Contents of /tags/mkinitrd-6_1_5/busybox/miscutils/inotifyd.c
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Wed Aug 5 17:52:52 2009 UTC (15 years, 1 month ago) by niro
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Wed Aug 5 17:52:52 2009 UTC (15 years, 1 month ago) by niro
File MIME type: text/plain
File size: 4151 byte(s)
tagged 'mkinitrd-6_1_5'
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * simple inotify daemon |
4 | * reports filesystem changes via userspace agent |
5 | * |
6 | * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com> |
7 | * |
8 | * Licensed under GPLv2, see file LICENSE in this tarball for details. |
9 | */ |
10 | |
11 | /* |
12 | * Use as follows: |
13 | * # inotifyd /user/space/agent dir/or/file/being/watched[:mask] ... |
14 | * |
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: |
17 | * $1. actual event(s) |
18 | * $2. file (or directory) name |
19 | * $3. name of subfile (if any), in case of watching a directory |
20 | * |
21 | * E.g. inotifyd ./dev-watcher /dev:n |
22 | * |
23 | * ./dev-watcher can be, say: |
24 | * #!/bin/sh |
25 | * echo "We have new device in here! Hello, $3!" |
26 | * |
27 | * See below for mask names explanation. |
28 | */ |
29 | |
30 | #include "libbb.h" |
31 | #include <sys/inotify.h> |
32 | |
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 |
46 | ; |
47 | |
48 | extern int inotify_init(void); |
49 | extern int inotify_add_watch(int fd, const char *path, uint32_t mask); |
50 | |
51 | int inotifyd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
52 | int inotifyd_main(int argc UNUSED_PARAM, char **argv) |
53 | { |
54 | int n; |
55 | unsigned mask = IN_ALL_EVENTS; // assume we want all events |
56 | struct pollfd pfd; |
57 | char **watched = ++argv; // watched name list |
58 | const char *args[] = { *argv, NULL, NULL, NULL, NULL }; |
59 | |
60 | // sanity check: agent and at least one watch must be given |
61 | if (!argv[1]) |
62 | bb_show_usage(); |
63 | |
64 | // open inotify |
65 | pfd.fd = inotify_init(); |
66 | if (pfd.fd < 0) |
67 | bb_perror_msg_and_die("no kernel support"); |
68 | |
69 | // setup watched |
70 | while (*++argv) { |
71 | char *path = *argv; |
72 | char *masks = strchr(path, ':'); |
73 | // if mask is specified -> |
74 | if (masks) { |
75 | *masks = '\0'; // split path and mask |
76 | // convert mask names to mask bitset |
77 | mask = 0; |
78 | while (*++masks) { |
79 | int i = strchr(mask_names, *masks) - mask_names; |
80 | if (i >= 0) { |
81 | mask |= (1 << i); |
82 | } |
83 | } |
84 | } |
85 | // add watch |
86 | n = inotify_add_watch(pfd.fd, path, mask); |
87 | if (n < 0) |
88 | bb_perror_msg_and_die("add watch (%s) failed", path); |
89 | //bb_error_msg("added %d [%s]:%4X", n, path, mask); |
90 | } |
91 | |
92 | // setup signals |
93 | bb_signals(BB_FATAL_SIGS, record_signo); |
94 | |
95 | // do watch |
96 | pfd.events = POLLIN; |
97 | while (1) { |
98 | ssize_t len; |
99 | void *buf; |
100 | struct inotify_event *ie; |
101 | |
102 | again: |
103 | if (bb_got_signal) |
104 | break; |
105 | n = poll(&pfd, 1, -1); |
106 | /* Signal interrupted us? */ |
107 | if (n < 0 && errno == EINTR) |
108 | goto again; |
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? |
117 | break; |
118 | |
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 |
125 | while (len > 0) { |
126 | int i; |
127 | char events[sizeof(mask_names)]; |
128 | char *s = events; |
129 | unsigned m = ie->mask; |
130 | |
131 | for (i = 0; i < sizeof(mask_names)-1; ++i, m >>= 1) { |
132 | if (m & 1) |
133 | *s++ = mask_names[i]; |
134 | } |
135 | *s = '\0'; |
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 : ""); |
138 | args[1] = events; |
139 | args[2] = watched[ie->wd]; |
140 | args[3] = ie->len ? ie->name : NULL; |
141 | wait4pid(xspawn((char **)args)); |
142 | // next event |
143 | i = sizeof(struct inotify_event) + ie->len; |
144 | len -= i; |
145 | ie = (void*)((char*)ie + i); |
146 | } |
147 | if (eventbuf != buf) |
148 | free(buf); |
149 | } |
150 | |
151 | return EXIT_SUCCESS; |
152 | } |