/* 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 <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!) 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; // 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'; // 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; }