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 #ifdef __weak_alias 63 __weak_alias(popen,_popen) 64 __weak_alias(pclose,_pclose) 65 #endif 66 67 static struct pid { 68 struct pid *next; 69 FILE *fp; 70 #ifdef _REENTRANT 71 int fd; 72 #endif 73 pid_t pid; 74 } *pidlist; 75 76 #ifdef _REENTRANT 77 static rwlock_t pidlist_lock = RWLOCK_INITIALIZER; 78 #endif 79 80 FILE * 81 popen(const char *command, const char *type) 82 { 83 struct pid *cur, *old; 84 FILE *iop; 85 const char * volatile xtype = type; 86 int pdes[2], pid, serrno; 87 volatile int twoway; 88 int flags; 89 90 _DIAGASSERT(command != NULL); 91 _DIAGASSERT(xtype != NULL); 92 93 flags = strchr(xtype, 'e') ? O_CLOEXEC : 0; 94 if (strchr(xtype, '+')) { 95 int stype = flags ? (SOCK_STREAM | SOCK_CLOEXEC) : SOCK_STREAM; 96 twoway = 1; 97 xtype = "r+"; 98 if (socketpair(AF_LOCAL, stype, 0, pdes) < 0) 99 return NULL; 100 } else { 101 twoway = 0; 102 xtype = strrchr(xtype, 'r') ? "r" : "w"; 103 if (pipe2(pdes, flags) == -1) 104 return NULL; 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 (void)rwlock_rdlock(&pidlist_lock); 115 (void)__readlockenv(); 116 switch (pid = vfork()) { 117 case -1: /* Error. */ 118 serrno = errno; 119 (void)__unlockenv(); 120 (void)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 (void)__unlockenv(); 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 (void)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(FILE *iop) 192 { 193 struct pid *cur, *last; 194 int pstat; 195 pid_t pid; 196 197 _DIAGASSERT(iop != NULL); 198 199 rwlock_wrlock(&pidlist_lock); 200 201 /* Find the appropriate file pointer. */ 202 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 203 if (cur->fp == iop) 204 break; 205 if (cur == NULL) { 206 (void)rwlock_unlock(&pidlist_lock); 207 return (-1); 208 } 209 210 (void)fclose(iop); 211 212 /* Remove the entry from the linked list. */ 213 if (last == NULL) 214 pidlist = cur->next; 215 else 216 last->next = cur->next; 217 218 (void)rwlock_unlock(&pidlist_lock); 219 220 do { 221 pid = waitpid(cur->pid, &pstat, 0); 222 } while (pid == -1 && errno == EINTR); 223 224 free(cur); 225 226 return (pid == -1 ? -1 : pstat); 227 } 228
