popen.c revision 108580
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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37#if defined(LIBC_SCCS) && !defined(lint) 38static char sccsid[] = "@(#)popen.c 8.3 (Berkeley) 5/3/95"; 39#endif /* LIBC_SCCS and not lint */ 40#include <sys/cdefs.h> 41__FBSDID("$FreeBSD: head/lib/libc/gen/popen.c 108580 2003-01-03 04:35:04Z tjr $"); 42 43#include "namespace.h" 44#include <sys/param.h> 45#include <sys/wait.h> 46 47#include <signal.h> 48#include <errno.h> 49#include <unistd.h> 50#include <stdio.h> 51#include <stdlib.h> 52#include <string.h> 53#include <paths.h> 54#include <pthread.h> 55#include "un-namespace.h" 56#include "libc_private.h" 57 58extern char **environ; 59 60static struct pid { 61 struct pid *next; 62 FILE *fp; 63 pid_t pid; 64} *pidlist; 65static pthread_mutex_t pidlist_mutex = PTHREAD_MUTEX_INITIALIZER; 66 67#define THREAD_LOCK() if (__isthreaded) _pthread_mutex_lock(&pidlist_mutex) 68#define THREAD_UNLOCK() if (__isthreaded) _pthread_mutex_unlock(&pidlist_mutex) 69 70FILE * 71popen(command, type) 72 const char *command, *type; 73{ 74 struct pid *cur; 75 FILE *iop; 76 int pdes[2], pid, twoway; 77 char *argv[4]; 78 struct pid *p; 79 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') || type[1]) 90 return (NULL); 91 } 92 if (pipe(pdes) < 0) 93 return (NULL); 94 95 if ((cur = malloc(sizeof(struct pid))) == NULL) { 96 (void)_close(pdes[0]); 97 (void)_close(pdes[1]); 98 return (NULL); 99 } 100 101 argv[0] = "sh"; 102 argv[1] = "-c"; 103 argv[2] = (char *)command; 104 argv[3] = NULL; 105 106 THREAD_LOCK(); 107 switch (pid = vfork()) { 108 case -1: /* Error. */ 109 THREAD_UNLOCK(); 110 (void)_close(pdes[0]); 111 (void)_close(pdes[1]); 112 free(cur); 113 return (NULL); 114 /* NOTREACHED */ 115 case 0: /* Child. */ 116 if (*type == 'r') { 117 /* 118 * The _dup2() to STDIN_FILENO is repeated to avoid 119 * writing to pdes[1], which might corrupt the 120 * parent's copy. This isn't good enough in 121 * general, since the _exit() is no return, so 122 * the compiler is free to corrupt all the local 123 * variables. 124 */ 125 (void)_close(pdes[0]); 126 if (pdes[1] != STDOUT_FILENO) { 127 (void)_dup2(pdes[1], STDOUT_FILENO); 128 (void)_close(pdes[1]); 129 if (twoway) 130 (void)_dup2(STDOUT_FILENO, STDIN_FILENO); 131 } else if (twoway && (pdes[1] != STDIN_FILENO)) 132 (void)_dup2(pdes[1], STDIN_FILENO); 133 } else { 134 if (pdes[0] != STDIN_FILENO) { 135 (void)_dup2(pdes[0], STDIN_FILENO); 136 (void)_close(pdes[0]); 137 } 138 (void)_close(pdes[1]); 139 } 140 for (p = pidlist; p; p = p->next) { 141 (void)_close(fileno(p->fp)); 142 } 143 _execve(_PATH_BSHELL, 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 (void)_close(pdes[1]); 153 } else { 154 iop = fdopen(pdes[1], type); 155 (void)_close(pdes[0]); 156 } 157 158 /* Link into list of file descriptors. */ 159 cur->fp = iop; 160 cur->pid = pid; 161 THREAD_LOCK(); 162 cur->next = pidlist; 163 pidlist = cur; 164 THREAD_UNLOCK(); 165 166 return (iop); 167} 168 169/* 170 * pclose -- 171 * Pclose returns -1 if stream is not associated with a `popened' command, 172 * if already `pclosed', or waitpid returns an error. 173 */ 174int 175pclose(iop) 176 FILE *iop; 177{ 178 struct pid *cur, *last; 179 int omask; 180 int pstat; 181 pid_t pid; 182 183 /* 184 * Find the appropriate file pointer and remove it from the list. 185 */ 186 THREAD_LOCK(); 187 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) 188 if (cur->fp == iop) 189 break; 190 if (cur == NULL) { 191 THREAD_UNLOCK(); 192 return (-1); 193 } 194 if (last == NULL) 195 pidlist = cur->next; 196 else 197 last->next = cur->next; 198 THREAD_UNLOCK(); 199 200 (void)fclose(iop); 201 202 do { 203 pid = _wait4(cur->pid, &pstat, 0, (struct rusage *)0); 204 } while (pid == -1 && errno == EINTR); 205 206 free(cur); 207 208 return (pid == -1 ? -1 : pstat); 209} 210