1 /* $NetBSD: popen.c,v 1.28 2003/09/15 22:30:38 cl 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)popen.c 8.3 (Berkeley) 5/3/95"; 39 #else 40 __RCSID("$NetBSD: popen.c,v 1.28 2003/09/15 22:30:38 cl Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include "namespace.h" 45 #include <sys/param.h> 46 #include <sys/wait.h> 47 #include <sys/socket.h> 48 49 #include <assert.h> 50 #include <errno.h> 51 #include <paths.h> 52 #include <signal.h> 53 #include <stdio.h> 54 #include <stdlib.h> 55 #include <string.h> 56 #include <unistd.h> 57 #include "reentrant.h" 58 59 #ifdef __weak_alias 60 __weak_alias(popen,_popen) 61 __weak_alias(pclose,_pclose) 62 #endif 63 64 #ifdef _REENTRANT 65 extern rwlock_t __environ_lock; 66 #endif 67 68 static struct pid { 69 struct pid *next; 70 FILE *fp; 71 #ifdef _REENTRANT 72 int fd; 73 #endif 74 pid_t pid; 75 } *pidlist; 76 77 #ifdef _REENTRANT 78 static rwlock_t pidlist_lock = RWLOCK_INITIALIZER; 79 #endif 80 81 FILE * 82 popen(command, type) 83 const char *command, *type; 84 { 85 struct pid *cur, *old; 86 FILE *iop; 87 int pdes[2], pid, twoway, serrno; 88 89 _DIAGASSERT(command != NULL); 90 _DIAGASSERT(type != NULL); 91 92 #ifdef __GNUC__ 93 /* This outrageous construct just to shut up a GCC warning. */ 94 (void) &cur; (void) &twoway; (void) &type; 95 #endif 96 97 if (strchr(type, '+')) { 98 twoway = 1; 99 type = "r+"; 100 if (socketpair(AF_LOCAL, SOCK_STREAM, 0, pdes) < 0) 101 return (NULL); 102 } else { 103 twoway = 0; 104 if ((*type != 'r' && *type != 'w') || type[1] || 105 (pipe(pdes) < 0)) { 106 errno = EINVAL; 107 return (NULL); 108 } 109 } 110 111 if ((cur = malloc(sizeof(struct pid))) == NULL) { 112 (void)close(pdes[0]); 113 (void)close(pdes[1]); 114 errno = ENOMEM; 115 return (NULL); 116 } 117 118 rwlock_rdlock(&pidlist_lock); 119 rwlock_rdlock(&__environ_lock); 120 switch (pid = vfork()) { 121 case -1: /* Error. */ 122 serrno = errno; 123 rwlock_unlock(&__environ_lock); 124 rwlock_unlock(&pidlist_lock); 125 free(cur); 126 (void)close(pdes[0]); 127 (void)close(pdes[1]); 128 errno = serrno; 129 return (NULL); 130 /* NOTREACHED */ 131 case 0: /* Child. */ 132 /* POSIX.2 B.3.2.2 "popen() shall ensure that any streams 133 from previous popen() calls that remain open in the 134 parent process are closed in the new child process. */ 135 for (old = pidlist; old; old = old->next) 136 #ifdef _REENTRANT 137 close(old->fd); /* don't allow a flush */ 138 #else 139 close(fileno(old->fp)); /* don't allow a flush */ 140 #endif 141 142 if (*type == 'r') { 143 (void)close(pdes[0]); 144 if (pdes[1] != STDOUT_FILENO) { 145 (void)dup2(pdes[1], STDOUT_FILENO); 146 (void)close(pdes[1]); 147 } 148 if (twoway) 149 (void)dup2(STDOUT_FILENO, STDIN_FILENO); 150 } else { 151 (void)close(pdes[1]); 152 if (pdes[0] != STDIN_FILENO) { 153 (void)dup2(pdes[0], STDIN_FILENO); 154 (void)close(pdes[0]); 155 } 156 } 157 158 execl(_PATH_BSHELL, "sh", "-c", command, NULL); 159 _exit(127); 160 /* NOTREACHED */ 161 } 162 rwlock_unlock(&__environ_lock); 163 164 /* Parent; assume fdopen can't fail. */ 165 if (*type == 'r') { 166 iop = fdopen(pdes[0], type); 167 #ifdef _REENTRANT 168 cur->fd = pdes[0]; 169 #endif 170 (void)close(pdes[1]); 171 } else { 172 iop = fdopen(pdes[1], type); 173 #ifdef _REENTRANT 174 cur->fd = pdes[1]; 175 #endif 176 (void)close(pdes[0]); 177 } 178 179 /* Link into list of file descriptors. */ 180 cur->fp = iop; 181 cur->pid = pid; 182 cur->next = pidlist; 183 pidlist = cur; 184 rwlock_unlock(&pidlist_lock); 185 186 return (iop); 187 } 188 189 /* 190 * pclose -- 191 * Pclose returns -1 if stream is not associated with a `popened' command, 192 * if already `pclosed', or waitpid returns an error. 193 */ 194 int 195 pclose(iop) 196 FILE *iop; 197 { 198 struct pid *cur, *last; 199 int pstat; 200 pid_t pid; 201 202 _DIAGASSERT(iop != NULL); 203 204 rwlock_wrlock(&pidlist_lock); 205 206 /* Find the appropriate file pointer. */ 207 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 208 if (cur->fp == iop) 209 break; 210 if (cur == NULL) { 211 rwlock_unlock(&pidlist_lock); 212 return (-1); 213 } 214 215 (void)fclose(iop); 216 217 /* Remove the entry from the linked list. */ 218 if (last == NULL) 219 pidlist = cur->next; 220 else 221 last->next = cur->next; 222 223 rwlock_unlock(&pidlist_lock); 224 225 do { 226 pid = waitpid(cur->pid, &pstat, 0); 227 } while (pid == -1 && errno == EINTR); 228 229 free(cur); 230 231 return (pid == -1 ? -1 : pstat); 232 } 233