inotify: new applet by Vladimir Dronnikov <dronnikov AT gmail.com>

function                                             old     new   delta
inotifyd_main                                          -     453    +453
packed_usage                                       24246   24450    +204
inotify_add_watch                                      -      47     +47
inotify_init                                           -      29     +29
mask_names                                             -      13     +13
signal_handler                                       130     140     +10
applet_names                                        1859    1868      +9
applet_main                                         1132    1136      +4
applet_nameofs                                       566     568      +2
signalled                                              1       2      +1

include/applets.h

@@ -185,6 +185,7 @@ USE_IFENSLAVE(APPLET(ifenslave, _BB_DIR_SBIN, _BB_SUID_NEVER))
 USE_IFUPDOWN(APPLET_ODDNAME(ifup, ifupdown, _BB_DIR_SBIN, _BB_SUID_NEVER, ifup))
 USE_INETD(APPLET(inetd, _BB_DIR_USR_SBIN, _BB_SUID_NEVER))
 USE_INIT(APPLET(init, _BB_DIR_SBIN, _BB_SUID_NEVER))
+USE_INOTIFYD(APPLET(inotifyd, _BB_DIR_SBIN, _BB_SUID_NEVER))
 USE_INSMOD(APPLET(insmod, _BB_DIR_SBIN, _BB_SUID_NEVER))
 USE_INSTALL(APPLET(install, _BB_DIR_USR_BIN, _BB_SUID_NEVER))
 #if ENABLE_FEATURE_IP_ADDRESS \

include/usage.h

@@ -1833,6 +1833,30 @@
 "	::shutdown:/bin/umount -a -r\n" \
 "	::shutdown:/sbin/swapoff -a\n"
 
+#define inotifyd_trivial_usage \
+	"/user/space/agent dir/or/file/being/watched[:mask] ..."
+#define inotifyd_full_usage "\n\n" \
+       "Spawn userspace agent on filesystem changes." \
+     "\nWhen a filesystem event matching the mask occurs" \
+     "\non specified file/directory an userspace agent is spawned" \
+     "\nwith the parameters:" \
+     "\n1. actual event(s)" \
+     "\n2. file/directory name" \
+     "\n3. name of subfile (if any), in case of watching a directory" \
+     "\n" \
+     "\n	a	File is accessed" \
+     "\n	c	File is modified" \
+     "\n	e	Metadata changed" \
+     "\n	w	Writtable file is closed" \
+     "\n	0	Unwrittable file is closed" \
+     "\n	r	File is opened" \
+     "\n	m	File is moved from X" \
+     "\n	y	File is moved to Y" \
+     "\n	n	Subfile is created" \
+     "\n	d	Subfile is deleted" \
+     "\n	D	Self is deleted" \
+     "\n	M	Self is moved" \
+
 #define insmod_trivial_usage \
 	USE_FEATURE_2_4_MODULES("[OPTION]... ") "MODULE [symbol=value]..."
 #define insmod_full_usage "\n\n" \

miscutils/Config.in

@@ -222,6 +222,12 @@ config FBSPLASH
 	    "NN" (ASCII decimal number) - percentage to show on progress bar
 	    "exit" - well you guessed it
 
+config INOTIFYD
+	bool "inotifyd"
+	default n
+	help
+	  Simple inotify daemon. Reports filesystem changes. Requires kernel >= 2.6.13
+
 config LAST
 	bool "last"
 	default n

miscutils/Kbuild

@@ -16,6 +16,7 @@ lib-$(CONFIG_DEVFSD)      += devfsd.o
 lib-$(CONFIG_EJECT)       += eject.o
 lib-$(CONFIG_FBSPLASH)    += fbsplash.o
 lib-$(CONFIG_HDPARM)      += hdparm.o
+lib-$(CONFIG_INOTIFYD)    += inotifyd.o
 lib-$(CONFIG_FEATURE_LAST_SMALL)+= last.o
 lib-$(CONFIG_FEATURE_LAST_FANCY)+= last_fancy.o
 lib-$(CONFIG_LESS)        += less.o

miscutils/inotifyd.c

@@ -0,0 +1,152 @@
+/* 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 tarball for details.
+ */
+
+/*
+ * 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.
+ */
+
+#include "libbb.h"
+#include <linux/inotify.h>
+
+static volatile smallint signalled;
+
+static void signal_handler(int signo)
+{
+	signalled = signo;
+}
+
+static const char mask_names[] ALIGN1 =
+	"a"	// 0x00000001	File was accessed
+	"c"	// 0x00000002	File was modified
+	"e"	// 0x00000004	Metadata changed
+	"w"	// 0x00000008	Writtable file was closed
+	"0"	// 0x00000010	Unwrittable 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
+;
+
+extern int inotify_init(void);
+extern int inotify_add_watch(int fd, const char *path, uint32_t mask);
+
+int inotifyd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int inotifyd_main(int argc ATTRIBUTE_UNUSED, char **argv)
+{
+	unsigned mask = IN_ALL_EVENTS; // assume we want all events
+	struct pollfd pfd;
+	char **watched = ++argv; // watched name list
+	const char *args[] = { *argv, NULL, NULL, NULL, NULL };
+
+	// sanity check: agent and at least one watch must be given
+	if (!argv[1])
+		bb_show_usage();
+
+	// open inotify
+	pfd.fd = inotify_init();
+	if (pfd.fd < 0)
+		bb_perror_msg_and_die("no kernel support");
+
+	// setup watched
+	while (*++argv) {
+		char *path = *argv;
+		char *masks = strchr(path, ':');
+		int wd; // watch descriptor
+		// if mask is specified ->
+		if (masks) {
+			*masks = '\0'; // split path and mask
+			// convert mask names to mask bitset
+			mask = 0;
+			while (*++masks) {
+				int i = strchr(mask_names, *masks) - mask_names;
+				if (i >= 0) {
+					mask |= (1 << i);
+				}
+			}
+		}
+		// add watch
+		wd = inotify_add_watch(pfd.fd, path, mask);
+		if (wd < 0) {
+			bb_perror_msg_and_die("add watch (%s) failed", path);
+//		} else {
+//			bb_error_msg("added %d [%s]:%4X", wd, path, mask);
+		}
+	}
+
+	// setup signals
+	bb_signals(0
+		+ (1 << SIGHUP)
+		+ (1 << SIGINT)
+		+ (1 << SIGTERM)
+		+ (1 << SIGPIPE)
+		, signal_handler);
+
+	// do watch
+
+//	pfd.fd = fd;
+	pfd.events = POLLIN;
+
+	while (!signalled && poll(&pfd, 1, -1) > 0) {
+		ssize_t len;
+		void *buf;
+		struct inotify_event *ie;
+
+		// read out all pending events
+		xioctl(pfd.fd, FIONREAD, &len);
+#define eventbuf bb_common_bufsiz1
+		ie = buf = (len <= sizeof(eventbuf)) ? eventbuf : xmalloc(len);
+		len = full_read(pfd.fd, buf, len);
+		// process events. N.B. events may vary in length
+		while (len > 0) {
+			int i;
+			char events[12];
+			char *s = events;
+			unsigned m = ie->mask;
+
+			for (i = 0; i < 12; ++i, m >>= 1) {
+				if (m & 1) {
+					*s++ = mask_names[i];
+				}
+			}
+			*s = '\0';
+//			bb_error_msg("exec %s %08X\t%s\t%s\t%s", agent, ie->mask, events, watched[ie->wd], ie->len ? ie->name : "");
+			args[1] = events;
+			args[2] = watched[ie->wd];
+			args[3] = ie->len ? ie->name : NULL;
+			xspawn((char **)args);
+			// next event
+			i = sizeof(struct inotify_event) + ie->len;
+			len -= i;
+			ie = (void*)((char*)ie + i);
+		}
+		if (eventbuf != buf)
+			free(buf);
+	}
+
+	return EXIT_SUCCESS;
+}