sysdeps/unix/sysv/linux/mmap64.c

   1 /* mmap - map files or devices into memory.  Linux version.
   2    Copyright (C) 1999-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <unistd.h>
  21 #include <sys/mman.h>
  22 #include <sysdep.h>
  23 #include <mmap_internal.h>
  24
  25 #ifdef __NR_mmap2
  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 #else
  32 /* Some ABIs might use __NR_mmap while having sizeof (off_t) smaller than
  33    sizeof (off64_t) (currently only MIPS64n32).  For this case just set
  34    zero the higher bits so mmap with large offset does not fail.  */
  35 # define MMAP_OFF_HIGH_MASK  0x0
  36 #endif
  37
  38 #define MMAP_OFF_MASK (MMAP_OFF_HIGH_MASK | MMAP_OFF_LOW_MASK)
  39
  40 /* An architecture may override this.  */
  41 #ifndef MMAP_PREPARE
  42 # define MMAP_PREPARE(addr, len, prot, flags, fd, offset)
  43 #endif
  44
  45 void *
  46 __mmap64 (void *addr, size_t len, int prot, int flags, int fd, off64_t offset)
  47 {
  48   MMAP_CHECK_PAGE_UNIT ();
  49
  50   if (offset & MMAP_OFF_MASK)
  51     return (void *) INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
  52
  53   MMAP_PREPARE (addr, len, prot, flags, fd, offset);
  54 #ifdef __NR_mmap2
  55   return (void *) MMAP_CALL (mmap2, addr, len, prot, flags, fd,
  56                              (off_t) (offset / MMAP2_PAGE_UNIT));
  57 #else
  58   return (void *) MMAP_CALL (mmap, addr, len, prot, flags, fd, offset);
  59 #endif
  60 }
  61 weak_alias (__mmap64, mmap64)
  62 libc_hidden_def (__mmap64)
  63
  64 #ifdef __OFF_T_MATCHES_OFF64_T
  65 weak_alias (__mmap64, mmap)
  66 weak_alias (__mmap64, __mmap)
  67 libc_hidden_def (__mmap)
  68 #endif