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simplify "symlink name stack"

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With well defined and kernel-supplied node names, we no longer need
to support a possible stack of conflicting symlinks and node names.
Only symlinks with identical names can be claimed by multiple devices.

This shrinks the former /dev/.udev/names/ significantly.

Also the /dev/{block,char}/MAJ:MIN" links are excluded from the name
stack - they are unique and can not conflict.
This commit is contained in:
Kay Sievers 2009-09-09 18:18:17 +02:00
parent 7f06ec2e19
commit 6c29f2b942
9 changed files with 127 additions and 192 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
NEWS
View file

@ -9,6 +9,10 @@ Please do not port anything to the new format again, everything in /dev/.udev
is and always was private to udev, and may and will change any time without
prior notice.
Multiple devices claiming the same names in /dev are limited to symlinks
only now. Mixing identical symlink names and node names is not supported.
This reduces the amount of data in the database significantly.
NAME="%k" causes a warning now. It's is and always was completely superfluous.
It will break kernel supplied DEVNAMEs and therefore it needs to be removed
from all rules.

7
TODO
View file

@ -1,11 +1,4 @@
o drop support for node names in name stack, support only symlinks
With well defined and kernel-supplied node names, we no longer need
to support a possible stack of conflicting symlinks and node names.
From there on, only symlinks with identical names can be claimed
by multiple devices. It will simplify the logic a lot and shrink
/dev/.udev/names/ significantly. Also exclude "*/MAJ:MIN" link names
from the name stack, they can not conflict.
o remove most NAME= rules (they are provided by the 2.6.31 kernel)
o convert firmware.sh to C
o "udevadm control" commands will only accept the --<command> syntax

13
libudev/libudev-device.c
View file

@ -123,7 +123,7 @@ int udev_device_read_db(struct udev_device *udev_device)
next = &next[1];
}
util_strscpyl(devlink, sizeof(devlink), udev_get_dev_path(udev_device->udev), "/", lnk, NULL);
udev_device_add_devlink(udev_device, devlink);
udev_device_add_devlink(udev_device, devlink, 0);
}
info(udev_device->udev, "device %p filled with db symlink data '%s'\n", udev_device, udev_device->devnode);
return 0;
@ -150,7 +150,7 @@ int udev_device_read_db(struct udev_device *udev_device)
break;
case 'S':
util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev_device->udev), "/", val, NULL);
udev_device_add_devlink(udev_device, filename);
udev_device_add_devlink(udev_device, filename, 0);
break;
case 'L':
udev_device_set_devlink_priority(udev_device, atoi(val));
@ -1118,11 +1118,16 @@ int udev_device_set_devnode(struct udev_device *udev_device, const char *devnode
return 0;
}
int udev_device_add_devlink(struct udev_device *udev_device, const char *devlink)
int udev_device_add_devlink(struct udev_device *udev_device, const char *devlink, int unique)
{
struct udev_list_entry *list_entry;
udev_device->devlinks_uptodate = 0;
if (udev_list_entry_add(udev_device->udev, &udev_device->devlinks_list, devlink, NULL, 1, 0) == NULL)
list_entry = udev_list_entry_add(udev_device->udev, &udev_device->devlinks_list, devlink, NULL, 1, 0);
if (list_entry == NULL)
return -ENOMEM;
if (unique)
udev_list_entry_set_flag(list_entry, 1);
return 0;
}

4
libudev/libudev-monitor.c
View file

@ -628,12 +628,12 @@ retry:
next = strchr(slink, ' ');
while (next != NULL) {
next[0] = '\0';
udev_device_add_devlink(udev_device, slink);
udev_device_add_devlink(udev_device, slink, 0);
slink = &next[1];
next = strchr(slink, ' ');
}
if (slink[0] != '\0')
udev_device_add_devlink(udev_device, slink);
udev_device_add_devlink(udev_device, slink, 0);
} else if (strncmp(key, "DRIVER=", 7) == 0) {
udev_device_set_driver(udev_device, &key[7]);
} else if (strncmp(key, "ACTION=", 7) == 0) {

2
libudev/libudev-private.h
View file

@ -69,7 +69,7 @@ int udev_device_set_syspath(struct udev_device *udev_device, const char *syspath
int udev_device_set_subsystem(struct udev_device *udev_device, const char *subsystem);
int udev_device_set_devtype(struct udev_device *udev_device, const char *devtype);
int udev_device_set_devnode(struct udev_device *udev_device, const char *devnode);
int udev_device_add_devlink(struct udev_device *udev_device, const char *devlink);
int udev_device_add_devlink(struct udev_device *udev_device, const char *devlink, int unique);
void udev_device_cleanup_devlinks_list(struct udev_device *udev_device);
struct udev_list_entry *udev_device_add_property(struct udev_device *udev_device, const char *key, const char *value);
struct udev_list_entry *udev_device_add_property_from_string(struct udev_device *udev_device, const char *property);

4
rules/rules.d/50-udev-default.rules
View file

@ -1,7 +1,7 @@
# do not edit this file, it will be overwritten on update
SUBSYSTEM=="block", SYMLINK+="block/%M:%m"
SUBSYSTEM!="block", SYMLINK+="char/%M:%m"
SUBSYSTEM=="block", SYMLINK{unique}+="block/%M:%m"
SUBSYSTEM!="block", SYMLINK{unique}+="char/%M:%m"
KERNEL=="pty[pqrstuvwxyzabcdef][0123456789abcdef]", GROUP="tty", MODE="0660"
KERNEL=="tty[pqrstuvwxyzabcdef][0123456789abcdef]", GROUP="tty", MODE="0660"

4
udev/udev-event.c
View file

@ -688,9 +688,9 @@ exit_add:
char devnode[UTIL_PATH_SIZE];
info(event->udev, "'%s' not found in database, using kernel name '%s'\n",
udev_device_get_syspath(dev), udev_device_get_sysname(dev));
udev_device_get_syspath(dev), udev_device_get_knodename(dev));
util_strscpyl(devnode, sizeof(devnode),
udev_get_dev_path(event->udev), "/", udev_device_get_sysname(dev), NULL);
udev_get_dev_path(event->udev), "/", udev_device_get_knodename(dev), NULL);
udev_device_set_devnode(dev, devnode);
}

239
udev/udev-node.c
View file

@ -1,5 +1,5 @@
/*
* Copyright (C) 2003-2008 Kay Sievers <kay.sievers@vrfy.org>
* Copyright (C) 2003-2009 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
@ -19,6 +19,7 @@
#include <string.h>
#include <stdio.h>
#include <stddef.h>
#include <stdbool.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
@ -31,29 +32,6 @@
#define TMP_FILE_EXT ".udev-tmp"
/* reverse mapping from the device file name to the devpath */
static int name_index(struct udev_device *dev, const char *name, int add)
{
struct udev *udev = udev_device_get_udev(dev);
char name_enc[UTIL_PATH_SIZE];
char filename[UTIL_PATH_SIZE * 2];
util_path_encode(&name[strlen(udev_get_dev_path(udev))+1], name_enc, sizeof(name_enc));
snprintf(filename, sizeof(filename), "%s/.udev/names/%s/%u:%u", udev_get_dev_path(udev), name_enc,
major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev)));
if (add) {
dbg(udev, "creating index: '%s'\n", filename);
util_create_path(udev, filename);
symlink(udev_device_get_devpath(dev), filename);
} else {
dbg(udev, "removing index: '%s'\n", filename);
unlink(filename);
util_delete_path(udev, filename);
}
return 0;
}
int udev_node_mknod(struct udev_device *dev, const char *file, dev_t devnum, mode_t mode, uid_t uid, gid_t gid)
{
struct udev *udev = udev_device_get_udev(dev);
@ -168,7 +146,7 @@ static int node_symlink(struct udev *udev, const char *node, const char *slink)
info(udev, "found existing node instead of symlink '%s'\n", slink);
if (lstat(node, &stats2) == 0) {
if ((stats.st_mode & S_IFMT) == (stats2.st_mode & S_IFMT) &&
stats.st_rdev == stats2.st_rdev) {
stats.st_rdev == stats2.st_rdev && stats.st_ino != stats2.st_ino) {
info(udev, "replace device node '%s' with symlink to our node '%s'\n",
slink, node);
} else {
@ -222,143 +200,115 @@ exit:
return err;
}
static int name_index_get_devices(struct udev *udev, const char *name, struct udev_list_node *dev_list)
/* find device node of device with highest priority */
static const char *link_find_prioritized(struct udev_device *dev, bool add, const char *stackdir, char *buf, size_t bufsize)
{
char dirname[UTIL_PATH_SIZE];
char *s;
size_t l;
struct udev *udev = udev_device_get_udev(dev);
DIR *dir;
int count = 0;
int priority = 0;
const char *target = NULL;
s = dirname;
l = util_strpcpyl(&s, sizeof(dirname), udev_get_dev_path(udev),
"/.udev/names/", NULL);
util_path_encode(&name[strlen(udev_get_dev_path(udev))+1], s, l);
dir = opendir(dirname);
if (dir == NULL) {
dbg(udev, "no index directory '%s': %m\n", dirname);
count = -1;
goto out;
if (add) {
priority = udev_device_get_devlink_priority(dev);
util_strscpy(buf, bufsize, udev_device_get_devnode(dev));
target = buf;
}
dbg(udev, "found index directory '%s'\n", dirname);
while (1) {
dir = opendir(stackdir);
if (dir == NULL)
return target;
for (;;) {
struct udev_device *dev_db;
struct dirent *dent;
char devpath[UTIL_PATH_SIZE];
char syspath[UTIL_PATH_SIZE];
int len;
ssize_t len;
dent = readdir(dir);
if (dent == NULL || dent->d_name[0] == '\0')
break;
if (dent->d_name[0] == '.')
continue;
dbg(udev, "found '%s/%s'\n", stackdir, dent->d_name);
len = readlinkat(dirfd(dir), dent->d_name, devpath, sizeof(devpath));
if (len < 0 || (size_t)len >= sizeof(devpath))
if (len <= 0 || len == (ssize_t)sizeof(devpath))
continue;
devpath[len] = '\0';
util_strscpyl(syspath, sizeof(syspath), udev_get_sys_path(udev), devpath, NULL);
udev_list_entry_add(udev, dev_list, syspath, NULL, 1, 0);
count++;
info(udev, "found '%s' claiming '%s'\n", syspath, stackdir);
/* did we find ourself? */
if (strcmp(udev_device_get_syspath(dev), syspath) == 0)
continue;
dev_db = udev_device_new_from_syspath(udev, syspath);
if (dev_db != NULL) {
const char *devnode;
devnode = udev_device_get_devnode(dev_db);
if (devnode != NULL) {
dbg(udev, "compare priority of '%s'(%i) > '%s'(%i)\n", target, priority,
udev_device_get_devnode(dev_db), udev_device_get_devlink_priority(dev_db));
if (target == NULL || udev_device_get_devlink_priority(dev_db) > priority) {
info(udev, "'%s' claims priority %i for '%s'\n",
syspath, udev_device_get_devlink_priority(dev_db), stackdir);
priority = udev_device_get_devlink_priority(dev_db);
util_strscpy(buf, bufsize, devnode);
target = buf;
}
}
udev_device_unref(dev_db);
}
}
closedir(dir);
out:
return count;
return target;
}
static int update_link(struct udev_device *dev, const char *slink)
/* manage "stack of names" with possibly specified device priorities */
static void link_update(struct udev_device *dev, const char *slink, bool add)
{
struct udev *udev = udev_device_get_udev(dev);
struct udev_list_node dev_list;
struct udev_list_entry *dev_entry;
char target[UTIL_PATH_SIZE];
int count;
int priority = 0;
int rc = 0;
char name_enc[UTIL_PATH_SIZE];
char filename[UTIL_PATH_SIZE * 2];
char dirname[UTIL_PATH_SIZE];
const char *target;
char buf[UTIL_PATH_SIZE];
dbg(udev, "update symlink '%s' of '%s'\n", slink, udev_device_get_syspath(dev));
udev_list_init(&dev_list);
count = name_index_get_devices(udev, slink, &dev_list);
if (count > 1)
info(udev, "found %i devices with name '%s'\n", count, slink);
util_path_encode(&slink[strlen(udev_get_dev_path(udev))+1], name_enc, sizeof(name_enc));
snprintf(dirname, sizeof(dirname), "%s/.udev/links/%s", udev_get_dev_path(udev), name_enc);
snprintf(filename, sizeof(filename), "%s/%c%u:%u", dirname,
strcmp(udev_device_get_subsystem(dev), "block") == 0 ? 'b' : 'c',
major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev)));
/* if we don't have a reference, delete it */
if (count <= 0) {
if (!add) {
dbg(udev, "removing index: '%s'\n", filename);
unlink(filename);
util_delete_path(udev, filename);
}
target = link_find_prioritized(dev, add, dirname, buf, sizeof(buf));
if (target == NULL) {
info(udev, "no reference left, remove '%s'\n", slink);
unlink(slink);
util_delete_path(udev, slink);
goto out;
} else {
util_create_path(udev, slink);
info(udev, "creating link '%s' to '%s'\n", slink, target);
node_symlink(udev, target, slink);
}
/* find the device with the highest priority */
target[0] = '\0';
udev_list_entry_foreach(dev_entry, udev_list_get_entry(&dev_list)) {
const char *syspath;
struct udev_device *dev_db;
const char *devnode;
syspath = udev_list_entry_get_name(dev_entry);
dbg(udev, "found '%s' for '%s'\n", syspath, slink);
/* did we find ourself? we win, if we have the same priority */
if (strcmp(udev_device_get_syspath(dev), syspath) == 0) {
dbg(udev, "compare (our own) priority of '%s' %i >= %i\n",
udev_device_get_devpath(dev), udev_device_get_devlink_priority(dev), priority);
if (strcmp(udev_device_get_devnode(dev), slink) == 0) {
info(udev, "'%s' is our device node, database inconsistent, skip link update\n",
udev_device_get_devnode(dev));
} else if (target[0] == '\0' || udev_device_get_devlink_priority(dev) >= priority) {
priority = udev_device_get_devlink_priority(dev);
util_strscpy(target, sizeof(target), udev_device_get_devnode(dev));
}
continue;
}
/* another device, read priority from database */
dev_db = udev_device_new_from_syspath(udev, syspath);
if (dev_db == NULL)
continue;
devnode = udev_device_get_devnode(dev_db);
if (devnode != NULL) {
if (strcmp(devnode, slink) == 0) {
info(udev, "'%s' is a device node of '%s', skip link update\n",
devnode, syspath);
} else {
dbg(udev, "compare priority of '%s' %i > %i\n",
udev_device_get_devpath(dev_db),
udev_device_get_devlink_priority(dev_db),
priority);
if (target[0] == '\0' || udev_device_get_devlink_priority(dev_db) > priority) {
priority = udev_device_get_devlink_priority(dev_db);
util_strscpy(target, sizeof(target), devnode);
}
}
}
udev_device_unref(dev_db);
if (add) {
dbg(udev, "creating index: '%s'\n", filename);
util_create_path(udev, filename);
symlink(udev_device_get_devpath(dev), filename);
}
udev_list_cleanup_entries(udev, &dev_list);
if (target[0] == '\0') {
info(udev, "no current target for '%s' found\n", slink);
rc = 1;
goto out;
}
/* create symlink to the target with the highest priority */
info(udev, "'%s' with target '%s' has the highest priority %i, create it\n", slink, target, priority);
util_create_path(udev, slink);
node_symlink(udev, target, slink);
out:
return rc;
}
void udev_node_update_old_links(struct udev_device *dev, struct udev_device *dev_old)
{
struct udev *udev = udev_device_get_udev(dev);
struct udev_list_entry *list_entry;
const char *devnode_old;
/* update possible left-over symlinks */
udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev_old)) {
@ -366,10 +316,6 @@ void udev_node_update_old_links(struct udev_device *dev, struct udev_device *dev
struct udev_list_entry *list_entry_current;
int found;
/* check if old link name is now our node name */
if (strcmp(name, udev_device_get_devnode(dev)) == 0)
continue;
/* check if old link name still belongs to this device */
found = 0;
udev_list_entry_foreach(list_entry_current, udev_device_get_devlinks_list_entry(dev)) {
@ -385,23 +331,7 @@ void udev_node_update_old_links(struct udev_device *dev, struct udev_device *dev
info(udev, "update old name, '%s' no longer belonging to '%s'\n",
name, udev_device_get_devpath(dev));
name_index(dev, name, 0);
update_link(dev, name);
}
/*
* if the node name has changed, delete the node,
* and possibly restore a symlink of a different device
*/
devnode_old = udev_device_get_devnode(dev_old);
if (devnode_old != NULL) {
const char *devnode = udev_device_get_devnode(dev);
if (devnode != NULL && strcmp(devnode_old, devnode) != 0) {
info(udev, "node has changed from '%s' to '%s'\n", devnode_old, devnode);
name_index(dev, devnode_old, 0);
update_link(dev, devnode_old);
}
link_update(dev, name, 0);
}
}
@ -441,13 +371,15 @@ int udev_node_add(struct udev_device *dev, mode_t mode, uid_t uid, gid_t gid)
}
}
/* add node to name index */
name_index(dev, udev_device_get_devnode(dev), 1);
/* create/update symlinks, add symlinks to name index */
udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev)) {
name_index(dev, udev_list_entry_get_name(list_entry), 1);
update_link(dev, udev_list_entry_get_name(list_entry));
if (udev_list_entry_get_flag(list_entry)) {
/* simple unmanaged link name */
util_create_path(udev, udev_list_entry_get_name(list_entry));
node_symlink(udev, udev_device_get_devnode(dev), udev_list_entry_get_name(list_entry));
} else {
link_update(dev, udev_list_entry_get_name(list_entry), 1);
}
}
exit:
return err;
@ -463,14 +395,9 @@ int udev_node_remove(struct udev_device *dev)
int err = 0;
int num;
/* remove node from name index */
name_index(dev, udev_device_get_devnode(dev), 0);
/* remove,update symlinks, remove symlinks from name index */
udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev)) {
name_index(dev, udev_list_entry_get_name(list_entry), 0);
update_link(dev, udev_list_entry_get_name(list_entry));
}
udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev))
link_update(dev, udev_list_entry_get_name(list_entry), 0);
devnode = udev_device_get_devnode(dev);
if (devnode == NULL)

42
udev/udev-rules.c
View file

@ -190,7 +190,8 @@ struct token {
unsigned int value_off;
union {
unsigned int attr_off;
int ignore_error;
int devlink_unique;
int fail_on_error;
unsigned int rule_goto;
mode_t mode;
uid_t uid;
@ -1011,7 +1012,6 @@ static int rule_add_key(struct rule_tmp *rule_tmp, enum token_type type,
case TK_A_GROUP:
case TK_A_MODE:
case TK_A_NAME:
case TK_A_DEVLINK:
case TK_A_GOTO:
token->key.value_off = add_string(rule_tmp->rules, value);
break;
@ -1024,6 +1024,10 @@ static int rule_add_key(struct rule_tmp *rule_tmp, enum token_type type,
token->key.value_off = add_string(rule_tmp->rules, value);
token->key.attr_off = add_string(rule_tmp->rules, attr);
break;
case TK_A_DEVLINK:
token->key.value_off = add_string(rule_tmp->rules, value);
token->key.devlink_unique = *(int *)data;
break;
case TK_M_TEST:
token->key.value_off = add_string(rule_tmp->rules, value);
if (data != NULL)
@ -1037,7 +1041,7 @@ static int rule_add_key(struct rule_tmp *rule_tmp, enum token_type type,
break;
case TK_A_RUN:
token->key.value_off = add_string(rule_tmp->rules, value);
token->key.ignore_error = *(int *)data;
token->key.fail_on_error = *(int *)data;
break;
case TK_A_INOTIFY_WATCH:
case TK_A_NUM_FAKE_PART:
@ -1432,10 +1436,16 @@ static int add_rule(struct udev_rules *rules, char *line,
}
if (strcmp(key, "SYMLINK") == 0) {
if (op < OP_MATCH_MAX)
if (op < OP_MATCH_MAX) {
rule_add_key(&rule_tmp, TK_M_DEVLINK, op, value, NULL);
else
rule_add_key(&rule_tmp, TK_A_DEVLINK, op, value, NULL);
} else {
int flag = 0;
attr = get_key_attribute(rules->udev, key + sizeof("SYMLINK")-1);
if (attr != NULL && strstr(attr, "unique") != NULL)
flag = 1;
rule_add_key(&rule_tmp, TK_A_DEVLINK, op, value, &flag);
}
rule_tmp.rule.rule.flags = 1;
continue;
}
@ -2445,26 +2455,22 @@ int udev_rules_apply_to_event(struct udev_rules *rules, struct udev_event *event
while (isspace(pos[0]))
pos++;
next = strchr(pos, ' ');
while (next) {
while (next != NULL) {
next[0] = '\0';
info(event->udev, "LINK '%s' %s:%u\n",
pos,
&rules->buf[rule->rule.filename_off],
rule->rule.filename_line);
info(event->udev, "LINK '%s' %s:%u\n", pos,
&rules->buf[rule->rule.filename_off], rule->rule.filename_line);
util_strscpyl(filename, sizeof(filename), udev_get_dev_path(event->udev), "/", pos, NULL);
udev_device_add_devlink(event->dev, filename);
udev_device_add_devlink(event->dev, filename, cur->key.devlink_unique);
while (isspace(next[1]))
next++;
pos = &next[1];
next = strchr(pos, ' ');
}
if (pos[0] != '\0') {
info(event->udev, "LINK '%s' %s:%u\n",
pos,
&rules->buf[rule->rule.filename_off],
rule->rule.filename_line);
info(event->udev, "LINK '%s' %s:%u\n", pos,
&rules->buf[rule->rule.filename_off], rule->rule.filename_line);
util_strscpyl(filename, sizeof(filename), udev_get_dev_path(event->udev), "/", pos, NULL);
udev_device_add_devlink(event->dev, filename);
udev_device_add_devlink(event->dev, filename, cur->key.devlink_unique);
}
}
break;
@ -2511,7 +2517,7 @@ int udev_rules_apply_to_event(struct udev_rules *rules, struct udev_event *event
rule->rule.filename_line);
list_entry = udev_list_entry_add(event->udev, &event->run_list,
&rules->buf[cur->key.value_off], NULL, 1, 0);
if (cur->key.ignore_error)
if (cur->key.fail_on_error)
udev_list_entry_set_flag(list_entry, 1);
break;
}