sysdeps/unix/sysv/linux/mmap64.c

   1 /* mmap - map files or devices into memory.  Linux version.
   2    Copyright (C) 1999-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Jakub Jelinek <jakub@redhat.com>, 1999.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <errno.h>
  21 #include <unistd.h>
  22 #include <sys/mman.h>
  23 #include <sysdep.h>
  24 #include <mmap_internal.h>
  25
  26 /* To avoid silent truncation of offset when using mmap2, do not accept
  27    offset larger than 1 << (page_shift + off_t bits).  For archictures with
  28    32 bits off_t and page size of 4096 it would be 1^44.  */
  29 #define MMAP_OFF_HIGH_MASK \
  30   ((-(MMAP2_PAGE_UNIT << 1) << (8 * sizeof (off_t) - 1)))
  31
  32 #define MMAP_OFF_MASK (MMAP_OFF_HIGH_MASK | MMAP_OFF_LOW_MASK)
  33
  34 /* An architecture may override this.  */
  35 #ifndef MMAP_PREPARE
  36 # define MMAP_PREPARE(addr, len, prot, flags, fd, offset)
  37 #endif
  38
  39 void *
  40 __mmap64 (void *addr, size_t len, int prot, int flags, int fd, off64_t offset)
  41 {
  42   MMAP_CHECK_PAGE_UNIT ();
  43
  44   if (offset & MMAP_OFF_MASK)
  45     return (void *) INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
  46
  47   MMAP_PREPARE (addr, len, prot, flags, fd, offset);
  48 #ifdef __NR_mmap2
  49   return (void *) MMAP_CALL (mmap2, addr, len, prot, flags, fd,
  50                              (off_t) (offset / MMAP2_PAGE_UNIT));
  51 #else
  52   return (void *) MMAP_CALL (mmap, addr, len, prot, flags, fd, offset);
  53 #endif
  54 }
  55 weak_alias (__mmap64, mmap64)
  56
  57 #ifdef __OFF_T_MATCHES_OFF64_T
  58 weak_alias (__mmap64, mmap)
  59 weak_alias (__mmap64, __mmap)
  60 #endif