filereader_gzip.cc

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/* SPDX-FileCopyrightText: 2004-2021 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

 
#include <cstdio>
#include <zlib.h>
 
#include "BLI_filereader.h"
 
#include "MEM_guardedalloc.h"
 
struct GzipReader {
  FileReader reader;
 
  FileReader *base;
 
  z_stream strm;
 
  void *in_buf;
  size_t in_size;
};
 
static int64_t gzip_read(FileReader *reader, void *buffer, size_t size)
{
  GzipReader *gzip = (GzipReader *)reader;
 
  gzip->strm.avail_out = size;
  gzip->strm.next_out = static_cast<Bytef *>(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 = static_cast<Bytef *>(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 (!ELEM(ret, Z_OK, Z_BUF_ERROR)) {
      break;
    }
  }
 
  int64_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(gzip->in_buf);
 
  gzip->base->close(gzip->base);
  MEM_freeN(gzip);
}
 
FileReader *BLI_filereader_new_gzip(FileReader *base)
{
  GzipReader *gzip = MEM_callocN<GzipReader>(__func__);
  gzip->base = base;
 
  if (inflateInit2(&gzip->strm, 16 + MAX_WBITS) != Z_OK) {
    MEM_freeN(gzip);
    return nullptr;
  }
 
  gzip->in_size = 256 * 2014;
  gzip->in_buf = MEM_mallocN(gzip->in_size, "gzip in buf");
 
  gzip->reader.read = gzip_read;
  gzip->reader.seek = nullptr;
  gzip->reader.close = gzip_close;
 
  return (FileReader *)gzip;
}