lib/libc/gen/popen.c

   1 /*      $NetBSD: popen.c,v 1.32 2012/06/25 22:32:43 abs Exp $   */
   2
   3 /*
   4  * Copyright (c) 1988, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software written by Ken Arnold and
   8  * published in UNIX Review, Vol. 6, No. 8.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 #if 0
  38 static char sccsid[] = "@(#)popen.c     8.3 (Berkeley) 5/3/95";
  39 #else
  40 __RCSID("$NetBSD: popen.c,v 1.32 2012/06/25 22:32:43 abs Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include "namespace.h"
  45 #include <sys/param.h>
  46 #include <sys/wait.h>
  47 #include <sys/socket.h>
  48
  49 #include <assert.h>
  50 #include <errno.h>
  51 #include <paths.h>
  52 #include <signal.h>
  53 #include <stdio.h>
  54 #include <stdlib.h>
  55 #include <string.h>
  56 #include <unistd.h>
  57 #include <fcntl.h>
  58
  59 #include "env.h"
  60 #include "reentrant.h"
  61
  62 #ifdef __weak_alias
  63 __weak_alias(popen,_popen)
  64 __weak_alias(pclose,_pclose)
  65 #endif
  66
  67 static struct pid {
  68         struct pid *next;
  69         FILE *fp;
  70 #ifdef _REENTRANT
  71         int fd;
  72 #endif
  73         pid_t pid;
  74 } *pidlist;
  75
  76 #ifdef _REENTRANT
  77 static rwlock_t pidlist_lock = RWLOCK_INITIALIZER;
  78 #endif
  79
  80 FILE *
  81 popen(const char *command, const char *type)
  82 {
  83         struct pid *cur, *old;
  84         FILE *iop;
  85         const char * volatile xtype = type;
  86         int pdes[2], pid, serrno;
  87         volatile int twoway;
  88         int flags;
  89
  90         _DIAGASSERT(command != NULL);
  91         _DIAGASSERT(xtype != NULL);
  92
  93         flags = strchr(xtype, 'e') ? O_CLOEXEC : 0;
  94         if (strchr(xtype, '+')) {
  95                 int stype = flags ? (SOCK_STREAM | SOCK_CLOEXEC) : SOCK_STREAM;
  96                 twoway = 1;
  97                 xtype = "r+";
  98                 if (socketpair(AF_LOCAL, stype, 0, pdes) < 0)
  99                         return NULL;
 100         } else  {
 101                 twoway = 0;
 102                 xtype = strrchr(xtype, 'r') ? "r" : "w";
 103                 if (pipe2(pdes, flags) == -1)
 104                         return NULL;
 105         }
 106
 107         if ((cur = malloc(sizeof(struct pid))) == NULL) {
 108                 (void)close(pdes[0]);
 109                 (void)close(pdes[1]);
 110                 errno = ENOMEM;
 111                 return (NULL);
 112         }
 113
 114 #if defined(__minix)
 115         rwlock_rdlock(&pidlist_lock);
 116 #else
 117         (void)rwlock_rdlock(&pidlist_lock);
 118 #endif /* defined(__minix) */
 119         (void)__readlockenv();
 120         switch (pid = vfork()) {
 121         case -1:                        /* Error. */
 122                 serrno = errno;
 123                 (void)__unlockenv();
 124 #if defined(__minix)
 125                 rwlock_unlock(&pidlist_lock);
 126 #else
 127                 (void)rwlock_unlock(&pidlist_lock);
 128 #endif /* defined(__minix) */
 129                 free(cur);
 130                 (void)close(pdes[0]);
 131                 (void)close(pdes[1]);
 132                 errno = serrno;
 133                 return (NULL);
 134                 /* NOTREACHED */
 135         case 0:                         /* Child. */
 136                 /* POSIX.2 B.3.2.2 "popen() shall ensure that any streams
 137                    from previous popen() calls that remain open in the
 138                    parent process are closed in the new child process. */
 139                 for (old = pidlist; old; old = old->next)
 140 #ifdef _REENTRANT
 141                         close(old->fd); /* don't allow a flush */
 142 #else
 143                         close(fileno(old->fp)); /* don't allow a flush */
 144 #endif
 145
 146                 if (*xtype == 'r') {
 147                         (void)close(pdes[0]);
 148                         if (pdes[1] != STDOUT_FILENO) {
 149                                 (void)dup2(pdes[1], STDOUT_FILENO);
 150                                 (void)close(pdes[1]);
 151                         }
 152                         if (twoway)
 153                                 (void)dup2(STDOUT_FILENO, STDIN_FILENO);
 154                 } else {
 155                         (void)close(pdes[1]);
 156                         if (pdes[0] != STDIN_FILENO) {
 157                                 (void)dup2(pdes[0], STDIN_FILENO);
 158                                 (void)close(pdes[0]);
 159                         }
 160                 }
 161
 162                 execl(_PATH_BSHELL, "sh", "-c", command, NULL);
 163                 _exit(127);
 164                 /* NOTREACHED */
 165         }
 166         (void)__unlockenv();
 167
 168         /* Parent; assume fdopen can't fail. */
 169         if (*xtype == 'r') {
 170                 iop = fdopen(pdes[0], xtype);
 171 #ifdef _REENTRANT
 172                 cur->fd = pdes[0];
 173 #endif
 174                 (void)close(pdes[1]);
 175         } else {
 176                 iop = fdopen(pdes[1], xtype);
 177 #ifdef _REENTRANT
 178                 cur->fd = pdes[1];
 179 #endif
 180                 (void)close(pdes[0]);
 181         }
 182
 183         /* Link into list of file descriptors. */
 184         cur->fp = iop;
 185         cur->pid =  pid;
 186         cur->next = pidlist;
 187         pidlist = cur;
 188 #if defined(__minix)
 189         rwlock_unlock(&pidlist_lock);
 190 #else
 191         (void)rwlock_unlock(&pidlist_lock);
 192 #endif /* defined(__minix) */
 193
 194         return (iop);
 195 }
 196
 197 /*
 198  * pclose --
 199  *      Pclose returns -1 if stream is not associated with a `popened' command,
 200  *      if already `pclosed', or waitpid returns an error.
 201  */
 202 int
 203 pclose(FILE *iop)
 204 {
 205         struct pid *cur, *last;
 206         int pstat;
 207         pid_t pid;
 208
 209         _DIAGASSERT(iop != NULL);
 210
 211         rwlock_wrlock(&pidlist_lock);
 212
 213         /* Find the appropriate file pointer. */
 214         for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
 215                 if (cur->fp == iop)
 216                         break;
 217         if (cur == NULL) {
 218 #if defined(__minix)
 219                 rwlock_unlock(&pidlist_lock);
 220 #else
 221                 (void)rwlock_unlock(&pidlist_lock);
 222 #endif /* defined(__minix) */
 223                 return (-1);
 224         }
 225
 226         (void)fclose(iop);
 227
 228         /* Remove the entry from the linked list. */
 229         if (last == NULL)
 230                 pidlist = cur->next;
 231         else
 232                 last->next = cur->next;
 233
 234 #if defined(__minix)
 235         rwlock_unlock(&pidlist_lock);
 236 #else
 237         (void)rwlock_unlock(&pidlist_lock);
 238 #endif /* defined(__minix) */
 239
 240         do {
 241                 pid = waitpid(cur->pid, &pstat, 0);
 242         } while (pid == -1 && errno == EINTR);
 243
 244         free(cur);
 245
 246         return (pid == -1 ? -1 : pstat);
 247 }