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timeout.c
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timeout.c
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/*
* Copyright (c) 1994-2011 Carnegie Mellon University. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The name "Carnegie Mellon University" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For permission or any legal
* details, please contact
* Carnegie Mellon University
* Center for Technology Transfer and Enterprise Creation
* 4615 Forbes Avenue
* Suite 302
* Pittsburgh, PA 15213
* (412) 268-7393, fax: (412) 268-7395
* innovation@andrew.cmu.edu
*
* 4. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by Computing Services
* at Carnegie Mellon University (http://www.cmu.edu/computing/)."
*
* CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
* FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <memory.h>
#include <sys/poll.h>
#include <sys/wait.h>
#include <sys/signal.h>
#include <errno.h>
#include "timeout.h"
static void (*timeout_callback)(void);
static pid_t timeout_pid = -1;
static int timeout_fd = -1;
#define PIPE_READ 0
#define PIPE_WRITE 1
#define CMD_BEGIN 'B'
#define CMD_END 'E'
static void sigusr1_handler(int sig __attribute__((unused)))
{
// fprintf(stderr, "timeout: received SIGUSR1\n");
if (timeout_callback)
timeout_callback();
}
static void timeout_mainloop(int fd, pid_t pid)
{
struct pollfd pfd;
char c;
int r;
int timeout = -1;
for (;;) {
memset(&pfd, 0, sizeof(pfd));
pfd.fd = fd;
pfd.events = POLLIN;
// if (timeout < 0)
// fprintf(stderr, "timeout: waiting for command\n");
// else
// fprintf(stderr, "timeout: waiting for command or %d.%03d sec\n", timeout/1000, timeout % 1000);
/* wait for command from the parent or timeout */
r = poll(&pfd, 1, timeout);
// fprintf(stderr, "timeout: awoke, r=%d\n", r);
if (r < 0) {
perror("timeout: poll");
exit(1);
}
if (r == 0) {
/* timed out */
// fprintf(stderr, "timeout: sending USR1 to %d\n", (int)pid);
kill(pid, SIGUSR1);
timeout = -1;
continue;
}
if (r != 1 || !pfd.revents) {
/* WTF?? */
fprintf(stderr, "timeout: weirdness from poll: "
"r=%d pfd.revents=%d\n",
r, pfd.revents);
exit(1);
}
r = read(fd, &c, 1);
if (r < 0) {
perror("timeout: read");
exit(1);
}
if (r == 0) {
/* EOF: parent closed pipe */
exit(0);
}
if (r != 1) {
fprintf(stderr, "timeout: short read\n");
exit(1);
}
switch (c) {
case CMD_BEGIN:
timeout = -1;
r = read(fd, &timeout, sizeof(timeout));
if (r < 0) {
perror("timeout: read");
exit(1);
}
if (r == 0) {
/* EOF: parent closed pipe */
exit(0);
}
if (r != sizeof(timeout)) {
fprintf(stderr, "timeout: short read\n");
exit(1);
}
break;
case CMD_END:
timeout = -1;
break;
default:
fprintf(stderr, "timeout: Unknown command '%c'\n", c);
exit(1);
}
}
}
int timeout_init(void (*cb)(void))
{
int pipefd[2];
pid_t pid;
struct sigaction sa;
int r;
timeout_callback = cb;
/* set up a pipe to communicate with the
* timeout process */
r = pipe(pipefd);
if (r < 0) {
perror("timeout: pipe");
return -1;
}
/* fork the timeout process */
pid = fork();
if (pid < 0) {
perror("timeout: fork");
return -1;
}
if (pid) {
/* parent */
timeout_pid = pid;
timeout_fd = dup2(pipefd[PIPE_WRITE], 253);
if (timeout_fd < 0) {
perror("timeout: dup2");
return -1;
}
close(pipefd[PIPE_READ]);
close(pipefd[PIPE_WRITE]);
memset(&sa, 0, sizeof(sa));
sa.sa_handler = sigusr1_handler;
sa.sa_flags = SA_NODEFER;
sigaction(SIGUSR1, &sa, NULL);
} else {
/* child */
close(pipefd[PIPE_WRITE]);
timeout_mainloop(pipefd[PIPE_READ], getppid());
exit(0);
}
return 0;
}
int timeout_begin(int millisec)
{
int c;
int r;
// fprintf(stderr, "timeout_begin\n");
if (timeout_fd < 0)
return -1;
c = CMD_BEGIN;
r = write(timeout_fd, &c, 1);
if (r < 0) {
perror("timeout: write");
return -1;
}
r = write(timeout_fd, &millisec, sizeof(millisec));
if (r < 0) {
perror("timeout: write");
return -1;
}
return 0;
}
int timeout_end(void)
{
int c;
int r;
// fprintf(stderr, "timeout_end\n");
if (timeout_fd < 0)
return -1;
c = CMD_END;
r = write(timeout_fd, &c, 1);
if (r < 0) {
perror("timeout: write");
return -1;
}
return 0;
}
void timeout_fini(void)
{
int r;
int status;
if (timeout_fd >= 0) {
close(timeout_fd);
timeout_fd = -1;
}
if (timeout_pid > 0) {
r = kill(timeout_pid, SIGTERM);
if (r < 0 && errno != ESRCH)
perror("timeout: kill");
else
waitpid(timeout_pid, &status, 0);
timeout_pid = -1;
}
signal(SIGUSR1, SIG_IGN);
}

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