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