1 /* $NetBSD: popen.c,v 1.26 2003/03/04 19:44:10 nathanw 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 8.3 (Berkeley) 5/3/95"; 43 #else 44 __RCSID("$NetBSD: popen.c,v 1.26 2003/03/04 19:44:10 nathanw 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 #include <sys/socket.h> 52 53 #include <assert.h> 54 #include <errno.h> 55 #include <paths.h> 56 #include <signal.h> 57 #include <stdio.h> 58 #include <stdlib.h> 59 #include <string.h> 60 #include <unistd.h> 61 #include "reentrant.h" 62 63 #ifdef __weak_alias 64 __weak_alias(popen,_popen) 65 __weak_alias(pclose,_pclose) 66 #endif 67 68 #ifdef _REENTRANT 69 extern rwlock_t __environ_lock; 70 #endif 71 72 static struct pid { 73 struct pid *next; 74 FILE *fp; 75 pid_t pid; 76 } *pidlist; 77 78 FILE * 79 popen(command, type) 80 const char *command, *type; 81 { 82 struct pid *cur, *old; 83 FILE *iop; 84 int pdes[2], pid, twoway, serrno; 85 86 _DIAGASSERT(command != NULL); 87 _DIAGASSERT(type != NULL); 88 89 #ifdef __GNUC__ 90 /* This outrageous construct just to shut up a GCC warning. */ 91 (void) &cur; (void) &twoway; (void) &type; 92 #endif 93 94 if (strchr(type, '+')) { 95 twoway = 1; 96 type = "r+"; 97 if (socketpair(AF_LOCAL, SOCK_STREAM, 0, pdes) < 0) 98 return (NULL); 99 } else { 100 twoway = 0; 101 if ((*type != 'r' && *type != 'w') || type[1] || 102 (pipe(pdes) < 0)) { 103 errno = EINVAL; 104 return (NULL); 105 } 106 } 107 108 if ((cur = malloc(sizeof(struct pid))) == NULL) { 109 (void)close(pdes[0]); 110 (void)close(pdes[1]); 111 errno = ENOMEM; 112 return (NULL); 113 } 114 115 rwlock_rdlock(&__environ_lock); 116 switch (pid = vfork()) { 117 case -1: /* Error. */ 118 serrno = errno; 119 rwlock_unlock(&__environ_lock); 120 free(cur); 121 (void)close(pdes[0]); 122 (void)close(pdes[1]); 123 errno = serrno; 124 return (NULL); 125 /* NOTREACHED */ 126 case 0: /* Child. */ 127 /* POSIX.2 B.3.2.2 "popen() shall ensure that any streams 128 from previous popen() calls that remain open in the 129 parent process are closed in the new child process. */ 130 for (old = pidlist; old; old = old->next) 131 close(fileno(old->fp)); /* don't allow a flush */ 132 133 if (*type == 'r') { 134 (void)close(pdes[0]); 135 if (pdes[1] != STDOUT_FILENO) { 136 (void)dup2(pdes[1], STDOUT_FILENO); 137 (void)close(pdes[1]); 138 } 139 if (twoway) 140 (void)dup2(STDOUT_FILENO, STDIN_FILENO); 141 } else { 142 (void)close(pdes[1]); 143 if (pdes[0] != STDIN_FILENO) { 144 (void)dup2(pdes[0], STDIN_FILENO); 145 (void)close(pdes[0]); 146 } 147 } 148 149 execl(_PATH_BSHELL, "sh", "-c", command, NULL); 150 _exit(127); 151 /* NOTREACHED */ 152 } 153 rwlock_unlock(&__environ_lock); 154 155 /* Parent; assume fdopen can't fail. */ 156 if (*type == 'r') { 157 iop = fdopen(pdes[0], type); 158 (void)close(pdes[1]); 159 } else { 160 iop = fdopen(pdes[1], type); 161 (void)close(pdes[0]); 162 } 163 164 /* Link into list of file descriptors. */ 165 cur->fp = iop; 166 cur->pid = pid; 167 cur->next = pidlist; 168 pidlist = cur; 169 170 return (iop); 171 } 172 173 /* 174 * pclose -- 175 * Pclose returns -1 if stream is not associated with a `popened' command, 176 * if already `pclosed', or waitpid returns an error. 177 */ 178 int 179 pclose(iop) 180 FILE *iop; 181 { 182 struct pid *cur, *last; 183 int pstat; 184 pid_t pid; 185 186 _DIAGASSERT(iop != NULL); 187 188 /* Find the appropriate file pointer. */ 189 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 190 if (cur->fp == iop) 191 break; 192 if (cur == NULL) 193 return (-1); 194 195 (void)fclose(iop); 196 197 do { 198 pid = waitpid(cur->pid, &pstat, 0); 199 } while (pid == -1 && errno == EINTR); 200 201 /* Remove the entry from the linked list. */ 202 if (last == NULL) 203 pidlist = cur->next; 204 else 205 last->next = cur->next; 206 free(cur); 207 208 return (pid == -1 ? -1 : pstat); 209 } 210