usr.sbin/autofs/popen.c

   1 /*
   2  * Copyright (c) 1988, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Copyright (c) 2014 The FreeBSD Foundation
   5  * 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  * Portions of this software were developed by Edward Tomasz Napierala
  11  * under sponsorship from the FreeBSD Foundation.
  12  *
  13  * Redistribution and use in source and binary forms, with or without
  14  * modification, are permitted provided that the following conditions
  15  * are met:
  16  * 1. Redistributions of source code must retain the above copyright
  17  *    notice, this list of conditions and the following disclaimer.
  18  * 2. Redistributions in binary form must reproduce the above copyright
  19  *    notice, this list of conditions and the following disclaimer in the
  20  *    documentation and/or other materials provided with the distribution.
  21  * 4. Neither the name of the University nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  *
  37  */
  38
  39 #include <sys/cdefs.h>
  40 __FBSDID("$FreeBSD$");
  41
  42 #include <sys/param.h>
  43 #include <sys/queue.h>
  44 #include <sys/wait.h>
  45
  46 #include <errno.h>
  47 #include <fcntl.h>
  48 #include <unistd.h>
  49 #include <stdarg.h>
  50 #include <stdio.h>
  51 #include <stdlib.h>
  52 #include <string.h>
  53 #include <paths.h>
  54
  55 #include "common.h"
  56
  57 extern char **environ;
  58
  59 struct pid {
  60         SLIST_ENTRY(pid) next;
  61         FILE *outfp;
  62         pid_t pid;
  63         char *command;
  64 };
  65 static SLIST_HEAD(, pid) pidlist = SLIST_HEAD_INITIALIZER(pidlist);
  66
  67 #define ARGV_LEN        42
  68
  69 /*
  70  * Replacement for popen(3), without stdin (which we do not use), but with
  71  * stderr, proper logging, and improved command line arguments passing.
  72  * Error handling is built in - if it returns, then it succeeded.
  73  */
  74 FILE *
  75 auto_popen(const char *argv0, ...)
  76 {
  77         va_list ap;
  78         struct pid *cur, *p;
  79         pid_t pid;
  80         int error, i, nullfd, outfds[2];
  81         char *arg, *argv[ARGV_LEN], *command;
  82
  83         nullfd = open(_PATH_DEVNULL, O_RDWR, 0);
  84         if (nullfd < 0)
  85                 log_err(1, "cannot open %s", _PATH_DEVNULL);
  86
  87         error = pipe(outfds);
  88         if (error != 0)
  89                 log_err(1, "pipe");
  90
  91         cur = malloc(sizeof(struct pid));
  92         if (cur == NULL)
  93                 log_err(1, "malloc");
  94
  95         argv[0] = checked_strdup(argv0);
  96         command = argv[0];
  97
  98         va_start(ap, argv0);
  99         for (i = 1;; i++) {
 100                 if (i >= ARGV_LEN)
 101                         log_errx(1, "too many arguments to auto_popen");
 102                 arg = va_arg(ap, char *);
 103                 argv[i] = arg;
 104                 if (arg == NULL)
 105                         break;
 106
 107                 command = concat(command, ' ', arg);
 108         }
 109         va_end(ap);
 110
 111         cur->command = checked_strdup(command);
 112
 113         switch (pid = fork()) {
 114         case -1:                        /* Error. */
 115                 log_err(1, "fork");
 116                 /* NOTREACHED */
 117         case 0:                         /* Child. */
 118                 dup2(nullfd, STDIN_FILENO);
 119                 dup2(outfds[1], STDOUT_FILENO);
 120
 121                 close(nullfd);
 122                 close(outfds[0]);
 123                 close(outfds[1]);
 124
 125                 SLIST_FOREACH(p, &pidlist, next)
 126                         close(fileno(p->outfp));
 127                 execvp(argv[0], argv);
 128                 log_err(1, "failed to execute %s", argv[0]);
 129                 /* NOTREACHED */
 130         }
 131
 132         log_debugx("executing \"%s\" as pid %d", command, pid);
 133
 134         /* Parent; assume fdopen cannot fail. */
 135         cur->outfp = fdopen(outfds[0], "r");
 136         close(nullfd);
 137         close(outfds[1]);
 138
 139         /* Link into list of file descriptors. */
 140         cur->pid = pid;
 141         SLIST_INSERT_HEAD(&pidlist, cur, next);
 142
 143         return (cur->outfp);
 144 }
 145
 146 int
 147 auto_pclose(FILE *iop)
 148 {
 149         struct pid *cur, *last = NULL;
 150         int status;
 151         pid_t pid;
 152
 153         /*
 154          * Find the appropriate file pointer and remove it from the list.
 155          */
 156         SLIST_FOREACH(cur, &pidlist, next) {
 157                 if (cur->outfp == iop)
 158                         break;
 159                 last = cur;
 160         }
 161         if (cur == NULL) {
 162                 return (-1);
 163         }
 164         if (last == NULL)
 165                 SLIST_REMOVE_HEAD(&pidlist, next);
 166         else
 167                 SLIST_REMOVE_AFTER(last, next);
 168
 169         fclose(cur->outfp);
 170
 171         do {
 172                 pid = wait4(cur->pid, &status, 0, NULL);
 173         } while (pid == -1 && errno == EINTR);
 174
 175         if (WIFSIGNALED(status)) {
 176                 log_warnx("\"%s\", pid %d, terminated with signal %d",
 177                     cur->command, pid, WTERMSIG(status));
 178                 return (status);
 179         }
 180
 181         if (WEXITSTATUS(status) != 0) {
 182                 log_warnx("\"%s\", pid %d, terminated with exit status %d",
 183                     cur->command, pid, WEXITSTATUS(status));
 184                 return (status);
 185         }
 186
 187         log_debugx("\"%s\", pid %d, terminated gracefully", cur->command, pid);
 188
 189         free(cur->command);
 190         free(cur);
 191
 192         return (pid == -1 ? -1 : status);
 193 }