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74f77840 RK |
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 | ||
32 | static int dbparams_cleanup(DB_TXN *tid); | |
33 | static void h_write_string(gcrypt_hash_handle h, | |
34 | const char *s); | |
35 | static 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 | */ | |
43 | void 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", |
74f77840 RK |
55 | oldparams, newparams); |
56 | else { | |
2e9ba080 RK |
57 | disorder_info("new database parameter string %s - removing old data", |
58 | newparams); | |
74f77840 RK |
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"); |
74f77840 RK |
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)); |
74f77840 RK |
86 | } |
87 | } | |
88 | } | |
89 | ||
90 | /** @brief Clean up databases */ | |
91 | static 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)); |
74f77840 RK |
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)); |
74f77840 RK |
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)); |
74f77840 RK |
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)); |
74f77840 RK |
125 | goto done; |
126 | } | |
127 | if(err != DB_NOTFOUND) | |
2e9ba080 | 128 | disorder_fatal(0, "cursor->c_get: %s", db_strerror(err)); |
74f77840 RK |
129 | err = 0; |
130 | done: | |
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 | */ | |
141 | static 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 | */ | |
149 | static 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)); |
74f77840 RK |
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 | /* | |
180 | Local Variables: | |
181 | c-basic-offset:2 | |
182 | comment-column:40 | |
183 | fill-column:79 | |
184 | indent-tabs-mode:nil | |
185 | End: | |
186 | */ |