1 /* 2 * Copyright 2007, Axel Dörfler, axeld@pinc-software.de. All rights reserved. 3 * Distributed under the terms of the MIT License. 4 */ 5 6 7 #include <errno.h> 8 #include <stdio.h> 9 #include <string.h> 10 #include <sys/wait.h> 11 #include <unistd.h> 12 13 14 /*! 15 wait() should wait only once. If any argument is given, waitpid() should return 16 an error (and errno to ECHILD), since there is no child with that process group ID. 17 */ 18 19 20 int 21 child2() 22 { 23 sleep(2); 24 return 2; 25 } 26 27 28 //! exits before child 2 29 int 30 child1() 31 { 32 setpgrp(); 33 // put us into a new process group 34 35 pid_t child = fork(); 36 if (child == 0) 37 return child2(); 38 39 sleep(1); 40 return 1; 41 } 42 43 44 int 45 main(int argc, char** argv) 46 { 47 bool waitForGroup = argc > 1; 48 49 pid_t child = fork(); 50 if (child == 0) 51 return child1(); 52 53 pid_t pid; 54 do { 55 int childStatus = -1; 56 if (waitForGroup) 57 pid = waitpid(0, &childStatus, 0); 58 else 59 pid = wait(&childStatus); 60 printf("wait() returned %ld (%s), child status %d\n", 61 pid, strerror(errno), childStatus); 62 } while (pid >= 0); 63 64 return 0; 65 } 66 67