1--- 2c: Copyright (C) Daniel Stenberg, <daniel.se>, et al. 3SPDX-License-Identifier: curl 4Title: curl_getdate 5Section: 3 6Source: libcurl 7See-also: 8 - CURLOPT_TIMECONDITION (3) 9 - CURLOPT_TIMEVALUE (3) 10 - curl_easy_escape (3) 11 - curl_easy_unescape (3) 12--- 13 14# NAME 15 16curl_getdate - Convert a date string to number of seconds 17 18# SYNOPSIS 19 20~~~c 21#include <curl/curl.h> 22 23time_t curl_getdate(const char *datestring, const time_t *now); 24~~~ 25 26# DESCRIPTION 27 28curl_getdate(3) returns the number of seconds since the Epoch, January 291st 1970 00:00:00 in the UTC time zone, for the date and time that the 30*datestring* parameter specifies. The *now* parameter is not used, 31pass a NULL there. 32 33This function works with valid dates and does not always detect and reject 34wrong dates, such as February 30. 35 36# PARSING DATES AND TIMES 37 38A "date" is a string containing several items separated by whitespace. The 39order of the items is immaterial. A date string may contain many flavors of 40items: 41 42## calendar date items 43 44Can be specified several ways. Month names can only be three-letter English 45abbreviations, numbers can be zero-prefixed and the year may use 2 or 4 46digits. Examples: 06 Nov 1994, 06-Nov-94 and Nov-94 6. 47 48## time of the day items 49 50This string specifies the time on a given day. You must specify it with 6 51digits with two colons: HH:MM:SS. If there is no time given in a provided date 52string, 00:00:00 is assumed. Example: 18:19:21. 53 54## time zone items 55 56Specifies international time zone. There are a few acronyms supported, but in 57general you should instead use the specific relative time compared to 58UTC. Supported formats include: -1200, MST, +0100. 59 60## day of the week items 61 62Specifies a day of the week. Days of the week may be spelled out in full 63(using English): `Sunday', `Monday', etc or they may be abbreviated to their 64first three letters. This is usually not info that adds anything. 65 66## pure numbers 67 68If a decimal number of the form YYYYMMDD appears, then YYYY is read as the 69year, MM as the month number and DD as the day of the month, for the specified 70calendar date. 71 72# EXAMPLE 73 74~~~c 75int main(void) 76{ 77 time_t t; 78 t = curl_getdate("Sun, 06 Nov 1994 08:49:37 GMT", NULL); 79 t = curl_getdate("Sunday, 06-Nov-94 08:49:37 GMT", NULL); 80 t = curl_getdate("Sun Nov 6 08:49:37 1994", NULL); 81 t = curl_getdate("06 Nov 1994 08:49:37 GMT", NULL); 82 t = curl_getdate("06-Nov-94 08:49:37 GMT", NULL); 83 t = curl_getdate("Nov 6 08:49:37 1994", NULL); 84 t = curl_getdate("06 Nov 1994 08:49:37", NULL); 85 t = curl_getdate("06-Nov-94 08:49:37", NULL); 86 t = curl_getdate("1994 Nov 6 08:49:37", NULL); 87 t = curl_getdate("GMT 08:49:37 06-Nov-94 Sunday", NULL); 88 t = curl_getdate("94 6 Nov 08:49:37", NULL); 89 t = curl_getdate("1994 Nov 6", NULL); 90 t = curl_getdate("06-Nov-94", NULL); 91 t = curl_getdate("Sun Nov 6 94", NULL); 92 t = curl_getdate("1994.Nov.6", NULL); 93 t = curl_getdate("Sun/Nov/6/94/GMT", NULL); 94 t = curl_getdate("Sun, 06 Nov 1994 08:49:37 CET", NULL); 95 t = curl_getdate("06 Nov 1994 08:49:37 EST", NULL); 96 t = curl_getdate("Sun, 12 Sep 2004 15:05:58 -0700", NULL); 97 t = curl_getdate("Sat, 11 Sep 2004 21:32:11 +0200", NULL); 98 t = curl_getdate("20040912 15:05:58 -0700", NULL); 99 t = curl_getdate("20040911 +0200", NULL); 100} 101~~~ 102 103# STANDARDS 104 105This parser handles date formats specified in RFC 822 (including the update in 106RFC 1123) using time zone name or time zone delta and RFC 850 (obsoleted by 107RFC 1036) and ANSI C's *asctime()* format. 108 109These formats are the only ones RFC 7231 says HTTP applications may use. 110 111# AVAILABILITY 112 113Always 114 115# RETURN VALUE 116 117This function returns -1 when it fails to parse the date string. Otherwise it 118returns the number of seconds as described. 119 120On systems with a signed 32 bit time_t: if the year is larger than 2037 or 121less than 1903, this function returns -1. 122 123On systems with an unsigned 32 bit time_t: if the year is larger than 2106 or 124less than 1970, this function returns -1. 125 126On systems with 64 bit time_t: if the year is less than 1583, this function 127returns -1. (The Gregorian calendar was first introduced 1582 so no "real" 128dates in this way of doing dates existed before then.) 129