popen.c revision 331722
1/* 2 * Copyright (c) 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software written by Ken Arnold and 6 * published in UNIX Review, Vol. 6, No. 8. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33#if defined(LIBC_SCCS) && !defined(lint) 34static char sccsid[] = "@(#)popen.c 8.3 (Berkeley) 5/3/95"; 35#endif /* LIBC_SCCS and not lint */ 36#include <sys/cdefs.h> 37__FBSDID("$FreeBSD: stable/11/lib/libc/gen/popen.c 331722 2018-03-29 02:50:57Z eadler $"); 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 56extern char **environ; 57 58struct pid { 59 SLIST_ENTRY(pid) next; 60 FILE *fp; 61 pid_t pid; 62}; 63static SLIST_HEAD(, pid) pidlist = SLIST_HEAD_INITIALIZER(pidlist); 64static pthread_mutex_t pidlist_mutex = PTHREAD_MUTEX_INITIALIZER; 65 66#define THREAD_LOCK() if (__isthreaded) _pthread_mutex_lock(&pidlist_mutex) 67#define THREAD_UNLOCK() if (__isthreaded) _pthread_mutex_unlock(&pidlist_mutex) 68 69FILE * 70popen(const char *command, const char *type) 71{ 72 struct pid *cur; 73 FILE *iop; 74 int pdes[2], pid, twoway, cloexec; 75 int pdes_unused_in_parent; 76 char *argv[4]; 77 struct pid *p; 78 79 cloexec = strchr(type, 'e') != NULL; 80 /* 81 * Lite2 introduced two-way popen() pipes using _socketpair(). 82 * FreeBSD's pipe() is bidirectional, so we use that. 83 */ 84 if (strchr(type, '+')) { 85 twoway = 1; 86 type = "r+"; 87 } else { 88 twoway = 0; 89 if ((*type != 'r' && *type != 'w') || 90 (type[1] && (type[1] != 'e' || type[2]))) 91 return (NULL); 92 } 93 if (pipe2(pdes, O_CLOEXEC) < 0) 94 return (NULL); 95 96 if ((cur = malloc(sizeof(struct pid))) == NULL) { 97 (void)_close(pdes[0]); 98 (void)_close(pdes[1]); 99 return (NULL); 100 } 101 102 if (*type == 'r') { 103 iop = fdopen(pdes[0], type); 104 pdes_unused_in_parent = pdes[1]; 105 } else { 106 iop = fdopen(pdes[1], type); 107 pdes_unused_in_parent = pdes[0]; 108 } 109 if (iop == NULL) { 110 (void)_close(pdes[0]); 111 (void)_close(pdes[1]); 112 free(cur); 113 return (NULL); 114 } 115 116 argv[0] = "sh"; 117 argv[1] = "-c"; 118 argv[2] = (char *)command; 119 argv[3] = NULL; 120 121 THREAD_LOCK(); 122 switch (pid = vfork()) { 123 case -1: /* Error. */ 124 THREAD_UNLOCK(); 125 /* 126 * The _close() closes the unused end of pdes[], while 127 * the fclose() closes the used end of pdes[], *and* cleans 128 * up iop. 129 */ 130 (void)_close(pdes_unused_in_parent); 131 free(cur); 132 (void)fclose(iop); 133 return (NULL); 134 /* NOTREACHED */ 135 case 0: /* Child. */ 136 if (*type == 'r') { 137 /* 138 * The _dup2() to STDIN_FILENO is repeated to avoid 139 * writing to pdes[1], which might corrupt the 140 * parent's copy. This isn't good enough in 141 * general, since the _exit() is no return, so 142 * the compiler is free to corrupt all the local 143 * variables. 144 */ 145 if (pdes[1] != STDOUT_FILENO) { 146 (void)_dup2(pdes[1], STDOUT_FILENO); 147 if (twoway) 148 (void)_dup2(STDOUT_FILENO, STDIN_FILENO); 149 } else if (twoway && (pdes[1] != STDIN_FILENO)) { 150 (void)_dup2(pdes[1], STDIN_FILENO); 151 (void)_fcntl(pdes[1], F_SETFD, 0); 152 } else 153 (void)_fcntl(pdes[1], F_SETFD, 0); 154 } else { 155 if (pdes[0] != STDIN_FILENO) { 156 (void)_dup2(pdes[0], STDIN_FILENO); 157 } else 158 (void)_fcntl(pdes[0], F_SETFD, 0); 159 } 160 SLIST_FOREACH(p, &pidlist, next) 161 (void)_close(fileno(p->fp)); 162 _execve(_PATH_BSHELL, argv, environ); 163 _exit(127); 164 /* NOTREACHED */ 165 } 166 THREAD_UNLOCK(); 167 168 /* Parent. */ 169 (void)_close(pdes_unused_in_parent); 170 171 /* Link into list of file descriptors. */ 172 cur->fp = iop; 173 cur->pid = pid; 174 THREAD_LOCK(); 175 SLIST_INSERT_HEAD(&pidlist, cur, next); 176 THREAD_UNLOCK(); 177 178 /* 179 * To guard against undesired fd passing with concurrent calls, 180 * only clear the close-on-exec flag after linking the file into 181 * the list which will cause an explicit close. 182 */ 183 if (!cloexec) 184 (void)_fcntl(*type == 'r' ? pdes[0] : pdes[1], F_SETFD, 0); 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 */ 194int 195pclose(FILE *iop) 196{ 197 struct pid *cur, *last = NULL; 198 int pstat; 199 pid_t pid; 200 201 /* 202 * Find the appropriate file pointer and remove it from the list. 203 */ 204 THREAD_LOCK(); 205 SLIST_FOREACH(cur, &pidlist, next) { 206 if (cur->fp == iop) 207 break; 208 last = cur; 209 } 210 if (cur == NULL) { 211 THREAD_UNLOCK(); 212 return (-1); 213 } 214 if (last == NULL) 215 SLIST_REMOVE_HEAD(&pidlist, next); 216 else 217 SLIST_REMOVE_AFTER(last, next); 218 THREAD_UNLOCK(); 219 220 (void)fclose(iop); 221 222 do { 223 pid = _wait4(cur->pid, &pstat, 0, (struct rusage *)0); 224 } while (pid == -1 && errno == EINTR); 225 226 free(cur); 227 228 return (pid == -1 ? -1 : pstat); 229} 230