gen/popen.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1988, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * This code is derived from software written by Ken Arnold and
  30  * published in UNIX Review, Vol. 6, No. 8.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  */
  60
  61 #include <sys/param.h>
  62 #include <sys/wait.h>
  63 #include <sys/socket.h>
  64
  65 #include <signal.h>
  66 #include <errno.h>
  67 #include <unistd.h>
  68 #include <stdio.h>
  69 #include <stdlib.h>
  70 #include <string.h>
  71 #include <paths.h>
  72 #include <crt_externs.h>
  73
  74 #define environ *(_NSGetEnviron())
  75
  76 static struct pid {
  77         struct pid *next;
  78         FILE *fp;
  79         pid_t pid;
  80 } *pidlist;
  81
  82 FILE *
  83 popen(command, type)
  84         const char *command, *type;
  85 {
  86         struct pid *cur;
  87         FILE *iop;
  88         int pdes[2], pid, twoway;
  89         char *argv[4];
  90         struct pid *p;
  91
  92         if (strchr(type, '+')) {
  93                 twoway = 1;
  94                 type = "r+";
  95                 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pdes) < 0)
  96                         return (NULL);
  97         } else  {
  98                 twoway = 0;
  99                 if ((*type != 'r' && *type != 'w') || type[1])
 100                         return (NULL);
 101         }
 102         if (pipe(pdes) < 0)
 103                 return (NULL);
 104
 105         if ((cur = malloc(sizeof(struct pid))) == NULL) {
 106                 (void)close(pdes[0]);
 107                 (void)close(pdes[1]);
 108                 return (NULL);
 109         }
 110
 111         argv[0] = "sh";
 112         argv[1] = "-c";
 113         argv[2] = (char *)command;
 114         argv[3] = NULL;
 115
 116         switch (pid = vfork()) {
 117         case -1:                        /* Error. */
 118                 (void)close(pdes[0]);
 119                 (void)close(pdes[1]);
 120                 free(cur);
 121                 return (NULL);
 122                 /* NOTREACHED */
 123         case 0:                         /* Child. */
 124                 if (*type == 'r') {
 125                         /*
 126                          * The _dup2() to STDIN_FILENO is repeated to avoid
 127                          * writing to pdes[1], which might corrupt the
 128                          * parent's copy.  This isn't good enough in
 129                          * general, since the _exit() is no return, so
 130                          * the compiler is free to corrupt all the local
 131                          * variables.
 132                          */
 133                         (void)close(pdes[0]);
 134                         if (pdes[1] != STDOUT_FILENO) {
 135                                 (void)dup2(pdes[1], STDOUT_FILENO);
 136                                 (void)close(pdes[1]);
 137                                 if (twoway)
 138                                         (void)dup2(STDOUT_FILENO, STDIN_FILENO);
 139                         } else if (twoway && (pdes[1] != STDIN_FILENO))
 140                                 (void)dup2(pdes[1], STDIN_FILENO);
 141                 } else {
 142                         if (pdes[0] != STDIN_FILENO) {
 143                                 (void)dup2(pdes[0], STDIN_FILENO);
 144                                 (void)close(pdes[0]);
 145                         }
 146                         (void)close(pdes[1]);
 147                         }
 148                 for (p = pidlist; p; p = p->next) {
 149                         (void)close(fileno(p->fp));
 150                 }
 151                 execve(_PATH_BSHELL, argv, environ);
 152                 _exit(127);
 153                 /* NOTREACHED */
 154         }
 155
 156         /* Parent; assume fdopen can't fail. */
 157         if (*type == 'r') {
 158                 iop = fdopen(pdes[0], type);
 159                 (void)close(pdes[1]);
 160         } else {
 161                 iop = fdopen(pdes[1], type);
 162                 (void)close(pdes[0]);
 163         }
 164
 165         /* Link into list of file descriptors. */
 166         cur->fp = iop;
 167         cur->pid =  pid;
 168         cur->next = pidlist;
 169         pidlist = cur;
 170
 171         return (iop);
 172 }
 173
 174 /*
 175  * pclose --
 176  *      Pclose returns -1 if stream is not associated with a `popened' command,
 177  *      if already `pclosed', or waitpid returns an error.
 178  */
 179 int
 180 pclose(iop)
 181         FILE *iop;
 182 {
 183         register struct pid *cur, *last;
 184         int pstat;
 185         pid_t pid;
 186
 187         /* Find the appropriate file pointer. */
 188         for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
 189                 if (cur->fp == iop)
 190                         break;
 191         if (cur == NULL)
 192                 return (-1);
 193
 194         (void)fclose(iop);
 195
 196         do {
 197                 pid = wait4(cur->pid, &pstat, 0, (struct rusage *)0);
 198         } while (pid == -1 && errno == EINTR);
 199
 200         /* Remove the entry from the linked list. */
 201         if (last == NULL)
 202                 pidlist = cur->next;
 203         else
 204                 last->next = cur->next;
 205         free(cur);
 206
 207         return (pid == -1 ? -1 : pstat);
 208 }