X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=signal.c;h=59a0d45aba7ad975fc287862308891435c4e9095;hp=f9b95f9006dee9c9cd558bb39bc0cc6c90ca1bb1;hb=8ea8abb73199b32fdd7afdf8825afa42ed8de244;hpb=9421d244243c0a5c6d3941905abfb0b516781465 diff --git a/signal.c b/signal.c index f9b95f90..59a0d45a 100644 --- a/signal.c +++ b/signal.c @@ -1,34 +1,22 @@ /* - * Copyright (C) 2004-2006 Andre Noll + * Copyright (C) 2004-2009 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 */ - +/** \file signal.c Signal handling functions. */ +#include +#include +#include #include "para.h" +#include "error.h" #include "fd.h" -#include - -#include "error.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 (Bernstein's trick). It should be called @@ -47,18 +35,20 @@ static int signal_pipe[2]; */ int para_signal_init(void) { - int ret = -E_SIGNAL_PIPE; - if (pipe(signal_pipe)) + int ret; + if (pipe(signal_pipe) < 0) { + ret = -ERRNO_TO_PARA_ERROR(errno); goto err_out; - ret = mark_fd_nonblock(signal_pipe[0]); + } + ret = mark_fd_nonblocking(signal_pipe[0]); if (ret < 0) goto err_out; - ret = mark_fd_nonblock(signal_pipe[1]); + 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)); + PARA_EMERG_LOG("%s\n", para_strerror(-ret)); exit(EXIT_FAILURE); } @@ -67,84 +57,143 @@ err_out: */ static void generic_signal_handler(int s) { - write(signal_pipe[1], &s, sizeof(int)); - //fprintf(stderr, "got sig %i, write returned %d\n", s, ret); + ssize_t ret = write(signal_pipe[1], &s, sizeof(int)); + + if (ret == sizeof(int)) + return; + if (ret < 0) + PARA_EMERG_LOG("%s\n", strerror(errno)); + else + PARA_EMERG_LOG("short write to signal pipe\n"); + exit(EXIT_FAILURE); } /** - * 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 Like \p waitpid(), this function returns the process ID of the - * terminated child; on error, \p -E_WAITPID is returned. - * \sa waitpid(2) + * \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. + * + * \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; - return pid; - } + 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 */ } /** - * wrapper around signal(2) - * \param sig the number of the signal to catch + * Install the given handler for the given signal. + * + * \param sig The number of the signal to catch. + * \param handler to be installed, \p SIG_IGN, or \p SIG_DFL. * - * This installs the generic signal handler for the given signal. - * \return This function returns 1 on success and \p -E_SIGNAL_SIG_ERR on errors. - * \sa signal(2) + * This either succeeds or calls exit(EXIT_FAILURE). + * + * \sa sigaction(2). */ -int para_install_sighandler(int sig) +void para_sigaction(int sig, void (*handler)(int)) { + struct sigaction act; + PARA_DEBUG_LOG("catching signal %d\n", sig); - return signal(sig, &generic_signal_handler) == SIG_ERR? -E_SIGNAL_SIG_ERR : 1; + act.sa_handler = handler; + sigemptyset(&act.sa_mask); + act.sa_flags = 0; + if (sig == SIGALRM) { + #ifdef SA_INTERRUPT /* SunOS */ + act.sa_flags |= SA_INTERRUPT; + #endif + } else { + #ifdef SA_RESTART /* BSD */ + act.sa_flags |= SA_RESTART; + #endif + } + if (sigaction(sig, &act, NULL) >= 0) + return; + PARA_EMERG_LOG("failed to install signal handler for signal %d\n", + sig); + exit(EXIT_FAILURE); } /** - * return number of next pending signal + * Install the generic signal handler for the given signal number. + * + * \param sig The number of the signal to catch. + * + * \sa signal(2), sigaction(2). + */ +void para_install_sighandler(int sig) +{ + para_sigaction(sig, &generic_signal_handler); +} + +/** + * Return the number of next pending signal. * * 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 - * pipe. If the read was interrupted by another signal the function returns 0. + * \return On success, the number of the received signal is returned. If the + * read returned zero or was interrupted by another signal the function returns + * 0. Otherwise, a negative error value is returned. */ int para_next_signal(void) { int s; - ssize_t r; + ssize_t r = read(signal_pipe[0], &s, sizeof(s)); - if ((r = read(signal_pipe[0], &s, sizeof(s)) == sizeof(s)) > 0) { - PARA_DEBUG_LOG("next signal: %d\n", s); - return s; + if (!r) { + PARA_CRIT_LOG("read from signal pipe returned zero\n"); + return 0; } - return r < 0 && (errno != EAGAIN)? 0 : -E_SIGNAL_READ; + if (r < 0) { + if (errno == EAGAIN || errno == EINTR) + return 0; + return -ERRNO_TO_PARA_ERROR(errno); + } + assert(r == sizeof(s)); + PARA_DEBUG_LOG("next signal: %d\n", s); + return s; +} + +/** + * Close the write end of the signal pipe. + */ +void para_signal_shutdown(void) +{ + close(signal_pipe[1]); }