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  * 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)
  38 static 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: src/lib/libc/gen/popen.c,v 1.18 2003/01/04 00:15:15 tjr Exp $");
  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
  58 extern char **environ;
  59
  60 static struct pid {
  61         struct pid *next;
  62         FILE *fp;
  63         pid_t pid;
  64 } *pidlist;
  65 static 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
  70 FILE *
  71 popen(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  */
 174 int
 175 pclose(iop)
 176         FILE *iop;
 177 {
 178         struct pid *cur, *last;
 179         int pstat;
 180         pid_t pid;
 181
 182         /*
 183          * Find the appropriate file pointer and remove it from the list.
 184          */
 185         THREAD_LOCK();
 186         for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
 187                 if (cur->fp == iop)
 188                         break;
 189         if (cur == NULL) {
 190                 THREAD_UNLOCK();
 191                 return (-1);
 192         }
 193         if (last == NULL)
 194                 pidlist = cur->next;
 195         else
 196                 last->next = cur->next;
 197         THREAD_UNLOCK();
 198
 199         (void)fclose(iop);
 200
 201         do {
 202                 pid = _wait4(cur->pid, &pstat, 0, (struct rusage *)0);
 203         } while (pid == -1 && errno == EINTR);
 204
 205         free(cur);
 206
 207         return (pid == -1 ? -1 : pstat);
 208 }