Contents of /trunk/mkinitrd-magellan/busybox/miscutils/inotifyd.c
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Wed Aug 18 21:56:57 2010 UTC (14 years, 1 month ago) by niro
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Wed Aug 18 21:56:57 2010 UTC (14 years, 1 month ago) by niro
File MIME type: text/plain
File size: 4891 byte(s)
-updated to busybox-1.17.1
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 Writable file was closed |
38 | "0" // 0x00000010 Unwritable 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 | "\0" // 0x00001000 (unused) |
47 | // Kernel events, always reported: |
48 | "u" // 0x00002000 Backing fs was unmounted |
49 | "o" // 0x00004000 Event queued overflowed |
50 | "x" // 0x00008000 File is no longer watched (usually deleted) |
51 | ; |
52 | enum { |
53 | MASK_BITS = sizeof(mask_names) - 1 |
54 | }; |
55 | |
56 | int inotifyd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
57 | int inotifyd_main(int argc, char **argv) |
58 | { |
59 | int n; |
60 | unsigned mask; |
61 | struct pollfd pfd; |
62 | char **watches; // names of files being watched |
63 | const char *args[5]; |
64 | |
65 | // sanity check: agent and at least one watch must be given |
66 | if (!argv[1] || !argv[2]) |
67 | bb_show_usage(); |
68 | |
69 | argv++; |
70 | // inotify_add_watch will number watched files |
71 | // starting from 1, thus watches[0] is unimportant, |
72 | // and 1st file name is watches[1]. |
73 | watches = argv; |
74 | args[0] = *argv; |
75 | args[4] = NULL; |
76 | argc -= 2; // number of files we watch |
77 | |
78 | // open inotify |
79 | pfd.fd = inotify_init(); |
80 | if (pfd.fd < 0) |
81 | bb_perror_msg_and_die("no kernel support"); |
82 | |
83 | // setup watches |
84 | while (*++argv) { |
85 | char *path = *argv; |
86 | char *masks = strchr(path, ':'); |
87 | |
88 | mask = 0x0fff; // assuming we want all non-kernel events |
89 | // if mask is specified -> |
90 | if (masks) { |
91 | *masks = '\0'; // split path and mask |
92 | // convert mask names to mask bitset |
93 | mask = 0; |
94 | while (*++masks) { |
95 | const char *found; |
96 | found = memchr(mask_names, *masks, MASK_BITS); |
97 | if (found) |
98 | mask |= (1 << (found - mask_names)); |
99 | } |
100 | } |
101 | // add watch |
102 | n = inotify_add_watch(pfd.fd, path, mask); |
103 | if (n < 0) |
104 | bb_perror_msg_and_die("add watch (%s) failed", path); |
105 | //bb_error_msg("added %d [%s]:%4X", n, path, mask); |
106 | } |
107 | |
108 | // setup signals |
109 | bb_signals(BB_FATAL_SIGS, record_signo); |
110 | |
111 | // do watch |
112 | pfd.events = POLLIN; |
113 | while (1) { |
114 | int len; |
115 | void *buf; |
116 | struct inotify_event *ie; |
117 | again: |
118 | if (bb_got_signal) |
119 | break; |
120 | n = poll(&pfd, 1, -1); |
121 | // Signal interrupted us? |
122 | if (n < 0 && errno == EINTR) |
123 | goto again; |
124 | // Under Linux, above if() is not necessary. |
125 | // Non-fatal signals, e.g. SIGCHLD, when set to SIG_DFL, |
126 | // are not interrupting poll(). |
127 | // Thus we can just break if n <= 0 (see below), |
128 | // because EINTR will happen only on SIGTERM et al. |
129 | // But this might be not true under other Unixes, |
130 | // and is generally way too subtle to depend on. |
131 | if (n <= 0) // strange error? |
132 | break; |
133 | |
134 | // read out all pending events |
135 | // (NB: len must be int, not ssize_t or long!) |
136 | xioctl(pfd.fd, FIONREAD, &len); |
137 | #define eventbuf bb_common_bufsiz1 |
138 | ie = buf = (len <= sizeof(eventbuf)) ? eventbuf : xmalloc(len); |
139 | len = full_read(pfd.fd, buf, len); |
140 | // process events. N.B. events may vary in length |
141 | while (len > 0) { |
142 | int i; |
143 | // cache relevant events mask |
144 | unsigned m = ie->mask & ((1 << MASK_BITS) - 1); |
145 | if (m) { |
146 | char events[MASK_BITS + 1]; |
147 | char *s = events; |
148 | for (i = 0; i < MASK_BITS; ++i, m >>= 1) { |
149 | if ((m & 1) && (mask_names[i] != '\0')) |
150 | *s++ = mask_names[i]; |
151 | } |
152 | *s = '\0'; |
153 | // bb_error_msg("exec %s %08X\t%s\t%s\t%s", args[0], |
154 | // ie->mask, events, watches[ie->wd], ie->len ? ie->name : ""); |
155 | args[1] = events; |
156 | args[2] = watches[ie->wd]; |
157 | args[3] = ie->len ? ie->name : NULL; |
158 | spawn_and_wait((char **)args); |
159 | // we are done if all files got final x event |
160 | if (ie->mask & 0x8000) { |
161 | if (--argc <= 0) |
162 | goto done; |
163 | inotify_rm_watch(pfd.fd, ie->wd); |
164 | } |
165 | } |
166 | // next event |
167 | i = sizeof(struct inotify_event) + ie->len; |
168 | len -= i; |
169 | ie = (void*)((char*)ie + i); |
170 | } |
171 | if (eventbuf != buf) |
172 | free(buf); |
173 | } // while (1) |
174 | done: |
175 | return bb_got_signal; |
176 | } |