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#define _GNU_SOURCE
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <sched.h>
#define STKS (4*4096)
#ifndef CLONE_NEWPID
#define CLONE_NEWPID 0x20000000
#endif
static int do_test(void *logf)
{
int fd, i = 0;
setsid();
close(0);
close(1);
close(2);
fd = open("/dev/null", O_RDONLY);
if (fd != 0) {
dup2(fd, 0);
close(fd);
}
fd = open(logf, O_WRONLY | O_TRUNC | O_CREAT, 0600);
dup2(fd, 1);
dup2(fd, 2);
if (fd != 1 && fd != 2)
close(fd);
while (1) {
sleep(1);
printf("%d\n", i++);
fflush(stdout);
}
return 0;
}
int main(int argc, char **argv)
{
int pid;
void *stk;
stk = mmap(NULL, STKS, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANON | MAP_GROWSDOWN, 0, 0);
pid = clone(do_test, stk + STKS, SIGCHLD | CLONE_NEWPID, argv[1]);
printf("Child forked, pid %d\n", pid);
return 0;
}
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