/src/httpd/server/util_time.c
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1 | | /* Licensed to the Apache Software Foundation (ASF) under one or more |
2 | | * contributor license agreements. See the NOTICE file distributed with |
3 | | * this work for additional information regarding copyright ownership. |
4 | | * The ASF licenses this file to You under the Apache License, Version 2.0 |
5 | | * (the "License"); you may not use this file except in compliance with |
6 | | * the License. You may obtain a copy of the License at |
7 | | * |
8 | | * http://www.apache.org/licenses/LICENSE-2.0 |
9 | | * |
10 | | * Unless required by applicable law or agreed to in writing, software |
11 | | * distributed under the License is distributed on an "AS IS" BASIS, |
12 | | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
13 | | * See the License for the specific language governing permissions and |
14 | | * limitations under the License. |
15 | | */ |
16 | | |
17 | | #include "util_time.h" |
18 | | #include "apr_env.h" |
19 | | |
20 | | |
21 | | |
22 | | /* Number of characters needed to format the microsecond part of a timestamp. |
23 | | * Microseconds have 6 digits plus one separator character makes 7. |
24 | | * */ |
25 | 0 | #define AP_CTIME_USEC_LENGTH 7 |
26 | | |
27 | | /* Length of ISO 8601 date/time (including trailing '\0') */ |
28 | 0 | #define AP_CTIME_COMPACT_LEN 20 |
29 | | |
30 | | /* Length of timezone offset from GMT ([+-]hhmm) plus leading space */ |
31 | 0 | #define AP_CTIME_GMTOFF_LEN 6 |
32 | | |
33 | | /* Cache for exploded values of recent timestamps |
34 | | */ |
35 | | |
36 | | struct exploded_time_cache_element { |
37 | | apr_int64_t t; |
38 | | apr_time_exp_t xt; |
39 | | apr_int64_t t_validate; /* please see comments in cached_explode() */ |
40 | | }; |
41 | | |
42 | | /* the "+ 1" is for the current second: */ |
43 | | #define TIME_CACHE_SIZE (AP_TIME_RECENT_THRESHOLD + 1) |
44 | | |
45 | | /* Note that AP_TIME_RECENT_THRESHOLD is defined to |
46 | | * be a power of two minus one in util_time.h, so that |
47 | | * we can replace a modulo operation with a bitwise AND |
48 | | * when hashing items into a cache of size |
49 | | * AP_TIME_RECENT_THRESHOLD+1 |
50 | | */ |
51 | 0 | #define TIME_CACHE_MASK (AP_TIME_RECENT_THRESHOLD) |
52 | | |
53 | | static struct exploded_time_cache_element exploded_cache_localtime[TIME_CACHE_SIZE]; |
54 | | static struct exploded_time_cache_element exploded_cache_gmt[TIME_CACHE_SIZE]; |
55 | | |
56 | | |
57 | | static apr_status_t cached_explode(apr_time_exp_t *xt, apr_time_t t, |
58 | | struct exploded_time_cache_element *cache, |
59 | | int use_gmt) |
60 | 0 | { |
61 | 0 | apr_int64_t seconds = apr_time_sec(t); |
62 | 0 | struct exploded_time_cache_element *cache_element = |
63 | 0 | &(cache[seconds & TIME_CACHE_MASK]); |
64 | 0 | struct exploded_time_cache_element cache_element_snapshot; |
65 | | |
66 | | /* The cache is implemented as a ring buffer. Each second, |
67 | | * it uses a different element in the buffer. The timestamp |
68 | | * in the element indicates whether the element contains the |
69 | | * exploded time for the current second (vs the time |
70 | | * 'now - AP_TIME_RECENT_THRESHOLD' seconds ago). If the |
71 | | * cached value is for the current time, we use it. Otherwise, |
72 | | * we compute the apr_time_exp_t and store it in this |
73 | | * cache element. Note that the timestamp in the cache |
74 | | * element is updated only after the exploded time. Thus |
75 | | * if two threads hit this cache element simultaneously |
76 | | * at the start of a new second, they'll both explode the |
77 | | * time and store it. I.e., the writers will collide, but |
78 | | * they'll be writing the same value. |
79 | | */ |
80 | 0 | if (cache_element->t >= seconds) { |
81 | | /* There is an intentional race condition in this design: |
82 | | * in a multithreaded app, one thread might be reading |
83 | | * from this cache_element to resolve a timestamp from |
84 | | * TIME_CACHE_SIZE seconds ago at the same time that |
85 | | * another thread is copying the exploded form of the |
86 | | * current time into the same cache_element. (I.e., the |
87 | | * first thread might hit this element of the ring buffer |
88 | | * just as the element is being recycled.) This can |
89 | | * also happen at the start of a new second, if a |
90 | | * reader accesses the cache_element after a writer |
91 | | * has updated cache_element.t but before the writer |
92 | | * has finished updating the whole cache_element. |
93 | | * |
94 | | * Rather than trying to prevent this race condition |
95 | | * with locks, we allow it to happen and then detect |
96 | | * and correct it. The detection works like this: |
97 | | * Step 1: Take a "snapshot" of the cache element by |
98 | | * copying it into a temporary buffer. |
99 | | * Step 2: Check whether the snapshot contains consistent |
100 | | * data: the timestamps at the start and end of |
101 | | * the cache_element should both match the 'seconds' |
102 | | * value that we computed from the input time. |
103 | | * If these three don't match, then the snapshot |
104 | | * shows the cache_element in the middle of an |
105 | | * update, and its contents are invalid. |
106 | | * Step 3: If the snapshot is valid, use it. Otherwise, |
107 | | * just give up on the cache and explode the |
108 | | * input time. |
109 | | */ |
110 | 0 | memcpy(&cache_element_snapshot, cache_element, |
111 | 0 | sizeof(struct exploded_time_cache_element)); |
112 | 0 | if ((seconds != cache_element_snapshot.t) || |
113 | 0 | (seconds != cache_element_snapshot.t_validate)) { |
114 | | /* Invalid snapshot */ |
115 | 0 | if (use_gmt) { |
116 | 0 | return apr_time_exp_gmt(xt, t); |
117 | 0 | } |
118 | 0 | else { |
119 | 0 | return apr_time_exp_lt(xt, t); |
120 | 0 | } |
121 | 0 | } |
122 | 0 | else { |
123 | | /* Valid snapshot */ |
124 | 0 | memcpy(xt, &(cache_element_snapshot.xt), |
125 | 0 | sizeof(apr_time_exp_t)); |
126 | 0 | } |
127 | 0 | } |
128 | 0 | else { |
129 | 0 | apr_status_t r; |
130 | 0 | if (use_gmt) { |
131 | 0 | r = apr_time_exp_gmt(xt, t); |
132 | 0 | } |
133 | 0 | else { |
134 | 0 | r = apr_time_exp_lt(xt, t); |
135 | 0 | } |
136 | 0 | if (r != APR_SUCCESS) { |
137 | 0 | return r; |
138 | 0 | } |
139 | 0 | cache_element->t = seconds; |
140 | 0 | memcpy(&(cache_element->xt), xt, sizeof(apr_time_exp_t)); |
141 | 0 | cache_element->t_validate = seconds; |
142 | 0 | } |
143 | 0 | xt->tm_usec = (int)apr_time_usec(t); |
144 | 0 | return APR_SUCCESS; |
145 | 0 | } |
146 | | |
147 | | |
148 | | AP_DECLARE(apr_status_t) ap_explode_recent_localtime(apr_time_exp_t * tm, |
149 | | apr_time_t t) |
150 | 0 | { |
151 | 0 | return cached_explode(tm, t, exploded_cache_localtime, 0); |
152 | 0 | } |
153 | | |
154 | | AP_DECLARE(apr_status_t) ap_explode_recent_gmt(apr_time_exp_t * tm, |
155 | | apr_time_t t) |
156 | 0 | { |
157 | 0 | return cached_explode(tm, t, exploded_cache_gmt, 1); |
158 | 0 | } |
159 | | |
160 | | AP_DECLARE(apr_status_t) ap_recent_ctime(char *date_str, apr_time_t t) |
161 | 0 | { |
162 | 0 | int len = APR_CTIME_LEN; |
163 | 0 | return ap_recent_ctime_ex(date_str, t, AP_CTIME_OPTION_NONE, &len); |
164 | 0 | } |
165 | | |
166 | | AP_DECLARE(apr_status_t) ap_recent_ctime_ex(char *date_str, apr_time_t t, |
167 | | int option, int *len) |
168 | 0 | { |
169 | | /* ### This code is a clone of apr_ctime(), except that it |
170 | | * uses ap_explode_recent_localtime() instead of apr_time_exp_lt(). |
171 | | */ |
172 | 0 | apr_time_exp_t xt; |
173 | 0 | const char *s; |
174 | 0 | int real_year; |
175 | 0 | int needed; |
176 | | |
177 | | |
178 | | /* Calculate the needed buffer length */ |
179 | 0 | if (option & AP_CTIME_OPTION_COMPACT) |
180 | 0 | needed = AP_CTIME_COMPACT_LEN; |
181 | 0 | else |
182 | 0 | needed = APR_CTIME_LEN; |
183 | |
|
184 | 0 | if (option & AP_CTIME_OPTION_USEC) { |
185 | 0 | needed += AP_CTIME_USEC_LENGTH; |
186 | 0 | } |
187 | |
|
188 | 0 | if (option & AP_CTIME_OPTION_GMTOFF) { |
189 | 0 | needed += AP_CTIME_GMTOFF_LEN; |
190 | 0 | } |
191 | | |
192 | | /* Check the provided buffer length (note: above AP_CTIME_COMPACT_LEN |
193 | | * and APR_CTIME_LEN include the trailing '\0'; so does 'needed' then). |
194 | | */ |
195 | 0 | if (len && *len >= needed) { |
196 | 0 | *len = needed; |
197 | 0 | } |
198 | 0 | else { |
199 | 0 | if (len != NULL) { |
200 | 0 | *len = 0; |
201 | 0 | } |
202 | 0 | return APR_ENOMEM; |
203 | 0 | } |
204 | | |
205 | | /* example without options: "Wed Jun 30 21:49:08 1993" */ |
206 | | /* example for compact format: "1993-06-30 21:49:08" */ |
207 | | /* example for compact+usec+gmtoff format: |
208 | | * "1993-06-30 22:49:08.123456 +0100" |
209 | | */ |
210 | | |
211 | 0 | ap_explode_recent_localtime(&xt, t); |
212 | 0 | real_year = 1900 + xt.tm_year; |
213 | 0 | if (option & AP_CTIME_OPTION_COMPACT) { |
214 | 0 | int real_month = xt.tm_mon + 1; |
215 | 0 | *date_str++ = real_year / 1000 + '0'; |
216 | 0 | *date_str++ = real_year % 1000 / 100 + '0'; |
217 | 0 | *date_str++ = real_year % 100 / 10 + '0'; |
218 | 0 | *date_str++ = real_year % 10 + '0'; |
219 | 0 | *date_str++ = '-'; |
220 | 0 | *date_str++ = real_month / 10 + '0'; |
221 | 0 | *date_str++ = real_month % 10 + '0'; |
222 | 0 | *date_str++ = '-'; |
223 | 0 | } |
224 | 0 | else { |
225 | 0 | s = &apr_day_snames[xt.tm_wday][0]; |
226 | 0 | *date_str++ = *s++; |
227 | 0 | *date_str++ = *s++; |
228 | 0 | *date_str++ = *s++; |
229 | 0 | *date_str++ = ' '; |
230 | 0 | s = &apr_month_snames[xt.tm_mon][0]; |
231 | 0 | *date_str++ = *s++; |
232 | 0 | *date_str++ = *s++; |
233 | 0 | *date_str++ = *s++; |
234 | 0 | *date_str++ = ' '; |
235 | 0 | } |
236 | 0 | *date_str++ = xt.tm_mday / 10 + '0'; |
237 | 0 | *date_str++ = xt.tm_mday % 10 + '0'; |
238 | 0 | *date_str++ = ' '; |
239 | 0 | *date_str++ = xt.tm_hour / 10 + '0'; |
240 | 0 | *date_str++ = xt.tm_hour % 10 + '0'; |
241 | 0 | *date_str++ = ':'; |
242 | 0 | *date_str++ = xt.tm_min / 10 + '0'; |
243 | 0 | *date_str++ = xt.tm_min % 10 + '0'; |
244 | 0 | *date_str++ = ':'; |
245 | 0 | *date_str++ = xt.tm_sec / 10 + '0'; |
246 | 0 | *date_str++ = xt.tm_sec % 10 + '0'; |
247 | 0 | if (option & AP_CTIME_OPTION_USEC) { |
248 | 0 | int div; |
249 | 0 | int usec = (int)xt.tm_usec; |
250 | 0 | *date_str++ = '.'; |
251 | 0 | for (div=100000; div>0; div=div/10) { |
252 | 0 | *date_str++ = usec / div + '0'; |
253 | 0 | usec = usec % div; |
254 | 0 | } |
255 | 0 | } |
256 | 0 | if (!(option & AP_CTIME_OPTION_COMPACT)) { |
257 | 0 | *date_str++ = ' '; |
258 | 0 | *date_str++ = real_year / 1000 + '0'; |
259 | 0 | *date_str++ = real_year % 1000 / 100 + '0'; |
260 | 0 | *date_str++ = real_year % 100 / 10 + '0'; |
261 | 0 | *date_str++ = real_year % 10 + '0'; |
262 | 0 | } |
263 | 0 | if (option & AP_CTIME_OPTION_GMTOFF) { |
264 | 0 | int off = xt.tm_gmtoff, off_hh, off_mm; |
265 | 0 | char sign = '+'; |
266 | 0 | if (off < 0) { |
267 | 0 | off = -off; |
268 | 0 | sign = '-'; |
269 | 0 | } |
270 | 0 | off_hh = off / 3600; |
271 | 0 | off_mm = off % 3600 / 60; |
272 | 0 | *date_str++ = ' '; |
273 | 0 | *date_str++ = sign; |
274 | 0 | *date_str++ = off_hh / 10 + '0'; |
275 | 0 | *date_str++ = off_hh % 10 + '0'; |
276 | 0 | *date_str++ = off_mm / 10 + '0'; |
277 | 0 | *date_str++ = off_mm % 10 + '0'; |
278 | 0 | } |
279 | 0 | *date_str = 0; |
280 | |
|
281 | 0 | return APR_SUCCESS; |
282 | 0 | } |
283 | | |
284 | | AP_DECLARE(apr_status_t) ap_recent_rfc822_date(char *date_str, apr_time_t t) |
285 | 0 | { |
286 | | /* ### This code is a clone of apr_rfc822_date(), except that it |
287 | | * uses ap_explode_recent_gmt() instead of apr_time_exp_gmt(). |
288 | | */ |
289 | 0 | apr_time_exp_t xt; |
290 | 0 | const char *s; |
291 | 0 | int real_year; |
292 | |
|
293 | 0 | ap_explode_recent_gmt(&xt, t); |
294 | | |
295 | | /* example: "Sat, 08 Jan 2000 18:31:41 GMT" */ |
296 | | /* 12345678901234567890123456789 */ |
297 | |
|
298 | 0 | s = &apr_day_snames[xt.tm_wday][0]; |
299 | 0 | *date_str++ = *s++; |
300 | 0 | *date_str++ = *s++; |
301 | 0 | *date_str++ = *s++; |
302 | 0 | *date_str++ = ','; |
303 | 0 | *date_str++ = ' '; |
304 | 0 | *date_str++ = xt.tm_mday / 10 + '0'; |
305 | 0 | *date_str++ = xt.tm_mday % 10 + '0'; |
306 | 0 | *date_str++ = ' '; |
307 | 0 | s = &apr_month_snames[xt.tm_mon][0]; |
308 | 0 | *date_str++ = *s++; |
309 | 0 | *date_str++ = *s++; |
310 | 0 | *date_str++ = *s++; |
311 | 0 | *date_str++ = ' '; |
312 | 0 | real_year = 1900 + xt.tm_year; |
313 | | /* This routine isn't y10k ready. */ |
314 | 0 | *date_str++ = real_year / 1000 + '0'; |
315 | 0 | *date_str++ = real_year % 1000 / 100 + '0'; |
316 | 0 | *date_str++ = real_year % 100 / 10 + '0'; |
317 | 0 | *date_str++ = real_year % 10 + '0'; |
318 | 0 | *date_str++ = ' '; |
319 | 0 | *date_str++ = xt.tm_hour / 10 + '0'; |
320 | 0 | *date_str++ = xt.tm_hour % 10 + '0'; |
321 | 0 | *date_str++ = ':'; |
322 | 0 | *date_str++ = xt.tm_min / 10 + '0'; |
323 | 0 | *date_str++ = xt.tm_min % 10 + '0'; |
324 | 0 | *date_str++ = ':'; |
325 | 0 | *date_str++ = xt.tm_sec / 10 + '0'; |
326 | 0 | *date_str++ = xt.tm_sec % 10 + '0'; |
327 | 0 | *date_str++ = ' '; |
328 | 0 | *date_str++ = 'G'; |
329 | 0 | *date_str++ = 'M'; |
330 | 0 | *date_str++ = 'T'; |
331 | 0 | *date_str++ = 0; |
332 | 0 | return APR_SUCCESS; |
333 | 0 | } |
334 | | |
335 | 0 | AP_DECLARE(void) ap_force_set_tz(apr_pool_t *p) { |
336 | | /* If the TZ variable is unset, many operating systems, |
337 | | * such as Linux, will at runtime read from /etc/localtime |
338 | | * and call fstat on it. |
339 | | * |
340 | | * By forcing the time zone to UTC if it is unset, we gain |
341 | | * about 2% in raw requests/second (since we format log files |
342 | | * in the local time, if present) |
343 | | * |
344 | | * For more info, see: |
345 | | * <http://www.gnu.org/s/hello/manual/libc/TZ-Variable.html> |
346 | | */ |
347 | 0 | char *v = NULL; |
348 | |
|
349 | 0 | if (apr_env_get(&v, "TZ", p) != APR_SUCCESS) { |
350 | 0 | apr_env_set("TZ", "UTC+0", p); |
351 | 0 | } |
352 | 0 | } |