1 /* $NetBSD: popen.c,v 1.30 2010/11/14 18:11:42 tron 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 1.30 2010/11/14 18:11:42 tron 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 58 #include "env.h" 59 #include "reentrant.h" 60 61 #ifdef __weak_alias 62 __weak_alias(popen,_popen) 63 __weak_alias(pclose,_pclose) 64 #endif 65 66 static struct pid { 67 struct pid *next; 68 FILE *fp; 69 #ifdef _REENTRANT 70 int fd; 71 #endif 72 pid_t pid; 73 } *pidlist; 74 75 #ifdef _REENTRANT 76 static rwlock_t pidlist_lock = RWLOCK_INITIALIZER; 77 #endif 78 79 FILE * 80 popen(const char *command, const char *type) 81 { 82 struct pid *cur, *old; 83 FILE *iop; 84 const char * volatile xtype = type; 85 int pdes[2], pid, serrno; 86 volatile int twoway; 87 88 _DIAGASSERT(command != NULL); 89 _DIAGASSERT(xtype != NULL); 90 91 if (strchr(xtype, '+')) { 92 twoway = 1; 93 type = "r+"; 94 if (socketpair(AF_LOCAL, SOCK_STREAM, 0, pdes) < 0) 95 return (NULL); 96 } else { 97 twoway = 0; 98 if ((*xtype != 'r' && *xtype != 'w') || xtype[1] || 99 (pipe(pdes) < 0)) { 100 errno = EINVAL; 101 return (NULL); 102 } 103 } 104 105 if ((cur = malloc(sizeof(struct pid))) == NULL) { 106 (void)close(pdes[0]); 107 (void)close(pdes[1]); 108 errno = ENOMEM; 109 return (NULL); 110 } 111 112 (void)rwlock_rdlock(&pidlist_lock); 113 (void)__readlockenv(); 114 switch (pid = vfork()) { 115 case -1: /* Error. */ 116 serrno = errno; 117 (void)__unlockenv(); 118 (void)rwlock_unlock(&pidlist_lock); 119 free(cur); 120 (void)close(pdes[0]); 121 (void)close(pdes[1]); 122 errno = serrno; 123 return (NULL); 124 /* NOTREACHED */ 125 case 0: /* Child. */ 126 /* POSIX.2 B.3.2.2 "popen() shall ensure that any streams 127 from previous popen() calls that remain open in the 128 parent process are closed in the new child process. */ 129 for (old = pidlist; old; old = old->next) 130 #ifdef _REENTRANT 131 close(old->fd); /* don't allow a flush */ 132 #else 133 close(fileno(old->fp)); /* don't allow a flush */ 134 #endif 135 136 if (*xtype == 'r') { 137 (void)close(pdes[0]); 138 if (pdes[1] != STDOUT_FILENO) { 139 (void)dup2(pdes[1], STDOUT_FILENO); 140 (void)close(pdes[1]); 141 } 142 if (twoway) 143 (void)dup2(STDOUT_FILENO, STDIN_FILENO); 144 } else { 145 (void)close(pdes[1]); 146 if (pdes[0] != STDIN_FILENO) { 147 (void)dup2(pdes[0], STDIN_FILENO); 148 (void)close(pdes[0]); 149 } 150 } 151 152 execl(_PATH_BSHELL, "sh", "-c", command, NULL); 153 _exit(127); 154 /* NOTREACHED */ 155 } 156 (void)__unlockenv(); 157 158 /* Parent; assume fdopen can't fail. */ 159 if (*xtype == 'r') { 160 iop = fdopen(pdes[0], xtype); 161 #ifdef _REENTRANT 162 cur->fd = pdes[0]; 163 #endif 164 (void)close(pdes[1]); 165 } else { 166 iop = fdopen(pdes[1], xtype); 167 #ifdef _REENTRANT 168 cur->fd = pdes[1]; 169 #endif 170 (void)close(pdes[0]); 171 } 172 173 /* Link into list of file descriptors. */ 174 cur->fp = iop; 175 cur->pid = pid; 176 cur->next = pidlist; 177 pidlist = cur; 178 (void)rwlock_unlock(&pidlist_lock); 179 180 return (iop); 181 } 182 183 /* 184 * pclose -- 185 * Pclose returns -1 if stream is not associated with a `popened' command, 186 * if already `pclosed', or waitpid returns an error. 187 */ 188 int 189 pclose(iop) 190 FILE *iop; 191 { 192 struct pid *cur, *last; 193 int pstat; 194 pid_t pid; 195 196 _DIAGASSERT(iop != NULL); 197 198 rwlock_wrlock(&pidlist_lock); 199 200 /* Find the appropriate file pointer. */ 201 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 202 if (cur->fp == iop) 203 break; 204 if (cur == NULL) { 205 (void)rwlock_unlock(&pidlist_lock); 206 return (-1); 207 } 208 209 (void)fclose(iop); 210 211 /* Remove the entry from the linked list. */ 212 if (last == NULL) 213 pidlist = cur->next; 214 else 215 last->next = cur->next; 216 217 (void)rwlock_unlock(&pidlist_lock); 218 219 do { 220 pid = waitpid(cur->pid, &pstat, 0); 221 } while (pid == -1 && errno == EINTR); 222 223 free(cur); 224 225 return (pid == -1 ? -1 : pstat); 226 } 227