1 /* $NetBSD: popen.c,v 1.15 1997/09/16 00:35:47 thorpej 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 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)popen.c 8.1 (Berkeley) 6/4/93"; 43 #else 44 __RCSID("$NetBSD: popen.c,v 1.15 1997/09/16 00:35:47 thorpej Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include "namespace.h" 49 #include <sys/param.h> 50 #include <sys/wait.h> 51 52 #include <signal.h> 53 #include <errno.h> 54 #include <unistd.h> 55 #include <stdio.h> 56 #include <stdlib.h> 57 #include <string.h> 58 #include <paths.h> 59 60 #ifdef __weak_alias 61 __weak_alias(popen,_popen); 62 __weak_alias(pclose,_pclose); 63 #endif 64 65 static struct pid { 66 struct pid *next; 67 FILE *fp; 68 pid_t pid; 69 } *pidlist; 70 71 FILE * 72 popen(program, type) 73 const char *program; 74 const char *type; 75 { 76 struct pid *cur, *old; 77 FILE *iop; 78 int pdes[2], pid; 79 #ifdef __GNUC__ 80 (void) &cur; 81 #endif 82 83 if ((*type != 'r' && *type != 'w') || type[1]) { 84 errno = EINVAL; 85 return (NULL); 86 } 87 88 if ((cur = malloc(sizeof(struct pid))) == NULL) 89 return (NULL); 90 91 if (pipe(pdes) < 0) { 92 free(cur); 93 return (NULL); 94 } 95 96 switch (pid = vfork()) { 97 case -1: /* Error. */ 98 (void)close(pdes[0]); 99 (void)close(pdes[1]); 100 free(cur); 101 return (NULL); 102 /* NOTREACHED */ 103 case 0: /* Child. */ 104 if (*type == 'r') { 105 if (pdes[1] != STDOUT_FILENO) { 106 (void)dup2(pdes[1], STDOUT_FILENO); 107 (void)close(pdes[1]); 108 } 109 (void) close(pdes[0]); 110 } else { 111 if (pdes[0] != STDIN_FILENO) { 112 (void)dup2(pdes[0], STDIN_FILENO); 113 (void)close(pdes[0]); 114 } 115 (void)close(pdes[1]); 116 } 117 118 /* POSIX.2 B.3.2.2 "popen() shall ensure that any streams 119 from previous popen() calls that remain open in the 120 parent process are closed in the new child process. */ 121 for (old = pidlist; old; old = old->next) 122 close(fileno(old->fp)); 123 124 execl(_PATH_BSHELL, "sh", "-c", program, NULL); 125 _exit(127); 126 /* NOTREACHED */ 127 } 128 129 /* Parent; assume fdopen can't fail. */ 130 if (*type == 'r') { 131 iop = fdopen(pdes[0], type); 132 (void)close(pdes[1]); 133 } else { 134 iop = fdopen(pdes[1], type); 135 (void)close(pdes[0]); 136 } 137 138 /* Link into list of file descriptors. */ 139 cur->fp = iop; 140 cur->pid = pid; 141 cur->next = pidlist; 142 pidlist = cur; 143 144 return (iop); 145 } 146 147 /* 148 * pclose -- 149 * Pclose returns -1 if stream is not associated with a `popened' command, 150 * if already `pclosed', or waitpid returns an error. 151 */ 152 int 153 pclose(iop) 154 FILE *iop; 155 { 156 register struct pid *cur, *last; 157 int pstat; 158 pid_t pid; 159 160 (void)fclose(iop); 161 162 /* Find the appropriate file pointer. */ 163 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 164 if (cur->fp == iop) 165 break; 166 if (cur == NULL) 167 return (-1); 168 169 do { 170 pid = waitpid(cur->pid, &pstat, 0); 171 } while (pid == -1 && errno == EINTR); 172 173 /* Remove the entry from the linked list. */ 174 if (last == NULL) 175 pidlist = cur->next; 176 else 177 last->next = cur->next; 178 free(cur); 179 180 return (pid == -1 ? -1 : pstat); 181 } 182