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 #include <git2/common.h>
   8
   9 #if !defined(GIT_WIN32) && !defined(NO_MMAP)
  10
  11 #include "map.h"
  12 #include <sys/mman.h>
  13 #include <unistd.h>
  14 #include <errno.h>
  15
  16 int git__page_size(size_t *page_size)
  17 {
  18         long sc_page_size = sysconf(_SC_PAGE_SIZE);
  19         if (sc_page_size < 0) {
  20                 giterr_set(GITERR_OS, "can't determine system page size");
  21                 return -1;
  22         }
  23         *page_size = (size_t) sc_page_size;
  24         return 0;
  25 }
  26
  27 int git__mmap_alignment(size_t *alignment)
  28 {
  29   return git__page_size(alignment);
  30 }
  31
  32 int p_mmap(git_map *out, size_t len, int prot, int flags, int fd, git_off_t offset)
  33 {
  34         int mprot = PROT_READ;
  35         int mflag = 0;
  36
  37         GIT_MMAP_VALIDATE(out, len, prot, flags);
  38
  39         out->data = NULL;
  40         out->len = 0;
  41
  42         if (prot & GIT_PROT_WRITE)
  43                 mprot |= PROT_WRITE;
  44
  45         if ((flags & GIT_MAP_TYPE) == GIT_MAP_SHARED)
  46                 mflag = MAP_SHARED;
  47         else if ((flags & GIT_MAP_TYPE) == GIT_MAP_PRIVATE)
  48                 mflag = MAP_PRIVATE;
  49         else
  50                 mflag = MAP_SHARED;
  51
  52         out->data = mmap(NULL, len, mprot, mflag, fd, offset);
  53
  54         if (!out->data || out->data == MAP_FAILED) {
  55                 giterr_set(GITERR_OS, "failed to mmap. Could not write data");
  56                 return -1;
  57         }
  58
  59         out->len = len;
  60
  61         return 0;
  62 }
  63
  64 int p_munmap(git_map *map)
  65 {
  66         assert(map != NULL);
  67         munmap(map->data, map->len);
  68
  69         return 0;
  70 }
  71
  72 #endif
  73