usr.sbin/autofs/popen.c

   1 /*
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 1988, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  * Copyright (c) 2016 The DragonFly Project
   7  * Copyright (c) 2014 The FreeBSD Foundation
   8  * All rights reserved.
   9  *
  10  * This code is derived from software written by Ken Arnold and
  11  * published in UNIX Review, Vol. 6, No. 8.
  12  *
  13  * Portions of this software were developed by Edward Tomasz Napierala
  14  * under sponsorship from the FreeBSD Foundation.
  15  *
  16  * Redistribution and use in source and binary forms, with or without
  17  * modification, are permitted provided that the following conditions
  18  * are met:
  19  * 1. Redistributions of source code must retain the above copyright
  20  *    notice, this list of conditions and the following disclaimer.
  21  * 2. Redistributions in binary form must reproduce the above copyright
  22  *    notice, this list of conditions and the following disclaimer in the
  23  *    documentation and/or other materials provided with the distribution.
  24  * 3. Neither the name of the University nor the names of its contributors
  25  *    may be used to endorse or promote products derived from this software
  26  *    without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  38  * SUCH DAMAGE.
  39  *
  40  */
  41
  42 #include <sys/types.h>
  43 #include <sys/queue.h>
  44 #include <sys/wait.h>
  45 #include <errno.h>
  46 #include <fcntl.h>
  47 #include <paths.h>
  48 #include <stdarg.h>
  49 #include <stdio.h>
  50 #include <stdlib.h>
  51 #include <string.h>
  52 #include <unistd.h>
  53
  54 #include "common.h"
  55
  56 extern char **environ;
  57
  58 struct pid {
  59         SLIST_ENTRY(pid) next;
  60         FILE *outfp;
  61         pid_t pid;
  62         char *command;
  63 };
  64 static SLIST_HEAD(, pid) pidlist = SLIST_HEAD_INITIALIZER(pidlist);
  65
  66 #define ARGV_LEN        42
  67
  68 /*
  69  * Replacement for popen(3), without stdin (which we do not use), but with
  70  * stderr, proper logging, and improved command line arguments passing.
  71  * Error handling is built in - if it returns, then it succeeded.
  72  */
  73 FILE *
  74 auto_popen(const char *argv0, ...)
  75 {
  76         va_list ap;
  77         struct pid *cur, *p;
  78         pid_t pid;
  79         int error, i, nullfd, outfds[2];
  80         char *arg, *argv[ARGV_LEN], *command;
  81
  82         nullfd = open(_PATH_DEVNULL, O_RDWR, 0);
  83         if (nullfd < 0)
  84                 log_err(1, "cannot open %s", _PATH_DEVNULL);
  85
  86         error = pipe(outfds);
  87         if (error != 0)
  88                 log_err(1, "pipe");
  89
  90         cur = malloc(sizeof(struct pid));
  91         if (cur == NULL)
  92                 log_err(1, "malloc");
  93
  94         argv[0] = checked_strdup(argv0);
  95         command = argv[0];
  96
  97         va_start(ap, argv0);
  98         for (i = 1;; i++) {
  99                 if (i >= ARGV_LEN)
 100                         log_errx(1, "too many arguments to auto_popen");
 101                 arg = va_arg(ap, char *);
 102                 argv[i] = arg;
 103                 if (arg == NULL)
 104                         break;
 105
 106                 command = concat(command, ' ', arg);
 107         }
 108         va_end(ap);
 109
 110         cur->command = checked_strdup(command);
 111
 112         switch (pid = fork()) {
 113         case -1:                        /* Error. */
 114                 log_err(1, "fork");
 115                 /* NOTREACHED */
 116         case 0:                         /* Child. */
 117                 dup2(nullfd, STDIN_FILENO);
 118                 dup2(outfds[1], STDOUT_FILENO);
 119
 120                 close(nullfd);
 121                 close(outfds[0]);
 122                 close(outfds[1]);
 123
 124                 SLIST_FOREACH(p, &pidlist, next)
 125                         close(fileno(p->outfp));
 126                 execvp(argv[0], argv);
 127                 log_err(1, "failed to execute %s", argv[0]);
 128                 /* NOTREACHED */
 129         }
 130
 131         log_debugx("executing \"%s\" as pid %d", command, pid);
 132
 133         /* Parent; assume fdopen cannot fail. */
 134         cur->outfp = fdopen(outfds[0], "r");
 135         close(nullfd);
 136         close(outfds[1]);
 137
 138         /* Link into list of file descriptors. */
 139         cur->pid = pid;
 140         SLIST_INSERT_HEAD(&pidlist, cur, next);
 141
 142         return (cur->outfp);
 143 }
 144
 145 int
 146 auto_pclose(FILE *iop)
 147 {
 148         struct pid *cur, *last = NULL;
 149         int status;
 150         pid_t pid;
 151
 152         /*
 153          * Find the appropriate file pointer and remove it from the list.
 154          */
 155         SLIST_FOREACH(cur, &pidlist, next) {
 156                 if (cur->outfp == iop)
 157                         break;
 158                 last = cur;
 159         }
 160         if (cur == NULL) {
 161                 return (-1);
 162         }
 163         if (last == NULL)
 164                 SLIST_REMOVE_HEAD(&pidlist, next);
 165         else
 166                 SLIST_REMOVE_AFTER(last, next);
 167
 168         fclose(cur->outfp);
 169
 170         do {
 171                 pid = wait4(cur->pid, &status, 0, NULL);
 172         } while (pid == -1 && errno == EINTR);
 173
 174         if (WIFSIGNALED(status)) {
 175                 log_warnx("\"%s\", pid %d, terminated with signal %d",
 176                     cur->command, pid, WTERMSIG(status));
 177                 return (status);
 178         }
 179
 180         if (WEXITSTATUS(status) != 0) {
 181                 log_warnx("\"%s\", pid %d, terminated with exit status %d",
 182                     cur->command, pid, WEXITSTATUS(status));
 183                 return (status);
 184         }
 185
 186         log_debugx("\"%s\", pid %d, terminated gracefully", cur->command, pid);
 187
 188         free(cur->command);
 189         free(cur);
 190
 191         return (pid == -1 ? -1 : status);
 192 }