1 /* 2 * Copyright (c) 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software written by Ken Arnold and 6 * published in UNIX Review, Vol. 6, No. 8. 7 * 8 * %sccs.include.redist.c% 9 */ 10 11 #if defined(LIBC_SCCS) && !defined(lint) 12 static char sccsid[] = "@(#)popen.c 8.2 (Berkeley) 04/27/95"; 13 #endif /* LIBC_SCCS and not lint */ 14 15 #include <sys/param.h> 16 #include <sys/wait.h> 17 18 #include <signal.h> 19 #include <errno.h> 20 #include <unistd.h> 21 #include <stdio.h> 22 #include <stdlib.h> 23 #include <string.h> 24 #include <paths.h> 25 26 static struct pid { 27 struct pid *next; 28 FILE *fp; 29 pid_t pid; 30 } *pidlist; 31 32 FILE * 33 popen(command, type) 34 const char *command, *type; 35 { 36 struct pid *cur; 37 FILE *iop; 38 int pdes[2], pid; 39 40 if (*type != 'r' && *type != 'w' || type[1]) { 41 errno = EINVAL; 42 return (NULL); 43 } 44 45 if ((cur = malloc(sizeof(struct pid))) == NULL) 46 return (NULL); 47 48 if (pipe(pdes) < 0) { 49 (void)free(cur); 50 return (NULL); 51 } 52 53 switch (pid = vfork()) { 54 case -1: /* Error. */ 55 (void)close(pdes[0]); 56 (void)close(pdes[1]); 57 (void)free(cur); 58 return (NULL); 59 /* NOTREACHED */ 60 case 0: /* Child. */ 61 if (*type == 'r') { 62 if (pdes[1] != STDOUT_FILENO) { 63 (void)dup2(pdes[1], STDOUT_FILENO); 64 (void)close(pdes[1]); 65 } 66 (void) close(pdes[0]); 67 } else { 68 if (pdes[0] != STDIN_FILENO) { 69 (void)dup2(pdes[0], STDIN_FILENO); 70 (void)close(pdes[0]); 71 } 72 (void)close(pdes[1]); 73 } 74 execl(_PATH_BSHELL, "sh", "-c", command, NULL); 75 _exit(127); 76 /* NOTREACHED */ 77 } 78 79 /* Parent; assume fdopen can't fail. */ 80 if (*type == 'r') { 81 iop = fdopen(pdes[0], type); 82 (void)close(pdes[1]); 83 } else { 84 iop = fdopen(pdes[1], type); 85 (void)close(pdes[0]); 86 } 87 88 /* Link into list of file descriptors. */ 89 cur->fp = iop; 90 cur->pid = pid; 91 cur->next = pidlist; 92 pidlist = cur; 93 94 return (iop); 95 } 96 97 /* 98 * pclose -- 99 * Pclose returns -1 if stream is not associated with a `popened' command, 100 * if already `pclosed', or waitpid returns an error. 101 */ 102 int 103 pclose(iop) 104 FILE *iop; 105 { 106 register struct pid *cur, *last; 107 int omask; 108 int pstat; 109 pid_t pid; 110 111 /* Find the appropriate file pointer. */ 112 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 113 if (cur->fp == iop) 114 break; 115 if (cur == NULL) 116 return (-1); 117 118 (void)fclose(iop); 119 120 do { 121 pid = waitpid(cur->pid, &pstat, 0); 122 } while (pid == -1 && errno == EINTR); 123 124 /* Remove the entry from the linked list. */ 125 if (last == NULL) 126 pidlist = cur->next; 127 else 128 last->next = cur->next; 129 free(cur); 130 131 return (pid == -1 ? -1 : pstat); 132 } 133