225 lines
6.5 KiB
C
225 lines
6.5 KiB
C
/* 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 occurred 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, $3!"
|
|
*
|
|
* See below for mask names explanation.
|
|
*/
|
|
//config:config INOTIFYD
|
|
//config: bool "inotifyd (3.5 kb)"
|
|
//config: default n # doesn't build on Knoppix 5
|
|
//config: help
|
|
//config: Simple inotify daemon. Reports filesystem changes. Requires
|
|
//config: kernel >= 2.6.13
|
|
|
|
//applet:IF_INOTIFYD(APPLET(inotifyd, BB_DIR_SBIN, BB_SUID_DROP))
|
|
|
|
//kbuild:lib-$(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;
|
|
}
|