1 /* $NetBSD: filemon_dev.c,v 1.9 2022/03/04 23:17:16 sjg 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 #ifndef MAKE_ATTR_UNUSED
50 #define MAKE_ATTR_UNUSED __attribute__((__unused__))
51 #endif
52
53 struct filemon {
54 int fd;
55 };
56
57 const char *
filemon_path(void)58 filemon_path(void)
59 {
60
61 return _PATH_FILEMON;
62 }
63
64 struct filemon *
filemon_open(void)65 filemon_open(void)
66 {
67 struct filemon *F;
68 unsigned i;
69 int error;
70
71 /* Allocate and zero a struct filemon object. */
72 F = calloc(1, sizeof *F);
73 if (F == NULL)
74 return NULL;
75
76 /* Try opening /dev/filemon, up to six times (cargo cult!). */
77 for (i = 0; (F->fd = open(_PATH_FILEMON, O_RDWR|O_CLOEXEC)) == -1; i++) {
78 if (i == 5) {
79 error = errno;
80 goto fail0;
81 }
82 }
83
84 /* Success! */
85 return F;
86
87 fail0: free(F);
88 errno = error;
89 return NULL;
90 }
91
92 int
filemon_setfd(struct filemon * F,int fd)93 filemon_setfd(struct filemon *F, int fd)
94 {
95
96 /* Point the kernel at this file descriptor. */
97 if (ioctl(F->fd, FILEMON_SET_FD, &fd) == -1)
98 return -1;
99
100 /* No need for it in userland any more; close it. */
101 (void)close(fd);
102
103 /* Success! */
104 return 0;
105 }
106
107 void
filemon_setpid_parent(struct filemon * F MAKE_ATTR_UNUSED,pid_t pid MAKE_ATTR_UNUSED)108 filemon_setpid_parent(struct filemon *F MAKE_ATTR_UNUSED, pid_t pid MAKE_ATTR_UNUSED)
109 {
110 /* Nothing to do! */
111 }
112
113 int
filemon_setpid_child(const struct filemon * F,pid_t pid)114 filemon_setpid_child(const struct filemon *F, pid_t pid)
115 {
116
117 /* Just pass it on to the kernel. */
118 return ioctl(F->fd, FILEMON_SET_PID, &pid);
119 }
120
121 int
filemon_close(struct filemon * F)122 filemon_close(struct filemon *F)
123 {
124 int error = 0;
125
126 /* Close the filemon device fd. */
127 if (close(F->fd) == -1 && error == 0)
128 error = errno;
129
130 /* Free the filemon descriptor. */
131 free(F);
132
133 /* Set errno and return -1 if anything went wrong. */
134 if (error != 0) {
135 errno = error;
136 return -1;
137 }
138
139 /* Success! */
140 return 0;
141 }
142
143 int
filemon_readfd(const struct filemon * F MAKE_ATTR_UNUSED)144 filemon_readfd(const struct filemon *F MAKE_ATTR_UNUSED)
145 {
146
147 return -1;
148 }
149
150 int
filemon_process(struct filemon * F MAKE_ATTR_UNUSED)151 filemon_process(struct filemon *F MAKE_ATTR_UNUSED)
152 {
153
154 return 0;
155 }
156