(header, "BLENDER", 7)) {
+      return BKE_READ_EXOTIC_OK_BLEND;
+    }
   }
   else {
-    gzfile = BLI_gzopen(name, "rb");
-    if (gzfile == NULL) {
-      retval = BKE_READ_EXOTIC_FAIL_OPEN;
-    }
-    else {
-      len = gzread(gzfile, header, sizeof(header));
-      gzclose(gzfile);
-      if (len == sizeof(header) && STREQLEN(header, "BLENDER", 7)) {
-        retval = BKE_READ_EXOTIC_OK_BLEND;
-      }
-      else {
-        /* We may want to support loading other file formats
-         * from their header bytes or file extension.
-         * This used to be supported in the code below and may be added
-         * back at some point. */
-#if 0
-        WM_cursor_wait(true);
-
-        if (is_foo_format(name)) {
-          read_foo(name);
-          retval = BKE_READ_EXOTIC_OK_OTHER;
-        }
-        else
-#endif
-        {
-          retval = BKE_READ_EXOTIC_FAIL_FORMAT;
-        }
-#if 0
-        WM_cursor_wait(false);
-#endif
-      }
-    }
+    rawfile->close(rawfile);
   }
 
-  return retval;
+  /* Add check for future file formats here. */
+
+  return BKE_READ_EXOTIC_FAIL_FORMAT;
 }
 
 /** \} */