blob: 7a1a6a2e533442bb77e5e642206169a86c62d6a3
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 source tree. |
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 | //usage:#define inotifyd_trivial_usage |
31 | //usage: "PROG FILE1[:MASK]..." |
32 | //usage:#define inotifyd_full_usage "\n\n" |
33 | //usage: "Run PROG on filesystem changes." |
34 | //usage: "\nWhen a filesystem event matching MASK occurs on FILEn," |
35 | //usage: "\nPROG ACTUAL_EVENTS FILEn [SUBFILE] is run." |
36 | //usage: "\nIf PROG is -, events are sent to stdout." |
37 | //usage: "\nEvents:" |
38 | //usage: "\n a File is accessed" |
39 | //usage: "\n c File is modified" |
40 | //usage: "\n e Metadata changed" |
41 | //usage: "\n w Writable file is closed" |
42 | //usage: "\n 0 Unwritable file is closed" |
43 | //usage: "\n r File is opened" |
44 | //usage: "\n D File is deleted" |
45 | //usage: "\n M File is moved" |
46 | //usage: "\n u Backing fs is unmounted" |
47 | //usage: "\n o Event queue overflowed" |
48 | //usage: "\n x File can't be watched anymore" |
49 | //usage: "\nIf watching a directory:" |
50 | //usage: "\n m Subfile is moved into dir" |
51 | //usage: "\n y Subfile is moved out of dir" |
52 | //usage: "\n n Subfile is created" |
53 | //usage: "\n d Subfile is deleted" |
54 | //usage: "\n" |
55 | //usage: "\ninotifyd waits for PROG to exit." |
56 | //usage: "\nWhen x event happens for all FILEs, inotifyd exits." |
57 | |
58 | #include "libbb.h" |
59 | #include <sys/inotify.h> |
60 | |
61 | static const char mask_names[] ALIGN1 = |
62 | "a" // 0x00000001 File was accessed |
63 | "c" // 0x00000002 File was modified |
64 | "e" // 0x00000004 Metadata changed |
65 | "w" // 0x00000008 Writable file was closed |
66 | "0" // 0x00000010 Unwritable file closed |
67 | "r" // 0x00000020 File was opened |
68 | "m" // 0x00000040 File was moved from X |
69 | "y" // 0x00000080 File was moved to Y |
70 | "n" // 0x00000100 Subfile was created |
71 | "d" // 0x00000200 Subfile was deleted |
72 | "D" // 0x00000400 Self was deleted |
73 | "M" // 0x00000800 Self was moved |
74 | "\0" // 0x00001000 (unused) |
75 | // Kernel events, always reported: |
76 | "u" // 0x00002000 Backing fs was unmounted |
77 | "o" // 0x00004000 Event queued overflowed |
78 | "x" // 0x00008000 File is no longer watched (usually deleted) |
79 | ; |
80 | enum { |
81 | MASK_BITS = sizeof(mask_names) - 1 |
82 | }; |
83 | |
84 | int inotifyd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
85 | int inotifyd_main(int argc, char **argv) |
86 | { |
87 | int n; |
88 | unsigned mask; |
89 | struct pollfd pfd; |
90 | char **watches; // names of files being watched |
91 | const char *args[5]; |
92 | |
93 | // sanity check: agent and at least one watch must be given |
94 | if (!argv[1] || !argv[2]) |
95 | bb_show_usage(); |
96 | |
97 | argv++; |
98 | // inotify_add_watch will number watched files |
99 | // starting from 1, thus watches[0] is unimportant, |
100 | // and 1st file name is watches[1]. |
101 | watches = argv; |
102 | args[0] = *argv; |
103 | args[4] = NULL; |
104 | argc -= 2; // number of files we watch |
105 | |
106 | // open inotify |
107 | pfd.fd = inotify_init(); |
108 | if (pfd.fd < 0) |
109 | bb_perror_msg_and_die("no kernel support"); |
110 | |
111 | // setup watches |
112 | while (*++argv) { |
113 | char *path = *argv; |
114 | char *masks = strchr(path, ':'); |
115 | |
116 | mask = 0x0fff; // assuming we want all non-kernel events |
117 | // if mask is specified -> |
118 | if (masks) { |
119 | *masks = '\0'; // split path and mask |
120 | // convert mask names to mask bitset |
121 | mask = 0; |
122 | while (*++masks) { |
123 | const char *found; |
124 | found = memchr(mask_names, *masks, MASK_BITS); |
125 | if (found) |
126 | mask |= (1 << (found - mask_names)); |
127 | } |
128 | } |
129 | // add watch |
130 | n = inotify_add_watch(pfd.fd, path, mask); |
131 | if (n < 0) |
132 | bb_perror_msg_and_die("add watch (%s) failed", path); |
133 | //bb_error_msg("added %d [%s]:%4X", n, path, mask); |
134 | } |
135 | |
136 | // setup signals |
137 | bb_signals(BB_FATAL_SIGS, record_signo); |
138 | |
139 | // do watch |
140 | pfd.events = POLLIN; |
141 | while (1) { |
142 | int len; |
143 | void *buf; |
144 | struct inotify_event *ie; |
145 | again: |
146 | if (bb_got_signal) |
147 | break; |
148 | n = poll(&pfd, 1, -1); |
149 | // Signal interrupted us? |
150 | if (n < 0 && errno == EINTR) |
151 | goto again; |
152 | // Under Linux, above if() is not necessary. |
153 | // Non-fatal signals, e.g. SIGCHLD, when set to SIG_DFL, |
154 | // are not interrupting poll(). |
155 | // Thus we can just break if n <= 0 (see below), |
156 | // because EINTR will happen only on SIGTERM et al. |
157 | // But this might be not true under other Unixes, |
158 | // and is generally way too subtle to depend on. |
159 | if (n <= 0) // strange error? |
160 | break; |
161 | |
162 | // read out all pending events |
163 | // (NB: len must be int, not ssize_t or long!) |
164 | xioctl(pfd.fd, FIONREAD, &len); |
165 | #define eventbuf bb_common_bufsiz1 |
166 | ie = buf = (len <= sizeof(eventbuf)) ? eventbuf : xmalloc(len); |
167 | len = full_read(pfd.fd, buf, len); |
168 | // process events. N.B. events may vary in length |
169 | while (len > 0) { |
170 | int i; |
171 | // cache relevant events mask |
172 | unsigned m = ie->mask & ((1 << MASK_BITS) - 1); |
173 | if (m) { |
174 | char events[MASK_BITS + 1]; |
175 | char *s = events; |
176 | for (i = 0; i < MASK_BITS; ++i, m >>= 1) { |
177 | if ((m & 1) && (mask_names[i] != '\0')) |
178 | *s++ = mask_names[i]; |
179 | } |
180 | *s = '\0'; |
181 | if (LONE_CHAR(args[0], '-')) { |
182 | /* "inotifyd - FILE": built-in echo */ |
183 | printf(ie->len ? "%s\t%s\t%s\n" : "%s\t%s\n", events, |
184 | watches[ie->wd], |
185 | ie->name); |
186 | fflush(stdout); |
187 | } else { |
188 | // bb_error_msg("exec %s %08X\t%s\t%s\t%s", args[0], |
189 | // ie->mask, events, watches[ie->wd], ie->len ? ie->name : ""); |
190 | args[1] = events; |
191 | args[2] = watches[ie->wd]; |
192 | args[3] = ie->len ? ie->name : NULL; |
193 | spawn_and_wait((char **)args); |
194 | } |
195 | // we are done if all files got final x event |
196 | if (ie->mask & 0x8000) { |
197 | if (--argc <= 0) |
198 | goto done; |
199 | inotify_rm_watch(pfd.fd, ie->wd); |
200 | } |
201 | } |
202 | // next event |
203 | i = sizeof(struct inotify_event) + ie->len; |
204 | len -= i; |
205 | ie = (void*)((char*)ie + i); |
206 | } |
207 | if (eventbuf != buf) |
208 | free(buf); |
209 | } // while (1) |
210 | done: |
211 | return bb_got_signal; |
212 | } |
213 |