CODEWITHSUNDEEP
cunixtimestamp
vytaute
vytaute

Reputation: 1480

How to implement futimens function in C to change time stamp on file

I have written this code using futimens() function:

int set_time(const char *name)
{
    int dskr = open_file( name );
    struct timespec now;
    int retval = clock_gettime(CLOCK_REALTIME, &now);
    printf("Clock_gettime returned %d \n", retval);
    printf("%ld \n", now.tv_sec);
    
    int status = futimens(dskr, &now);
    handle_error("futimens", status);
    close_file(dskr);
    return 0;
}

It gives such output:

Clock_gettime returned 0
1619210402
futimens status: -1
futimens() error: Invalid argument

ow do I use futimens function to change file timestamp to current time?

I am quite new in C so I am really struggling to find needed information to implement the solution.

P.S. handle_error() function is just my function to catch exceptions.

Upvotes: 0

Views: 324

Answers (1)

Emanuel P
Emanuel P

Reputation: 1452

futimens requires an array of two struct timespec. That's why you get an invalid argument error. The zeroth element is the access time, and the first is the modification time. So you could set the modification time like this:

struct timespec now[2];
now[0].tv_nsec = UTIME_OMIT;
int retval = clock_gettime(CLOCK_REALTIME, &now[1]);
int status = futimens(dskr, now);

Or, alternatively:

struct timespec now[2];
now[0].tv_nsec = UTIME_OMIT;
now[1].tv_nsec = UTIME_NOW;
int status = futimens(dskr, now);

See the man page.

Upvotes: 1

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