src/util/win32/map.c

   1 /*
   2  * Copyright (C) the libgit2 contributors. All rights reserved.
   3  *
   4  * This file is part of libgit2, distributed under the GNU GPL v2 with
   5  * a Linking Exception. For full terms see the included COPYING file.
   6  */
   7
   8 #include "git2_util.h"
   9
  10 #include "map.h"
  11 #include <errno.h>
  12
  13 #ifndef NO_MMAP
  14
  15 static DWORD get_page_size(void)
  16 {
  17         static DWORD page_size;
  18         SYSTEM_INFO sys;
  19
  20         if (!page_size) {
  21                 GetSystemInfo(&sys);
  22                 page_size = sys.dwPageSize;
  23         }
  24
  25         return page_size;
  26 }
  27
  28 static DWORD get_allocation_granularity(void)
  29 {
  30         static DWORD granularity;
  31         SYSTEM_INFO sys;
  32
  33         if (!granularity) {
  34                 GetSystemInfo(&sys);
  35                 granularity = sys.dwAllocationGranularity;
  36         }
  37
  38         return granularity;
  39 }
  40
  41 int git__page_size(size_t *page_size)
  42 {
  43         *page_size = get_page_size();
  44         return 0;
  45 }
  46
  47 int git__mmap_alignment(size_t *page_size)
  48 {
  49         *page_size = get_allocation_granularity();
  50         return 0;
  51 }
  52
  53 int p_mmap(git_map *out, size_t len, int prot, int flags, int fd, off64_t offset)
  54 {
  55         HANDLE fh = (HANDLE)_get_osfhandle(fd);
  56         DWORD alignment = get_allocation_granularity();
  57         DWORD fmap_prot = 0;
  58         DWORD view_prot = 0;
  59         DWORD off_low = 0;
  60         DWORD off_hi = 0;
  61         off64_t page_start;
  62         off64_t page_offset;
  63
  64         GIT_MMAP_VALIDATE(out, len, prot, flags);
  65
  66         out->data = NULL;
  67         out->len = 0;
  68         out->fmh = NULL;
  69
  70         if (fh == INVALID_HANDLE_VALUE) {
  71                 errno = EBADF;
  72                 git_error_set(GIT_ERROR_OS, "failed to mmap. Invalid handle value");
  73                 return -1;
  74         }
  75
  76         if (prot & GIT_PROT_WRITE)
  77                 fmap_prot |= PAGE_READWRITE;
  78         else if (prot & GIT_PROT_READ)
  79                 fmap_prot |= PAGE_READONLY;
  80
  81         if (prot & GIT_PROT_WRITE)
  82                 view_prot |= FILE_MAP_WRITE;
  83         if (prot & GIT_PROT_READ)
  84                 view_prot |= FILE_MAP_READ;
  85
  86         page_start = (offset / alignment) * alignment;
  87         page_offset = offset - page_start;
  88
  89         if (page_offset != 0) { /* offset must be multiple of the allocation granularity */
  90                 errno = EINVAL;
  91                 git_error_set(GIT_ERROR_OS, "failed to mmap. Offset must be multiple of allocation granularity");
  92                 return -1;
  93         }
  94
  95         out->fmh = CreateFileMapping(fh, NULL, fmap_prot, 0, 0, NULL);
  96         if (!out->fmh || out->fmh == INVALID_HANDLE_VALUE) {
  97                 git_error_set(GIT_ERROR_OS, "failed to mmap. Invalid handle value");
  98                 out->fmh = NULL;
  99                 return -1;
 100         }
 101
 102         off_low = (DWORD)(page_start);
 103         off_hi = (DWORD)(page_start >> 32);
 104         out->data = MapViewOfFile(out->fmh, view_prot, off_hi, off_low, len);
 105         if (!out->data) {
 106                 git_error_set(GIT_ERROR_OS, "failed to mmap. No data written");
 107                 CloseHandle(out->fmh);
 108                 out->fmh = NULL;
 109                 return -1;
 110         }
 111         out->len = len;
 112
 113         return 0;
 114 }
 115
 116 int p_munmap(git_map *map)
 117 {
 118         int error = 0;
 119
 120         GIT_ASSERT_ARG(map);
 121
 122         if (map->data) {
 123                 if (!UnmapViewOfFile(map->data)) {
 124                         git_error_set(GIT_ERROR_OS, "failed to munmap. Could not unmap view of file");
 125                         error = -1;
 126                 }
 127                 map->data = NULL;
 128         }
 129
 130         if (map->fmh) {
 131                 if (!CloseHandle(map->fmh)) {
 132                         git_error_set(GIT_ERROR_OS, "failed to munmap. Could not close handle");
 133                         error = -1;
 134                 }
 135                 map->fmh = NULL;
 136         }
 137
 138         return error;
 139 }
 140
 141 #endif