1 /* Cache handling for group lookup.
2 Copyright (C) 1998-2013 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)
78 bool all_written = true;
81 time_t t = time (NULL);
83 /* We allocate all data in one memory block: the iov vector,
84 the response header and the dataset itself. */
88 gr_response_header resp;
92 assert (offsetof (struct dataset, resp) == offsetof (struct datahead, data));
94 time_t timeout = MAX_TIMEOUT_VALUE;
97 if (he != NULL && errval == EAGAIN)
99 /* If we have an old record available but cannot find one
100 now because the service is not available we keep the old
101 record and make sure it does not get removed. */
102 if (reload_count != UINT_MAX)
103 /* Do not reset the value if we never not reload the record. */
104 dh->nreloads = reload_count - 1;
106 /* Reload with the same time-to-live value. */
107 timeout = dh->timeout = t + db->postimeout;
113 /* We have no data. This means we send the standard reply for this
115 total = sizeof (notfound);
118 written = TEMP_FAILURE_RETRY (send (fd, ¬found, total,
123 /* If we have a transient error or cannot permanently store
124 the result, so be it. */
125 if (errno == EAGAIN || __builtin_expect (db->negtimeout == 0, 0))
127 /* Mark the old entry as obsolete. */
131 else if ((dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len, 1)) != NULL)
133 dataset->head.allocsize = sizeof (struct dataset) + req->key_len;
134 dataset->head.recsize = total;
135 dataset->head.notfound = true;
136 dataset->head.nreloads = 0;
137 dataset->head.usable = true;
139 /* Compute the timeout time. */
140 timeout = dataset->head.timeout = t + db->negtimeout;
142 /* This is the reply. */
143 memcpy (&dataset->resp, ¬found, total);
145 /* Copy the key data. */
146 memcpy (dataset->strdata, key, req->key_len);
148 /* If necessary, we also propagate the data to disk. */
152 uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
153 msync ((void *) pval,
154 ((uintptr_t) dataset & pagesize_m1)
155 + sizeof (struct dataset) + req->key_len, MS_ASYNC);
158 (void) cache_add (req->type, &dataset->strdata, req->key_len,
159 &dataset->head, true, db, owner, he == NULL);
161 pthread_rwlock_unlock (&db->lock);
163 /* Mark the old entry as obsolete. */
171 /* Determine the I/O structure. */
172 size_t gr_name_len = strlen (grp->gr_name) + 1;
173 size_t gr_passwd_len = strlen (grp->gr_passwd) + 1;
174 size_t gr_mem_cnt = 0;
175 uint32_t *gr_mem_len;
176 size_t gr_mem_len_total = 0;
179 const size_t key_len = strlen (key);
180 const size_t buf_len = 3 * sizeof (grp->gr_gid) + key_len + 1;
181 size_t alloca_used = 0;
182 char *buf = alloca_account (buf_len, alloca_used);
186 /* We need this to insert the `bygid' entry. */
188 n = snprintf (buf, buf_len, "%d%c%n%s", grp->gr_gid, '\0',
189 &key_offset, (char *) key) + 1;
191 /* Determine the length of all members. */
192 while (grp->gr_mem[gr_mem_cnt])
194 gr_mem_len = alloca_account (gr_mem_cnt * sizeof (uint32_t), alloca_used);
195 for (gr_mem_cnt = 0; grp->gr_mem[gr_mem_cnt]; ++gr_mem_cnt)
197 gr_mem_len[gr_mem_cnt] = strlen (grp->gr_mem[gr_mem_cnt]) + 1;
198 gr_mem_len_total += gr_mem_len[gr_mem_cnt];
201 written = total = (offsetof (struct dataset, strdata)
202 + gr_mem_cnt * sizeof (uint32_t)
203 + gr_name_len + gr_passwd_len + gr_mem_len_total);
205 /* If we refill the cache, first assume the reconrd did not
206 change. Allocate memory on the cache since it is likely
207 discarded anyway. If it turns out to be necessary to have a
208 new record we can still allocate real memory. */
209 bool dataset_temporary = false;
210 bool dataset_malloced = false;
214 dataset = (struct dataset *) mempool_alloc (db, total + n, 1);
218 /* We cannot permanently add the result in the moment. But
219 we can provide the result as is. Store the data in some
221 if (! __libc_use_alloca (alloca_used + total + n))
223 dataset = malloc (total + n);
224 /* Perhaps we should log a message that we were unable
225 to allocate memory for a large request. */
228 dataset_malloced = true;
231 dataset = alloca_account (total + n, alloca_used);
233 /* We cannot add this record to the permanent database. */
234 dataset_temporary = true;
237 dataset->head.allocsize = total + n;
238 dataset->head.recsize = total - offsetof (struct dataset, resp);
239 dataset->head.notfound = false;
240 dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1);
241 dataset->head.usable = true;
243 /* Compute the timeout time. */
244 timeout = dataset->head.timeout = t + db->postimeout;
246 dataset->resp.version = NSCD_VERSION;
247 dataset->resp.found = 1;
248 dataset->resp.gr_name_len = gr_name_len;
249 dataset->resp.gr_passwd_len = gr_passwd_len;
250 dataset->resp.gr_gid = grp->gr_gid;
251 dataset->resp.gr_mem_cnt = gr_mem_cnt;
253 cp = dataset->strdata;
255 /* This is the member string length array. */
256 cp = mempcpy (cp, gr_mem_len, gr_mem_cnt * sizeof (uint32_t));
258 cp = mempcpy (cp, grp->gr_name, gr_name_len);
259 cp = mempcpy (cp, grp->gr_passwd, gr_passwd_len);
261 for (cnt = 0; cnt < gr_mem_cnt; ++cnt)
262 cp = mempcpy (cp, grp->gr_mem[cnt], gr_mem_len[cnt]);
264 /* Finally the stringified GID value. */
266 char *key_copy = cp + key_offset;
267 assert (key_copy == (char *) rawmemchr (cp, '\0') + 1);
269 assert (cp == dataset->strdata + total - offsetof (struct dataset,
272 /* Now we can determine whether on refill we have to create a new
278 if (total + n == dh->allocsize
279 && total - offsetof (struct dataset, resp) == dh->recsize
280 && memcmp (&dataset->resp, dh->data,
281 dh->allocsize - offsetof (struct dataset, resp)) == 0)
283 /* The data has not changed. We will just bump the
284 timeout value. Note that the new record has been
285 allocated on the stack and need not be freed. */
286 dh->timeout = dataset->head.timeout;
289 /* If the new record was allocated via malloc, then we must free
291 if (dataset_malloced)
296 /* We have to create a new record. Just allocate
297 appropriate memory and copy it. */
299 = (struct dataset *) mempool_alloc (db, total + n, 1);
302 /* Adjust pointers into the memory block. */
303 gr_name = (char *) newp + (gr_name - (char *) dataset);
304 cp = (char *) newp + (cp - (char *) dataset);
305 key_copy = (char *) newp + (key_copy - (char *) dataset);
307 dataset = memcpy (newp, dataset, total + n);
308 dataset_temporary = false;
311 /* Mark the old record as obsolete. */
317 /* We write the dataset before inserting it to the database
318 since while inserting this thread might block and so would
319 unnecessarily let the receiver wait. */
323 if (__builtin_expect (db->mmap_used, 1) && ! dataset_temporary)
325 assert (db->wr_fd != -1);
326 assert ((char *) &dataset->resp > (char *) db->data);
327 assert ((char *) dataset - (char *) db->head
329 <= (sizeof (struct database_pers_head)
330 + db->head->module * sizeof (ref_t)
331 + db->head->data_size));
332 written = sendfileall (fd, db->wr_fd,
333 (char *) &dataset->resp
334 - (char *) db->head, dataset->head.recsize);
335 # ifndef __ASSUME_SENDFILE
336 if (written == -1 && errno == ENOSYS)
341 # ifndef __ASSUME_SENDFILE
345 written = writeall (fd, &dataset->resp, dataset->head.recsize);
347 if (written != dataset->head.recsize)
351 /* Add the record to the database. But only if it has not been
352 stored on the stack. */
353 if (! dataset_temporary)
355 /* If necessary, we also propagate the data to disk. */
359 uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
360 msync ((void *) pval,
361 ((uintptr_t) dataset & pagesize_m1) + total + n,
365 /* NB: in the following code we always must add the entry
366 marked with FIRST first. Otherwise we end up with
367 dangling "pointers" in case a latter hash entry cannot be
371 /* If the request was by GID, add that entry first. */
372 if (req->type == GETGRBYGID)
374 if (cache_add (GETGRBYGID, cp, key_offset, &dataset->head, true,
375 db, owner, he == NULL) < 0)
380 /* If the key is different from the name add a separate entry. */
381 else if (strcmp (key_copy, gr_name) != 0)
383 if (cache_add (GETGRBYNAME, key_copy, key_len + 1,
384 &dataset->head, true, db, owner, he == NULL) < 0)
390 /* We have to add the value for both, byname and byuid. */
391 if ((req->type == GETGRBYNAME || db->propagate)
392 && __builtin_expect (cache_add (GETGRBYNAME, gr_name,
394 &dataset->head, first, db, owner,
398 if (req->type == GETGRBYNAME && db->propagate)
399 (void) cache_add (GETGRBYGID, cp, key_offset, &dataset->head,
400 false, db, owner, false);
404 pthread_rwlock_unlock (&db->lock);
408 if (__builtin_expect (!all_written, 0) && debug_level > 0)
411 dbg_log (_("short write in %s: %s"), __FUNCTION__,
412 strerror_r (errno, buf, sizeof (buf)));
427 lookup (int type, union keytype key, struct group *resultbufp, char *buffer,
428 size_t buflen, struct group **grp)
430 if (type == GETGRBYNAME)
431 return __getgrnam_r (key.v, resultbufp, buffer, buflen, grp);
433 return __getgrgid_r (key.g, resultbufp, buffer, buflen, grp);
438 addgrbyX (struct database_dyn *db, int fd, request_header *req,
439 union keytype key, const char *keystr, uid_t uid,
440 struct hashentry *he, struct datahead *dh)
442 /* Search for the entry matching the key. Please note that we don't
443 look again in the table whether the dataset is now available. We
444 simply insert it. It does not matter if it is in there twice. The
445 pruning function only will look at the timestamp. */
446 size_t buflen = 1024;
447 char *buffer = (char *) alloca (buflen);
448 struct group resultbuf;
450 bool use_malloc = false;
453 if (__builtin_expect (debug_level > 0, 0))
456 dbg_log (_("Haven't found \"%s\" in group cache!"), keystr);
458 dbg_log (_("Reloading \"%s\" in group cache!"), keystr);
461 while (lookup (req->type, key, &resultbuf, buffer, buflen, &grp) != 0
462 && (errval = errno) == ERANGE)
466 if (__builtin_expect (buflen > 32768, 0))
468 char *old_buffer = buffer;
470 buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen);
473 /* We ran out of memory. We cannot do anything but
474 sending a negative response. In reality this should
479 /* We set the error to indicate this is (possibly) a
480 temporary error and that it does not mean the entry
481 is not available at all. */
488 /* Allocate a new buffer on the stack. If possible combine it
489 with the previously allocated buffer. */
490 buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen);
493 time_t timeout = cache_addgr (db, fd, req, keystr, grp, uid, he, dh, errval);
503 addgrbyname (struct database_dyn *db, int fd, request_header *req,
504 void *key, uid_t uid)
506 union keytype u = { .v = key };
508 addgrbyX (db, fd, req, u, key, uid, NULL, NULL);
513 readdgrbyname (struct database_dyn *db, struct hashentry *he,
521 union keytype u = { .v = db->data + he->key };
523 return addgrbyX (db, -1, &req, u, db->data + he->key, he->owner, he, dh);
528 addgrbygid (struct database_dyn *db, int fd, request_header *req,
529 void *key, uid_t uid)
532 gid_t gid = strtoul ((char *) key, &ep, 10);
534 if (*(char *) key == '\0' || *ep != '\0') /* invalid numeric uid */
537 dbg_log (_("Invalid numeric gid \"%s\"!"), (char *) key);
543 union keytype u = { .g = gid };
545 addgrbyX (db, fd, req, u, key, uid, NULL, NULL);
550 readdgrbygid (struct database_dyn *db, struct hashentry *he,
554 gid_t gid = strtoul (db->data + he->key, &ep, 10);
556 /* Since the key has been added before it must be OK. */
557 assert (*(db->data + he->key) != '\0' && *ep == '\0');
564 union keytype u = { .g = gid };
566 return addgrbyX (db, -1, &req, u, db->data + he->key, he->owner, he, dh);