popen.c revision 250827
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: head/lib/libc/gen/popen.c 250827 2013-05-20 17:31:18Z jilles $"); 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(command, type) 71 const char *command, *type; 72{ 73 struct pid *cur; 74 FILE *iop; 75 int pdes[2], pid, twoway, cloexec; 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 ((cloexec ? pipe2(pdes, O_CLOEXEC) : pipe(pdes)) < 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 argv[0] = "sh"; 103 argv[1] = "-c"; 104 argv[2] = (char *)command; 105 argv[3] = NULL; 106 107 THREAD_LOCK(); 108 switch (pid = vfork()) { 109 case -1: /* Error. */ 110 THREAD_UNLOCK(); 111 (void)_close(pdes[0]); 112 (void)_close(pdes[1]); 113 free(cur); 114 return (NULL); 115 /* NOTREACHED */ 116 case 0: /* Child. */ 117 if (*type == 'r') { 118 /* 119 * The _dup2() to STDIN_FILENO is repeated to avoid 120 * writing to pdes[1], which might corrupt the 121 * parent's copy. This isn't good enough in 122 * general, since the _exit() is no return, so 123 * the compiler is free to corrupt all the local 124 * variables. 125 */ 126 if (!cloexec) 127 (void)_close(pdes[0]); 128 if (pdes[1] != STDOUT_FILENO) { 129 (void)_dup2(pdes[1], STDOUT_FILENO); 130 if (!cloexec) 131 (void)_close(pdes[1]); 132 if (twoway) 133 (void)_dup2(STDOUT_FILENO, STDIN_FILENO); 134 } else if (twoway && (pdes[1] != STDIN_FILENO)) { 135 (void)_dup2(pdes[1], STDIN_FILENO); 136 if (cloexec) 137 (void)_fcntl(pdes[1], F_SETFD, 0); 138 } else if (cloexec) 139 (void)_fcntl(pdes[1], F_SETFD, 0); 140 } else { 141 if (pdes[0] != STDIN_FILENO) { 142 (void)_dup2(pdes[0], STDIN_FILENO); 143 if (!cloexec) 144 (void)_close(pdes[0]); 145 } else if (cloexec) 146 (void)_fcntl(pdes[0], F_SETFD, 0); 147 if (!cloexec) 148 (void)_close(pdes[1]); 149 } 150 SLIST_FOREACH(p, &pidlist, next) 151 (void)_close(fileno(p->fp)); 152 _execve(_PATH_BSHELL, argv, environ); 153 _exit(127); 154 /* NOTREACHED */ 155 } 156 THREAD_UNLOCK(); 157 158 /* Parent; assume fdopen can't fail. */ 159 if (*type == 'r') { 160 iop = fdopen(pdes[0], type); 161 (void)_close(pdes[1]); 162 } else { 163 iop = fdopen(pdes[1], type); 164 (void)_close(pdes[0]); 165 } 166 167 /* Link into list of file descriptors. */ 168 cur->fp = iop; 169 cur->pid = pid; 170 THREAD_LOCK(); 171 SLIST_INSERT_HEAD(&pidlist, cur, next); 172 THREAD_UNLOCK(); 173 174 return (iop); 175} 176 177/* 178 * pclose -- 179 * Pclose returns -1 if stream is not associated with a `popened' command, 180 * if already `pclosed', or waitpid returns an error. 181 */ 182int 183pclose(iop) 184 FILE *iop; 185{ 186 struct pid *cur, *last = NULL; 187 int pstat; 188 pid_t pid; 189 190 /* 191 * Find the appropriate file pointer and remove it from the list. 192 */ 193 THREAD_LOCK(); 194 SLIST_FOREACH(cur, &pidlist, next) { 195 if (cur->fp == iop) 196 break; 197 last = cur; 198 } 199 if (cur == NULL) { 200 THREAD_UNLOCK(); 201 return (-1); 202 } 203 if (last == NULL) 204 SLIST_REMOVE_HEAD(&pidlist, next); 205 else 206 SLIST_REMOVE_AFTER(last, next); 207 THREAD_UNLOCK(); 208 209 (void)fclose(iop); 210 211 do { 212 pid = _wait4(cur->pid, &pstat, 0, (struct rusage *)0); 213 } while (pid == -1 && errno == EINTR); 214 215 free(cur); 216 217 return (pid == -1 ? -1 : pstat); 218} 219