1 /* $NetBSD: popen.c,v 1.12 1996/06/29 00:51:49 jtc Exp $ */ 2 3 /* 4 * Copyright (c) 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software written by Ken Arnold and 8 * published in UNIX Review, Vol. 6, No. 8. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #if defined(LIBC_SCCS) && !defined(lint) 40 #if 0 41 static char sccsid[] = "@(#)popen.c 8.1 (Berkeley) 6/4/93"; 42 #else 43 static char rcsid[] = "$NetBSD: popen.c,v 1.12 1996/06/29 00:51:49 jtc Exp $"; 44 #endif 45 #endif /* LIBC_SCCS and not lint */ 46 47 #include <sys/param.h> 48 #include <sys/wait.h> 49 50 #include <signal.h> 51 #include <errno.h> 52 #include <unistd.h> 53 #include <stdio.h> 54 #include <stdlib.h> 55 #include <string.h> 56 #include <paths.h> 57 58 static struct pid { 59 struct pid *next; 60 FILE *fp; 61 pid_t pid; 62 } *pidlist; 63 64 FILE * 65 popen(program, type) 66 const char *program; 67 const char *type; 68 { 69 struct pid *cur; 70 FILE *iop; 71 int pdes[2], pid; 72 73 if (*type != 'r' && *type != 'w' || type[1]) { 74 errno = EINVAL; 75 return (NULL); 76 } 77 78 if ((cur = malloc(sizeof(struct pid))) == NULL) 79 return (NULL); 80 81 if (pipe(pdes) < 0) { 82 free(cur); 83 return (NULL); 84 } 85 86 switch (pid = vfork()) { 87 case -1: /* Error. */ 88 (void)close(pdes[0]); 89 (void)close(pdes[1]); 90 free(cur); 91 return (NULL); 92 /* NOTREACHED */ 93 case 0: /* Child. */ 94 if (*type == 'r') { 95 if (pdes[1] != STDOUT_FILENO) { 96 (void)dup2(pdes[1], STDOUT_FILENO); 97 (void)close(pdes[1]); 98 } 99 (void) close(pdes[0]); 100 } else { 101 if (pdes[0] != STDIN_FILENO) { 102 (void)dup2(pdes[0], STDIN_FILENO); 103 (void)close(pdes[0]); 104 } 105 (void)close(pdes[1]); 106 } 107 108 /* POSIX.2 B.3.2.2 "popen() shall ensure that any streams 109 from previous popen() calls that remain open in the 110 parent process are closed in the new child process. */ 111 for (cur = pidlist; cur; cur = cur->next) 112 close(fileno(cur->fp)); 113 114 execl(_PATH_BSHELL, "sh", "-c", program, NULL); 115 _exit(127); 116 /* NOTREACHED */ 117 } 118 119 /* Parent; assume fdopen can't fail. */ 120 if (*type == 'r') { 121 iop = fdopen(pdes[0], type); 122 (void)close(pdes[1]); 123 } else { 124 iop = fdopen(pdes[1], type); 125 (void)close(pdes[0]); 126 } 127 128 /* Link into list of file descriptors. */ 129 cur->fp = iop; 130 cur->pid = pid; 131 cur->next = pidlist; 132 pidlist = cur; 133 134 return (iop); 135 } 136 137 /* 138 * pclose -- 139 * Pclose returns -1 if stream is not associated with a `popened' command, 140 * if already `pclosed', or waitpid returns an error. 141 */ 142 int 143 pclose(iop) 144 FILE *iop; 145 { 146 register struct pid *cur, *last; 147 int pstat; 148 pid_t pid; 149 150 (void)fclose(iop); 151 152 /* Find the appropriate file pointer. */ 153 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 154 if (cur->fp == iop) 155 break; 156 if (cur == NULL) 157 return (-1); 158 159 do { 160 pid = waitpid(cur->pid, &pstat, 0); 161 } while (pid == -1 && errno == EINTR); 162 163 /* Remove the entry from the linked list. */ 164 if (last == NULL) 165 pidlist = cur->next; 166 else 167 last->next = cur->next; 168 free(cur); 169 170 return (pid == -1 ? -1 : pstat); 171 } 172