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- Committer: Colin Watson
- Date: 2014-03-03 17:01:37 UTC
- mto: This revision was merged to the branch mainline in revision 354.
- Revision ID: cjwatson@canonical.com-20140303170137-4gs1zjmqtgkvzphq
Move an initial core of functionality (database, hooks, osextras, query,
user) from Python into a new "libclick" library, allowing
performance-critical clients to avoid the cost of starting a new Python
interpreter (LP: #1282311).
user) from Python into a new "libclick" library, allowing
performance-critical clients to avoid the cost of starting a new Python
interpreter (LP: #1282311).
- files added:
- click/tests/Makefile.am
- lib
- lib/click
- files removed:
- click/database.py
- files modified:
- .bzrignore
added
removed
lib/click/user.vala
1
/* Copyright (C) 2013, 2014 Canonical Ltd.
2
* Author: Colin Watson <cjwatson@ubuntu.com>
3
*
4
* This program is free software: you can redistribute it and/or modify
5
* it under the terms of the GNU General Public License as published by
6
* the Free Software Foundation; version 3 of the License.
7
*
8
* This program is distributed in the hope that it will be useful,
9
* but WITHOUT ANY WARRANTY; without even the implied warranty of
10
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11
* GNU General Public License for more details.
12
*
13
* You should have received a copy of the GNU General Public License
14
* along with this program. If not, see <http://www.gnu.org/licenses/>.
15
*/
16
17
/* Registry of user-installed Click packages.
18
*
19
* Click packages are installed into per-package/version directories, so it
20
* is quite feasible for more than one version of a given package to be
21
* installed at once, allowing per-user installations; for instance, one
22
* user of a tablet may be uncomfortable with granting some new permission
23
* to an app, but another may be just fine with it. To make this useful, we
24
* also need a registry of which users have which versions of each package
25
* installed.
26
*
27
* We might have chosen to use a proper database. However, a major goal of
28
* Click packages is extreme resilience; we must never get into a situation
29
* where some previous error in package installation or removal makes it
30
* hard for the user to install or remove other packages. Furthermore, the
31
* simpler application execution can be the better. So, instead, we use
32
* just about the simplest "database" format imaginable: a directory of
33
* symlinks per user.
34
*/
35
36
namespace Click {
37
38
/* Pseudo-usernames selected to be invalid as a real username, and alluding
39
* to group syntaxes used in other systems.
40
*/
41
private const string ALL_USERS = "@all";
42
private const string GC_IN_USE_USER = "@gcinuse";
43
44
/* Pseudo-versions. In this case the @ doesn't allude to group syntaxes,
45
* but since @ is conveniently invalid in version numbers we stick to the
46
* same prefix used for pseudo-usernames.
47
*/
48
private const string HIDDEN_VERSION = "@hidden";
49
50
public errordomain UserError {
51
/**
52
* Failure to get password file entry.
53
*/
54
GETPWNAM,
55
/**
56
* Failure to create database directory.
57
*/
58
CREATE_DB,
59
/**
60
* Failure to set ownership of database directory.
61
*/
62
CHOWN_DB,
63
/**
64
* Requested user does not exist.
65
*/
66
NO_SUCH_USER,
67
/**
68
* Failure to drop privileges.
69
*/
70
DROP_PRIVS,
71
/**
72
* Failure to regain privileges.
73
*/
74
REGAIN_PRIVS,
75
/**
76
* Requested package is hidden.
77
*/
78
HIDDEN_PACKAGE,
79
/**
80
* Requested package does not exist.
81
*/
82
NO_SUCH_PACKAGE,
83
/**
84
* Failure to rename file.
85
*/
86
RENAME
87
}
88
89
private string
90
db_top (string root)
91
{
92
/* This is deliberately outside any user's home directory so that it
93
* can safely be iterated etc. as root.
94
*/
95
return Path.build_filename (root, ".click", "users");
96
}
97
98
private string
99
db_for_user (string root, string user)
100
{
101
return Path.build_filename (db_top (root), user);
102
}
103
104
private void
105
try_create (string path) throws UserError
106
{
107
if (DirUtils.create (path, 0777) < 0)
108
throw new UserError.CREATE_DB
109
("Cannot create database directory %s: %s",
110
path, strerror (errno));
111
}
112
113
private void
114
try_chown (string path, Posix.Passwd pw) throws UserError
115
{
116
if (Posix.chown (path, pw.pw_uid, pw.pw_gid) < 0)
117
throw new UserError.CHOWN_DB
118
("Cannot set ownership of database directory %s: %s",
119
path, strerror (errno));
120
}
121
122
public class Users : Object {
123
public DB db { private get; construct; }
124
private unowned Posix.Passwd? click_pw;
125
126
public Users (DB db)
127
{
128
Object (db: db);
129
click_pw = null;
130
}
131
132
/**
133
* get_click_pw:
134
*
135
* Returns: The password file entry for the `clickpkg` user.
136
*/
137
private unowned Posix.Passwd
138
get_click_pw () throws UserError
139
{
140
if (click_pw == null) {
141
errno = 0;
142
click_pw = Posix.getpwnam ("clickpkg");
143
if (click_pw == null)
144
throw new UserError.GETPWNAM
145
("Cannot get password file entry " +
146
"for clickpkg: %s", strerror (errno));
147
}
148
return click_pw;
149
}
150
151
internal void
152
ensure_db () throws UserError
153
{
154
var create = new List<string> ();
155
156
/* Only modify the last database. */
157
var try_path = db_top (db.overlay);
158
while (! FileUtils.test (try_path, FileTest.EXISTS)) {
159
create.prepend (try_path);
160
try_path = Path.get_dirname (try_path);
161
}
162
163
foreach (var path in create) {
164
try_create (path);
165
if (Posix.geteuid () == 0)
166
try_chown (path, get_click_pw ());
167
}
168
}
169
170
/**
171
* get_user_names:
172
*
173
* Returns: A list of user names with registrations.
174
*/
175
public List<string>
176
get_user_names () throws Error
177
{
178
var entries = new List<string> ();
179
var seen = new Gee.HashSet<string> ();
180
foreach (var single_db in db) {
181
var users_db = db_top (single_db.root);
182
foreach (var entry in Click.Dir.open (users_db)) {
183
if (entry in seen)
184
continue;
185
var path = Path.build_filename (users_db,
186
entry);
187
if (FileUtils.test (path, FileTest.IS_DIR)) {
188
seen.add (entry.dup ());
189
entries.prepend (entry.dup ());
190
}
191
}
192
}
193
entries.reverse ();
194
return entries;
195
}
196
197
/**
198
* get_user:
199
* @user_name: A user name.
200
*
201
* Returns: (transfer full): A new #ClickUser instance for @user.
202
*/
203
public User
204
get_user (string user_name) throws Error
205
{
206
foreach (var single_db in db) {
207
var path = db_for_user (single_db.root, user_name);
208
if (FileUtils.test (path, FileTest.IS_DIR))
209
/* We only require the user path to exist in
210
* any database; it doesn't matter which.
211
*/
212
return new User.for_user (db, user_name);
213
}
214
throw new UserError.NO_SUCH_USER(
215
"User %s does not exist in any database", user_name);
216
}
217
}
218
219
public class User : Object {
220
public DB db { private get; construct; }
221
public string name { private get; construct; }
222
223
private Users? users;
224
private unowned Posix.Passwd? user_pw;
225
private int dropped_privileges_count;
226
private Posix.mode_t? old_umask;
227
228
private User (DB db, string? name = null) {
229
string real_name;
230
if (name != null)
231
real_name = name;
232
else
233
real_name = Environment.get_user_name ().dup ();
234
Object (db: db, name: real_name);
235
users = null;
236
user_pw = null;
237
dropped_privileges_count = 0;
238
old_umask = null;
239
}
240
241
public User.for_user (DB db, string? name = null) {
242
this (db, name);
243
}
244
245
public User.for_all_users (DB db) {
246
this (db, ALL_USERS);
247
}
248
249
public User.for_gc_in_use (DB db) {
250
this (db, GC_IN_USE_USER);
251
}
252
253
/**
254
* True if and only if this user is a pseudo-user.
255
*/
256
public bool is_pseudo_user { get { return name.has_prefix ("@"); } }
257
258
/**
259
* True if and only if this user is the pseudo-user indicating that
260
* a registration was in use at the time of package removal.
261
*/
262
public bool is_gc_in_use { get { return name == GC_IN_USE_USER; } }
263
264
/**
265
* get_user_pw:
266
*
267
* Returns: The password file entry for this user.
268
*/
269
private unowned Posix.Passwd
270
get_user_pw () throws UserError
271
{
272
assert (! is_pseudo_user);
273
274
if (user_pw == null) {
275
errno = 0;
276
user_pw = Posix.getpwnam (name);
277
if (user_pw == null)
278
throw new UserError.GETPWNAM
279
("Cannot get password file entry for " +
280
"%s: %s", name, strerror (errno));
281
}
282
return user_pw;
283
}
284
285
/**
286
* get_overlay_db:
287
*
288
* Returns: The path to the overlay database for this user, i.e. the
289
* path where new packages will be installed.
290
*/
291
public string
292
get_overlay_db ()
293
{
294
return db_for_user (db.overlay, name);
295
}
296
297
private void
298
ensure_db () throws UserError
299
{
300
if (users == null)
301
users = new Users (db);
302
users.ensure_db ();
303
var path = get_overlay_db ();
304
if (! FileUtils.test (path, FileTest.EXISTS)) {
305
try_create (path);
306
if (Posix.geteuid () == 0 && ! is_pseudo_user)
307
try_chown (path, get_user_pw ());
308
}
309
}
310
311
/* Note on privilege handling:
312
* We can normally get away without dropping privilege when reading,
313
* but some filesystems are strict about how much they let root work
314
* with user files (e.g. NFS root_squash). It is better to play it
315
* safe and drop privileges for any operations on the user's
316
* database.
317
*/
318
319
private void
320
priv_drop_failure (string name) throws UserError
321
{
322
throw new UserError.DROP_PRIVS
323
("Cannot drop privileges (%s): %s",
324
name, strerror (errno));
325
}
326
327
internal void
328
drop_privileges () throws UserError
329
{
330
if (dropped_privileges_count == 0 &&
331
Posix.getuid () == 0 && ! is_pseudo_user) {
332
/* We don't bother with setgroups here; we only need
333
* the user/group of created filesystem nodes to be
334
* correct.
335
*/
336
unowned Posix.Passwd? pw = get_user_pw ();
337
if (PosixExtra.setegid (pw.pw_gid) < 0)
338
priv_drop_failure ("setegid");
339
if (PosixExtra.seteuid (pw.pw_uid) < 0)
340
priv_drop_failure ("seteuid");
341
old_umask = Posix.umask (get_umask () | Posix.S_IWOTH);
342
}
343
344
++dropped_privileges_count;
345
}
346
347
private void
348
priv_regain_failure (string name)
349
{
350
/* It is too dangerous to carry on from this point, even if
351
* the caller has an exception handler.
352
*/
353
error ("Cannot regain privileges (%s): %s",
354
name, strerror (errno));
355
}
356
357
internal void
358
regain_privileges ()
359
{
360
--dropped_privileges_count;
361
362
if (dropped_privileges_count == 0 &&
363
Posix.getuid () == 0 && ! is_pseudo_user) {
364
if (old_umask != null)
365
Posix.umask (old_umask);
366
if (PosixExtra.seteuid (0) < 0)
367
priv_regain_failure ("seteuid");
368
if (PosixExtra.setegid (0) < 0)
369
priv_regain_failure ("setegid");
370
}
371
}
372
373
private bool
374
is_valid_link (string path)
375
{
376
if (! is_symlink (path))
377
return false;
378
379
try {
380
var target = FileUtils.read_link (path);
381
return ! target.has_prefix ("@");
382
} catch (FileError e) {
383
return false;
384
}
385
}
386
387
private List<string>
388
get_package_names_dropped () throws Error
389
{
390
var entries = new List<string> ();
391
var hidden = new Gee.HashSet<string> ();
392
for (int i = db.size - 1; i >= 0; --i) {
393
var user_db = db_for_user (db[i].root, name);
394
foreach (var entry in Click.Dir.open (user_db)) {
395
if (entries.find_custom (entry, strcmp)
396
!= null ||
397
entry in hidden)
398
continue;
399
var path = Path.build_filename (user_db, entry);
400
if (is_valid_link (path))
401
entries.prepend (entry.dup ());
402
else if (is_symlink (path))
403
hidden.add (entry.dup ());
404
}
405
406
if (name != ALL_USERS) {
407
var all_users_db = db_for_user (db[i].root,
408
ALL_USERS);
409
foreach (var entry in Click.Dir.open
410
(all_users_db)) {
411
if (entries.find_custom (entry, strcmp)
412
!= null ||
413
entry in hidden)
414
continue;
415
var path = Path.build_filename
416
(all_users_db, entry);
417
if (is_valid_link (path))
418
entries.prepend (entry.dup ());
419
else if (is_symlink (path))
420
hidden.add (entry.dup ());
421
}
422
}
423
}
424
entries.reverse ();
425
return entries;
426
}
427
428
/**
429
* get_package_names:
430
*
431
* Returns: (transfer full): A list of package names installed for
432
* this user.
433
*/
434
public List<string>
435
get_package_names () throws Error
436
{
437
drop_privileges ();
438
try {
439
return get_package_names_dropped ();
440
} finally {
441
regain_privileges ();
442
}
443
}
444
445
/**
446
* has_package_name:
447
* @package: A package name.
448
*
449
* Returns: True if this user has a version of @package registered,
450
* otherwise false.
451
*/
452
public bool
453
has_package_name (string package)
454
{
455
try {
456
get_version (package);
457
return true;
458
} catch (UserError e) {
459
return false;
460
}
461
}
462
463
/**
464
* get_version:
465
* @package: A package name.
466
*
467
* Returns: The version of @package registered for this user.
468
*/
469
public string
470
get_version (string package) throws UserError
471
{
472
for (int i = db.size - 1; i >= 0; --i) {
473
var user_db = db_for_user (db[i].root, name);
474
var path = Path.build_filename (user_db, package);
475
drop_privileges ();
476
try {
477
if (is_valid_link (path)) {
478
try {
479
var target =
480
FileUtils.read_link
481
(path);
482
return Path.get_basename
483
(target);
484
} catch (FileError e) {
485
}
486
} else if (is_symlink (path))
487
throw new UserError.HIDDEN_PACKAGE
488
("%s is hidden for user %s",
489
package, name);
490
} finally {
491
regain_privileges ();
492
}
493
494
var all_users_db = db_for_user (db[i].root, ALL_USERS);
495
path = Path.build_filename (all_users_db, package);
496
if (is_valid_link (path)) {
497
try {
498
var target = FileUtils.read_link
499
(path);
500
return Path.get_basename (target);
501
} catch (FileError e) {
502
}
503
} else if (is_symlink (path))
504
throw new UserError.HIDDEN_PACKAGE
505
("%s is hidden for all users",
506
package);
507
}
508
509
throw new UserError.NO_SUCH_PACKAGE
510
("%s does not exist in any database for user %s",
511
package, name);
512
}
513
514
/**
515
* set_version:
516
* @package: A package name.
517
* @version: A version string.
518
*
519
* Register version @version of @package for this user.
520
*/
521
public void
522
set_version (string package, string version) throws Error
523
{
524
/* Only modify the last database. */
525
var user_db = get_overlay_db ();
526
var path = Path.build_filename (user_db, package);
527
var new_path = Path.build_filename (user_db, @".$package.new");
528
ensure_db ();
529
string? old_version = null;
530
try {
531
old_version = get_version (package);
532
} catch (UserError e) {
533
}
534
drop_privileges ();
535
try {
536
var target = db.get_path (package, version);
537
bool done = false;
538
if (is_valid_link (path)) {
539
unlink_force (path);
540
try {
541
if (get_version (package) == version)
542
done = true;
543
} catch (UserError e) {
544
}
545
}
546
if (! done) {
547
symlink_force (target, new_path);
548
if (FileUtils.rename (new_path, path) < 0)
549
throw new UserError.RENAME
550
("rename %s -> %s failed: %s",
551
new_path, path,
552
strerror (errno));
553
}
554
} finally {
555
regain_privileges ();
556
}
557
if (! is_pseudo_user)
558
package_install_hooks (db, package,
559
old_version, version, name);
560
}
561
562
/**
563
* remove:
564
* @package: A package name.
565
*
566
* Remove this user's registration of @package.
567
*/
568
public void
569
remove (string package) throws Error
570
{
571
/* Only modify the last database. */
572
var user_db = get_overlay_db ();
573
var path = Path.build_filename (user_db, package);
574
string old_version;
575
if (is_valid_link (path)) {
576
var target = FileUtils.read_link (path);
577
old_version = Path.get_basename (target);
578
drop_privileges ();
579
try {
580
unlink_force (path);
581
} finally {
582
regain_privileges ();
583
}
584
} else {
585
try {
586
old_version = get_version (package);
587
} catch (UserError e) {
588
throw new UserError.NO_SUCH_PACKAGE
589
("%s does not exist in any database " +
590
"for user %s", package, name);
591
}
592
ensure_db ();
593
drop_privileges ();
594
try {
595
symlink_force (HIDDEN_VERSION, path);
596
} finally {
597
regain_privileges ();
598
}
599
}
600
if (! is_pseudo_user)
601
package_remove_hooks (db, package, old_version, name);
602
}
603
604
/**
605
* get_path:
606
* @package: A package name.
607
*
608
* Returns: The path at which @package is registered for this user.
609
*/
610
public string
611
get_path (string package) throws UserError
612
{
613
for (int i = db.size - 1; i >= 0; --i) {
614
var user_db = db_for_user (db[i].root, name);
615
var path = Path.build_filename (user_db, package);
616
if (is_valid_link (path))
617
return path;
618
else if (is_symlink (path))
619
throw new UserError.HIDDEN_PACKAGE
620
("%s is hidden for user %s",
621
package, name);
622
623
var all_users_db = db_for_user (db[i].root, ALL_USERS);
624
path = Path.build_filename (all_users_db, package);
625
if (is_valid_link (path))
626
return path;
627
else if (is_symlink (path))
628
throw new UserError.HIDDEN_PACKAGE
629
("%s is hidden for all users",
630
package);
631
}
632
633
throw new UserError.NO_SUCH_PACKAGE
634
("%s does not exist in any database for user %s",
635
package, name);
636
}
637
638
/**
639
* is_removable:
640
* @package: A package name.
641
*
642
* Returns: True if @package is removable for this user, otherwise
643
* False.
644
*/
645
public bool
646
is_removable (string package)
647
{
648
var user_db = get_overlay_db ();
649
var path = Path.build_filename (user_db, package);
650
if (FileUtils.test (path, FileTest.EXISTS))
651
return true;
652
else if (is_symlink (path))
653
/* Already hidden. */
654
return false;
655
var all_users_db = db_for_user (db.overlay, ALL_USERS);
656
path = Path.build_filename (all_users_db, package);
657
if (is_valid_link (path))
658
return true;
659
else if (is_symlink (path))
660
/* Already hidden. */
661
return false;
662
string? version = null;
663
try {
664
version = get_version (package);
665
} catch (UserError e) {
666
}
667
if (version != null)
668
/* Not in overlay database, but can be hidden. */
669
return true;
670
else
671
return false;
672
}
673
}
674
675
}
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