X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=signal.c;h=cc49da11f2b647c83cb068b0cecab439419eb571;hp=82444cc81b9c1ffa7248e701ad36cd606b8fc877;hb=741dc05a35312034c8f1e20c5c08a6755812ba67;hpb=2ed89c59f0efcd0a2763f47c7d3455663241e623 diff --git a/signal.c b/signal.c index 82444cc8..cc49da11 100644 --- a/signal.c +++ b/signal.c @@ -1,33 +1,27 @@ /* * Copyright (C) 2004-2006 Andre Noll * - * This program 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 2 of the License, or - * (at your option) any later version. - * - * This program 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 this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. + * Licensed under the GPL v2. For licencing details see COPYING. */ /** \file signal.c signal handling functions */ +#include +#include +#include + #include "para.h" #include "error.h" +#include "fd.h" + static int signal_pipe[2]; /** - * initialize the paraslash signal subsystem + * Initialize the paraslash signal subsystem. * - * This function creates a pipe, the signal pipe, to deliver pending signals to - * the application. It should be called during the application's startup part, - * followed by subsequent calls to para_install_sighandler() for each signal - * that should be caught. + * This function creates a pipe, the signal pipe, to deliver pending + * signals to the application (Bernstein's trick). It should be called + * during the application's startup part, followed by subsequent calls + * to para_install_sighandler() for each signal that should be caught. * * para_signal_init() installs a generic signal handler which is used for all * signals simultaneously. When a signal arrives, this generic signal handler @@ -41,9 +35,20 @@ static int signal_pipe[2]; */ int para_signal_init(void) { - if (!pipe(signal_pipe)) - return signal_pipe[0]; - PARA_EMERG_LOG("%s", "pipe error: Can not setup signal pipe"); + int ret; + if (pipe(signal_pipe) < 0) { + ret = -ERRNO_TO_PARA_ERROR(errno); + goto err_out; + } + ret = mark_fd_nonblocking(signal_pipe[0]); + if (ret < 0) + goto err_out; + ret = mark_fd_nonblocking(signal_pipe[1]); + if (ret < 0) + goto err_out; + return signal_pipe[0]; +err_out: + PARA_EMERG_LOG("%s\n", PARA_STRERROR(-ret)); exit(EXIT_FAILURE); } @@ -57,45 +62,50 @@ static void generic_signal_handler(int s) } /** - * reap one child + * Reap one child. + * + * \param pid In case a child died, its pid is returned here. + * + * Call waitpid() and print a log message containing the pid and the cause of + * the child's death. * - * call waitpid() and print a log message containing the pid - * and the cause of the child's death. + * \return A (negative) paraslash error code on errors, zero, if no child died, + * one otherwise. If and only if the function returns one, the content of \a + * pid is meaningful. * - * \return Like \p waitpid(), this function returns the process ID of the - * terminated child; on error, \p -E_WAITPID is returned. * \sa waitpid(2) */ -pid_t para_reap_child(void) +int para_reap_child(pid_t *pid) { int status; - pid_t pid = waitpid(-1, &status, WNOHANG); + *pid = waitpid(-1, &status, WNOHANG); - if (pid <= 0) { - if (pid < 0) - pid = -E_WAITPID; + if (!*pid) return 0; - } + if (*pid < 0) + return -ERRNO_TO_PARA_ERROR(errno); if (WIFEXITED(status)) - PARA_DEBUG_LOG("child %i exited. Exit status: %i\n", pid, + PARA_DEBUG_LOG("child %i exited. Exit status: %i\n", (int)*pid, WEXITSTATUS(status)); else if (WIFSIGNALED(status)) - PARA_DEBUG_LOG("child %i was killed by signal %i\n", pid, + PARA_DEBUG_LOG("child %i was killed by signal %i\n", (int)*pid, WTERMSIG(status)); else - PARA_WARNING_LOG("child %i terminated abormally\n", pid); - return pid; + PARA_WARNING_LOG("child %i terminated abormally\n", (int)*pid); + return 1; } /** - * paraslash's zombie killer + * Paraslash's zombie killer. * * It just calls \p para_reap_child() until there are no more children left to * reap. */ void para_reap_children(void) { - while (para_reap_child() > 0) + pid_t pid; + + while (para_reap_child(&pid) > 0) ; /* nothing */ } @@ -119,7 +129,7 @@ int para_install_sighandler(int sig) * This should be called if the fd for the signal pipe is ready for reading. * * \return On success, the number of the received signal is returned. \p - * -E_SIGNAL_READ is returned if a read error occured while reading the signal + * -E_SIGNAL_READ is returned if a read error occurred while reading the signal * pipe. If the read was interrupted by another signal the function returns 0. */ int para_next_signal(void) @@ -127,9 +137,18 @@ int para_next_signal(void) int s; ssize_t r; - if ((r = read(signal_pipe[0], &s, sizeof(s)) == sizeof(s)) > 0) { + r = read(signal_pipe[0], &s, sizeof(s)); + if (r == sizeof(s)) { PARA_DEBUG_LOG("next signal: %d\n", s); return s; } return r < 0 && (errno != EAGAIN)? 0 : -E_SIGNAL_READ; } + +/** + * Close the signal pipe. + */ +void para_signal_shutdown(void) +{ + close(signal_pipe[1]); +}