1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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 #if defined(LIBC_SCCS) && !defined(lint) 36 static char sccsid[] = "@(#)popen.c 8.3 (Berkeley) 5/3/95"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "namespace.h" 42 #include <sys/param.h> 43 #include <sys/queue.h> 44 #include <sys/wait.h> 45 46 #include <signal.h> 47 #include <errno.h> 48 #include <fcntl.h> 49 #include <unistd.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <paths.h> 54 #include <pthread.h> 55 #include "un-namespace.h" 56 #include "libc_private.h" 57 58 extern char **environ; 59 60 struct pid { 61 SLIST_ENTRY(pid) next; 62 FILE *fp; 63 pid_t pid; 64 }; 65 static SLIST_HEAD(, pid) pidlist = SLIST_HEAD_INITIALIZER(pidlist); 66 static pthread_mutex_t pidlist_mutex = PTHREAD_MUTEX_INITIALIZER; 67 68 #define THREAD_LOCK() if (__isthreaded) _pthread_mutex_lock(&pidlist_mutex) 69 #define THREAD_UNLOCK() if (__isthreaded) _pthread_mutex_unlock(&pidlist_mutex) 70 71 FILE * 72 popen(const char *command, const char *type) 73 { 74 struct pid *cur; 75 FILE *iop; 76 int pdes[2], pid, twoway, cloexec; 77 int pdes_unused_in_parent; 78 char *argv[4]; 79 struct pid *p; 80 81 cloexec = strchr(type, 'e') != NULL; 82 /* 83 * Lite2 introduced two-way popen() pipes using _socketpair(). 84 * FreeBSD's pipe() is bidirectional, so we use that. 85 */ 86 if (strchr(type, '+')) { 87 twoway = 1; 88 type = "r+"; 89 } else { 90 twoway = 0; 91 if ((*type != 'r' && *type != 'w') || 92 (type[1] && (type[1] != 'e' || type[2]))) 93 return (NULL); 94 } 95 if (pipe2(pdes, O_CLOEXEC) < 0) 96 return (NULL); 97 98 if ((cur = malloc(sizeof(struct pid))) == NULL) { 99 (void)_close(pdes[0]); 100 (void)_close(pdes[1]); 101 return (NULL); 102 } 103 104 if (*type == 'r') { 105 iop = fdopen(pdes[0], type); 106 pdes_unused_in_parent = pdes[1]; 107 } else { 108 iop = fdopen(pdes[1], type); 109 pdes_unused_in_parent = pdes[0]; 110 } 111 if (iop == NULL) { 112 (void)_close(pdes[0]); 113 (void)_close(pdes[1]); 114 free(cur); 115 return (NULL); 116 } 117 118 argv[0] = "sh"; 119 argv[1] = "-c"; 120 argv[2] = (char *)command; 121 argv[3] = NULL; 122 123 THREAD_LOCK(); 124 switch (pid = vfork()) { 125 case -1: /* Error. */ 126 THREAD_UNLOCK(); 127 /* 128 * The _close() closes the unused end of pdes[], while 129 * the fclose() closes the used end of pdes[], *and* cleans 130 * up iop. 131 */ 132 (void)_close(pdes_unused_in_parent); 133 free(cur); 134 (void)fclose(iop); 135 return (NULL); 136 /* NOTREACHED */ 137 case 0: /* Child. */ 138 if (*type == 'r') { 139 /* 140 * The _dup2() to STDIN_FILENO is repeated to avoid 141 * writing to pdes[1], which might corrupt the 142 * parent's copy. This isn't good enough in 143 * general, since the _exit() is no return, so 144 * the compiler is free to corrupt all the local 145 * variables. 146 */ 147 if (pdes[1] != STDOUT_FILENO) { 148 (void)_dup2(pdes[1], STDOUT_FILENO); 149 if (twoway) 150 (void)_dup2(STDOUT_FILENO, STDIN_FILENO); 151 } else if (twoway && (pdes[1] != STDIN_FILENO)) { 152 (void)_dup2(pdes[1], STDIN_FILENO); 153 (void)_fcntl(pdes[1], F_SETFD, 0); 154 } else 155 (void)_fcntl(pdes[1], F_SETFD, 0); 156 } else { 157 if (pdes[0] != STDIN_FILENO) { 158 (void)_dup2(pdes[0], STDIN_FILENO); 159 } else 160 (void)_fcntl(pdes[0], F_SETFD, 0); 161 } 162 SLIST_FOREACH(p, &pidlist, next) 163 (void)_close(fileno(p->fp)); 164 _execve(_PATH_BSHELL, argv, environ); 165 _exit(127); 166 /* NOTREACHED */ 167 } 168 THREAD_UNLOCK(); 169 170 /* Parent. */ 171 (void)_close(pdes_unused_in_parent); 172 173 /* Link into list of file descriptors. */ 174 cur->fp = iop; 175 cur->pid = pid; 176 THREAD_LOCK(); 177 SLIST_INSERT_HEAD(&pidlist, cur, next); 178 THREAD_UNLOCK(); 179 180 /* 181 * To guard against undesired fd passing with concurrent calls, 182 * only clear the close-on-exec flag after linking the file into 183 * the list which will cause an explicit close. 184 */ 185 if (!cloexec) 186 (void)_fcntl(*type == 'r' ? pdes[0] : pdes[1], F_SETFD, 0); 187 188 return (iop); 189 } 190 191 /* 192 * pclose -- 193 * Pclose returns -1 if stream is not associated with a `popened' command, 194 * if already `pclosed', or waitpid returns an error. 195 */ 196 int 197 pclose(FILE *iop) 198 { 199 struct pid *cur, *last = NULL; 200 int pstat; 201 pid_t pid; 202 203 /* 204 * Find the appropriate file pointer and remove it from the list. 205 */ 206 THREAD_LOCK(); 207 SLIST_FOREACH(cur, &pidlist, next) { 208 if (cur->fp == iop) 209 break; 210 last = cur; 211 } 212 if (cur == NULL) { 213 THREAD_UNLOCK(); 214 return (-1); 215 } 216 if (last == NULL) 217 SLIST_REMOVE_HEAD(&pidlist, next); 218 else 219 SLIST_REMOVE_AFTER(last, next); 220 THREAD_UNLOCK(); 221 222 (void)fclose(iop); 223 224 do { 225 pid = _wait4(cur->pid, &pstat, 0, (struct rusage *)0); 226 } while (pid == -1 && errno == EINTR); 227 228 free(cur); 229 230 return (pid == -1 ? -1 : pstat); 231 } 232