1 /* $NetBSD: popen.c,v 1.32 2012/06/25 22:32:43 abs 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 1.32 2012/06/25 22:32:43 abs 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 <fcntl.h> 58 59 #include "env.h" 60 #include "reentrant.h" 61 62 #if defined(__minix) && !defined(O_CLOEXEC) 63 #define O_CLOEXEC 0 64 #endif 65 66 #ifdef __weak_alias 67 __weak_alias(popen,_popen) 68 __weak_alias(pclose,_pclose) 69 #endif 70 71 static struct pid { 72 struct pid *next; 73 FILE *fp; 74 #ifdef _REENTRANT 75 int fd; 76 #endif 77 pid_t pid; 78 } *pidlist; 79 80 #ifdef _REENTRANT 81 static rwlock_t pidlist_lock = RWLOCK_INITIALIZER; 82 #endif 83 84 FILE * 85 popen(const char *command, const char *type) 86 { 87 struct pid *cur, *old; 88 FILE *iop; 89 const char * volatile xtype = type; 90 int pdes[2], pid, serrno; 91 volatile int twoway; 92 int flags; 93 94 _DIAGASSERT(command != NULL); 95 _DIAGASSERT(xtype != NULL); 96 97 flags = strchr(xtype, 'e') ? O_CLOEXEC : 0; 98 if (strchr(xtype, '+')) { 99 int stype = flags ? (SOCK_STREAM | SOCK_CLOEXEC) : SOCK_STREAM; 100 twoway = 1; 101 xtype = "r+"; 102 if (socketpair(AF_LOCAL, stype, 0, pdes) < 0) 103 return NULL; 104 } else { 105 twoway = 0; 106 xtype = strrchr(xtype, 'r') ? "r" : "w"; 107 if (pipe2(pdes, flags) == -1) 108 return NULL; 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 (void)rwlock_rdlock(&pidlist_lock); 119 (void)__readlockenv(); 120 switch (pid = vfork()) { 121 case -1: /* Error. */ 122 serrno = errno; 123 (void)__unlockenv(); 124 (void)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 (*xtype == '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 (void)__unlockenv(); 163 164 /* Parent; assume fdopen can't fail. */ 165 if (*xtype == 'r') { 166 iop = fdopen(pdes[0], xtype); 167 #ifdef _REENTRANT 168 cur->fd = pdes[0]; 169 #endif 170 (void)close(pdes[1]); 171 } else { 172 iop = fdopen(pdes[1], xtype); 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 (void)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(FILE *iop) 196 { 197 struct pid *cur, *last; 198 int pstat; 199 pid_t pid; 200 201 _DIAGASSERT(iop != NULL); 202 203 rwlock_wrlock(&pidlist_lock); 204 205 /* Find the appropriate file pointer. */ 206 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 207 if (cur->fp == iop) 208 break; 209 if (cur == NULL) { 210 (void)rwlock_unlock(&pidlist_lock); 211 return (-1); 212 } 213 214 (void)fclose(iop); 215 216 /* Remove the entry from the linked list. */ 217 if (last == NULL) 218 pidlist = cur->next; 219 else 220 last->next = cur->next; 221 222 (void)rwlock_unlock(&pidlist_lock); 223 224 do { 225 pid = waitpid(cur->pid, &pstat, 0); 226 } while (pid == -1 && errno == EINTR); 227 228 free(cur); 229 230 return (pid == -1 ? -1 : pstat); 231 } 232