lib/libc/gen/popen.c

   1 /*      $NetBSD: popen.c,v 1.35 2015/02/02 22:07:05 christos 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 1.35 2015/02/02 22:07:05 christos 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
  61 #ifdef __weak_alias
  62 __weak_alias(popen,_popen)
  63 __weak_alias(pclose,_pclose)
  64 #endif
  65
  66 static struct pid {
  67         struct pid *next;
  68         FILE *fp;
  69 #ifdef _REENTRANT
  70         int fd;
  71 #endif
  72         pid_t pid;
  73 } *pidlist;
  74
  75 #ifdef _REENTRANT
  76 static rwlock_t pidlist_lock = RWLOCK_INITIALIZER;
  77 #endif
  78
  79 static struct pid *
  80 pdes_get(int *pdes, const char **type)
  81 {
  82         struct pid *cur;
  83         int flags = strchr(*type, 'e') ? O_CLOEXEC : 0;
  84         int serrno;
  85
  86         if (strchr(*type, '+')) {
  87                 int stype = flags ? (SOCK_STREAM | SOCK_CLOEXEC) : SOCK_STREAM;
  88                 *type = "r+";
  89                 if (socketpair(AF_LOCAL, stype, 0, pdes) < 0)
  90                         return NULL;
  91         } else  {
  92                 *type = strrchr(*type, 'r') ? "r" : "w";
  93                 if (pipe2(pdes, flags) == -1)
  94                         return NULL;
  95         }
  96
  97         if ((cur = malloc(sizeof(*cur))) != NULL)
  98                 return cur;
  99         serrno = errno;
 100         (void)close(pdes[0]);
 101         (void)close(pdes[1]);
 102         errno = serrno;
 103         return NULL;
 104 }
 105
 106 static void
 107 pdes_child(int *pdes, const char *type)
 108 {
 109         struct pid *old;
 110
 111         /* POSIX.2 B.3.2.2 "popen() shall ensure that any streams
 112            from previous popen() calls that remain open in the
 113            parent process are closed in the new child process. */
 114         for (old = pidlist; old; old = old->next)
 115 #ifdef _REENTRANT
 116                 (void)close(old->fd); /* don't allow a flush */
 117 #else
 118                 (void)close(fileno(old->fp)); /* don't allow a flush */
 119 #endif
 120
 121         if (type[0] == 'r') {
 122                 (void)close(pdes[0]);
 123                 if (pdes[1] != STDOUT_FILENO) {
 124                         (void)dup2(pdes[1], STDOUT_FILENO);
 125                         (void)close(pdes[1]);
 126                 }
 127                 if (type[1] == '+')
 128                         (void)dup2(STDOUT_FILENO, STDIN_FILENO);
 129         } else {
 130                 (void)close(pdes[1]);
 131                 if (pdes[0] != STDIN_FILENO) {
 132                         (void)dup2(pdes[0], STDIN_FILENO);
 133                         (void)close(pdes[0]);
 134                 }
 135         }
 136 }
 137
 138 static void
 139 pdes_parent(int *pdes, struct pid *cur, pid_t pid, const char *type)
 140 {
 141         FILE *iop;
 142
 143         /* Parent; assume fdopen can't fail. */
 144         if (*type == 'r') {
 145                 iop = fdopen(pdes[0], type);
 146 #ifdef _REENTRANT
 147                 cur->fd = pdes[0];
 148 #endif
 149                 (void)close(pdes[1]);
 150         } else {
 151                 iop = fdopen(pdes[1], type);
 152 #ifdef _REENTRANT
 153                 cur->fd = pdes[1];
 154 #endif
 155                 (void)close(pdes[0]);
 156         }
 157
 158         /* Link into list of file descriptors. */
 159         cur->fp = iop;
 160         cur->pid =  pid;
 161         cur->next = pidlist;
 162         pidlist = cur;
 163 }
 164
 165 static void
 166 pdes_error(int *pdes, struct pid *cur)
 167 {
 168         free(cur);
 169         (void)close(pdes[0]);
 170         (void)close(pdes[1]);
 171 }
 172
 173 FILE *
 174 popen(const char *cmd, const char *type)
 175 {
 176         struct pid *cur;
 177         int pdes[2], serrno;
 178         pid_t pid;
 179
 180         _DIAGASSERT(cmd != NULL);
 181         _DIAGASSERT(type != NULL);
 182
 183         if ((cur = pdes_get(pdes, &type)) == NULL)
 184                 return NULL;
 185
 186 #ifdef _REENTRANT
 187         (void)rwlock_rdlock(&pidlist_lock);
 188 #endif
 189         (void)__readlockenv();
 190         switch (pid = vfork()) {
 191         case -1:                        /* Error. */
 192                 serrno = errno;
 193                 (void)__unlockenv();
 194 #ifdef _REENTRANT
 195                 (void)rwlock_unlock(&pidlist_lock);
 196 #endif
 197                 pdes_error(pdes, cur);
 198                 errno = serrno;
 199                 return NULL;
 200                 /* NOTREACHED */
 201         case 0:                         /* Child. */
 202                 pdes_child(pdes, type);
 203                 execl(_PATH_BSHELL, "sh", "-c", cmd, NULL);
 204                 _exit(127);
 205                 /* NOTREACHED */
 206         }
 207         (void)__unlockenv();
 208
 209         pdes_parent(pdes, cur, pid, type);
 210
 211 #ifdef _REENTRANT
 212         (void)rwlock_unlock(&pidlist_lock);
 213 #endif
 214
 215         return cur->fp;
 216 }
 217
 218 FILE *
 219 popenve(const char *cmd, char *const *argv, char *const *envp, const char *type)
 220 {
 221         struct pid *cur;
 222         int pdes[2], serrno;
 223         pid_t pid;
 224
 225         _DIAGASSERT(cmd != NULL);
 226         _DIAGASSERT(type != NULL);
 227
 228         if ((cur = pdes_get(pdes, &type)) == NULL)
 229                 return NULL;
 230
 231 #ifdef _REENTRANT
 232         (void)rwlock_rdlock(&pidlist_lock);
 233 #endif
 234         switch (pid = vfork()) {
 235         case -1:                        /* Error. */
 236                 serrno = errno;
 237 #ifdef _REENTRANT
 238                 (void)rwlock_unlock(&pidlist_lock);
 239 #endif
 240                 pdes_error(pdes, cur);
 241                 errno = serrno;
 242                 return NULL;
 243                 /* NOTREACHED */
 244         case 0:                         /* Child. */
 245                 pdes_child(pdes, type);
 246                 execve(cmd, argv, envp);
 247                 _exit(127);
 248                 /* NOTREACHED */
 249         }
 250
 251         pdes_parent(pdes, cur, pid, type);
 252
 253 #ifdef _REENTRANT
 254         (void)rwlock_unlock(&pidlist_lock);
 255 #endif
 256
 257         return cur->fp;
 258 }
 259
 260 /*
 261  * pclose --
 262  *      Pclose returns -1 if stream is not associated with a `popened' command,
 263  *      if already `pclosed', or waitpid returns an error.
 264  */
 265 int
 266 pclose(FILE *iop)
 267 {
 268         struct pid *cur, *last;
 269         int pstat;
 270         pid_t pid;
 271
 272         _DIAGASSERT(iop != NULL);
 273
 274 #ifdef _REENTRANT
 275         rwlock_wrlock(&pidlist_lock);
 276 #endif
 277
 278         /* Find the appropriate file pointer. */
 279         for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
 280                 if (cur->fp == iop)
 281                         break;
 282         if (cur == NULL) {
 283 #ifdef _REENTRANT
 284                 (void)rwlock_unlock(&pidlist_lock);
 285 #endif
 286                 errno = ESRCH;
 287                 return -1;
 288         }
 289
 290         (void)fclose(iop);
 291
 292         /* Remove the entry from the linked list. */
 293         if (last == NULL)
 294                 pidlist = cur->next;
 295         else
 296                 last->next = cur->next;
 297
 298 #ifdef _REENTRANT
 299         (void)rwlock_unlock(&pidlist_lock);
 300 #endif
 301
 302         do {
 303                 pid = waitpid(cur->pid, &pstat, 0);
 304         } while (pid == -1 && errno == EINTR);
 305
 306         free(cur);
 307
 308         return pid == -1 ? -1 : pstat;
 309 }