1 /* $NetBSD: popen.c,v 1.29 2006/10/15 16:12:02 christos 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 1.29 2006/10/15 16:12:02 christos 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(const char *command, const char *type) 83 { 84 struct pid *cur, *old; 85 FILE *iop; 86 const char * volatile xtype = type; 87 int pdes[2], pid, serrno; 88 volatile int twoway; 89 90 _DIAGASSERT(command != NULL); 91 _DIAGASSERT(xtype != NULL); 92 93 if (strchr(xtype, '+')) { 94 twoway = 1; 95 type = "r+"; 96 if (socketpair(AF_LOCAL, SOCK_STREAM, 0, pdes) < 0) 97 return (NULL); 98 } else { 99 twoway = 0; 100 if ((*xtype != 'r' && *xtype != 'w') || xtype[1] || 101 (pipe(pdes) < 0)) { 102 errno = EINVAL; 103 return (NULL); 104 } 105 } 106 107 if ((cur = malloc(sizeof(struct pid))) == NULL) { 108 (void)close(pdes[0]); 109 (void)close(pdes[1]); 110 errno = ENOMEM; 111 return (NULL); 112 } 113 114 rwlock_rdlock(&pidlist_lock); 115 rwlock_rdlock(&__environ_lock); 116 switch (pid = vfork()) { 117 case -1: /* Error. */ 118 serrno = errno; 119 rwlock_unlock(&__environ_lock); 120 rwlock_unlock(&pidlist_lock); 121 free(cur); 122 (void)close(pdes[0]); 123 (void)close(pdes[1]); 124 errno = serrno; 125 return (NULL); 126 /* NOTREACHED */ 127 case 0: /* Child. */ 128 /* POSIX.2 B.3.2.2 "popen() shall ensure that any streams 129 from previous popen() calls that remain open in the 130 parent process are closed in the new child process. */ 131 for (old = pidlist; old; old = old->next) 132 #ifdef _REENTRANT 133 close(old->fd); /* don't allow a flush */ 134 #else 135 close(fileno(old->fp)); /* don't allow a flush */ 136 #endif 137 138 if (*xtype == 'r') { 139 (void)close(pdes[0]); 140 if (pdes[1] != STDOUT_FILENO) { 141 (void)dup2(pdes[1], STDOUT_FILENO); 142 (void)close(pdes[1]); 143 } 144 if (twoway) 145 (void)dup2(STDOUT_FILENO, STDIN_FILENO); 146 } else { 147 (void)close(pdes[1]); 148 if (pdes[0] != STDIN_FILENO) { 149 (void)dup2(pdes[0], STDIN_FILENO); 150 (void)close(pdes[0]); 151 } 152 } 153 154 execl(_PATH_BSHELL, "sh", "-c", command, NULL); 155 _exit(127); 156 /* NOTREACHED */ 157 } 158 rwlock_unlock(&__environ_lock); 159 160 /* Parent; assume fdopen can't fail. */ 161 if (*xtype == 'r') { 162 iop = fdopen(pdes[0], xtype); 163 #ifdef _REENTRANT 164 cur->fd = pdes[0]; 165 #endif 166 (void)close(pdes[1]); 167 } else { 168 iop = fdopen(pdes[1], xtype); 169 #ifdef _REENTRANT 170 cur->fd = pdes[1]; 171 #endif 172 (void)close(pdes[0]); 173 } 174 175 /* Link into list of file descriptors. */ 176 cur->fp = iop; 177 cur->pid = pid; 178 cur->next = pidlist; 179 pidlist = cur; 180 rwlock_unlock(&pidlist_lock); 181 182 return (iop); 183 } 184 185 /* 186 * pclose -- 187 * Pclose returns -1 if stream is not associated with a `popened' command, 188 * if already `pclosed', or waitpid returns an error. 189 */ 190 int 191 pclose(iop) 192 FILE *iop; 193 { 194 struct pid *cur, *last; 195 int pstat; 196 pid_t pid; 197 198 _DIAGASSERT(iop != NULL); 199 200 rwlock_wrlock(&pidlist_lock); 201 202 /* Find the appropriate file pointer. */ 203 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 204 if (cur->fp == iop) 205 break; 206 if (cur == NULL) { 207 rwlock_unlock(&pidlist_lock); 208 return (-1); 209 } 210 211 (void)fclose(iop); 212 213 /* Remove the entry from the linked list. */ 214 if (last == NULL) 215 pidlist = cur->next; 216 else 217 last->next = cur->next; 218 219 rwlock_unlock(&pidlist_lock); 220 221 do { 222 pid = waitpid(cur->pid, &pstat, 0); 223 } while (pid == -1 && errno == EINTR); 224 225 free(cur); 226 227 return (pid == -1 ? -1 : pstat); 228 } 229