file library: implement file_close

[perlun]

We have support for opening, and reading from files, but we don't have any support at the moment for closing file handles... 😉

[doverhill]

Or deallocating memory... ;)

…

--- Henrik Doverhill Ägare och produktchef, Caspeco AB

________________________________ From: Per Lundberg <notifications@github.com> Sent: Friday, October 6, 2017 10:59:16 PM To: chaos4ever/chaos Cc: Subscribed Subject: [chaos4ever/chaos] file library: implement file_close (#100) We have support for opening, and reading from files, but we don't have any support at the moment for closing file handles... 😉 — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub<#100>, or mute the thread<https://github.com/notifications/unsubscribe-auth/ABYvu0Blk32SCZB7B_Xe7OPYonHGEt9eks5sppSkgaJpZM4PxBrj>.

[perlun]

Or deallocating memory... ;)

We actually have that implemented, but it's not enabled by default. Probably doesn't work very well. But yes, we should definitely fix that. I've also given the general subject a bit of thought, see #4. (discusses sbrk etc.)

chaos/storm/generic/memory.c

Lines 84 to 132 in 54cfe96

	/* Deallocate the given block. */
	/* FIXME: Think about whether the virtual or physical memory should be
	deallocated first. */
	return_type memory_deallocate (void **address)
	{
	uint32_t page_number = ((uint32_t) *address) / SIZE_PAGE;
	if (!current_tss->initialised)
	{
	return STORM_RETURN_ACCESS_DENIED;
	}
	#ifndef DEALLOCATE
	return STORM_RETURN_SUCCESS;
	#endif
	mutex_kernel_wait (&memory_mutex);
	switch (memory_virtual_deallocate (page_number))
	{
	case RETURN_SUCCESS:
	{
	page_table_entry *page_table = (page_table_entry *)
	(BASE_PROCESS_PAGE_TABLES + (page_number / (1 * MB)) * SIZE_PAGE);
	uint32_t physical_page = page_table[page_number % 1024].page_base;
	/* FIXME: Check the return value from this call. But what do we
	do should it fail? */
	memory_physical_deallocate (physical_page);
	mutex_kernel_signal (&memory_mutex);
	*address = NULL;
	return STORM_RETURN_SUCCESS;
	}
	case RETURN_MEMORY_NOT_ALLOCATED:
	{
	mutex_kernel_signal (&memory_mutex);
	return STORM_RETURN_MEMORY_NOT_ALLOCATED;
	}
	default:
	{
	DEBUG_HALT ("Unknown return code.");
	}
	}
	}

[perlun]

For the record: I tested enabling memory deallocation but it made the system run into errors, so we definitely have a problem there. Continuing in #4