1 /*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * 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 #define LOG_TAG "MtpUtils"
18
19 #include <stdio.h>
20 #include <time.h>
21
22 #include "MtpUtils.h"
23
24 namespace android {
25
26 /*
27 DateTime strings follow a compatible subset of the definition found in ISO 8601, and
28 take the form of a Unicode string formatted as: "YYYYMMDDThhmmss.s". In this
29 representation, YYYY shall be replaced by the year, MM replaced by the month (01-12),
30 DD replaced by the day (01-31), T is a constant character 'T' delimiting time from date,
31 hh is replaced by the hour (00-23), mm is replaced by the minute (00-59), and ss by the
32 second (00-59). The ".s" is optional, and represents tenths of a second.
33 This is followed by a UTC offset given as "[+-]zzzz" or the literal "Z", meaning UTC.
34 */
35
parseDateTime(const char * dateTime,time_t & outSeconds)36 bool parseDateTime(const char* dateTime, time_t& outSeconds) {
37 int year, month, day, hour, minute, second;
38 if (sscanf(dateTime, "%04d%02d%02dT%02d%02d%02d",
39 &year, &month, &day, &hour, &minute, &second) != 6)
40 return false;
41
42 // skip optional tenth of second
43 const char* tail = dateTime + 15;
44 if (tail[0] == '.' && tail[1]) tail += 2;
45
46 // FIXME: "Z" means UTC, but non-"Z" doesn't mean local time.
47 // It might be that you're in Asia/Seoul on vacation and your Android
48 // device has noticed this via the network, but your camera was set to
49 // America/Los_Angeles once when you bought it and doesn't know where
50 // it is right now, so the camera says "20160106T081700-0800" but we
51 // just ignore the "-0800" and assume local time which is actually "+0900".
52 // I think to support this (without switching to Java or using icu4c)
53 // you'd want to always use timegm(3) and then manually add/subtract
54 // the UTC offset parsed from the string (taking care of wrapping).
55 // mktime(3) ignores the tm_gmtoff field, so you can't let it do the work.
56 bool useUTC = (tail[0] == 'Z');
57
58 struct tm tm = {};
59 tm.tm_sec = second;
60 tm.tm_min = minute;
61 tm.tm_hour = hour;
62 tm.tm_mday = day;
63 tm.tm_mon = month - 1; // mktime uses months in 0 - 11 range
64 tm.tm_year = year - 1900;
65 tm.tm_isdst = -1;
66 outSeconds = useUTC ? timegm(&tm) : mktime(&tm);
67
68 return true;
69 }
70
formatDateTime(time_t seconds,char * buffer,int bufferLength)71 void formatDateTime(time_t seconds, char* buffer, int bufferLength) {
72 struct tm tm;
73
74 localtime_r(&seconds, &tm);
75 snprintf(buffer, bufferLength, "%04d%02d%02dT%02d%02d%02d",
76 tm.tm_year + 1900,
77 tm.tm_mon + 1, // localtime_r uses months in 0 - 11 range
78 tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
79 }
80
81 } // namespace android
82