thodg/libgit2/src/win32/map.c

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• Hash : 0c7f49dd
  Author :
  Date : 2017-06-30T13:39:01
  

  Make sure to always include "common.h" first
  
  Next to including several files, our "common.h" header also declares
  various macros which are then used throughout the project. As such, we
  have to make sure to always include this file first in all
  implementation files. Otherwise, we might encounter problems or even
  silent behavioural differences due to macros or defines not being
  defined as they should be. So in fact, our header and implementation
  files should make sure to always include "common.h" first.
  
  This commit does so by establishing a common include pattern. Header
  files inside of "src" will now always include "common.h" as its first
  other file, separated by a newline from all the other includes to make
  it stand out as special. There are two cases for the implementation
  files. If they do have a matching header file, they will always include
  this one first, leading to "common.h" being transitively included as
  first file. If they do not have a matching header file, they instead
  include "common.h" as first file themselves.
  
  This fixes the outlined problems and will become our standard practice
  for header and source files inside of the "src/" from now on.
  

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• src/win32/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 "common.h"
  
  #include "map.h"
  #include <errno.h>
  
  #ifndef NO_MMAP
  
  static DWORD get_page_size(void)
  {
  	static DWORD page_size;
  	SYSTEM_INFO sys;
  
  	if (!page_size) {
  		GetSystemInfo(&sys);
  		page_size = sys.dwPageSize;
  	}
  
  	return page_size;
  }
  
  static DWORD get_allocation_granularity(void)
  {
  	static DWORD granularity;
  	SYSTEM_INFO sys;
  
  	if (!granularity) {
  		GetSystemInfo(&sys);
  		granularity = sys.dwAllocationGranularity;
  	}
  
  	return granularity;
  }
  
  int git__page_size(size_t *page_size)
  {
  	*page_size = get_page_size();
  	return 0;
  }
  
  int git__mmap_alignment(size_t *page_size)
  {
  	*page_size = get_allocation_granularity();
  	return 0;
  }
  
  int p_mmap(git_map *out, size_t len, int prot, int flags, int fd, git_off_t offset)
  {
  	HANDLE fh = (HANDLE)_get_osfhandle(fd);
  	DWORD alignment = get_allocation_granularity();
  	DWORD fmap_prot = 0;
  	DWORD view_prot = 0;
  	DWORD off_low = 0;
  	DWORD off_hi = 0;
  	git_off_t page_start;
  	git_off_t page_offset;
  
  	GIT_MMAP_VALIDATE(out, len, prot, flags);
  
  	out->data = NULL;
  	out->len = 0;
  	out->fmh = NULL;
  
  	if (fh == INVALID_HANDLE_VALUE) {
  		errno = EBADF;
  		giterr_set(GITERR_OS, "failed to mmap. Invalid handle value");
  		return -1;
  	}
  
  	if (prot & GIT_PROT_WRITE)
  		fmap_prot |= PAGE_READWRITE;
  	else if (prot & GIT_PROT_READ)
  		fmap_prot |= PAGE_READONLY;
  
  	if (prot & GIT_PROT_WRITE)
  		view_prot |= FILE_MAP_WRITE;
  	if (prot & GIT_PROT_READ)
  		view_prot |= FILE_MAP_READ;
  
  	page_start = (offset / alignment) * alignment;
  	page_offset = offset - page_start;
  
  	if (page_offset != 0) { /* offset must be multiple of the allocation granularity */
  		errno = EINVAL;
  		giterr_set(GITERR_OS, "failed to mmap. Offset must be multiple of allocation granularity");
  		return -1;
  	}
  
  	out->fmh = CreateFileMapping(fh, NULL, fmap_prot, 0, 0, NULL);
  	if (!out->fmh || out->fmh == INVALID_HANDLE_VALUE) {
  		giterr_set(GITERR_OS, "failed to mmap. Invalid handle value");
  		out->fmh = NULL;
  		return -1;
  	}
  
  	assert(sizeof(git_off_t) == 8);
  
  	off_low = (DWORD)(page_start);
  	off_hi = (DWORD)(page_start >> 32);
  	out->data = MapViewOfFile(out->fmh, view_prot, off_hi, off_low, len);
  	if (!out->data) {
  		giterr_set(GITERR_OS, "failed to mmap. No data written");
  		CloseHandle(out->fmh);
  		out->fmh = NULL;
  		return -1;
  	}
  	out->len = len;
  
  	return 0;
  }
  
  int p_munmap(git_map *map)
  {
  	int error = 0;
  
  	assert(map != NULL);
  
  	if (map->data) {
  		if (!UnmapViewOfFile(map->data)) {
  			giterr_set(GITERR_OS, "failed to munmap. Could not unmap view of file");
  			error = -1;
  		}
  		map->data = NULL;
  	}
  
  	if (map->fmh) {
  		if (!CloseHandle(map->fmh)) {
  			giterr_set(GITERR_OS, "failed to munmap. Could not close handle");
  			error = -1;
  		}
  		map->fmh = NULL;
  	}
  
  	return error;
  }
  
  #endif
  

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