ZIP_FILE_SET_MTIME(3) Library Functions Manual ZIP_FILE_SET_MTIME(3)

zip_file_set_dostime, zip_file_set_mtime —
set last modification time (mtime) for file in zip

libzip (-lzip)

#include <zip.h>

int
zip_file_set_dostime(zip_t *archive, zip_uint64_t index, zip_uint16_t dostime, zip_uint16_t dosdate, zip_flags_t flags);

int
zip_file_set_mtime(zip_t *archive, zip_uint64_t index, time_t mtime, zip_flags_t flags);

The zip_file_set_mtime() function sets the last modification time (mtime) for the file at position index in the zip archive to mtime. Currently, no support for any flags is implemented.

In the zip archive, the time and date are saved as two 16-bit integers. To set the values directly, call the zip_file_set_dostime() function. The values of the time bytes are defined as follows:

0-4
seconds divided by two (1-2 = 1, 3-4 = 2, ...)
5-10
minute (0-59)
11-15
hour (0-23)

The values of the date bytes are defined as follows:

0-4
day of the month (1-31)
5-8
month (January = 1, February = 2, ...)
9-15
year offset from 1980 (1980 = 0, 1981 = 1, ...)

Upon successful completion 0 is returned. Otherwise, -1 is returned and the error information in archive is set to indicate the error.

zip_file_set_dostime() and zip_file_set_mtime() fail if:
[]
index is not a valid file index in archive.
[]
Required memory could not be allocated.
[]
The archive was opened in read-only mode.

libzip(3), zip_stat(3)

zip_file_set_mtime() was added in libzip 1.0. zip_file_set_dostime() was added in libzip 1.6.

Dieter Baron <dillo@nih.at> and Thomas Klausner <tk@giga.or.at>

Following historical practice, the zip_file_set_mtime() function translates the time from the zip archive into the local time zone. If you want to avoid this, use the zip_file_set_dostime() function instead.
August 24, 2020 NiH