| #define _GNU_SOURCE |
| #include <errno.h> |
| #include <sched.h> |
| #include <signal.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <sys/mman.h> |
| #include <sys/wait.h> |
| #include <unistd.h> |
| |
| #define STACK_SIZE (1024 * 1024) /* Stack size for cloned child */ |
| |
| struct clone_args { |
| char **argv; |
| }; |
| |
| // child_exec is the func that will be executed as the result of clone |
| static int child_exec(void *stuff) |
| { |
| struct clone_args *args = (struct clone_args *)stuff; |
| if (execvp(args->argv[0], args->argv) != 0) { |
| fprintf(stderr, "failed to execvp arguments %s\n", |
| strerror(errno)); |
| exit(-1); |
| } |
| // we should never reach here! |
| exit(EXIT_FAILURE); |
| } |
| |
| int main(int argc, char **argv) |
| { |
| struct clone_args args; |
| args.argv = &argv[1]; |
| |
| int clone_flags = CLONE_NEWNS | CLONE_NEWPID | SIGCHLD; |
| |
| // allocate stack for child |
| char *stack; /* Start of stack buffer */ |
| char *child_stack; /* End of stack buffer */ |
| stack = |
| mmap(NULL, STACK_SIZE, PROT_READ | PROT_WRITE, |
| MAP_SHARED | MAP_ANON | MAP_STACK, -1, 0); |
| if (stack == MAP_FAILED) { |
| fprintf(stderr, "mmap failed: %s\n", strerror(errno)); |
| exit(EXIT_FAILURE); |
| } |
| child_stack = stack + STACK_SIZE; /* Assume stack grows downward */ |
| |
| // the result of this call is that our child_exec will be run in another |
| // process returning its pid |
| pid_t pid = clone(child_exec, child_stack, clone_flags, &args); |
| if (pid < 0) { |
| fprintf(stderr, "clone failed: %s\n", strerror(errno)); |
| exit(EXIT_FAILURE); |
| } |
| // lets wait on our child process here before we, the parent, exits |
| if (waitpid(pid, NULL, 0) == -1) { |
| fprintf(stderr, "failed to wait pid %d\n", pid); |
| exit(EXIT_FAILURE); |
| } |
| exit(EXIT_SUCCESS); |
| } |