chiark / gitweb /
Fix a few of the things the Clang static analyzer detects:
[disorder] / server / dbparams.c
CommitLineData
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1/*
2 * This file is part of DisOrder
3 * Copyright (C) 2009 Richard Kettlewell
4 *
5 * This program is free software: you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, either version 3 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
17 */
18/** @file server/dbparams.c
19 * @brief Parameters affecting the database
20 *
21 * Rescan can regenerate aliases and the search and tag databases but
22 * we rather assume that they are either empty or good. Therefore we
23 * need to store anything that can affect these values and erase them
24 * if they change.
25 *
26 * The solution is a global pref _dbparams which contains the hash of
27 * the alias, stopword and namepart data.
28 */
29#include "disorder-server.h"
30#include <gcrypt.h>
31
32static int dbparams_cleanup(DB_TXN *tid);
33static void h_write_string(gcrypt_hash_handle h,
34 const char *s);
35static char *compute_dbparams(void);
36
37/** @brief Check whether database parameters have changed
38 *
39 * If the database parameters have changed then deletes the search and
40 * tag database contents and all aliases. The subsequent rescan will
41 * regenerate them.
42 */
43void dbparams_check(void) {
44 const char *newparams = compute_dbparams();
45 const char *oldparams = trackdb_get_global("_dbparams");
46
47 // If the parameters match, return straight away
48 if(oldparams && !strcmp(newparams, oldparams))
49 return;
50 // Log what we're going to do
51 for(;;) {
52 DB_TXN *tid;
53 if(oldparams)
2e9ba080 54 disorder_info("database parameter string changed from %s to %s - removing old data",
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55 oldparams, newparams);
56 else {
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57 disorder_info("new database parameter string %s - removing old data",
58 newparams);
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59 /* This is a slightly annoying case; the global pref wasn't present. In
60 * practice this is almost certainly either an upgrade (with no change to
61 * any relevant parameters) or a new installation (with no tracks).
62 *
63 * The new installation case doesn't matter much; clearing an empty
64 * search database and iterating over a likewise track database won't
65 * take long.
66 *
67 * However for upgrade this will throw away a lot of data and laboriously
68 * regenerate it, which is rather a shame.
69 */
70 }
71 tid = trackdb_begin_transaction();
72 int err = dbparams_cleanup(tid);
73 if(!err)
74 err = trackdb_set_global_tid("_dbparams", newparams, tid);
75 switch(err) {
76 case 0:
77 trackdb_commit_transaction(tid);
2e9ba080 78 disorder_info("removed old data OK, will regenerate on rescan");
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79 return;
80 case DB_LOCK_DEADLOCK:
81 /* Deadlocked, try again */
82 trackdb_abort_transaction(tid);
83 break;
84 default:
2e9ba080 85 disorder_fatal(0, "error updating database: %s", db_strerror(err));
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86 }
87 }
88}
89
90/** @brief Clean up databases */
91static int dbparams_cleanup(DB_TXN *tid) {
92 int err;
93 u_int32_t count;
94
95 /* We'll regenerate search.db based on the new set of stopwords */
96 if((err = trackdb_searchdb->truncate(trackdb_searchdb, tid, &count, 0))) {
2e9ba080 97 disorder_error(err, "truncating search.db: %s", db_strerror(err));
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98 return err;
99 }
100 /* We'll regenerate aliases based on the new alias/namepart settings, so
101 * delete all the alias records currently present
102 *
103 * TODO this looks suspiciously similar to part of dump.c
104 */
105 DBC *cursor;
106 DBT k, d;
107 cursor = trackdb_opencursor(trackdb_tracksdb, tid);
108 if((err = cursor->c_get(cursor, prepare_data(&k), prepare_data(&d),
109 DB_FIRST)) == DB_LOCK_DEADLOCK) {
2e9ba080 110 disorder_error(0, "cursor->c_get: %s", db_strerror(err));
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111 goto done;
112 }
113 while(err == 0) {
114 struct kvp *data = kvp_urldecode(d.data, d.size);
115 if(kvp_get(data, "_alias_for")) {
116 if((err = cursor->c_del(cursor, 0))) {
2e9ba080 117 disorder_error(0, "cursor->c_del: %s", db_strerror(err));
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118 goto done;
119 }
120 }
121 err = cursor->c_get(cursor, prepare_data(&k), prepare_data(&d), DB_NEXT);
122 }
123 if(err == DB_LOCK_DEADLOCK) {
2e9ba080 124 disorder_error(0, "cursor operation: %s", db_strerror(err));
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125 goto done;
126 }
127 if(err != DB_NOTFOUND)
2e9ba080 128 disorder_fatal(0, "cursor->c_get: %s", db_strerror(err));
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129 err = 0;
130done:
131 if(trackdb_closecursor(cursor) && !err) err = DB_LOCK_DEADLOCK;
132 return err;
133}
134
135/** @brief Write a string into a gcrypt hash function
136 * @param h Hash handle
137 * @param s String to write
138 *
139 * The 0 terminator is included in the byte written.
140 */
141static void h_write_string(gcrypt_hash_handle h,
142 const char *s) {
143 gcry_md_write(h, s, strlen(s) + 1);
144}
145
146/** @brief Compute database parameters hash
147 * @return Opaque string encapsulating database parameters
148 */
149static char *compute_dbparams(void) {
150 gcry_error_t e;
151 gcrypt_hash_handle h;
152
153 if((e = gcry_md_open(&h, GCRY_MD_SHA256, 0)))
2e9ba080 154 disorder_fatal(0, "gcry_md_open: %s", gcry_strerror(e));
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155 h_write_string(h, "alias");
156 h_write_string(h, config->alias);
157 for(int n = 0; n < config->stopword.n; ++n) {
158 h_write_string(h, "stopword");
159 h_write_string(h, config->stopword.s[n]);
160 }
161 for(int n = 0; n < config->namepart.n; ++n) {
162 h_write_string(h, "namepart");
163 h_write_string(h, config->namepart.s[n].part);
164 h_write_string(h, config->namepart.s[n].res);
165 h_write_string(h, config->namepart.s[n].replace);
166 h_write_string(h, config->namepart.s[n].context);
167 char buffer[64];
168 snprintf(buffer, sizeof buffer, "%u", config->namepart.s[n].reflags);
169 h_write_string(h, buffer);
170 }
171 char *result;
172 byte_xasprintf(&result, "dbparams-0-sha256:%s",
173 hex(gcry_md_read(h, GCRY_MD_SHA256),
174 gcry_md_get_algo_dlen(GCRY_MD_SHA256)));
175 gcry_md_close(h);
176 return result;
177}
178
179/*
180Local Variables:
181c-basic-offset:2
182comment-column:40
183fill-column:79
184indent-tabs-mode:nil
185End:
186*/