thodg/libgit2/src/win32/map.c

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• Hash : 79ca2edc
  Author :
  Date : 2009-03-20T19:51:48
  

  win32: Add routines to abstract memory-mapped file functions In particular, the git__mmap() and git__munmap() routines provide the interface to platform specific memory-mapped file facilities. We provide implementations for unix and win32, which can be found in their own sub-directories. Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

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• src/win32/map.c

• 
  #include "map.h"
  #include <errno.h>
  
  
  static DWORD get_page_size(void)
  {
  	static DWORD page_size;
  	SYSTEM_INFO sys;
  
  	if (!page_size) {
  		GetSystemInfo(&sys);
  		page_size = sys.dwAllocationGranularity;
  	}
  
  	return page_size;
  }
  
  int git__mmap(git_map *out, size_t len, int prot, int flags, int fd, off_t offset)
  {
  	HANDLE fh = (HANDLE)_get_osfhandle(fd);
  	DWORD page_size = get_page_size();
  	DWORD fmap_prot = 0;
  	DWORD view_prot = 0;
  	DWORD off_low = 0;
  	DWORD off_hi  = 0;
  	off_t page_start;
  	off_t page_offset;
  
  	assert((out != NULL) && (len > 0));
  
  	if ((out == NULL) || (len == 0)) {
  		errno = EINVAL;
  		return GIT_ERROR;
  	}
  
  	out->data = NULL;
  	out->len = 0;
  	out->fmh = NULL;
  
  	if (fh == INVALID_HANDLE_VALUE) {
  		errno = EBADF;
  		return GIT_ERROR;
  	}
  
  	if (prot & GIT_PROT_WRITE)
  		fmap_prot |= PAGE_READWRITE;
  	else if (prot & GIT_PROT_READ)
  		fmap_prot |= PAGE_READONLY;
  	else {
  		errno = EINVAL;
  		return GIT_ERROR;
  	}
  
  	if (prot & GIT_PROT_WRITE)
  		view_prot |= FILE_MAP_WRITE;
  	if (prot & GIT_PROT_READ)
  		view_prot |= FILE_MAP_READ;
  
  	if (flags & GIT_MAP_FIXED) {
  		errno = EINVAL;
  		return GIT_ERROR;
  	}
  
  	page_start = (offset / page_size) * page_size;
  	page_offset = offset - page_start;
  
  	if (page_offset != 0) {  /* offset must be multiple of page size */
  		errno = EINVAL;
  		return GIT_ERROR;
  	}
  
  	out->fmh = CreateFileMapping(fh, NULL, fmap_prot, 0, 0, NULL);
  	if (!out->fmh || out->fmh == INVALID_HANDLE_VALUE) {
  		/* errno = ? */
  		out->fmh = NULL;
  		return GIT_ERROR;
  	}
  
  	off_low = (DWORD)(page_start);
  	if (sizeof(off_t) > 4)
  		off_hi = (DWORD)(page_start >> 32);
  	out->data = MapViewOfFile(out->fmh, view_prot, off_hi, off_low, len);
  	if (!out->data) {
  		/* errno = ? */
  		CloseHandle(out->fmh);
  		out->fmh = NULL;
  		return GIT_ERROR;
  	}
  	out->len = len;
  
  	return GIT_SUCCESS;
  }
  
  int git__munmap(git_map *map)
  {
  	assert(map != NULL);
  
  	if (!map)
  		return GIT_ERROR;
  
  	if (map->data) {
  		if (!UnmapViewOfFile(map->data)) {
  			/* errno = ? */
  			CloseHandle(map->fmh);
  			map->data = NULL;
  			map->fmh = NULL;
  			return GIT_ERROR;
  		}
  		map->data = NULL;
  	}
  
  	if (map->fmh) {
  		if (!CloseHandle(map->fmh)) {
  			/* errno = ? */
  			map->fmh = NULL;
  			return GIT_ERROR;
  		}
  		map->fmh = NULL;
  	}
  
  	return GIT_SUCCESS;
  }
  
  
  

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