thodg/libgit2/src/unix/map.c

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• Hash : 87c18197
  Author :
  Date : 2016-03-16T19:05:11
  

  Split the page size from the mmap alignment
  
  While often similar, these are not the same on Windows. We want to use the page
  size on Windows for the pools, but for mmap we need to use the allocation
  granularity as the alignment.
  
  On the other platforms these values remain the same.
  

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• src/unix/map.c

• /*
   * Copyright (C) the libgit2 contributors. All rights reserved.
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  #include <git2/common.h>
  
  #if !defined(GIT_WIN32) && !defined(NO_MMAP)
  
  #include "map.h"
  #include <sys/mman.h>
  #include <unistd.h>
  #include <errno.h>
  
  int git__page_size(size_t *page_size)
  {
  	long sc_page_size = sysconf(_SC_PAGE_SIZE);
  	if (sc_page_size < 0) {
  		giterr_set(GITERR_OS, "can't determine system page size");
  		return -1;
  	}
  	*page_size = (size_t) sc_page_size;
  	return 0;
  }
  
  int git__mmap_alignment(size_t *alignment)
  {
    return git__page_size(alignment);
  }
  
  int p_mmap(git_map *out, size_t len, int prot, int flags, int fd, git_off_t offset)
  {
  	int mprot = PROT_READ;
  	int mflag = 0;
  
  	GIT_MMAP_VALIDATE(out, len, prot, flags);
  
  	out->data = NULL;
  	out->len = 0;
  
  	if (prot & GIT_PROT_WRITE)
  		mprot |= PROT_WRITE;
  
  	if ((flags & GIT_MAP_TYPE) == GIT_MAP_SHARED)
  		mflag = MAP_SHARED;
  	else if ((flags & GIT_MAP_TYPE) == GIT_MAP_PRIVATE)
  		mflag = MAP_PRIVATE;
  	else
  		mflag = MAP_SHARED;
  
  	out->data = mmap(NULL, len, mprot, mflag, fd, offset);
  
  	if (!out->data || out->data == MAP_FAILED) {
  		giterr_set(GITERR_OS, "Failed to mmap. Could not write data");
  		return -1;
  	}
  
  	out->len = len;
  
  	return 0;
  }
  
  int p_munmap(git_map *map)
  {
  	assert(map != NULL);
  	munmap(map->data, map->len);
  
  	return 0;
  }
  
  #endif
  
  

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