dostime.c File Reference

Functions to convert times between Unix and MS-DOS times. More...

#include "dostime.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

Include dependency graph for dostime.c:

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Functions
time_t	dos2unixtime (dostime_t dostime)
	Convert a DOS time to a Unix time.
dostime_t	dostime (int year, int month, int day, int hour, int minute, int second)
dostime_t	maxdostime ()
	Return the maximum possible value .
dostime_t	mindostime ()
	Return the minimum possible value.
dostime_t	unix2dostime (time_t unix_time)
	Convert a Unix date to a DOS date.

Detailed Description

These functions make use of the old date and time format defined to implement the FAT file system. This is defined on the Microsoft website here:

https://msdn.microsoft.com/en-us/library/windows/desktop/ms724247%28v=vs.85%29.aspx

As a quick recap, we have:

Date (actually we view those as bit 16 to 31)

0-4    Day of the month (1-31)
5-8    Month (1 = January, 2 = February, and so on)
9-15   Year offset from 1980 (add 1980 to get actual year)

Time

0-4    Second divided by 2
5-10   Minute (0-59)
11-15  Hour (0-23 on a 24-hour clock)

Note

This implementation uses C code.

Definition in file dostime.c.

Function Documentation

dos2unixtime()

time_t dos2unixtime

(

dostime_t

dostime

)

This function returns the Unix time_t value (GMT/UTC time) from the DOS format (local) time dostime, where dostime is a four byte value (date in most significant word, time in least significant word), see dostime() function.

If the input DOS time is invalid, then the function returns -1.

Note

If the dostime is not valid (one of the parameters is out of range) then the function returns -1.

Parameters

[in]

dostime

A DOS time value as found in a zip file.

Returns

The DOS time converted to a Unix time or -1.

See also

dostime()

Todo:

Maximum for tm_mday depends on month/year.

Definition at line 131 of file dostime.c.

References dostime().

Referenced by main(), zipios::ZipCentralDirectoryEntry::read(), zipios::ZipLocalEntry::read(), and zipios::FileEntry::setTime().

dostime()

dostime_t dostime	(	int	year,
		int	month,
		int	day,
		int	hour,
		int	minute,
		int	second
	)

Definition at line 188 of file dostime.c.

Referenced by dos2unixtime(), zipios::ZipCentralDirectoryEntry::read(), zipios::ZipLocalEntry::read(), zipios::FileEntry::setTime(), unix2dostime(), zipios::ZipCentralDirectoryEntry::write(), and zipios::ZipLocalEntry::write().

maxdostime()

dostime_t maxdostime

(

)

This function returns the maximum DOS time that can be represented in a dostime_t parameter.

At this time we use a 32 bit field (like the Zip archive) so the maximum is Dec 31, 2107 23:59:59.

Note

To get the corresponding Unix time, use the dos2unixtime() as in:

time_t max(dos2unixtime(maxdostime()));

Returns

The largest possible DOS time.

Definition at line 105 of file dostime.c.

mindostime()

dostime_t mindostime

(

)

This function returns the minimum DOS time that can be represented in a dostime_t parameter.

At this time we use a 32 bit field (like the Zip archive) so the maximum is Dec 31, 2107 23:59:59.

Note

To get the corresponding Unix time, use the dos2unixtime() as in:

time_t min(dos2unixtime(mindostime()));

Returns

The smallest possible DOS time.

Definition at line 81 of file dostime.c.

unix2dostime()

dostime_t unix2dostime

(

time_t

unix_time

)

This function return the Unix time_t converted in DOS format, rounded up to the next even second.

Parameters

[in]

unix_time

A Unix time_t value.

Returns

The Unix date in DOS format unless it is out of range for a DOS time and date in which case zero (0) is returned.

Definition at line 219 of file dostime.c.

References dostime().

Referenced by zipios::FileEntry::getTime(), main(), zipios::ZipCentralDirectoryEntry::write(), and zipios::ZipLocalEntry::write().