From bd284db142c1d3fb6e2a709678c8828c12c52466 Mon Sep 17 00:00:00 2001 From: Scott James Remnant Date: Wed, 11 Feb 2009 17:38:56 +0000 Subject: [PATCH] udevd: optionally watch device nodes with inotify This allows you to re-process the rules if the content of the device has been changed, most useful for block subsystem to cause vol_id to be run again. --- NEWS | 2 + udev/Makefile.am | 1 + udev/udev-event.c | 8 ++ udev/udev-rules.c | 12 +++ udev/udev-watch.c | 236 ++++++++++++++++++++++++++++++++++++++++++++++ udev/udev.h | 16 ++++ udev/udev.xml | 7 ++ udev/udevd.c | 84 ++++++++++++----- 8 files changed, 340 insertions(+), 26 deletions(-) create mode 100644 udev/udev-watch.c diff --git a/NEWS b/NEWS index 1737d9fa..98f4937f 100644 --- a/NEWS +++ b/NEWS @@ -1,5 +1,7 @@ udev 138 ======== +Device nodes can be watched for changes with inotify with OPTIONS="watch". If +closed after being opened for writing, a "change" uevent will occur. udev 137 ======== diff --git a/udev/Makefile.am b/udev/Makefile.am index 2d185f47..fa8279dd 100644 --- a/udev/Makefile.am +++ b/udev/Makefile.am @@ -16,6 +16,7 @@ common_files = \ udev.h \ udev-sysdeps.h \ udev-event.c \ + udev-watch.c \ udev-node.c \ udev-rules.c \ udev-util.c \ diff --git a/udev/udev-event.c b/udev/udev-event.c index e34f09cf..592da010 100644 --- a/udev/udev-event.c +++ b/udev/udev-event.c @@ -600,6 +600,14 @@ int udev_event_execute_rules(struct udev_event *event, struct udev_rules *rules) /* create new node and symlinks */ err = udev_node_add(dev, event->mode, event->uid, event->gid); + + /* watch for changes */ + if (event->inotify_watch && inotify_fd != -1) { + info(event->udev, "device will be watched for changes\n"); + udev_watch_begin(event->udev, event->dev); + } else { + udev_watch_clear(event->udev, event->dev); + } goto exit; } diff --git a/udev/udev-rules.c b/udev/udev-rules.c index f0b11aa8..3751cbb3 100644 --- a/udev/udev-rules.c +++ b/udev/udev-rules.c @@ -140,6 +140,7 @@ enum token_type { TK_A_IGNORE_DEVICE, TK_A_STRING_ESCAPE_NONE, TK_A_STRING_ESCAPE_REPLACE, + TK_A_INOTIFY_WATCH, TK_A_NUM_FAKE_PART, /* int */ TK_A_DEVLINK_PRIO, /* int */ TK_A_OWNER, /* val */ @@ -270,6 +271,7 @@ static const char *token_str(enum token_type type) [TK_A_IGNORE_DEVICE] = "A IGNORE_DEVICE", [TK_A_STRING_ESCAPE_NONE] = "A STRING_ESCAPE_NONE", [TK_A_STRING_ESCAPE_REPLACE] = "A STRING_ESCAPE_REPLACE", + [TK_A_INOTIFY_WATCH] = "A INOTIFY_WATCH", [TK_A_NUM_FAKE_PART] = "A NUM_FAKE_PART", [TK_A_DEVLINK_PRIO] = "A DEVLINK_PRIO", [TK_A_OWNER] = "A OWNER", @@ -352,6 +354,7 @@ static void dump_token(struct udev_rules *rules, struct token *token) case TK_A_IGNORE_DEVICE: case TK_A_STRING_ESCAPE_NONE: case TK_A_STRING_ESCAPE_REPLACE: + case TK_A_INOTIFY_WATCH: case TK_A_LAST_RULE: case TK_A_IGNORE_REMOVE: dbg(rules->udev, "%s\n", token_str(type)); @@ -1020,6 +1023,7 @@ static int rule_add_key(struct rule_tmp *rule_tmp, enum token_type type, case TK_A_IGNORE_DEVICE: case TK_A_STRING_ESCAPE_NONE: case TK_A_STRING_ESCAPE_REPLACE: + case TK_A_INOTIFY_WATCH: case TK_A_IGNORE_REMOVE: case TK_A_LAST_RULE: break; @@ -1512,6 +1516,11 @@ static int add_rule(struct udev_rules *rules, char *line, rule_add_key(&rule_tmp, TK_A_NUM_FAKE_PART, 0, NULL, &num); dbg(rules->udev, "creation of partition nodes requested\n"); } + pos = strstr(value, "watch"); + if (pos != NULL) { + rule_add_key(&rule_tmp, TK_A_INOTIFY_WATCH, 0, NULL, NULL); + dbg(rules->udev, "inotify watch of device requested\n"); + } continue; } err(rules->udev, "unknown key '%s' in %s:%u\n", key, filename, lineno); @@ -2244,6 +2253,9 @@ int udev_rules_apply_to_event(struct udev_rules *rules, struct udev_event *event break; udev_device_set_num_fake_partitions(event->dev, cur->key.num_fake_part); break; + case TK_A_INOTIFY_WATCH: + event->inotify_watch = 1; + break; case TK_A_DEVLINK_PRIO: udev_device_set_devlink_priority(event->dev, cur->key.devlink_prio); break; diff --git a/udev/udev-watch.c b/udev/udev-watch.c new file mode 100644 index 00000000..24df481c --- /dev/null +++ b/udev/udev-watch.c @@ -0,0 +1,236 @@ +/* + * Copyright (C) 2004-2008 Kay Sievers + * Copyright (C) 2009 Canonical Ltd. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#ifdef HAVE_INOTIFY +#include +#endif + +#include "udev.h" + +int inotify_fd = -1; + +/* inotify descriptor, will be shared with rules directory; + * set to cloexec since we need our children to be able to add + * watches for us + */ +void udev_watch_init(struct udev *udev) +{ + inotify_fd = inotify_init(); + if (inotify_fd >= 0) { + int flags; + + flags = fcntl(inotify_fd, F_GETFD); + if (flags < 0) + flags = FD_CLOEXEC; + else + flags |= FD_CLOEXEC; + fcntl(inotify_fd, F_SETFD, flags); + } else if (errno == ENOSYS) + info(udev, "unable to use inotify, udevd will not monitor rule files changes\n"); + else + err(udev, "inotify_init failed: %m\n"); +} + +/* move any old watches directory out of the way, and then restore + * the watches + */ +void udev_watch_restore(struct udev *udev) +{ + char filename[UTIL_PATH_SIZE], oldname[UTIL_PATH_SIZE]; + + if (inotify_fd < 0) + return; + + util_strlcpy(oldname, udev_get_dev_path(udev), sizeof(oldname)); + util_strlcat(oldname, "/.udev/watch.old", sizeof(oldname)); + + util_strlcpy(filename, udev_get_dev_path(udev), sizeof(filename)); + util_strlcat(filename, "/.udev/watch", sizeof(filename)); + + if (rename(filename, oldname) == 0) { + DIR *dir; + struct dirent *ent; + + dir = opendir(oldname); + if (dir == NULL) { + err(udev, "unable to open old watches dir '%s', old watches will not be restored: %m", oldname); + return; + } + + while ((ent = readdir(dir)) != NULL) { + char path[UTIL_PATH_SIZE]; + char buf[UTIL_PATH_SIZE]; + ssize_t len; + struct udev_device *dev; + + if (ent->d_name[0] < '0' || ent->d_name[0] > '9') + continue; + + util_strlcpy(path, oldname, sizeof(path)); + util_strlcat(path, "/", sizeof(path)); + util_strlcat(path, ent->d_name, sizeof(path)); + + len = readlink(path, buf, sizeof(buf)); + if (len <= 0) { + unlink(path); + continue; + } + + buf[len] = '\0'; + dbg(udev, "old watch to '%s' found\n", buf); + + dev = udev_device_new_from_syspath(udev, buf); + if (dev == NULL) { + unlink(path); + continue; + } + + udev_device_read_db(dev); + udev_device_set_info_loaded(dev); + + info(udev, "restoring old watch on '%s'\n", udev_device_get_devnode(dev)); + udev_watch_begin(udev, dev); + + udev_device_unref(dev); + + unlink(path); + } + + closedir(dir); + rmdir(oldname); + + } else if (errno != ENOENT) { + err(udev, "unable to move watches dir '%s', old watches will not be restored: %m", filename); + } +} + +static const char *udev_watch_filename(struct udev *udev, int wd) +{ + static char filename[UTIL_PATH_SIZE]; + char str[32]; + + sprintf(str, "%d", wd); + util_strlcpy(filename, udev_get_dev_path(udev), sizeof(filename)); + util_strlcat(filename, "/.udev/watch/", sizeof(filename)); + util_strlcat(filename, str, sizeof(filename)); + + return filename; +} + +void udev_watch_begin(struct udev *udev, struct udev_device *dev) +{ + const char *filename; + int wd; + + if (inotify_fd < 0) + return; + + wd = inotify_add_watch (inotify_fd, udev_device_get_devnode(dev), IN_CLOSE_WRITE); + if (wd < 0) { + err(udev, "inotify_add_watch(%d, %s, %o) failed: %m\n", + inotify_fd, udev_device_get_devnode(dev), IN_CLOSE_WRITE); + } + + filename = udev_watch_filename(udev, wd); + util_create_path(udev, filename); + unlink(filename); + symlink(udev_device_get_syspath(dev), filename); +} + +void udev_watch_clear(struct udev *udev, struct udev_device *dev) +{ + static char filename[UTIL_PATH_SIZE]; + DIR *dir; + struct dirent *ent; + + util_strlcpy(filename, udev_get_dev_path(udev), sizeof(filename)); + util_strlcat(filename, "/.udev/watch", sizeof(filename)); + + dir = opendir(filename); + if (dir == NULL) + return; + + while ((ent = readdir(dir)) != NULL) { + char path[UTIL_PATH_SIZE]; + char buf[UTIL_PATH_SIZE]; + ssize_t len; + + if (ent->d_name[0] < '0' || ent->d_name[0] > '9') + continue; + + util_strlcpy(path, filename, sizeof(path)); + util_strlcat(path, "/", sizeof(path)); + util_strlcat(path, ent->d_name, sizeof(path)); + + len = readlink(path, buf, sizeof(buf)); + if (len <= 0) + continue; + + buf[len] = '\0'; + if (strcmp(buf, udev_device_get_syspath(dev))) + continue; + + /* this is the watch we're looking for */ + info(udev, "clearing existing watch on '%s'\n", udev_device_get_devnode(dev)); + udev_watch_end(udev, atoi(ent->d_name)); + } + + closedir(dir); +} + +void udev_watch_end(struct udev *udev, int wd) +{ + const char *filename; + + if (inotify_fd < 0 || wd < 0) + return; + + inotify_rm_watch(inotify_fd, wd); + + filename = udev_watch_filename(udev, wd); + unlink(filename); +} + +const char *udev_watch_lookup(struct udev *udev, int wd) +{ + const char *filename; + static char buf[UTIL_PATH_SIZE]; + ssize_t len; + + if (inotify_fd < 0 || wd < 0) + return NULL; + + filename = udev_watch_filename(udev, wd); + len = readlink(filename, buf, sizeof(buf)); + if (len > 0) { + buf[len] = '\0'; + + return buf; + } + + return NULL; +} diff --git a/udev/udev.h b/udev/udev.h index d1b20719..57e2d73c 100644 --- a/udev/udev.h +++ b/udev/udev.h @@ -75,9 +75,16 @@ struct udev_event { unsigned int devlink_final:1; unsigned int run_final:1; unsigned int ignore_device:1; + unsigned int inotify_watch:1; unsigned int trace:1; }; +struct udev_watch { + struct udev_list_node node; + int handle; + char *name; +}; + /* udev-rules.c */ struct udev_rules; extern struct udev_rules *udev_rules_new(struct udev *udev, int resolve_names); @@ -93,6 +100,15 @@ extern void udev_event_apply_format(struct udev_event *event, char *string, size extern int udev_event_apply_subsys_kernel(struct udev_event *event, const char *string, char *result, size_t maxsize, int read_value); +/* udev-watch.c */ +extern int inotify_fd; +extern void udev_watch_init(struct udev *udev); +extern void udev_watch_restore(struct udev *udev); +extern void udev_watch_begin(struct udev *udev, struct udev_device *dev); +extern void udev_watch_clear(struct udev *udev, struct udev_device *dev); +extern void udev_watch_end(struct udev *udev, int wd); +extern const char *udev_watch_lookup(struct udev *udev, int wd); + /* udev-node.c */ extern int udev_node_mknod(struct udev_device *dev, const char *file, dev_t devnum, mode_t mode, uid_t uid, gid_t gid); extern int udev_node_add(struct udev_device *dev, mode_t mode, uid_t uid, gid_t gid); diff --git a/udev/udev.xml b/udev/udev.xml index 6a92154c..084c13bd 100644 --- a/udev/udev.xml +++ b/udev/udev.xml @@ -457,6 +457,13 @@ with this option. + + + + Watch the device node with inotify, when closed after being opened for + writing, a change uevent will be synthesised. + + diff --git a/udev/udevd.c b/udev/udevd.c index d08cf30f..d93781f4 100644 --- a/udev/udevd.c +++ b/udev/udevd.c @@ -65,7 +65,6 @@ static int debug_trace; static struct udev_rules *rules; static struct udev_ctrl *udev_ctrl; static struct udev_monitor *kernel_monitor; -static int inotify_fd = -1; static volatile int sigchilds_waiting; static volatile int udev_exit; static volatile int reload_config; @@ -195,8 +194,6 @@ static void event_fork(struct udev_event *event) /* child */ udev_monitor_unref(kernel_monitor); udev_ctrl_unref(udev_ctrl); - if (inotify_fd >= 0) - close(inotify_fd); logging_close(); logging_init("udevd-event"); setpriority(PRIO_PROCESS, 0, UDEV_PRIORITY); @@ -513,6 +510,58 @@ static void handle_ctrl_msg(struct udev_ctrl *uctrl) udev_ctrl_msg_unref(ctrl_msg); } +/* read inotify messages */ +static int handle_inotify(struct udev *udev) +{ + int nbytes, pos; + char *buf; + struct inotify_event *ev; + int reload_config = 0; + + if ((ioctl(inotify_fd, FIONREAD, &nbytes) < 0) || (nbytes <= 0)) + return 0; + + buf = malloc(nbytes); + if (buf == NULL) { + err(udev, "error getting buffer for inotify, disable watching\n"); + close(inotify_fd); + inotify_fd = -1; + return 0; + } + + read(inotify_fd, buf, nbytes); + + for (pos = 0, ev = (struct inotify_event *)(buf + pos); pos < nbytes; pos += sizeof(struct inotify_event) + ev->len) { + const char *syspath; + + dbg(udev, "inotify event: %x for %d (%s)\n", ev->mask, ev->wd, ev->len ? ev->name : "*"); + + syspath = udev_watch_lookup(udev, ev->wd); + if (syspath != NULL) { + dbg(udev, "inotify event: %x for %s\n", ev->mask, syspath); + if (ev->mask & IN_CLOSE_WRITE) { + char filename[UTIL_PATH_SIZE]; + int fd; + + info(udev, "device %s closed, synthesising write\n", syspath); + util_strlcpy(filename, syspath, sizeof(filename)); + util_strlcat(filename, "/uevent", sizeof(filename)); + fd = open(filename, O_WRONLY); + if (fd < 0 || write(fd, "change", 6) < 0) + info(udev, "error writing uevent: %m\n"); + close(fd); + } + if (ev->mask & IN_IGNORED) + udev_watch_end(udev, ev->wd); + } else { + reload_config = 1; + } + } + + free (buf); + return reload_config; +} + static void asmlinkage sig_handler(int signum) { switch (signum) { @@ -838,7 +887,7 @@ int main(int argc, char *argv[]) sigaction(SIGHUP, &act, NULL); /* watch rules directory */ - inotify_fd = inotify_init(); + udev_watch_init(udev); if (inotify_fd >= 0) { if (udev_get_rules_path(udev) != NULL) { inotify_add_watch(inotify_fd, udev_get_rules_path(udev), @@ -857,10 +906,9 @@ int main(int argc, char *argv[]) inotify_add_watch(inotify_fd, filename, IN_CREATE | IN_DELETE | IN_MOVE | IN_CLOSE_WRITE); } - } else if (errno == ENOSYS) - info(udev, "unable to use inotify, udevd will not monitor rule files changes\n"); - else - err(udev, "inotify_init failed: %m\n"); + + udev_watch_restore(udev); + } /* in trace mode run one event after the other */ if (debug_trace) { @@ -936,24 +984,8 @@ int main(int argc, char *argv[]) } /* rules directory inotify watch */ - if (inotify_poll && (inotify_poll->revents & POLLIN)) { - int nbytes; - - /* discard all possible events, we can just reload the config */ - if ((ioctl(inotify_fd, FIONREAD, &nbytes) == 0) && nbytes > 0) { - char *buf; - - reload_config = 1; - buf = malloc(nbytes); - if (buf == NULL) { - err(udev, "error getting buffer for inotify, disable watching\n"); - close(inotify_fd); - inotify_fd = -1; - } - read(inotify_fd, buf, nbytes); - free(buf); - } - } + if (inotify_poll && (inotify_poll->revents & POLLIN)) + reload_config = handle_inotify(udev); handle_signals: signal_received = 0; -- 2.39.5