1 /* Auxiliary code for filtering of data through a subprocess. 2 Copyright (C) 2001-2003, 2008-2021 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 #ifdef _AIX 30 /* On AIX, despite having select() and despite having put the file descriptor 31 in non-blocking mode, it can happen that select() reports that fd[1] is 32 writable but writing a large amount of data to fd[1] then fails with errno 33 EAGAIN. Seen with test-pipe-filter-gi1 on AIX 7.2, with data sizes of 34 29 KB. So, limit the size of data passed to the write() call to 4 KB. */ 35 # undef SSIZE_MAX 36 # define SSIZE_MAX 4096 37 #endif 38 39 /* We use a child process, and communicate through a bidirectional pipe. 40 To avoid deadlocks, let the child process decide when it wants to read 41 or to write, and let the parent behave accordingly. The parent uses 42 select() to know whether it must write or read. On platforms without 43 select(), we use non-blocking I/O. (This means the parent is busy 44 looping while waiting for the child. Not good. But hardly any platform 45 lacks select() nowadays.) */ 46 47 /* On BeOS and OS/2 kLIBC select() works only on sockets, not on normal file 48 descriptors. */ 49 #if defined __BEOS__ || defined __KLIBC__ 50 # undef HAVE_SELECT 51 #endif 52 53 #ifdef EINTR 54 55 /* EINTR handling for close(), read(), write(), select(). 56 These functions can return -1/EINTR even though we don't have any 57 signal handlers set up, namely when we get interrupted via SIGSTOP. */ 58 59 PIPE_FILTER_AUX_INLINE int 60 nonintr_close (int fd) /* */ 61 { 62 int retval; 63 64 do 65 retval = close (fd); 66 while (retval < 0 && errno == EINTR); 67 68 return retval; 69 } 70 #undef close /* avoid warning related to gnulib module unistd */ 71 #define close nonintr_close 72 73 PIPE_FILTER_AUX_INLINE ssize_t 74 nonintr_read (int fd, void *buf, size_t count) /* */ 75 { 76 ssize_t retval; 77 78 do 79 retval = read (fd, buf, count); 80 while (retval < 0 && errno == EINTR); 81 82 return retval; 83 } 84 #undef read /* avoid warning related to gnulib module unistd */ 85 #define read nonintr_read 86 87 PIPE_FILTER_AUX_INLINE ssize_t 88 nonintr_write (int fd, const void *buf, size_t count) /* */ 89 { 90 ssize_t retval; 91 92 do 93 retval = write (fd, buf, count); 94 while (retval < 0 && errno == EINTR); 95 96 return retval; 97 } 98 #undef write /* avoid warning on VMS */ 99 #define write nonintr_write 100 101 #endif 102 103 /* Non-blocking I/O. */ 104 #if HAVE_SELECT 105 # define IS_EAGAIN(errcode) 0 106 #else 107 # ifdef EWOULDBLOCK 108 # define IS_EAGAIN(errcode) ((errcode) == EAGAIN || (errcode) == EWOULDBLOCK) 109 # else 110 # define IS_EAGAIN(errcode) ((errcode) == EAGAIN) 111 # endif 112 #endif 113 114 _GL_INLINE_HEADER_END