sysdeps/unix/sysv/linux/readv.c

   1 /* readv supports all Linux kernels >= 2.0.
   2    Copyright (C) 1997-2013 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <stddef.h>
  21 #include <sys/param.h>
  22 #include <sys/uio.h>
  23
  24 #include <sysdep-cancel.h>
  25 #include <sys/syscall.h>
  26 #include <bp-checks.h>
  27 #include <kernel-features.h>
  28
  29 #ifndef __ASSUME_COMPLETE_READV_WRITEV
  30 static ssize_t __atomic_readv_replacement (int, const struct iovec *,
  31                                            int) internal_function;
  32 #endif
  33
  34
  35 /* Not all versions of the kernel support the large number of records.  */
  36 #ifndef UIO_FASTIOV
  37 # define UIO_FASTIOV    8       /* 8 is a safe number.  */
  38 #endif
  39
  40
  41 ssize_t
  42 __libc_readv (fd, vector, count)
  43      int fd;
  44      const struct iovec *vector;
  45      int count;
  46 {
  47   ssize_t result;
  48
  49   if (SINGLE_THREAD_P)
  50     result = INLINE_SYSCALL (readv, 3, fd, CHECK_N (vector, count), count);
  51   else
  52     {
  53       int oldtype = LIBC_CANCEL_ASYNC ();
  54
  55       result = INLINE_SYSCALL (readv, 3, fd, CHECK_N (vector, count), count);
  56
  57       LIBC_CANCEL_RESET (oldtype);
  58     }
  59
  60 #ifdef __ASSUME_COMPLETE_READV_WRITEV
  61   return result;
  62 #else
  63   if (result >= 0 || errno != EINVAL || count <= UIO_FASTIOV)
  64     return result;
  65
  66   return __atomic_readv_replacement (fd, vector, count);
  67 #endif
  68 }
  69 strong_alias (__libc_readv, __readv)
  70 weak_alias (__libc_readv, readv)
  71
  72 #ifndef __ASSUME_COMPLETE_READV_WRITEV
  73 # define __libc_readv static internal_function __atomic_readv_replacement
  74 # include <sysdeps/posix/readv.c>
  75 #endif