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