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filemon_dev.c revision 1.4 
      1 /*	$NetBSD: filemon_dev.c,v 1.4 2020/11/05 17:27:16 rillig Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2020 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Taylor R. Campbell.
      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  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include "filemon.h"
     33 
     34 #include <sys/ioctl.h>
     35 
     36 #include <errno.h>
     37 #include <fcntl.h>
     38 #include <stdlib.h>
     39 #include <unistd.h>
     40 
     41 #ifdef HAVE_FILEMON_H
     42 #  include <filemon.h>
     43 #endif
     44 
     45 #ifndef _PATH_FILEMON
     46 #define	_PATH_FILEMON	"/dev/filemon"
     47 #endif
     48 
     49 struct filemon {
     50 	int	fd;
     51 };
     52 
     53 const char *
     54 filemon_path(void)
     55 {
     56 
     57 	return _PATH_FILEMON;
     58 }
     59 
     60 struct filemon *
     61 filemon_open(void)
     62 {
     63 	struct filemon *F;
     64 	unsigned i;
     65 	int error;
     66 
     67 	/* Allocate and zero a struct filemon object.  */
     68 	F = calloc(1, sizeof *F);
     69 	if (F == NULL)
     70 		return NULL;
     71 
     72 	/* Try opening /dev/filemon, up to six times (cargo cult!).  */
     73 	for (i = 0; (F->fd = open(_PATH_FILEMON, O_RDWR|O_CLOEXEC)) == -1; i++) {
     74 		if (i == 5) {
     75 			error = errno;
     76 			goto fail0;
     77 		}
     78 	}
     79 
     80 	/* Success!  */
     81 	return F;
     82 
     83 fail0:	free(F);
     84 	errno = error;
     85 	return NULL;
     86 }
     87 
     88 int
     89 filemon_setfd(struct filemon *F, int fd)
     90 {
     91 
     92 	/* Point the kernel at this file descriptor.  */
     93 	if (ioctl(F->fd, FILEMON_SET_FD, &fd) == -1)
     94 		return -1;
     95 
     96 	/* No need for it in userland any more; close it.  */
     97 	(void)close(fd);
     98 
     99 	/* Success!  */
    100 	return 0;
    101 }
    102 
    103 void
    104 filemon_setpid_parent(struct filemon *F, pid_t pid)
    105 {
    106 	/* Nothing to do!  */
    107 }
    108 
    109 int
    110 filemon_setpid_child(const struct filemon *F, pid_t pid)
    111 {
    112 
    113 	/* Just pass it on to the kernel.  */
    114 	return ioctl(F->fd, FILEMON_SET_PID, &pid);
    115 }
    116 
    117 int
    118 filemon_close(struct filemon *F)
    119 {
    120 	int error = 0;
    121 
    122 	/* Close the filemon device fd.  */
    123 	if (close(F->fd) == -1 && error == 0)
    124 		error = errno;
    125 
    126 	/* Free the filemon descriptor.  */
    127 	free(F);
    128 
    129 	/* Set errno and return -1 if anything went wrong.  */
    130 	if (error) {
    131 		errno = error;
    132 		return -1;
    133 	}
    134 
    135 	/* Success!  */
    136 	return 0;
    137 }
    138 
    139 int
    140 filemon_readfd(const struct filemon *F)
    141 {
    142 
    143 	return -1;
    144 }
    145 
    146 int
    147 filemon_process(struct filemon *F)
    148 {
    149 
    150 	return 0;
    151 }
    152