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 * 3. 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 * @(#)popen.c 8.3 (Berkeley) 5/3/95 33 * $FreeBSD: src/lib/libc/gen/popen.c,v 1.20 2008/07/29 16:29:59 ed Exp $ 34 * $DragonFly: src/lib/libc/gen/popen.3,v 1.4 2006/04/08 08:17:06 swildner Exp $ 35 */ 36 37 #include "namespace.h" 38 #include <sys/param.h> 39 #include <sys/queue.h> 40 #include <sys/wait.h> 41 42 #include <signal.h> 43 #include <errno.h> 44 #include <unistd.h> 45 #include <stdio.h> 46 #include <stdlib.h> 47 #include <string.h> 48 #include <paths.h> 49 #include <fcntl.h> 50 #include <pthread.h> 51 #include "un-namespace.h" 52 #include "libc_private.h" 53 54 extern char **environ; 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 const char *argv[4]; 74 struct pid *p; 75 76 cloexec = (strchr(type, 'e') != NULL); 77 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 _close(pdes[0]); 96 _close(pdes[1]); 97 return (NULL); 98 } 99 100 argv[0] = "sh"; 101 argv[1] = "-c"; 102 argv[2] = command; 103 argv[3] = NULL; 104 105 THREAD_LOCK(); 106 switch (pid = vfork()) { 107 case -1: /* Error. */ 108 THREAD_UNLOCK(); 109 _close(pdes[0]); 110 _close(pdes[1]); 111 free(cur); 112 return (NULL); 113 /* NOTREACHED */ 114 case 0: /* Child. */ 115 if (*type == 'r') { 116 /* 117 * The _dup2() to STDIN_FILENO is repeated to avoid 118 * writing to pdes[1], which might corrupt the 119 * parent's copy. This isn't good enough in 120 * general, since the _exit() is no return, so 121 * the compiler is free to corrupt all the local 122 * variables. 123 */ 124 _close(pdes[0]); 125 _fcntl(pdes[1], F_SETFD, 0); 126 if (pdes[1] != STDOUT_FILENO) { 127 _dup2(pdes[1], STDOUT_FILENO); 128 _close(pdes[1]); 129 if (twoway) 130 _dup2(STDOUT_FILENO, STDIN_FILENO); 131 } else if (twoway && (pdes[1] != STDIN_FILENO)) 132 _dup2(pdes[1], STDIN_FILENO); 133 } else { 134 _fcntl(pdes[0], F_SETFD, 0); 135 if (pdes[0] != STDIN_FILENO) { 136 _dup2(pdes[0], STDIN_FILENO); 137 _close(pdes[0]); 138 } 139 _close(pdes[1]); 140 } 141 SLIST_FOREACH(p, &pidlist, next) 142 _close(__sfileno(p->fp)); 143 _execve(_PATH_BSHELL, __DECONST(char * const *, argv), environ); 144 _exit(127); 145 /* NOTREACHED */ 146 } 147 THREAD_UNLOCK(); 148 149 /* Parent; assume fdopen can't fail. */ 150 if (*type == 'r') { 151 iop = fdopen(pdes[0], type); 152 _close(pdes[1]); 153 } else { 154 iop = fdopen(pdes[1], type); 155 _close(pdes[0]); 156 } 157 158 /* Link into list of file descriptors. */ 159 cur->fp = iop; 160 cur->pid = pid; 161 THREAD_LOCK(); 162 SLIST_INSERT_HEAD(&pidlist, cur, next); 163 THREAD_UNLOCK(); 164 165 if (!cloexec) { 166 int fd = (*type == 'r') ? pdes[0] : pdes[1]; 167 _fcntl(fd, F_SETFD, 0); 168 } 169 170 return (iop); 171 } 172 173 /* 174 * pclose -- 175 * Pclose returns -1 if stream is not associated with a `popened' command, 176 * if already `pclosed', or waitpid returns an error. 177 */ 178 int 179 pclose(FILE *iop) 180 { 181 struct pid *cur, *last = NULL; 182 int pstat; 183 pid_t pid; 184 185 /* 186 * Find the appropriate file pointer and remove it from the list. 187 */ 188 THREAD_LOCK(); 189 SLIST_FOREACH(cur, &pidlist, next) { 190 if (cur->fp == iop) 191 break; 192 last = cur; 193 } 194 if (cur == NULL) { 195 THREAD_UNLOCK(); 196 return (-1); 197 } 198 if (last == NULL) 199 SLIST_REMOVE_HEAD(&pidlist, next); 200 else 201 SLIST_REMOVE_AFTER(last, next); 202 203 /* re-apply close-on-exec for unlock/fclose race */ 204 _fcntl(__sfileno(iop), F_SETFD, FD_CLOEXEC); 205 206 THREAD_UNLOCK(); 207 208 fclose(iop); 209 210 do { 211 pid = _wait4(cur->pid, &pstat, 0, NULL); 212 } while (pid == -1 && errno == EINTR); 213 214 free(cur); 215 216 return (pid == -1 ? -1 : pstat); 217 } 218