thodg/libgit2/src/util/win32/map.c

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• Hash : c3b7ace9
  Author :
  Date : 2021-11-14T16:43:53
  

  refactor: make util an object library Instead of simply including the utility files directly, make them a cmake object library for easy reusability between other projects within libgit2. Now the top-level `src` is responsible for platform selection, while the next-level `libgit2` and `util` configurations are responsible for identifying what objects they include.

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• src/util/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 "git2_util.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, off64_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;
  	off64_t page_start;
  	off64_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;
  		git_error_set(GIT_ERROR_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;
  		git_error_set(GIT_ERROR_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) {
  		git_error_set(GIT_ERROR_OS, "failed to mmap. Invalid handle value");
  		out->fmh = NULL;
  		return -1;
  	}
  
  	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) {
  		git_error_set(GIT_ERROR_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;
  
  	GIT_ASSERT_ARG(map);
  
  	if (map->data) {
  		if (!UnmapViewOfFile(map->data)) {
  			git_error_set(GIT_ERROR_OS, "failed to munmap. Could not unmap view of file");
  			error = -1;
  		}
  		map->data = NULL;
  	}
  
  	if (map->fmh) {
  		if (!CloseHandle(map->fmh)) {
  			git_error_set(GIT_ERROR_OS, "failed to munmap. Could not close handle");
  			error = -1;
  		}
  		map->fmh = NULL;
  	}
  
  	return error;
  }
  
  #endif
  

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