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 #include "git2/common.h"
  11
  12 #if !defined(GIT_WIN32) && !defined(NO_MMAP)
  13
  14 #include "map.h"
  15 #include <sys/mman.h>
  16 #include <unistd.h>
  17 #include <errno.h>
  18
  19 int git__page_size(size_t *page_size)
  20 {
  21         long sc_page_size = sysconf(_SC_PAGE_SIZE);
  22         if (sc_page_size < 0) {
  23                 git_error_set(GIT_ERROR_OS, "can't determine system page size");
  24                 return -1;
  25         }
  26         *page_size = (size_t) sc_page_size;
  27         return 0;
  28 }
  29
  30 int git__mmap_alignment(size_t *alignment)
  31 {
  32   return git__page_size(alignment);
  33 }
  34
  35 int p_mmap(git_map *out, size_t len, int prot, int flags, int fd, off64_t offset)
  36 {
  37         int mprot = PROT_READ;
  38         int mflag = 0;
  39
  40         GIT_MMAP_VALIDATE(out, len, prot, flags);
  41
  42         out->data = NULL;
  43         out->len = 0;
  44
  45         if (prot & GIT_PROT_WRITE)
  46                 mprot |= PROT_WRITE;
  47
  48         if ((flags & GIT_MAP_TYPE) == GIT_MAP_SHARED)
  49                 mflag = MAP_SHARED;
  50         else if ((flags & GIT_MAP_TYPE) == GIT_MAP_PRIVATE)
  51                 mflag = MAP_PRIVATE;
  52         else
  53                 mflag = MAP_SHARED;
  54
  55         out->data = mmap(NULL, len, mprot, mflag, fd, offset);
  56
  57         if (!out->data || out->data == MAP_FAILED) {
  58                 git_error_set(GIT_ERROR_OS, "failed to mmap. Could not write data");
  59                 return -1;
  60         }
  61
  62         out->len = len;
  63
  64         return 0;
  65 }
  66
  67 int p_munmap(git_map *map)
  68 {
  69         assert(map != NULL);
  70         munmap(map->data, map->len);
  71
  72         return 0;
  73 }
  74
  75 #endif
  76