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