core: add helper functions to format / parse timestamps

To save datetime-based filter constraints to git or XML,
it is preferrable to use human-readable representations.
Therefore, add helper functions to format / parse timestamp_t
64-bit values in the "YYYY-MM-DD hh:mm:ss" format.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
This commit is contained in:
Berthold Stoeger 2020-08-27 07:10:33 +02:00 committed by Dirk Hohndel
parent f9721fce4b
commit 8f898477cb
2 changed files with 54 additions and 0 deletions

View file

@ -14,6 +14,10 @@ extern void utc_mkdate(timestamp_t, struct tm *tm);
extern int utc_year(timestamp_t timestamp);
extern int utc_weekday(timestamp_t timestamp);
/* parse and format date times of the form YYYY-MM-DD hh:mm:ss */
extern timestamp_t parse_datetime(const char *s); /* returns 0 on error */
extern char *format_datetime(timestamp_t timestamp); /* ownership of string passed to caller */
#ifdef __cplusplus
}
#endif

View file

@ -1,6 +1,9 @@
// SPDX-License-Identifier: GPL-2.0
#include "subsurface-time.h"
#include "subsurface-string.h"
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
/*
* The date handling internally works in seconds since
@ -163,3 +166,50 @@ int utc_weekday(timestamp_t timestamp)
utc_mkdate(timestamp, &tm);
return tm.tm_wday;
}
/*
* Try to parse datetime of the form "YYYY-MM-DD hh:mm:ss" or as
* an 64-bit decimal and return 64-bit timestamp. On failure or
* if passed an empty string, return 0.
*/
extern timestamp_t parse_datetime(const char *s)
{
int y, m, d;
int hr, min, sec;
struct tm tm;
if (empty_string(s))
return 0;
if (sscanf(s, "%d-%d-%d %d:%d:%d", &y, &m, &d, &hr, &min, &sec) != 6) {
char *endptr;
timestamp_t res = strtoull(s, &endptr, 10);
return *endptr == '\0' ? res : 0;
}
tm.tm_year = y;
tm.tm_mon = m - 1;
tm.tm_mday = d;
tm.tm_hour = hr;
tm.tm_min = min;
tm.tm_sec = sec;
return utc_mktime(&tm);
}
/*
* Format 64-bit timestamp in the form "YYYY-MM-DD hh:mm:ss".
* Returns the empty string for timestamp = 0
*/
extern char *format_datetime(timestamp_t timestamp)
{
char buf[32];
struct tm tm;
if (!timestamp)
return strdup("");
utc_mkdate(timestamp, &tm);
snprintf(buf, sizeof(buf), "%04u-%02u-%02u %02u:%02u:%02u",
tm.tm_year, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
return strdup(buf);
}