1 /* vi: set sw=4 ts=4: */
3 * simple inotify daemon
4 * reports filesystem changes via userspace agent
6 * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
8 * Licensed under GPLv2, see file LICENSE in this tarball for details.
13 * # inotifyd /user/space/agent dir/or/file/being/watched[:mask] ...
15 * When a filesystem event matching the specified mask is occured on specified file (or directory)
16 * a userspace agent is spawned and given the following parameters:
18 * $2. file (or directory) name
19 * $3. name of subfile (if any), in case of watching a directory
21 * E.g. inotifyd ./dev-watcher /dev:n
23 * ./dev-watcher can be, say:
25 * echo "We have new device in here! Hello, $3!"
27 * See below for mask names explanation.
31 #include <sys/inotify.h>
33 static const char mask_names[] ALIGN1 =
34 "a" // 0x00000001 File was accessed
35 "c" // 0x00000002 File was modified
36 "e" // 0x00000004 Metadata changed
37 "w" // 0x00000008 Writtable file was closed
38 "0" // 0x00000010 Unwrittable file closed
39 "r" // 0x00000020 File was opened
40 "m" // 0x00000040 File was moved from X
41 "y" // 0x00000080 File was moved to Y
42 "n" // 0x00000100 Subfile was created
43 "d" // 0x00000200 Subfile was deleted
44 "D" // 0x00000400 Self was deleted
45 "M" // 0x00000800 Self was moved
48 extern int inotify_init(void);
49 extern int inotify_add_watch(int fd, const char *path, uint32_t mask);
51 int inotifyd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
52 int inotifyd_main(int argc UNUSED_PARAM, char **argv)
55 unsigned mask = IN_ALL_EVENTS; // assume we want all events
57 char **watched = ++argv; // watched name list
58 const char *args[] = { *argv, NULL, NULL, NULL, NULL };
60 // sanity check: agent and at least one watch must be given
65 pfd.fd = inotify_init();
67 bb_perror_msg_and_die("no kernel support");
72 char *masks = strchr(path, ':');
73 // if mask is specified ->
75 *masks = '\0'; // split path and mask
76 // convert mask names to mask bitset
79 int i = strchr(mask_names, *masks) - mask_names;
86 n = inotify_add_watch(pfd.fd, path, mask);
88 bb_perror_msg_and_die("add watch (%s) failed", path);
89 //bb_error_msg("added %d [%s]:%4X", n, path, mask);
93 bb_signals(BB_FATAL_SIGS, record_signo);
100 struct inotify_event *ie;
105 n = poll(&pfd, 1, -1);
106 // Signal interrupted us?
107 if (n < 0 && errno == EINTR)
109 // Under Linux, above if() is not necessary.
110 // Non-fatal signals, e.g. SIGCHLD, when set to SIG_DFL,
111 // are not interrupting poll().
112 // Thus we can just break if n <= 0 (see below),
113 // because EINTR will happen only on SIGTERM et al.
114 // But this might be not true under other Unixes,
115 // and is generally way too subtle to depend on.
116 if (n <= 0) // strange error?
119 // read out all pending events
120 xioctl(pfd.fd, FIONREAD, &len);
121 #define eventbuf bb_common_bufsiz1
122 ie = buf = (len <= sizeof(eventbuf)) ? eventbuf : xmalloc(len);
123 len = full_read(pfd.fd, buf, len);
124 // process events. N.B. events may vary in length
127 char events[sizeof(mask_names)];
129 unsigned m = ie->mask;
131 for (i = 0; i < sizeof(mask_names)-1; ++i, m >>= 1) {
133 *s++ = mask_names[i];
136 //bb_error_msg("exec %s %08X\t%s\t%s\t%s", agent,
137 // ie->mask, events, watched[ie->wd], ie->len ? ie->name : "");
139 args[2] = watched[ie->wd];
140 args[3] = ie->len ? ie->name : NULL;
141 wait4pid(xspawn((char **)args));
143 i = sizeof(struct inotify_event) + ie->len;
145 ie = (void*)((char*)ie + i);