153 lines
3.8 KiB
C
153 lines
3.8 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* simple inotify daemon
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* reports filesystem changes via userspace agent
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*
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* Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
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*
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* Licensed under GPLv2, see file LICENSE in this tarball for details.
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*/
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/*
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* Use as follows:
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* # inotifyd /user/space/agent dir/or/file/being/watched[:mask] ...
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*
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* When a filesystem event matching the specified mask is occured on specified file (or directory)
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* a userspace agent is spawned and given the following parameters:
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* $1. actual event(s)
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* $2. file (or directory) name
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* $3. name of subfile (if any), in case of watching a directory
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*
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* E.g. inotifyd ./dev-watcher /dev:n
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*
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* ./dev-watcher can be, say:
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* #!/bin/sh
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* echo "We have new device in here! Hello, $3!"
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*
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* See below for mask names explanation.
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*/
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#include "libbb.h"
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#include <linux/inotify.h>
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static volatile smallint signalled;
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static void signal_handler(int signo)
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{
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signalled = signo;
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}
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static const char mask_names[] ALIGN1 =
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"a" // 0x00000001 File was accessed
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"c" // 0x00000002 File was modified
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"e" // 0x00000004 Metadata changed
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"w" // 0x00000008 Writtable file was closed
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"0" // 0x00000010 Unwrittable file closed
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"r" // 0x00000020 File was opened
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"m" // 0x00000040 File was moved from X
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"y" // 0x00000080 File was moved to Y
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"n" // 0x00000100 Subfile was created
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"d" // 0x00000200 Subfile was deleted
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"D" // 0x00000400 Self was deleted
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"M" // 0x00000800 Self was moved
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;
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extern int inotify_init(void);
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extern int inotify_add_watch(int fd, const char *path, uint32_t mask);
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int inotifyd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int inotifyd_main(int argc UNUSED_PARAM, char **argv)
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{
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unsigned mask = IN_ALL_EVENTS; // assume we want all events
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struct pollfd pfd;
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char **watched = ++argv; // watched name list
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const char *args[] = { *argv, NULL, NULL, NULL, NULL };
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// sanity check: agent and at least one watch must be given
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if (!argv[1])
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bb_show_usage();
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// open inotify
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pfd.fd = inotify_init();
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if (pfd.fd < 0)
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bb_perror_msg_and_die("no kernel support");
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// setup watched
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while (*++argv) {
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char *path = *argv;
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char *masks = strchr(path, ':');
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int wd; // watch descriptor
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// if mask is specified ->
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if (masks) {
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*masks = '\0'; // split path and mask
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// convert mask names to mask bitset
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mask = 0;
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while (*++masks) {
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int i = strchr(mask_names, *masks) - mask_names;
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if (i >= 0) {
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mask |= (1 << i);
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}
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}
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}
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// add watch
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wd = inotify_add_watch(pfd.fd, path, mask);
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if (wd < 0) {
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bb_perror_msg_and_die("add watch (%s) failed", path);
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// } else {
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// bb_error_msg("added %d [%s]:%4X", wd, path, mask);
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}
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}
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// setup signals
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bb_signals(0
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+ (1 << SIGHUP)
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+ (1 << SIGINT)
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+ (1 << SIGTERM)
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+ (1 << SIGPIPE)
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, signal_handler);
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// do watch
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// pfd.fd = fd;
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pfd.events = POLLIN;
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while (!signalled && poll(&pfd, 1, -1) > 0) {
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ssize_t len;
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void *buf;
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struct inotify_event *ie;
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// read out all pending events
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xioctl(pfd.fd, FIONREAD, &len);
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#define eventbuf bb_common_bufsiz1
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ie = buf = (len <= sizeof(eventbuf)) ? eventbuf : xmalloc(len);
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len = full_read(pfd.fd, buf, len);
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// process events. N.B. events may vary in length
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while (len > 0) {
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int i;
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char events[12];
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char *s = events;
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unsigned m = ie->mask;
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for (i = 0; i < 12; ++i, m >>= 1) {
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if (m & 1) {
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*s++ = mask_names[i];
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}
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}
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*s = '\0';
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// bb_error_msg("exec %s %08X\t%s\t%s\t%s", agent, ie->mask, events, watched[ie->wd], ie->len ? ie->name : "");
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args[1] = events;
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args[2] = watched[ie->wd];
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args[3] = ie->len ? ie->name : NULL;
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xspawn((char **)args);
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// next event
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i = sizeof(struct inotify_event) + ie->len;
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len -= i;
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ie = (void*)((char*)ie + i);
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}
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if (eventbuf != buf)
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free(buf);
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}
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return EXIT_SUCCESS;
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}
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