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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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#define _GNU_SOURCE#include <err.h>#include <errno.h>#include <fcntl.h>#include <inttypes.h>#include <limits.h>#include <sched.h>#include <signal.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <sys/stat.h>#include <sys/syscall.h>#include <sys/types.h>#include <sys/wait.h>#include <unistd.h>
#ifndef CLONE_PIDFD#define CLONE_PIDFD 0x00001000#endif
#ifndef __NR_pidfd_send_signal#define __NR_pidfd_send_signal -1#endif
static int do_child(void *args){ printf("%d\n", getpid()); _exit(EXIT_SUCCESS);}
static pid_t pidfd_clone(int flags, int *pidfd){ size_t stack_size = 1024; char *stack[1024] = { 0 };
#ifdef __ia64__ return __clone2(do_child, stack, stack_size, flags | SIGCHLD, NULL, pidfd);#else return clone(do_child, stack + stack_size, flags | SIGCHLD, NULL, pidfd);#endif}
static inline int sys_pidfd_send_signal(int pidfd, int sig, siginfo_t *info, unsigned int flags){ return syscall(__NR_pidfd_send_signal, pidfd, sig, info, flags);}
static int pidfd_metadata_fd(pid_t pid, int pidfd){ int procfd, ret; char path[100];
snprintf(path, sizeof(path), "/proc/%d", pid); procfd = open(path, O_DIRECTORY | O_RDONLY | O_CLOEXEC); if (procfd < 0) { warn("Failed to open %s\n", path); return -1; }
/* * Verify that the pid has not been recycled and our /proc/<pid> handle * is still valid. */ ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0); if (ret < 0) { switch (errno) { case EPERM: /* Process exists, just not allowed to signal it. */ break; default: warn("Failed to signal process\n"); close(procfd); procfd = -1; } }
return procfd;}
int main(int argc, char *argv[]){ int pidfd = -1, ret = EXIT_FAILURE; char buf[4096] = { 0 }; pid_t pid; int procfd, statusfd; ssize_t bytes;
pid = pidfd_clone(CLONE_PIDFD, &pidfd); if (pid < 0) err(ret, "CLONE_PIDFD"); if (pidfd == -1) { warnx("CLONE_PIDFD is not supported by the kernel"); goto out; }
procfd = pidfd_metadata_fd(pid, pidfd); close(pidfd); if (procfd < 0) goto out;
statusfd = openat(procfd, "status", O_RDONLY | O_CLOEXEC); close(procfd); if (statusfd < 0) goto out;
bytes = read(statusfd, buf, sizeof(buf)); if (bytes > 0) bytes = write(STDOUT_FILENO, buf, bytes); close(statusfd); ret = EXIT_SUCCESS;
out: (void)wait(NULL);
exit(ret);}