gen/FreeBSD/popen.c

   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)
  34 static 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: src/lib/libc/gen/popen.c,v 1.21 2009/05/27 19:28:04 ed Exp $");
  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 <unistd.h>
  47 #include <stdio.h>
  48 #include <stdlib.h>
  49 #include <string.h>
  50 #include <paths.h>
  51 #include <pthread.h>
  52 #include "un-namespace.h"
  53 #include "libc_private.h"
  54
  55 extern char **environ;
  56
  57 struct pid {
  58         SLIST_ENTRY(pid) next;
  59         FILE *fp;
  60         pid_t pid;
  61 };
  62 static SLIST_HEAD(, pid) pidlist = SLIST_HEAD_INITIALIZER(pidlist);
  63 static pthread_mutex_t pidlist_mutex = PTHREAD_MUTEX_INITIALIZER;
  64
  65 #define THREAD_LOCK()   if (__isthreaded) _pthread_mutex_lock(&pidlist_mutex)
  66 #define THREAD_UNLOCK() if (__isthreaded) _pthread_mutex_unlock(&pidlist_mutex)
  67
  68 FILE *
  69 popen(command, type)
  70         const char *command, *type;
  71 {
  72         struct pid *cur;
  73         FILE *iop;
  74         int pdes[2], pid, twoway;
  75         char *argv[4];
  76         struct pid *p;
  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') || type[1])
  88                         return (NULL);
  89         }
  90         if (pipe(pdes) < 0)
  91                 return (NULL);
  92
  93         if ((cur = malloc(sizeof(struct pid))) == NULL) {
  94                 (void)_close(pdes[0]);
  95                 (void)_close(pdes[1]);
  96                 return (NULL);
  97         }
  98
  99         argv[0] = "sh";
 100         argv[1] = "-c";
 101         argv[2] = (char *)command;
 102         argv[3] = NULL;
 103
 104         THREAD_LOCK();
 105         switch (pid = vfork()) {
 106         case -1:                        /* Error. */
 107                 THREAD_UNLOCK();
 108                 (void)_close(pdes[0]);
 109                 (void)_close(pdes[1]);
 110                 free(cur);
 111                 return (NULL);
 112                 /* NOTREACHED */
 113         case 0:                         /* Child. */
 114                 if (*type == 'r') {
 115                         /*
 116                          * The _dup2() to STDIN_FILENO is repeated to avoid
 117                          * writing to pdes[1], which might corrupt the
 118                          * parent's copy.  This isn't good enough in
 119                          * general, since the _exit() is no return, so
 120                          * the compiler is free to corrupt all the local
 121                          * variables.
 122                          */
 123                         (void)_close(pdes[0]);
 124                         if (pdes[1] != STDOUT_FILENO) {
 125                                 (void)_dup2(pdes[1], STDOUT_FILENO);
 126                                 (void)_close(pdes[1]);
 127                                 if (twoway)
 128                                         (void)_dup2(STDOUT_FILENO, STDIN_FILENO);
 129                         } else if (twoway && (pdes[1] != STDIN_FILENO))
 130                                 (void)_dup2(pdes[1], STDIN_FILENO);
 131                 } else {
 132                         if (pdes[0] != STDIN_FILENO) {
 133                                 (void)_dup2(pdes[0], STDIN_FILENO);
 134                                 (void)_close(pdes[0]);
 135                         }
 136                         (void)_close(pdes[1]);
 137                 }
 138                 SLIST_FOREACH(p, &pidlist, next)
 139                         (void)_close(fileno(p->fp));
 140                 _execve(_PATH_BSHELL, argv, environ);
 141                 _exit(127);
 142                 /* NOTREACHED */
 143         }
 144         THREAD_UNLOCK();
 145
 146         /* Parent; assume fdopen can't fail. */
 147         if (*type == 'r') {
 148                 iop = fdopen(pdes[0], type);
 149                 (void)_close(pdes[1]);
 150         } else {
 151                 iop = fdopen(pdes[1], type);
 152                 (void)_close(pdes[0]);
 153         }
 154
 155         /* Link into list of file descriptors. */
 156         cur->fp = iop;
 157         cur->pid = pid;
 158         THREAD_LOCK();
 159         SLIST_INSERT_HEAD(&pidlist, cur, next);
 160         THREAD_UNLOCK();
 161
 162         return (iop);
 163 }
 164
 165 /*
 166  * pclose --
 167  *      Pclose returns -1 if stream is not associated with a `popened' command,
 168  *      if already `pclosed', or waitpid returns an error.
 169  */
 170 int
 171 pclose(iop)
 172         FILE *iop;
 173 {
 174         struct pid *cur, *last = NULL;
 175         int pstat;
 176         pid_t pid;
 177
 178         /*
 179          * Find the appropriate file pointer and remove it from the list.
 180          */
 181         THREAD_LOCK();
 182         SLIST_FOREACH(cur, &pidlist, next) {
 183                 if (cur->fp == iop)
 184                         break;
 185                 last = cur;
 186         }
 187         if (cur == NULL) {
 188                 THREAD_UNLOCK();
 189                 return (-1);
 190         }
 191         if (last == NULL)
 192                 SLIST_REMOVE_HEAD(&pidlist, next);
 193         else
 194                 SLIST_REMOVE_AFTER(last, next);
 195         THREAD_UNLOCK();
 196
 197         (void)fclose(iop);
 198
 199         do {
 200                 pid = _wait4(cur->pid, &pstat, 0, (struct rusage *)0);
 201         } while (pid == -1 && errno == EINTR);
 202
 203         free(cur);
 204
 205         return (pid == -1 ? -1 : pstat);
 206 }