Method: File#truncate

Defined in:

file.c

#truncate(integer) ⇒ 0

Truncates file to at most integer bytes. The file must be opened for writing. Not available on all platforms.

f = File.new("out", "w")
f.syswrite("1234567890")   #=> 10
f.truncate(5)              #=> 0
f.close()                  #=> nil
File.size("out")           #=> 5

Returns:

• (0)

# File 'file.c', line 5078

static VALUE
rb_file_truncate(VALUE obj, VALUE len)
{
    rb_io_t *fptr;
    struct ftruncate_arg fa;

    fa.pos = NUM2POS(len);
    GetOpenFile(obj, fptr);
    if (!(fptr->mode & FMODE_WRITABLE)) {
	rb_raise(rb_eIOError, "not opened for writing");
    }
    rb_io_flush_raw(obj, 0);
    fa.fd = fptr->fd;
    if ((int)rb_thread_io_blocking_region(nogvl_ftruncate, &fa, fa.fd) < 0) {
	rb_sys_fail_path(fptr->pathv);
    }
    return INT2FIX(0);
#undef NUM2POS
}