lib/pipe-filter-aux.h

   1 /* Auxiliary code for filtering of data through a subprocess.
   2    Copyright (C) 2001-2003, 2008-2019 Free Software Foundation, Inc.
   3    Written by Bruno Haible <haible@clisp.cons.org>, 2009.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _GL_INLINE_HEADER_BEGIN
  19  #error "Please include config.h first."
  20 #endif
  21 _GL_INLINE_HEADER_BEGIN
  22 #ifndef PIPE_FILTER_AUX_INLINE
  23 # define PIPE_FILTER_AUX_INLINE _GL_INLINE
  24 #endif
  25
  26 #ifndef SSIZE_MAX
  27 # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
  28 #endif
  29
  30 /* We use a child process, and communicate through a bidirectional pipe.
  31    To avoid deadlocks, let the child process decide when it wants to read
  32    or to write, and let the parent behave accordingly.  The parent uses
  33    select() to know whether it must write or read.  On platforms without
  34    select(), we use non-blocking I/O.  (This means the parent is busy
  35    looping while waiting for the child.  Not good.  But hardly any platform
  36    lacks select() nowadays.)  */
  37
  38 /* On BeOS and OS/2 kLIBC select() works only on sockets, not on normal file
  39    descriptors.  */
  40 #if defined __BEOS__ || defined __KLIBC__
  41 # undef HAVE_SELECT
  42 #endif
  43
  44 #ifdef EINTR
  45
  46 /* EINTR handling for close(), read(), write(), select().
  47    These functions can return -1/EINTR even though we don't have any
  48    signal handlers set up, namely when we get interrupted via SIGSTOP.  */
  49
  50 PIPE_FILTER_AUX_INLINE int
  51 nonintr_close (int fd)
  52 {
  53   int retval;
  54
  55   do
  56     retval = close (fd);
  57   while (retval < 0 && errno == EINTR);
  58
  59   return retval;
  60 }
  61 #undef close /* avoid warning related to gnulib module unistd */
  62 #define close nonintr_close
  63
  64 PIPE_FILTER_AUX_INLINE ssize_t
  65 nonintr_read (int fd, void *buf, size_t count)
  66 {
  67   ssize_t retval;
  68
  69   do
  70     retval = read (fd, buf, count);
  71   while (retval < 0 && errno == EINTR);
  72
  73   return retval;
  74 }
  75 #define read nonintr_read
  76
  77 PIPE_FILTER_AUX_INLINE ssize_t
  78 nonintr_write (int fd, const void *buf, size_t count)
  79 {
  80   ssize_t retval;
  81
  82   do
  83     retval = write (fd, buf, count);
  84   while (retval < 0 && errno == EINTR);
  85
  86   return retval;
  87 }
  88 #undef write /* avoid warning on VMS */
  89 #define write nonintr_write
  90
  91 #endif
  92
  93 /* Non-blocking I/O.  */
  94 #if HAVE_SELECT
  95 # define IS_EAGAIN(errcode) 0
  96 #else
  97 # ifdef EWOULDBLOCK
  98 #  define IS_EAGAIN(errcode) ((errcode) == EAGAIN || (errcode) == EWOULDBLOCK)
  99 # else
 100 #  define IS_EAGAIN(errcode) ((errcode) == EAGAIN)
 101 # endif
 102 #endif
 103
 104 _GL_INLINE_HEADER_END