From ce037545dd28cd658f3037e8494089b9771177b1 Mon Sep 17 00:00:00 2001 From: Jon Lund Steffensen Date: Wed, 16 Aug 2017 21:06:41 -0700 Subject: pipeutils: Add utils for pipe signals Add pipeutils.c with utility functions for working with pipes as signals across threads. Using pipes for signals makes it easy for the main thread to wait on (multiple) file descriptors with or without a timeout. --- src/pipeutils.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) create mode 100644 src/pipeutils.c (limited to 'src/pipeutils.c') diff --git a/src/pipeutils.c b/src/pipeutils.c new file mode 100644 index 0000000..75302cb --- /dev/null +++ b/src/pipeutils.c @@ -0,0 +1,98 @@ +/* pipeutils.c -- Utilities for using pipes as signals + This file is part of Redshift. + + Redshift is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + Redshift is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with Redshift. If not, see . + + Copyright (c) 2017 Jon Lund Steffensen +*/ + +#include +#include +#include + + +#ifndef _WIN32 + +/* Create non-blocking set of pipe fds. */ +int +pipeutils_create_nonblocking(int pipefds[2]) +{ + int r = pipe(pipefds); + if (r == -1) { + perror("pipe"); + return -1; + } + + int flags = fcntl(pipefds[0], F_GETFL); + if (flags == -1) { + perror("fcntl"); + close(pipefds[0]); + close(pipefds[1]); + return -1; + } + + r = fcntl(pipefds[0], F_SETFL, flags | O_NONBLOCK); + if (r == -1) { + perror("fcntl"); + close(pipefds[0]); + close(pipefds[1]); + return -1; + } + + flags = fcntl(pipefds[1], F_GETFL); + if (flags == -1) { + perror("fcntl"); + close(pipefds[0]); + close(pipefds[1]); + return -1; + } + + r = fcntl(pipefds[1], F_SETFL, flags | O_NONBLOCK); + if (r == -1) { + perror("fcntl"); + close(pipefds[0]); + close(pipefds[1]); + return -1; + } + + return 0; +} + +#else /* _WIN32 */ + +/* Create non-blocking set of pipe fds. + + Not supported on Windows! Always fails. */ +int +pipeutils_create_nonblocking(int pipefds[2]) +{ + return -1; +} + +#endif + +/* Signal on write-end of pipe. */ +void +pipeutils_signal(int write_fd) +{ + write(write_fd, "", 1); +} + +/* Mark signal as handled on read-end of pipe. */ +void +pipeutils_handle_signal(int read_fd) +{ + char data; + read(read_fd, &data, 1); +} -- cgit v1.2.3-70-g09d2