src/unix/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 "common.h"
   9
  10 #if !defined(GIT_WIN32) && !defined(NO_MMAP)
  11
  12 #include "map.h"
  13 #include <sys/mman.h>
  14 #include <unistd.h>
  15 #include <errno.h>
  16
  17 int git__page_size(size_t *page_size)
  18 {
  19         long sc_page_size = sysconf(_SC_PAGE_SIZE);
  20         if (sc_page_size < 0) {
  21                 git_error_set(GIT_ERROR_OS, "can't determine system page size");
  22                 return -1;
  23         }
  24         *page_size = (size_t) sc_page_size;
  25         return 0;
  26 }
  27
  28 int git__mmap_alignment(size_t *alignment)
  29 {
  30   return git__page_size(alignment);
  31 }
  32
  33 int p_mmap(git_map *out, size_t len, int prot, int flags, int fd, off64_t offset)
  34 {
  35         int mprot = PROT_READ;
  36         int mflag = 0;
  37
  38         GIT_MMAP_VALIDATE(out, len, prot, flags);
  39
  40         out->data = NULL;
  41         out->len = 0;
  42
  43         if (prot & GIT_PROT_WRITE)
  44                 mprot |= PROT_WRITE;
  45
  46         if ((flags & GIT_MAP_TYPE) == GIT_MAP_SHARED)
  47                 mflag = MAP_SHARED;
  48         else if ((flags & GIT_MAP_TYPE) == GIT_MAP_PRIVATE)
  49                 mflag = MAP_PRIVATE;
  50         else
  51                 mflag = MAP_SHARED;
  52
  53         out->data = mmap(NULL, len, mprot, mflag, fd, offset);
  54
  55         if (!out->data || out->data == MAP_FAILED) {
  56                 git_error_set(GIT_ERROR_OS, "failed to mmap. Could not write data");
  57                 return -1;
  58         }
  59
  60         out->len = len;
  61
  62         return 0;
  63 }
  64
  65 int p_munmap(git_map *map)
  66 {
  67         GIT_ASSERT_ARG(map);
  68         munmap(map->data, map->len);
  69         map->data = NULL;
  70         map->len = 0;
  71
  72         return 0;
  73 }
  74
  75 #endif
  76