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- /* vi: set sw=4 ts=4: */
- /*
- * simple inotify daemon
- * reports filesystem changes via userspace agent
- *
- * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
- *
- * Licensed under GPLv2, see file LICENSE in this source tree.
- */
- /*
- * Use as follows:
- * # inotifyd /user/space/agent dir/or/file/being/watched[:mask] ...
- *
- * When a filesystem event matching the specified mask is occured on specified file (or directory)
- * a userspace agent is spawned and given the following parameters:
- * $1. actual event(s)
- * $2. file (or directory) name
- * $3. name of subfile (if any), in case of watching a directory
- *
- * E.g. inotifyd ./dev-watcher /dev:n
- *
- * ./dev-watcher can be, say:
- * #!/bin/sh
- * echo "We have new device in here! Hello, $3!"
- *
- * See below for mask names explanation.
- */
- //config:config INOTIFYD
- //config: bool "inotifyd"
- //config: default n # doesn't build on Knoppix 5
- //config: help
- //config: Simple inotify daemon. Reports filesystem changes. Requires
- //config: kernel >= 2.6.13
- //applet:IF_INOTIFYD(APPLET(inotifyd, BB_DIR_SBIN, BB_SUID_DROP))
- //kbuild:lib-$(CONFIG_INOTIFYD) += inotifyd.o
- //usage:#define inotifyd_trivial_usage
- //usage: "PROG FILE1[:MASK]..."
- //usage:#define inotifyd_full_usage "\n\n"
- //usage: "Run PROG on filesystem changes."
- //usage: "\nWhen a filesystem event matching MASK occurs on FILEn,"
- //usage: "\nPROG ACTUAL_EVENTS FILEn [SUBFILE] is run."
- //usage: "\nIf PROG is -, events are sent to stdout."
- //usage: "\nEvents:"
- //usage: "\n a File is accessed"
- //usage: "\n c File is modified"
- //usage: "\n e Metadata changed"
- //usage: "\n w Writable file is closed"
- //usage: "\n 0 Unwritable file is closed"
- //usage: "\n r File is opened"
- //usage: "\n D File is deleted"
- //usage: "\n M File is moved"
- //usage: "\n u Backing fs is unmounted"
- //usage: "\n o Event queue overflowed"
- //usage: "\n x File can't be watched anymore"
- //usage: "\nIf watching a directory:"
- //usage: "\n y Subfile is moved into dir"
- //usage: "\n m Subfile is moved out of dir"
- //usage: "\n n Subfile is created"
- //usage: "\n d Subfile is deleted"
- //usage: "\n"
- //usage: "\ninotifyd waits for PROG to exit."
- //usage: "\nWhen x event happens for all FILEs, inotifyd exits."
- #include "libbb.h"
- #include "common_bufsiz.h"
- #include <sys/inotify.h>
- static const char mask_names[] ALIGN1 =
- "a" // 0x00000001 File was accessed
- "c" // 0x00000002 File was modified
- "e" // 0x00000004 Metadata changed
- "w" // 0x00000008 Writable file was closed
- "0" // 0x00000010 Unwritable file closed
- "r" // 0x00000020 File was opened
- "m" // 0x00000040 File was moved from X
- "y" // 0x00000080 File was moved to Y
- "n" // 0x00000100 Subfile was created
- "d" // 0x00000200 Subfile was deleted
- "D" // 0x00000400 Self was deleted
- "M" // 0x00000800 Self was moved
- "\0" // 0x00001000 (unused)
- // Kernel events, always reported:
- "u" // 0x00002000 Backing fs was unmounted
- "o" // 0x00004000 Event queued overflowed
- "x" // 0x00008000 File is no longer watched (usually deleted)
- ;
- enum {
- MASK_BITS = sizeof(mask_names) - 1
- };
- int inotifyd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
- int inotifyd_main(int argc, char **argv)
- {
- int n;
- unsigned mask;
- struct pollfd pfd;
- char **watches; // names of files being watched
- const char *args[5];
- // sanity check: agent and at least one watch must be given
- if (!argv[1] || !argv[2])
- bb_show_usage();
- argv++;
- // inotify_add_watch will number watched files
- // starting from 1, thus watches[0] is unimportant,
- // and 1st file name is watches[1].
- watches = argv;
- args[0] = *argv;
- args[4] = NULL;
- argc -= 2; // number of files we watch
- // open inotify
- pfd.fd = inotify_init();
- if (pfd.fd < 0)
- bb_perror_msg_and_die("no kernel support");
- // setup watches
- while (*++argv) {
- char *path = *argv;
- char *masks = strchr(path, ':');
- mask = 0x0fff; // assuming we want all non-kernel events
- // if mask is specified ->
- if (masks) {
- *masks = '\0'; // split path and mask
- // convert mask names to mask bitset
- mask = 0;
- while (*++masks) {
- const char *found;
- found = memchr(mask_names, *masks, MASK_BITS);
- if (found)
- mask |= (1 << (found - mask_names));
- }
- }
- // add watch
- n = inotify_add_watch(pfd.fd, path, mask);
- if (n < 0)
- bb_perror_msg_and_die("add watch (%s) failed", path);
- //bb_error_msg("added %d [%s]:%4X", n, path, mask);
- }
- // setup signals
- bb_signals(BB_FATAL_SIGS, record_signo);
- // do watch
- pfd.events = POLLIN;
- while (1) {
- int len;
- void *buf;
- struct inotify_event *ie;
- again:
- if (bb_got_signal)
- break;
- n = poll(&pfd, 1, -1);
- // Signal interrupted us?
- if (n < 0 && errno == EINTR)
- goto again;
- // Under Linux, above if() is not necessary.
- // Non-fatal signals, e.g. SIGCHLD, when set to SIG_DFL,
- // are not interrupting poll().
- // Thus we can just break if n <= 0 (see below),
- // because EINTR will happen only on SIGTERM et al.
- // But this might be not true under other Unixes,
- // and is generally way too subtle to depend on.
- if (n <= 0) // strange error?
- break;
- // read out all pending events
- // (NB: len must be int, not ssize_t or long!)
- #define eventbuf bb_common_bufsiz1
- setup_common_bufsiz();
- xioctl(pfd.fd, FIONREAD, &len);
- ie = buf = (len <= COMMON_BUFSIZE) ? eventbuf : xmalloc(len);
- len = full_read(pfd.fd, buf, len);
- // process events. N.B. events may vary in length
- while (len > 0) {
- int i;
- // cache relevant events mask
- unsigned m = ie->mask & ((1 << MASK_BITS) - 1);
- if (m) {
- char events[MASK_BITS + 1];
- char *s = events;
- for (i = 0; i < MASK_BITS; ++i, m >>= 1) {
- if ((m & 1) && (mask_names[i] != '\0'))
- *s++ = mask_names[i];
- }
- *s = '\0';
- if (LONE_CHAR(args[0], '-')) {
- /* "inotifyd - FILE": built-in echo */
- printf(ie->len ? "%s\t%s\t%s\n" : "%s\t%s\n", events,
- watches[ie->wd],
- ie->name);
- fflush(stdout);
- } else {
- // bb_error_msg("exec %s %08X\t%s\t%s\t%s", args[0],
- // ie->mask, events, watches[ie->wd], ie->len ? ie->name : "");
- args[1] = events;
- args[2] = watches[ie->wd];
- args[3] = ie->len ? ie->name : NULL;
- spawn_and_wait((char **)args);
- }
- // we are done if all files got final x event
- if (ie->mask & 0x8000) {
- if (--argc <= 0)
- goto done;
- inotify_rm_watch(pfd.fd, ie->wd);
- }
- }
- // next event
- i = sizeof(struct inotify_event) + ie->len;
- len -= i;
- ie = (void*)((char*)ie + i);
- }
- if (eventbuf != buf)
- free(buf);
- } // while (1)
- done:
- return bb_got_signal;
- }
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