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#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <netdb.h>
#include <signal.h>
int flag = 0;
void sig_handler(int signo)
{
if (signo == SIGUSR1)
flag = 1;
else if (signo == SIGINT || signo == SIGTERM)
flag = 2;
}
int main(int argc, const char *argv[])
{
if (argc != 3)
{
fprintf(stderr, "USAGE: %s EXEC_PROCESS PORT\n"
"Bootstrap for workflow server to restart gracefully.\n",
argv[0]);
exit(1);
}
unsigned short port = atoi(argv[2]);
int listen_fd = socket(AF_INET, SOCK_STREAM, 0);
struct sockaddr_in sin;
memset(&sin, 0, sizeof sin);
sin.sin_family = AF_INET;
sin.sin_port = htons(port);
sin.sin_addr.s_addr = htonl(INADDR_ANY);
if (bind(listen_fd, (struct sockaddr *)&sin, sizeof sin) < 0)
{
close(listen_fd);
perror("bind error");
exit(1);
}
pid_t pid;
int pipe_fd[2];
ssize_t len;
char buf[100];
int status;
int ret;
char listen_fd_str[10] = { 0 };
char write_fd_str[10] = { 0 };
sprintf(listen_fd_str, "%d", listen_fd);
signal(SIGINT, sig_handler);
signal(SIGTERM, sig_handler);
signal(SIGUSR1, sig_handler);
while (flag < 2)
{
if (pipe(pipe_fd) == -1)
{
perror("open pipe error");
exit(1);
}
memset(write_fd_str, 0, sizeof write_fd_str);
sprintf(write_fd_str, "%d", pipe_fd[1]);
pid = fork();
if (pid < 0)
{
perror("fork error");
close(pipe_fd[0]);
close(pipe_fd[1]);
break;
}
else if (pid == 0)
{
close(pipe_fd[0]);
execlp(argv[1], argv[1], listen_fd_str, write_fd_str, NULL);
}
else
{
close(pipe_fd[1]);
status = 0;
ret = 0;
flag = 0;
fprintf(stderr, "Bootstrap daemon running with server pid-%d. "
"Send SIGUSR1 to RESTART or SIGTERM to STOP.\n", pid);
while (1)
{
ret = waitpid(pid, &status, WNOHANG);
if (ret == -1 || !WIFEXITED(status) || flag != 0)
break;
sleep(3);
}
if (ret != -1 && WIFEXITED(status))
{
signal(SIGCHLD, SIG_IGN);
kill(pid, SIGUSR1);
fprintf(stderr, "Bootstrap daemon SIGUSR1 to pid-%ld %sing.\n",
(long)pid, flag == 1 ? "restart" : "stop");
len = read(pipe_fd[0], buf, 7);
fprintf(stderr, "Bootstrap server served %*s.\n", (int)len, buf);
}
else
{
fprintf(stderr, "child exit. status = %d, waitpid ret = %d\n",
WEXITSTATUS(status), ret);
flag = 2;
}
close(pipe_fd[0]);
}
}
close(listen_fd);
return 0;
}
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