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Systemd/udev/lib/libudev-private.h
Scott James Remnant bb38678e3c udevadm: settle - synchronise with the udev daemon 
There's still a slight race condition when using udevadm settle, if the
udev daemon has a pending inotify event but hasn't yet generated the
"change" uevent for it, the kernel and udev sequence numbers will match
and settle will exit.

Now udevadm settle will send a control message to udevd, which will
respond by sending SIGUSR1 back to the waiting udevadm settle once it
has completed the main loop iteration in which it received the control
message.

If there were no pending inotify events, this will simply wake up the
udev daemon and allow settle to continue.  If there are pending inotify
events, they are handled first in the main loop so when settle is
continued they will have been turned into uevents and the kernel
sequence number will have been incremented.

Since the inotify event is pending for udevd when the close() system
call returns (it's queued as part of the kernel handling for that system
call), and since the kernel sequence number is incremented by writing to
the uevent file (as udevd does), this solves the race.

When the settle continues, if there were pending inotify events that
udevd had not read, they are now pending uevents which settle can wait
for.

Signed-off-by: Scott James Remnant <scott@ubuntu.com>
2009-03-12 10:02:37 +00:00

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/*
* libudev - interface to udev device information
*
* Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
*
* 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 <http://www.gnu.org/licenses/>.
*/
#ifndef _LIBUDEV_PRIVATE_H_
#define _LIBUDEV_PRIVATE_H_
#include <syslog.h>
#include "libudev.h"
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
static inline void __attribute__ ((format(printf, 2, 3)))
udev_log_null(struct udev *udev, const char *format, ...) {}
#ifdef USE_LOG
# ifdef DEBUG
# define dbg(udev, arg...) udev_log(udev, LOG_DEBUG, __FILE__, __LINE__, __FUNCTION__, ## arg)
# else
# define dbg(udev, arg...) udev_log_null(udev, ## arg)
# endif
# define info(udev, arg...) udev_log(udev, LOG_INFO, __FILE__, __LINE__, __FUNCTION__, ## arg)
# define err(udev, arg...) udev_log(udev, LOG_ERR, __FILE__, __LINE__, __FUNCTION__, ## arg)
#else
# define dbg(udev, arg...) udev_log_null(udev, ## arg)
# define info(udev, arg...) udev_log_null(udev, ## arg)
# define err(udev, arg...) udev_log_null(udev, ## arg)
#endif
/* libudev */
void udev_log(struct udev *udev,
int priority, const char *file, int line, const char *fn,
const char *format, ...)
__attribute__ ((format(printf, 6, 7)));
extern struct udev_device *device_new(struct udev *udev);
extern const char *udev_get_rules_path(struct udev *udev);
extern int udev_get_run(struct udev *udev);
extern struct udev_list_entry *udev_add_property(struct udev *udev, const char *key, const char *value);
extern struct udev_list_entry *udev_get_properties_list_entry(struct udev *udev);
/* libudev-device */
extern int udev_device_set_syspath(struct udev_device *udev_device, const char *syspath);
extern int udev_device_set_subsystem(struct udev_device *udev_device, const char *subsystem);
extern int udev_device_set_devtype(struct udev_device *udev_device, const char *devtype);
extern int udev_device_set_devnode(struct udev_device *udev_device, const char *devnode);
extern int udev_device_add_devlink(struct udev_device *udev_device, const char *devlink);
extern void udev_device_cleanup_devlinks_list(struct udev_device *udev_device);
extern struct udev_list_entry *udev_device_add_property(struct udev_device *udev_device, const char *key, const char *value);
extern struct udev_list_entry *udev_device_add_property_from_string(struct udev_device *udev_device, const char *property);
extern char **udev_device_get_properties_envp(struct udev_device *udev_device);
extern ssize_t udev_device_get_properties_monitor_buf(struct udev_device *udev_device, const char **buf);
extern int udev_device_read_db(struct udev_device *udev_device);
extern int udev_device_read_uevent_file(struct udev_device *udev_device);
extern int udev_device_set_action(struct udev_device *udev_device, const char *action);
extern int udev_device_set_driver(struct udev_device *udev_device, const char *driver);
extern const char *udev_device_get_devpath_old(struct udev_device *udev_device);
extern int udev_device_set_devpath_old(struct udev_device *udev_device, const char *devpath_old);
extern const char *udev_device_get_physdevpath(struct udev_device *udev_device);
extern int udev_device_set_physdevpath(struct udev_device *udev_device, const char *physdevpath);
extern int udev_device_get_timeout(struct udev_device *udev_device);
extern int udev_device_set_timeout(struct udev_device *udev_device, int timeout);
extern int udev_device_get_event_timeout(struct udev_device *udev_device);
extern int udev_device_set_event_timeout(struct udev_device *udev_device, int event_timeout);
extern int udev_device_set_devnum(struct udev_device *udev_device, dev_t devnum);
extern int udev_device_set_seqnum(struct udev_device *udev_device, unsigned long long int seqnum);
extern int udev_device_get_num_fake_partitions(struct udev_device *udev_device);
extern int udev_device_set_num_fake_partitions(struct udev_device *udev_device, int num);
extern int udev_device_get_devlink_priority(struct udev_device *udev_device);
extern int udev_device_set_devlink_priority(struct udev_device *udev_device, int prio);
extern int udev_device_get_ignore_remove(struct udev_device *udev_device);
extern int udev_device_set_ignore_remove(struct udev_device *udev_device, int ignore);
extern int udev_device_get_watch_handle(struct udev_device *udev_device);
extern int udev_device_set_watch_handle(struct udev_device *udev_device, int handle);
extern void udev_device_set_info_loaded(struct udev_device *device);
/* libudev-device-db-write.c */
extern int udev_device_update_db(struct udev_device *udev_device);
extern int udev_device_delete_db(struct udev_device *udev_device);
extern int udev_device_rename_db(struct udev_device *udev_device, const char *devpath);
/* libudev-monitor - netlink/unix socket communication */
extern int udev_monitor_send_device(struct udev_monitor *udev_monitor, struct udev_device *udev_device);
extern int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size);
/* libudev-ctrl - daemon runtime setup */
struct udev_ctrl;
extern struct udev_ctrl *udev_ctrl_new_from_socket(struct udev *udev, const char *socket_path);
extern int udev_ctrl_enable_receiving(struct udev_ctrl *uctrl);
extern struct udev_ctrl *udev_ctrl_ref(struct udev_ctrl *uctrl);
extern void udev_ctrl_unref(struct udev_ctrl *uctrl);
extern struct udev *udev_ctrl_get_udev(struct udev_ctrl *uctrl);
extern int udev_ctrl_get_fd(struct udev_ctrl *uctrl);
extern int udev_ctrl_send_set_log_level(struct udev_ctrl *uctrl, int priority);
extern int udev_ctrl_send_stop_exec_queue(struct udev_ctrl *uctrl);
extern int udev_ctrl_send_start_exec_queue(struct udev_ctrl *uctrl);
extern int udev_ctrl_send_reload_rules(struct udev_ctrl *uctrl);
extern int udev_ctrl_send_settle(struct udev_ctrl *uctrl);
extern int udev_ctrl_send_set_env(struct udev_ctrl *uctrl, const char *key);
extern int udev_ctrl_send_set_max_childs(struct udev_ctrl *uctrl, int count);
struct udev_ctrl_msg;
extern struct udev_ctrl_msg *udev_ctrl_msg(struct udev_ctrl *uctrl);
extern struct udev_ctrl_msg *udev_ctrl_receive_msg(struct udev_ctrl *uctrl);
extern struct udev_ctrl_msg *udev_ctrl_msg_ref(struct udev_ctrl_msg *ctrl_msg);
extern void udev_ctrl_msg_unref(struct udev_ctrl_msg *ctrl_msg);
extern int udev_ctrl_get_set_log_level(struct udev_ctrl_msg *ctrl_msg);
extern int udev_ctrl_get_stop_exec_queue(struct udev_ctrl_msg *ctrl_msg);
extern int udev_ctrl_get_start_exec_queue(struct udev_ctrl_msg *ctrl_msg);
extern int udev_ctrl_get_reload_rules(struct udev_ctrl_msg *ctrl_msg);
extern pid_t udev_ctrl_get_settle(struct udev_ctrl_msg *ctrl_msg);
extern const char *udev_ctrl_get_set_env(struct udev_ctrl_msg *ctrl_msg);
extern int udev_ctrl_get_set_max_childs(struct udev_ctrl_msg *ctrl_msg);
/* libudev-list */
struct udev_list_node {
struct udev_list_node *next, *prev;
};
extern void udev_list_init(struct udev_list_node *list);
extern int udev_list_is_empty(struct udev_list_node *list);
extern void udev_list_node_append(struct udev_list_node *new, struct udev_list_node *list);
extern void udev_list_node_remove(struct udev_list_node *entry);
#define udev_list_node_foreach(node, list) \
for (node = (list)->next; \
node != list; \
node = (node)->next)
#define udev_list_node_foreach_safe(node, tmp, list) \
for (node = (list)->next, tmp = (node)->next; \
node != list; \
node = tmp, tmp = (tmp)->next)
extern struct udev_list_entry *udev_list_entry_add(struct udev *udev, struct udev_list_node *list,
const char *name, const char *value,
int unique, int sort);
extern void udev_list_entry_delete(struct udev_list_entry *entry);
extern void udev_list_entry_remove(struct udev_list_entry *entry);
extern void udev_list_entry_insert_before(struct udev_list_entry *new, struct udev_list_entry *entry);
extern void udev_list_entry_append(struct udev_list_entry *new, struct udev_list_node *list);
extern void udev_list_cleanup_entries(struct udev *udev, struct udev_list_node *name_list);
extern struct udev_list_entry *udev_list_get_entry(struct udev_list_node *list);
extern int udev_list_entry_get_flag(struct udev_list_entry *list_entry);
extern void udev_list_entry_set_flag(struct udev_list_entry *list_entry, int flag);
#define udev_list_entry_foreach_safe(entry, tmp, first) \
for (entry = first, tmp = udev_list_entry_get_next(entry); \
entry != NULL; \
entry = tmp, tmp = udev_list_entry_get_next(tmp))
/* libudev-queue */
extern int udev_queue_export_udev_seqnum(struct udev_queue *udev_queue, unsigned long long int seqnum);
extern int udev_queue_export_device_queued(struct udev_queue *udev_queue, struct udev_device *udev_device);
extern int udev_queue_export_device_finished(struct udev_queue *udev_queue, struct udev_device *udev_device);
extern int udev_queue_export_device_failed(struct udev_queue *udev_queue, struct udev_device *udev_device);
/* libudev-utils */
#define UTIL_PATH_SIZE 1024
#define UTIL_LINE_SIZE 2048
#define UTIL_NAME_SIZE 512
#define UDEV_ALLOWED_CHARS_INPUT "/ $%?,"
extern ssize_t util_get_sys_subsystem(struct udev *udev, const char *syspath, char *subsystem, size_t size);
extern ssize_t util_get_sys_driver(struct udev *udev, const char *syspath, char *driver, size_t size);
extern int util_resolve_sys_link(struct udev *udev, char *syspath, size_t size);
extern int util_log_priority(const char *priority);
extern size_t util_path_encode(char *s, size_t len);
extern size_t util_path_decode(char *s);
extern void util_remove_trailing_chars(char *path, char c);
extern size_t util_strlcpy(char *dst, const char *src, size_t size);
extern size_t util_strlcat(char *dst, const char *src, size_t size);
extern int udev_util_replace_whitespace(const char *str, char *to, size_t len);
extern int udev_util_replace_chars(char *str, const char *white);
extern int udev_util_encode_string(const char *str, char *str_enc, size_t len);
#endif
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