lib/safe-write.h

   1 /* An interface to write() that retries after interrupts.
   2    Copyright (C) 2002, 2009-2019 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Some system calls may be interrupted and fail with errno = EINTR in the
  18    following situations:
  19      - The process is stopped and restarted (signal SIGSTOP and SIGCONT, user
  20        types Ctrl-Z) on some platforms: Mac OS X.
  21      - The process receives a signal for which a signal handler was installed
  22        with sigaction() with an sa_flags field that does not contain
  23        SA_RESTART.
  24      - The process receives a signal for which a signal handler was installed
  25        with signal() and for which no call to siginterrupt(sig,0) was done,
  26        on some platforms: AIX, HP-UX, IRIX, OSF/1, Solaris.
  27
  28    This module provides a wrapper around write() that handles EINTR.  */
  29
  30 #include <stddef.h>
  31
  32 #define SAFE_WRITE_ERROR ((size_t) -1)
  33
  34 /* Write up to COUNT bytes at BUF to descriptor FD, retrying if interrupted.
  35    Return the actual number of bytes written, zero for EOF, or SAFE_WRITE_ERROR
  36    upon error.  */
  37 extern size_t safe_write (int fd, const void *buf, size_t count);