1 /* Cache handling for group lookup.
2 Copyright (C) 1998-2008, 2009, 2011, 2012 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published
8 by the Free Software Foundation; version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, see <http://www.gnu.org/licenses/>. */
33 #include <sys/socket.h>
34 #include <stackinfo.h>
39 # include <kernel-features.h>
42 /* This is the standard reply in case the service is disabled. */
43 static const gr_response_header disabled =
45 .version = NSCD_VERSION,
53 /* This is the struct describing how to write this record. */
54 const struct iovec grp_iov_disabled =
56 .iov_base = (void *) &disabled,
57 .iov_len = sizeof (disabled)
61 /* This is the standard reply in case we haven't found the dataset. */
62 static const gr_response_header notfound =
64 .version = NSCD_VERSION,
74 cache_addgr (struct database_dyn *db, int fd, request_header *req,
75 const void *key, struct group *grp, uid_t owner,
76 struct hashentry *const he, struct datahead *dh, int errval)
80 time_t t = time (NULL);
82 /* We allocate all data in one memory block: the iov vector,
83 the response header and the dataset itself. */
87 gr_response_header resp;
91 assert (offsetof (struct dataset, resp) == offsetof (struct datahead, data));
93 time_t timeout = MAX_TIMEOUT_VALUE;
96 if (he != NULL && errval == EAGAIN)
98 /* If we have an old record available but cannot find one
99 now because the service is not available we keep the old
100 record and make sure it does not get removed. */
101 if (reload_count != UINT_MAX)
102 /* Do not reset the value if we never not reload the record. */
103 dh->nreloads = reload_count - 1;
105 /* Reload with the same time-to-live value. */
106 timeout = dh->timeout = t + db->postimeout;
112 /* We have no data. This means we send the standard reply for this
114 total = sizeof (notfound);
117 written = TEMP_FAILURE_RETRY (send (fd, ¬found, total,
122 /* If we have a transient error or cannot permanently store
123 the result, so be it. */
124 if (errno == EAGAIN || __builtin_expect (db->negtimeout == 0, 0))
126 /* Mark the old entry as obsolete. */
130 else if ((dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len, 1)) != NULL)
132 dataset->head.allocsize = sizeof (struct dataset) + req->key_len;
133 dataset->head.recsize = total;
134 dataset->head.notfound = true;
135 dataset->head.nreloads = 0;
136 dataset->head.usable = true;
138 /* Compute the timeout time. */
139 timeout = dataset->head.timeout = t + db->negtimeout;
141 /* This is the reply. */
142 memcpy (&dataset->resp, ¬found, total);
144 /* Copy the key data. */
145 memcpy (dataset->strdata, key, req->key_len);
147 /* If necessary, we also propagate the data to disk. */
151 uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
152 msync ((void *) pval,
153 ((uintptr_t) dataset & pagesize_m1)
154 + sizeof (struct dataset) + req->key_len, MS_ASYNC);
157 (void) cache_add (req->type, &dataset->strdata, req->key_len,
158 &dataset->head, true, db, owner, he == NULL);
160 pthread_rwlock_unlock (&db->lock);
162 /* Mark the old entry as obsolete. */
170 /* Determine the I/O structure. */
171 size_t gr_name_len = strlen (grp->gr_name) + 1;
172 size_t gr_passwd_len = strlen (grp->gr_passwd) + 1;
173 size_t gr_mem_cnt = 0;
174 uint32_t *gr_mem_len;
175 size_t gr_mem_len_total = 0;
178 const size_t key_len = strlen (key);
179 const size_t buf_len = 3 * sizeof (grp->gr_gid) + key_len + 1;
180 char *buf = alloca (buf_len);
184 /* We need this to insert the `bygid' entry. */
186 n = snprintf (buf, buf_len, "%d%c%n%s", grp->gr_gid, '\0',
187 &key_offset, (char *) key) + 1;
189 /* Determine the length of all members. */
190 while (grp->gr_mem[gr_mem_cnt])
192 gr_mem_len = (uint32_t *) alloca (gr_mem_cnt * sizeof (uint32_t));
193 for (gr_mem_cnt = 0; grp->gr_mem[gr_mem_cnt]; ++gr_mem_cnt)
195 gr_mem_len[gr_mem_cnt] = strlen (grp->gr_mem[gr_mem_cnt]) + 1;
196 gr_mem_len_total += gr_mem_len[gr_mem_cnt];
199 written = total = (offsetof (struct dataset, strdata)
200 + gr_mem_cnt * sizeof (uint32_t)
201 + gr_name_len + gr_passwd_len + gr_mem_len_total);
203 /* If we refill the cache, first assume the reconrd did not
204 change. Allocate memory on the cache since it is likely
205 discarded anyway. If it turns out to be necessary to have a
206 new record we can still allocate real memory. */
207 bool alloca_used = false;
211 dataset = (struct dataset *) mempool_alloc (db, total + n, 1);
215 /* We cannot permanently add the result in the moment. But
216 we can provide the result as is. Store the data in some
218 dataset = (struct dataset *) alloca (total + n);
220 /* We cannot add this record to the permanent database. */
224 dataset->head.allocsize = total + n;
225 dataset->head.recsize = total - offsetof (struct dataset, resp);
226 dataset->head.notfound = false;
227 dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1);
228 dataset->head.usable = true;
230 /* Compute the timeout time. */
231 timeout = dataset->head.timeout = t + db->postimeout;
233 dataset->resp.version = NSCD_VERSION;
234 dataset->resp.found = 1;
235 dataset->resp.gr_name_len = gr_name_len;
236 dataset->resp.gr_passwd_len = gr_passwd_len;
237 dataset->resp.gr_gid = grp->gr_gid;
238 dataset->resp.gr_mem_cnt = gr_mem_cnt;
240 cp = dataset->strdata;
242 /* This is the member string length array. */
243 cp = mempcpy (cp, gr_mem_len, gr_mem_cnt * sizeof (uint32_t));
245 cp = mempcpy (cp, grp->gr_name, gr_name_len);
246 cp = mempcpy (cp, grp->gr_passwd, gr_passwd_len);
248 for (cnt = 0; cnt < gr_mem_cnt; ++cnt)
249 cp = mempcpy (cp, grp->gr_mem[cnt], gr_mem_len[cnt]);
251 /* Finally the stringified GID value. */
253 char *key_copy = cp + key_offset;
254 assert (key_copy == (char *) rawmemchr (cp, '\0') + 1);
256 assert (cp == dataset->strdata + total - offsetof (struct dataset,
259 /* Now we can determine whether on refill we have to create a new
265 if (total + n == dh->allocsize
266 && total - offsetof (struct dataset, resp) == dh->recsize
267 && memcmp (&dataset->resp, dh->data,
268 dh->allocsize - offsetof (struct dataset, resp)) == 0)
270 /* The data has not changed. We will just bump the
271 timeout value. Note that the new record has been
272 allocated on the stack and need not be freed. */
273 dh->timeout = dataset->head.timeout;
278 /* We have to create a new record. Just allocate
279 appropriate memory and copy it. */
281 = (struct dataset *) mempool_alloc (db, total + n, 1);
284 /* Adjust pointers into the memory block. */
285 gr_name = (char *) newp + (gr_name - (char *) dataset);
286 cp = (char *) newp + (cp - (char *) dataset);
287 key_copy = (char *) newp + (key_copy - (char *) dataset);
289 dataset = memcpy (newp, dataset, total + n);
293 /* Mark the old record as obsolete. */
299 /* We write the dataset before inserting it to the database
300 since while inserting this thread might block and so would
301 unnecessarily let the receiver wait. */
305 if (__builtin_expect (db->mmap_used, 1) && !alloca_used)
307 assert (db->wr_fd != -1);
308 assert ((char *) &dataset->resp > (char *) db->data);
309 assert ((char *) dataset - (char *) db->head
311 <= (sizeof (struct database_pers_head)
312 + db->head->module * sizeof (ref_t)
313 + db->head->data_size));
314 written = sendfileall (fd, db->wr_fd,
315 (char *) &dataset->resp
316 - (char *) db->head, dataset->head.recsize);
317 # ifndef __ASSUME_SENDFILE
318 if (written == -1 && errno == ENOSYS)
323 # ifndef __ASSUME_SENDFILE
327 written = writeall (fd, &dataset->resp, dataset->head.recsize);
330 /* Add the record to the database. But only if it has not been
331 stored on the stack. */
334 /* If necessary, we also propagate the data to disk. */
338 uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
339 msync ((void *) pval,
340 ((uintptr_t) dataset & pagesize_m1) + total + n,
344 /* NB: in the following code we always must add the entry
345 marked with FIRST first. Otherwise we end up with
346 dangling "pointers" in case a latter hash entry cannot be
350 /* If the request was by GID, add that entry first. */
351 if (req->type == GETGRBYGID)
353 if (cache_add (GETGRBYGID, cp, key_offset, &dataset->head, true,
354 db, owner, he == NULL) < 0)
359 /* If the key is different from the name add a separate entry. */
360 else if (strcmp (key_copy, gr_name) != 0)
362 if (cache_add (GETGRBYNAME, key_copy, key_len + 1,
363 &dataset->head, true, db, owner, he == NULL) < 0)
369 /* We have to add the value for both, byname and byuid. */
370 if ((req->type == GETGRBYNAME || db->propagate)
371 && __builtin_expect (cache_add (GETGRBYNAME, gr_name,
373 &dataset->head, first, db, owner,
377 if (req->type == GETGRBYNAME && db->propagate)
378 (void) cache_add (GETGRBYGID, cp, key_offset, &dataset->head,
379 false, db, owner, false);
383 pthread_rwlock_unlock (&db->lock);
387 if (__builtin_expect (written != total, 0) && debug_level > 0)
390 dbg_log (_("short write in %s: %s"), __FUNCTION__,
391 strerror_r (errno, buf, sizeof (buf)));
406 lookup (int type, union keytype key, struct group *resultbufp, char *buffer,
407 size_t buflen, struct group **grp)
409 if (type == GETGRBYNAME)
410 return __getgrnam_r (key.v, resultbufp, buffer, buflen, grp);
412 return __getgrgid_r (key.g, resultbufp, buffer, buflen, grp);
417 addgrbyX (struct database_dyn *db, int fd, request_header *req,
418 union keytype key, const char *keystr, uid_t uid,
419 struct hashentry *he, struct datahead *dh)
421 /* Search for the entry matching the key. Please note that we don't
422 look again in the table whether the dataset is now available. We
423 simply insert it. It does not matter if it is in there twice. The
424 pruning function only will look at the timestamp. */
425 size_t buflen = 1024;
426 char *buffer = (char *) alloca (buflen);
427 struct group resultbuf;
429 bool use_malloc = false;
432 if (__builtin_expect (debug_level > 0, 0))
435 dbg_log (_("Haven't found \"%s\" in group cache!"), keystr);
437 dbg_log (_("Reloading \"%s\" in group cache!"), keystr);
440 while (lookup (req->type, key, &resultbuf, buffer, buflen, &grp) != 0
441 && (errval = errno) == ERANGE)
445 if (__builtin_expect (buflen > 32768, 0))
447 char *old_buffer = buffer;
449 buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen);
452 /* We ran out of memory. We cannot do anything but
453 sending a negative response. In reality this should
458 /* We set the error to indicate this is (possibly) a
459 temporary error and that it does not mean the entry
460 is not available at all. */
467 /* Allocate a new buffer on the stack. If possible combine it
468 with the previously allocated buffer. */
469 buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen);
472 time_t timeout = cache_addgr (db, fd, req, keystr, grp, uid, he, dh, errval);
482 addgrbyname (struct database_dyn *db, int fd, request_header *req,
483 void *key, uid_t uid)
485 union keytype u = { .v = key };
487 addgrbyX (db, fd, req, u, key, uid, NULL, NULL);
492 readdgrbyname (struct database_dyn *db, struct hashentry *he,
500 union keytype u = { .v = db->data + he->key };
502 return addgrbyX (db, -1, &req, u, db->data + he->key, he->owner, he, dh);
507 addgrbygid (struct database_dyn *db, int fd, request_header *req,
508 void *key, uid_t uid)
511 gid_t gid = strtoul ((char *) key, &ep, 10);
513 if (*(char *) key == '\0' || *ep != '\0') /* invalid numeric uid */
516 dbg_log (_("Invalid numeric gid \"%s\"!"), (char *) key);
522 union keytype u = { .g = gid };
524 addgrbyX (db, fd, req, u, key, uid, NULL, NULL);
529 readdgrbygid (struct database_dyn *db, struct hashentry *he,
533 gid_t gid = strtoul (db->data + he->key, &ep, 10);
535 /* Since the key has been added before it must be OK. */
536 assert (*(db->data + he->key) != '\0' && *ep == '\0');
543 union keytype u = { .g = gid };
545 return addgrbyX (db, -1, &req, u, db->data + he->key, he->owner, he, dh);