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#define _POSIX_SOURCE
#include <sys/types.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <signal.h>
#define TEMPLATE "/tmp/lsof-test-ux-%ld.s"
static void do_nothing(int n) {}
int main(void) {
int rendezvous[2];
if (pipe(rendezvous) < 0) {
perror("pipe");
return 1;
}
pid_t pid = fork();
if (pid > 0) {
close(rendezvous[0]);
/* parent: server */
int server = socket(AF_UNIX, SOCK_STREAM, 0);
if (server < 0) {
perror("socket (server)");
return 1;
}
struct sockaddr_un un = {
.sun_family = AF_UNIX,
};
snprintf(un.sun_path, 108, TEMPLATE, (long int)getpid());
unlink(un.sun_path);
if (bind(server, (void *)&un, sizeof(un)) < 0) {
perror("bind (server)");
return 1;
}
if (listen(server, 0) < 0) {
perror("listen (server)");
return 1;
}
char b = 1;
if (write(rendezvous[1], &b, 1) < 0) {
perror("write rendezvous pipe (server)");
return 1;
}
b++;
int client;
if ((client = accept(server, NULL, 0)) < 0) {
perror("listen (server)");
return 1;
}
char buf[1024];
if (read(client, buf, 1024) < 0) {
perror("read (server)");
return 1;
}
fputs(buf, stdout);
printf("ppid %ld\nlisten %d\naccept %d\npath %s\n", (long int)getpid(),
server, client, un.sun_path);
fputs("end\n", stdout);
fflush(stdout);
signal(SIGCONT, do_nothing);
pause();
unlink(un.sun_path);
(void)write(rendezvous[1], &b, 1);
b++;
return 0;
} else if (pid == 0) {
char b;
/* child: client */
close(rendezvous[1]);
if (read(rendezvous[0], &b, 1) < 0) {
perror("read rendezvous pipe (client)");
/* TODO: kill the parent process. */
return 1;
}
int server = socket(AF_UNIX, SOCK_STREAM, 0);
if (server < 0) {
perror("socket (client)");
return 1;
}
struct sockaddr_un un = {
.sun_family = AF_UNIX,
};
snprintf(un.sun_path, 108, TEMPLATE, (long int)getppid());
if (connect(server, (void *)&un, sizeof(un)) < 0) {
perror("connect (client)");
return 1;
}
FILE *serverf = fdopen(server, "w");
if (!serverf) {
perror("fdopen (client)");
return 1;
}
int server2 = socket(AF_UNIX, SOCK_STREAM, 0);
if (server2 < 0) {
perror("socket (client)");
return 1;
}
if (connect(server2, (void *)&un, sizeof(un)) < 0) {
perror("connect (client (server2))");
return 1;
}
fprintf(serverf, "pid %ld\nconnect %d\nconnect2 %d\n",
(long int)getpid(), server, server2);
putc('\0', serverf);
fflush(serverf);
if (read(rendezvous[0], &b, 1) < 0) {
perror("read rendezvous pipe (client)");
return 1;
}
return 0;
}
perror("fork");
return 1;
}
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