| /* Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "util_time.h" |
| #include "apr_env.h" |
| |
| |
| |
| /* Number of characters needed to format the microsecond part of a timestamp. |
| * Microseconds have 6 digits plus one separator character makes 7. |
| * */ |
| #define AP_CTIME_USEC_LENGTH 7 |
| |
| /* Length of ISO 8601 date/time */ |
| #define AP_CTIME_COMPACT_LEN 20 |
| |
| |
| /* Cache for exploded values of recent timestamps |
| */ |
| |
| struct exploded_time_cache_element { |
| apr_int64_t t; |
| apr_time_exp_t xt; |
| apr_int64_t t_validate; /* please see comments in cached_explode() */ |
| }; |
| |
| /* the "+ 1" is for the current second: */ |
| #define TIME_CACHE_SIZE (AP_TIME_RECENT_THRESHOLD + 1) |
| |
| /* Note that AP_TIME_RECENT_THRESHOLD is defined to |
| * be a power of two minus one in util_time.h, so that |
| * we can replace a modulo operation with a bitwise AND |
| * when hashing items into a cache of size |
| * AP_TIME_RECENT_THRESHOLD+1 |
| */ |
| #define TIME_CACHE_MASK (AP_TIME_RECENT_THRESHOLD) |
| |
| static struct exploded_time_cache_element exploded_cache_localtime[TIME_CACHE_SIZE]; |
| static struct exploded_time_cache_element exploded_cache_gmt[TIME_CACHE_SIZE]; |
| |
| |
| static apr_status_t cached_explode(apr_time_exp_t *xt, apr_time_t t, |
| struct exploded_time_cache_element *cache, |
| int use_gmt) |
| { |
| apr_int64_t seconds = apr_time_sec(t); |
| struct exploded_time_cache_element *cache_element = |
| &(cache[seconds & TIME_CACHE_MASK]); |
| struct exploded_time_cache_element cache_element_snapshot; |
| |
| /* The cache is implemented as a ring buffer. Each second, |
| * it uses a different element in the buffer. The timestamp |
| * in the element indicates whether the element contains the |
| * exploded time for the current second (vs the time |
| * 'now - AP_TIME_RECENT_THRESHOLD' seconds ago). If the |
| * cached value is for the current time, we use it. Otherwise, |
| * we compute the apr_time_exp_t and store it in this |
| * cache element. Note that the timestamp in the cache |
| * element is updated only after the exploded time. Thus |
| * if two threads hit this cache element simultaneously |
| * at the start of a new second, they'll both explode the |
| * time and store it. I.e., the writers will collide, but |
| * they'll be writing the same value. |
| */ |
| if (cache_element->t >= seconds) { |
| /* There is an intentional race condition in this design: |
| * in a multithreaded app, one thread might be reading |
| * from this cache_element to resolve a timestamp from |
| * TIME_CACHE_SIZE seconds ago at the same time that |
| * another thread is copying the exploded form of the |
| * current time into the same cache_element. (I.e., the |
| * first thread might hit this element of the ring buffer |
| * just as the element is being recycled.) This can |
| * also happen at the start of a new second, if a |
| * reader accesses the cache_element after a writer |
| * has updated cache_element.t but before the writer |
| * has finished updating the whole cache_element. |
| * |
| * Rather than trying to prevent this race condition |
| * with locks, we allow it to happen and then detect |
| * and correct it. The detection works like this: |
| * Step 1: Take a "snapshot" of the cache element by |
| * copying it into a temporary buffer. |
| * Step 2: Check whether the snapshot contains consistent |
| * data: the timestamps at the start and end of |
| * the cache_element should both match the 'seconds' |
| * value that we computed from the input time. |
| * If these three don't match, then the snapshot |
| * shows the cache_element in the middle of an |
| * update, and its contents are invalid. |
| * Step 3: If the snapshot is valid, use it. Otherwise, |
| * just give up on the cache and explode the |
| * input time. |
| */ |
| memcpy(&cache_element_snapshot, cache_element, |
| sizeof(struct exploded_time_cache_element)); |
| if ((seconds != cache_element_snapshot.t) || |
| (seconds != cache_element_snapshot.t_validate)) { |
| /* Invalid snapshot */ |
| if (use_gmt) { |
| return apr_time_exp_gmt(xt, t); |
| } |
| else { |
| return apr_time_exp_lt(xt, t); |
| } |
| } |
| else { |
| /* Valid snapshot */ |
| memcpy(xt, &(cache_element_snapshot.xt), |
| sizeof(apr_time_exp_t)); |
| } |
| } |
| else { |
| apr_status_t r; |
| if (use_gmt) { |
| r = apr_time_exp_gmt(xt, t); |
| } |
| else { |
| r = apr_time_exp_lt(xt, t); |
| } |
| if (r != APR_SUCCESS) { |
| return r; |
| } |
| cache_element->t = seconds; |
| memcpy(&(cache_element->xt), xt, sizeof(apr_time_exp_t)); |
| cache_element->t_validate = seconds; |
| } |
| xt->tm_usec = (int)apr_time_usec(t); |
| return APR_SUCCESS; |
| } |
| |
| |
| AP_DECLARE(apr_status_t) ap_explode_recent_localtime(apr_time_exp_t * tm, |
| apr_time_t t) |
| { |
| return cached_explode(tm, t, exploded_cache_localtime, 0); |
| } |
| |
| AP_DECLARE(apr_status_t) ap_explode_recent_gmt(apr_time_exp_t * tm, |
| apr_time_t t) |
| { |
| return cached_explode(tm, t, exploded_cache_gmt, 1); |
| } |
| |
| AP_DECLARE(apr_status_t) ap_recent_ctime(char *date_str, apr_time_t t) |
| { |
| int len = APR_CTIME_LEN; |
| return ap_recent_ctime_ex(date_str, t, AP_CTIME_OPTION_NONE, &len); |
| } |
| |
| AP_DECLARE(apr_status_t) ap_recent_ctime_ex(char *date_str, apr_time_t t, |
| int option, int *len) |
| { |
| /* ### This code is a clone of apr_ctime(), except that it |
| * uses ap_explode_recent_localtime() instead of apr_time_exp_lt(). |
| */ |
| apr_time_exp_t xt; |
| const char *s; |
| int real_year; |
| int needed; |
| |
| |
| /* Calculate the needed buffer length */ |
| if (option & AP_CTIME_OPTION_COMPACT) |
| needed = AP_CTIME_COMPACT_LEN; |
| else |
| needed = APR_CTIME_LEN; |
| |
| if (option & AP_CTIME_OPTION_USEC) { |
| needed += AP_CTIME_USEC_LENGTH; |
| } |
| |
| /* Check the provided buffer length */ |
| if (len && *len >= needed) { |
| *len = needed; |
| } |
| else { |
| if (len != NULL) { |
| *len = 0; |
| } |
| return APR_ENOMEM; |
| } |
| |
| /* example without options: "Wed Jun 30 21:49:08 1993" */ |
| /* 123456789012345678901234 */ |
| /* example for compact format: "1993-06-30 21:49:08" */ |
| /* 1234567890123456789 */ |
| |
| ap_explode_recent_localtime(&xt, t); |
| real_year = 1900 + xt.tm_year; |
| if (option & AP_CTIME_OPTION_COMPACT) { |
| int real_month = xt.tm_mon + 1; |
| *date_str++ = real_year / 1000 + '0'; |
| *date_str++ = real_year % 1000 / 100 + '0'; |
| *date_str++ = real_year % 100 / 10 + '0'; |
| *date_str++ = real_year % 10 + '0'; |
| *date_str++ = '-'; |
| *date_str++ = real_month / 10 + '0'; |
| *date_str++ = real_month % 10 + '0'; |
| *date_str++ = '-'; |
| } |
| else { |
| s = &apr_day_snames[xt.tm_wday][0]; |
| *date_str++ = *s++; |
| *date_str++ = *s++; |
| *date_str++ = *s++; |
| *date_str++ = ' '; |
| s = &apr_month_snames[xt.tm_mon][0]; |
| *date_str++ = *s++; |
| *date_str++ = *s++; |
| *date_str++ = *s++; |
| *date_str++ = ' '; |
| } |
| *date_str++ = xt.tm_mday / 10 + '0'; |
| *date_str++ = xt.tm_mday % 10 + '0'; |
| *date_str++ = ' '; |
| *date_str++ = xt.tm_hour / 10 + '0'; |
| *date_str++ = xt.tm_hour % 10 + '0'; |
| *date_str++ = ':'; |
| *date_str++ = xt.tm_min / 10 + '0'; |
| *date_str++ = xt.tm_min % 10 + '0'; |
| *date_str++ = ':'; |
| *date_str++ = xt.tm_sec / 10 + '0'; |
| *date_str++ = xt.tm_sec % 10 + '0'; |
| if (option & AP_CTIME_OPTION_USEC) { |
| int div; |
| int usec = (int)xt.tm_usec; |
| *date_str++ = '.'; |
| for (div=100000; div>0; div=div/10) { |
| *date_str++ = usec / div + '0'; |
| usec = usec % div; |
| } |
| } |
| if (!(option & AP_CTIME_OPTION_COMPACT)) { |
| *date_str++ = ' '; |
| *date_str++ = real_year / 1000 + '0'; |
| *date_str++ = real_year % 1000 / 100 + '0'; |
| *date_str++ = real_year % 100 / 10 + '0'; |
| *date_str++ = real_year % 10 + '0'; |
| } |
| *date_str++ = 0; |
| |
| return APR_SUCCESS; |
| } |
| |
| AP_DECLARE(apr_status_t) ap_recent_rfc822_date(char *date_str, apr_time_t t) |
| { |
| /* ### This code is a clone of apr_rfc822_date(), except that it |
| * uses ap_explode_recent_gmt() instead of apr_time_exp_gmt(). |
| */ |
| apr_time_exp_t xt; |
| const char *s; |
| int real_year; |
| |
| ap_explode_recent_gmt(&xt, t); |
| |
| /* example: "Sat, 08 Jan 2000 18:31:41 GMT" */ |
| /* 12345678901234567890123456789 */ |
| |
| s = &apr_day_snames[xt.tm_wday][0]; |
| *date_str++ = *s++; |
| *date_str++ = *s++; |
| *date_str++ = *s++; |
| *date_str++ = ','; |
| *date_str++ = ' '; |
| *date_str++ = xt.tm_mday / 10 + '0'; |
| *date_str++ = xt.tm_mday % 10 + '0'; |
| *date_str++ = ' '; |
| s = &apr_month_snames[xt.tm_mon][0]; |
| *date_str++ = *s++; |
| *date_str++ = *s++; |
| *date_str++ = *s++; |
| *date_str++ = ' '; |
| real_year = 1900 + xt.tm_year; |
| /* This routine isn't y10k ready. */ |
| *date_str++ = real_year / 1000 + '0'; |
| *date_str++ = real_year % 1000 / 100 + '0'; |
| *date_str++ = real_year % 100 / 10 + '0'; |
| *date_str++ = real_year % 10 + '0'; |
| *date_str++ = ' '; |
| *date_str++ = xt.tm_hour / 10 + '0'; |
| *date_str++ = xt.tm_hour % 10 + '0'; |
| *date_str++ = ':'; |
| *date_str++ = xt.tm_min / 10 + '0'; |
| *date_str++ = xt.tm_min % 10 + '0'; |
| *date_str++ = ':'; |
| *date_str++ = xt.tm_sec / 10 + '0'; |
| *date_str++ = xt.tm_sec % 10 + '0'; |
| *date_str++ = ' '; |
| *date_str++ = 'G'; |
| *date_str++ = 'M'; |
| *date_str++ = 'T'; |
| *date_str++ = 0; |
| return APR_SUCCESS; |
| } |
| |
| AP_DECLARE(void) ap_force_set_tz(apr_pool_t *p) { |
| /* If the TZ variable is unset, many operating systems, |
| * such as Linux, will at runtime read from /etc/localtime |
| * and call fstat on it. |
| * |
| * By forcing the time zone to UTC if it is unset, we gain |
| * about 2% in raw requests/second (since we format log files |
| * in the local time, if present) |
| * |
| * For more info, see: |
| * <http://www.gnu.org/s/hello/manual/libc/TZ-Variable.html> |
| */ |
| char *v = NULL; |
| |
| if (apr_env_get(&v, "TZ", p) != APR_SUCCESS) { |
| apr_env_set("TZ", "UTC+0", p); |
| } |
| } |
