564 lines
16 KiB
C
564 lines
16 KiB
C
/* Cache handling for group lookup.
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Copyright (C) 1998-2008, 2009, 2011, 2012 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published
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by the Free Software Foundation; version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, see <http://www.gnu.org/licenses/>. */
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#include <alloca.h>
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#include <assert.h>
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#include <errno.h>
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#include <error.h>
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#include <grp.h>
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#include <libintl.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <sys/socket.h>
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#include <stackinfo.h>
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#include "nscd.h"
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#include "dbg_log.h"
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#ifdef HAVE_SENDFILE
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# include <kernel-features.h>
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#endif
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/* This is the standard reply in case the service is disabled. */
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static const gr_response_header disabled =
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{
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.version = NSCD_VERSION,
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.found = -1,
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.gr_name_len = 0,
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.gr_passwd_len = 0,
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.gr_gid = -1,
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.gr_mem_cnt = 0,
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};
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/* This is the struct describing how to write this record. */
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const struct iovec grp_iov_disabled =
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{
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.iov_base = (void *) &disabled,
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.iov_len = sizeof (disabled)
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};
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/* This is the standard reply in case we haven't found the dataset. */
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static const gr_response_header notfound =
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{
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.version = NSCD_VERSION,
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.found = 0,
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.gr_name_len = 0,
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.gr_passwd_len = 0,
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.gr_gid = -1,
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.gr_mem_cnt = 0,
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};
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static time_t
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cache_addgr (struct database_dyn *db, int fd, request_header *req,
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const void *key, struct group *grp, uid_t owner,
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struct hashentry *const he, struct datahead *dh, int errval)
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{
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ssize_t total;
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ssize_t written;
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time_t t = time (NULL);
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/* We allocate all data in one memory block: the iov vector,
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the response header and the dataset itself. */
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struct dataset
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{
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struct datahead head;
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gr_response_header resp;
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char strdata[0];
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} *dataset;
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assert (offsetof (struct dataset, resp) == offsetof (struct datahead, data));
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time_t timeout = MAX_TIMEOUT_VALUE;
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if (grp == NULL)
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{
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if (he != NULL && errval == EAGAIN)
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{
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/* If we have an old record available but cannot find one
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now because the service is not available we keep the old
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record and make sure it does not get removed. */
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if (reload_count != UINT_MAX)
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/* Do not reset the value if we never not reload the record. */
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dh->nreloads = reload_count - 1;
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/* Reload with the same time-to-live value. */
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timeout = dh->timeout = t + db->postimeout;
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written = total = 0;
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}
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else
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{
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/* We have no data. This means we send the standard reply for this
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case. */
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total = sizeof (notfound);
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if (fd != -1)
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written = TEMP_FAILURE_RETRY (send (fd, ¬found, total,
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MSG_NOSIGNAL));
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else
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written = total;
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/* If we have a transient error or cannot permanently store
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the result, so be it. */
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if (errno == EAGAIN || __builtin_expect (db->negtimeout == 0, 0))
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{
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/* Mark the old entry as obsolete. */
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if (dh != NULL)
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dh->usable = false;
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}
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else if ((dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len, 1)) != NULL)
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{
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dataset->head.allocsize = sizeof (struct dataset) + req->key_len;
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dataset->head.recsize = total;
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dataset->head.notfound = true;
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dataset->head.nreloads = 0;
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dataset->head.usable = true;
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/* Compute the timeout time. */
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timeout = dataset->head.timeout = t + db->negtimeout;
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/* This is the reply. */
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memcpy (&dataset->resp, ¬found, total);
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/* Copy the key data. */
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memcpy (dataset->strdata, key, req->key_len);
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/* If necessary, we also propagate the data to disk. */
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if (db->persistent)
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{
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// XXX async OK?
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uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
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msync ((void *) pval,
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((uintptr_t) dataset & pagesize_m1)
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+ sizeof (struct dataset) + req->key_len, MS_ASYNC);
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}
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(void) cache_add (req->type, &dataset->strdata, req->key_len,
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&dataset->head, true, db, owner, he == NULL);
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pthread_rwlock_unlock (&db->lock);
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/* Mark the old entry as obsolete. */
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if (dh != NULL)
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dh->usable = false;
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}
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}
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}
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else
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{
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/* Determine the I/O structure. */
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size_t gr_name_len = strlen (grp->gr_name) + 1;
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size_t gr_passwd_len = strlen (grp->gr_passwd) + 1;
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size_t gr_mem_cnt = 0;
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uint32_t *gr_mem_len;
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size_t gr_mem_len_total = 0;
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char *gr_name;
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char *cp;
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const size_t key_len = strlen (key);
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const size_t buf_len = 3 * sizeof (grp->gr_gid) + key_len + 1;
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size_t alloca_used = 0;
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char *buf = alloca_account (buf_len, alloca_used);
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ssize_t n;
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size_t cnt;
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/* We need this to insert the `bygid' entry. */
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int key_offset;
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n = snprintf (buf, buf_len, "%d%c%n%s", grp->gr_gid, '\0',
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&key_offset, (char *) key) + 1;
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/* Determine the length of all members. */
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while (grp->gr_mem[gr_mem_cnt])
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++gr_mem_cnt;
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gr_mem_len = alloca_account (gr_mem_cnt * sizeof (uint32_t), alloca_used);
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for (gr_mem_cnt = 0; grp->gr_mem[gr_mem_cnt]; ++gr_mem_cnt)
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{
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gr_mem_len[gr_mem_cnt] = strlen (grp->gr_mem[gr_mem_cnt]) + 1;
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gr_mem_len_total += gr_mem_len[gr_mem_cnt];
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}
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written = total = (offsetof (struct dataset, strdata)
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+ gr_mem_cnt * sizeof (uint32_t)
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+ gr_name_len + gr_passwd_len + gr_mem_len_total);
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/* If we refill the cache, first assume the reconrd did not
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change. Allocate memory on the cache since it is likely
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discarded anyway. If it turns out to be necessary to have a
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new record we can still allocate real memory. */
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bool dataset_temporary = false;
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bool dataset_malloced = false;
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dataset = NULL;
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if (he == NULL)
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dataset = (struct dataset *) mempool_alloc (db, total + n, 1);
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if (dataset == NULL)
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{
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/* We cannot permanently add the result in the moment. But
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we can provide the result as is. Store the data in some
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temporary memory. */
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if (! __libc_use_alloca (alloca_used + total + n))
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{
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dataset = malloc (total + n);
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/* Perhaps we should log a message that we were unable
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to allocate memory for a large request. */
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if (dataset == NULL)
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goto out;
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dataset_malloced = true;
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}
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else
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dataset = alloca_account (total + n, alloca_used);
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/* We cannot add this record to the permanent database. */
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dataset_temporary = true;
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}
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dataset->head.allocsize = total + n;
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dataset->head.recsize = total - offsetof (struct dataset, resp);
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dataset->head.notfound = false;
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dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1);
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dataset->head.usable = true;
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/* Compute the timeout time. */
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timeout = dataset->head.timeout = t + db->postimeout;
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dataset->resp.version = NSCD_VERSION;
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dataset->resp.found = 1;
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dataset->resp.gr_name_len = gr_name_len;
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dataset->resp.gr_passwd_len = gr_passwd_len;
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dataset->resp.gr_gid = grp->gr_gid;
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dataset->resp.gr_mem_cnt = gr_mem_cnt;
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cp = dataset->strdata;
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/* This is the member string length array. */
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cp = mempcpy (cp, gr_mem_len, gr_mem_cnt * sizeof (uint32_t));
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gr_name = cp;
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cp = mempcpy (cp, grp->gr_name, gr_name_len);
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cp = mempcpy (cp, grp->gr_passwd, gr_passwd_len);
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for (cnt = 0; cnt < gr_mem_cnt; ++cnt)
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cp = mempcpy (cp, grp->gr_mem[cnt], gr_mem_len[cnt]);
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/* Finally the stringified GID value. */
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memcpy (cp, buf, n);
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char *key_copy = cp + key_offset;
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assert (key_copy == (char *) rawmemchr (cp, '\0') + 1);
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assert (cp == dataset->strdata + total - offsetof (struct dataset,
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strdata));
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/* Now we can determine whether on refill we have to create a new
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record or not. */
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if (he != NULL)
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{
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assert (fd == -1);
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if (total + n == dh->allocsize
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&& total - offsetof (struct dataset, resp) == dh->recsize
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&& memcmp (&dataset->resp, dh->data,
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dh->allocsize - offsetof (struct dataset, resp)) == 0)
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{
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/* The data has not changed. We will just bump the
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timeout value. Note that the new record has been
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allocated on the stack and need not be freed. */
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dh->timeout = dataset->head.timeout;
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++dh->nreloads;
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/* If the new record was allocated via malloc, then we must free
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it here. */
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if (dataset_malloced)
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free (dataset);
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}
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else
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{
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/* We have to create a new record. Just allocate
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appropriate memory and copy it. */
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struct dataset *newp
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= (struct dataset *) mempool_alloc (db, total + n, 1);
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if (newp != NULL)
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{
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/* Adjust pointers into the memory block. */
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gr_name = (char *) newp + (gr_name - (char *) dataset);
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cp = (char *) newp + (cp - (char *) dataset);
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key_copy = (char *) newp + (key_copy - (char *) dataset);
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dataset = memcpy (newp, dataset, total + n);
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dataset_temporary = false;
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}
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/* Mark the old record as obsolete. */
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dh->usable = false;
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}
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}
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else
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{
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/* We write the dataset before inserting it to the database
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since while inserting this thread might block and so would
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unnecessarily let the receiver wait. */
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assert (fd != -1);
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#ifdef HAVE_SENDFILE
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if (__builtin_expect (db->mmap_used, 1) && ! dataset_temporary)
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{
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assert (db->wr_fd != -1);
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assert ((char *) &dataset->resp > (char *) db->data);
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assert ((char *) dataset - (char *) db->head
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+ total
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<= (sizeof (struct database_pers_head)
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+ db->head->module * sizeof (ref_t)
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+ db->head->data_size));
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written = sendfileall (fd, db->wr_fd,
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(char *) &dataset->resp
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- (char *) db->head, dataset->head.recsize);
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# ifndef __ASSUME_SENDFILE
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if (written == -1 && errno == ENOSYS)
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goto use_write;
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# endif
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}
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else
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# ifndef __ASSUME_SENDFILE
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use_write:
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# endif
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#endif
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written = writeall (fd, &dataset->resp, dataset->head.recsize);
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}
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/* Add the record to the database. But only if it has not been
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stored on the stack. */
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if (! dataset_temporary)
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{
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/* If necessary, we also propagate the data to disk. */
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if (db->persistent)
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{
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// XXX async OK?
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uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
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msync ((void *) pval,
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((uintptr_t) dataset & pagesize_m1) + total + n,
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MS_ASYNC);
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}
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/* NB: in the following code we always must add the entry
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marked with FIRST first. Otherwise we end up with
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dangling "pointers" in case a latter hash entry cannot be
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added. */
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bool first = true;
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/* If the request was by GID, add that entry first. */
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if (req->type == GETGRBYGID)
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{
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if (cache_add (GETGRBYGID, cp, key_offset, &dataset->head, true,
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db, owner, he == NULL) < 0)
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goto out;
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first = false;
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}
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/* If the key is different from the name add a separate entry. */
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else if (strcmp (key_copy, gr_name) != 0)
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{
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if (cache_add (GETGRBYNAME, key_copy, key_len + 1,
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&dataset->head, true, db, owner, he == NULL) < 0)
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goto out;
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first = false;
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}
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/* We have to add the value for both, byname and byuid. */
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if ((req->type == GETGRBYNAME || db->propagate)
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&& __builtin_expect (cache_add (GETGRBYNAME, gr_name,
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gr_name_len,
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&dataset->head, first, db, owner,
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he == NULL)
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== 0, 1))
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{
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if (req->type == GETGRBYNAME && db->propagate)
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(void) cache_add (GETGRBYGID, cp, key_offset, &dataset->head,
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false, db, owner, false);
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}
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out:
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pthread_rwlock_unlock (&db->lock);
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}
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}
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if (__builtin_expect (written != total, 0) && debug_level > 0)
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{
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char buf[256];
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dbg_log (_("short write in %s: %s"), __FUNCTION__,
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strerror_r (errno, buf, sizeof (buf)));
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}
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return timeout;
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}
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union keytype
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{
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void *v;
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gid_t g;
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};
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static int
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lookup (int type, union keytype key, struct group *resultbufp, char *buffer,
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size_t buflen, struct group **grp)
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{
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if (type == GETGRBYNAME)
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return __getgrnam_r (key.v, resultbufp, buffer, buflen, grp);
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else
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return __getgrgid_r (key.g, resultbufp, buffer, buflen, grp);
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}
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static time_t
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addgrbyX (struct database_dyn *db, int fd, request_header *req,
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union keytype key, const char *keystr, uid_t uid,
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struct hashentry *he, struct datahead *dh)
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{
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/* Search for the entry matching the key. Please note that we don't
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look again in the table whether the dataset is now available. We
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simply insert it. It does not matter if it is in there twice. The
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pruning function only will look at the timestamp. */
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size_t buflen = 1024;
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char *buffer = (char *) alloca (buflen);
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struct group resultbuf;
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struct group *grp;
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bool use_malloc = false;
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int errval = 0;
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if (__builtin_expect (debug_level > 0, 0))
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{
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if (he == NULL)
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dbg_log (_("Haven't found \"%s\" in group cache!"), keystr);
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else
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dbg_log (_("Reloading \"%s\" in group cache!"), keystr);
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}
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while (lookup (req->type, key, &resultbuf, buffer, buflen, &grp) != 0
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&& (errval = errno) == ERANGE)
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{
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errno = 0;
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if (__builtin_expect (buflen > 32768, 0))
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{
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char *old_buffer = buffer;
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buflen *= 2;
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buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen);
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if (buffer == NULL)
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{
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/* We ran out of memory. We cannot do anything but
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sending a negative response. In reality this should
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never happen. */
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grp = NULL;
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buffer = old_buffer;
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/* We set the error to indicate this is (possibly) a
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temporary error and that it does not mean the entry
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is not available at all. */
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errval = EAGAIN;
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break;
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}
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use_malloc = true;
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}
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else
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/* Allocate a new buffer on the stack. If possible combine it
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with the previously allocated buffer. */
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buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen);
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}
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time_t timeout = cache_addgr (db, fd, req, keystr, grp, uid, he, dh, errval);
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if (use_malloc)
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free (buffer);
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return timeout;
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}
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void
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addgrbyname (struct database_dyn *db, int fd, request_header *req,
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void *key, uid_t uid)
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{
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union keytype u = { .v = key };
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addgrbyX (db, fd, req, u, key, uid, NULL, NULL);
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}
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time_t
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readdgrbyname (struct database_dyn *db, struct hashentry *he,
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struct datahead *dh)
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{
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request_header req =
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{
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.type = GETGRBYNAME,
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.key_len = he->len
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};
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union keytype u = { .v = db->data + he->key };
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return addgrbyX (db, -1, &req, u, db->data + he->key, he->owner, he, dh);
|
|
}
|
|
|
|
|
|
void
|
|
addgrbygid (struct database_dyn *db, int fd, request_header *req,
|
|
void *key, uid_t uid)
|
|
{
|
|
char *ep;
|
|
gid_t gid = strtoul ((char *) key, &ep, 10);
|
|
|
|
if (*(char *) key == '\0' || *ep != '\0') /* invalid numeric uid */
|
|
{
|
|
if (debug_level > 0)
|
|
dbg_log (_("Invalid numeric gid \"%s\"!"), (char *) key);
|
|
|
|
errno = EINVAL;
|
|
return;
|
|
}
|
|
|
|
union keytype u = { .g = gid };
|
|
|
|
addgrbyX (db, fd, req, u, key, uid, NULL, NULL);
|
|
}
|
|
|
|
|
|
time_t
|
|
readdgrbygid (struct database_dyn *db, struct hashentry *he,
|
|
struct datahead *dh)
|
|
{
|
|
char *ep;
|
|
gid_t gid = strtoul (db->data + he->key, &ep, 10);
|
|
|
|
/* Since the key has been added before it must be OK. */
|
|
assert (*(db->data + he->key) != '\0' && *ep == '\0');
|
|
|
|
request_header req =
|
|
{
|
|
.type = GETGRBYGID,
|
|
.key_len = he->len
|
|
};
|
|
union keytype u = { .g = gid };
|
|
|
|
return addgrbyX (db, -1, &req, u, db->data + he->key, he->owner, he, dh);
|
|
}
|