/* BEGIN_ICS_COPYRIGHT4 ****************************************

Copyright (c) 2015, Intel Corporation

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** END_ICS_COPYRIGHT4   ****************************************/

#include "imemory.h"
#include "idebug.h"
#include "iproc_fs.h"

// General purpose function to support proc file reads
//
// config_data, config_alloc, total_size - static variables in proc function
//		will be managed here to maintain context across multiple read calls to
//		this file.
// func - function to allocate space to text contents and format it
// func_data - will be passed as argument to provide context of what to format
// buf, start, offset, maxlen, eof - standard proc read arguments

IBA_PROC_RET
iba_proc_read_wrapper(char **config_data, char **config_alloc, int *total_size,
		IBA_PROC_FORMAT_FUNC func, void* func_data,
 		char *buf, char **start, IBA_PROC_OFFSET offset, int maxlen,
		int *eof)
{
	int cur_size;

	if (! *config_data) {
		*total_size = 0;	// in case format fails to allocate space
		*config_data = *config_alloc = (*func)(func_data, total_size);
	}

	/*
	 * How much data is available for read: OS spits reads into 512b blocks
	 * and asks each individualy via a separate call to you each time.
	 */
	cur_size = (*total_size <= maxlen ? *total_size : maxlen);

	/*
	 * Is this the last read.. do something to generate
	 * an EOF
	 */
	if (cur_size <= 0) {
		*config_data = NULL;
		if (*config_alloc != NULL)
			MemoryDeallocate(*config_alloc);
		*config_alloc = NULL;
		*eof = 1;
		return 0;
	}
	MemoryCopy((void *)buf, (void *)*config_data, cur_size);

	/*
	 * setup for next call
	 */
	*total_size -= cur_size; // Compute #bytes left to deliver.
	*config_data += cur_size;

	if (*total_size <= 0)
		*eof = 1;
	else
		*eof = 0;

	*start = (char *)(uintn)cur_size;
	return cur_size;
}

void
SimpleProcInitState(SIMPLE_PROC *pProc)
{
	MemoryClear(pProc, sizeof(*pProc));
}

// internal format function if callback occurs for
// /proc object which is uninitialize (eg. being destroyed)
static
char * SimpleProcFormatUninit(void *data, int* total_size)
{
	return NULL;
}

static
IBA_PROC_RET SimpleProcRead(char *buf, char **start, IBA_PROC_OFFSET offset, int maxlen, int *eof, void *data)
{
	SIMPLE_PROC *pProc = (SIMPLE_PROC*)data;

	return iba_proc_read_wrapper(&pProc->config_data, &pProc->config_alloc,
			&pProc->total_size,
			pProc->Initialized ? pProc->FormatFunc
					: SimpleProcFormatUninit,
			pProc->Context,
			buf, start, offset, maxlen, eof);
}

static
IBA_PROC_RET SimpleProcWrite(IBA_PROC_FILE *file, const char *buffer, unsigned long length, void *data)
{
	SIMPLE_PROC *pProc = (SIMPLE_PROC*)data;

	if (pProc->Initialized);
		(*pProc->ClearFunc)(pProc->Context);
	return length;
}

// create and initialize /proc file
// Inputs:
//	pProc - object to initialize
//	Name - relative filename in ProcDir
//	ProcDir - parent directory
//	Context - context to pass to FormatFunc and ClearFunc
//	FormatFunc - function to allocate and format /proc read data
//	ClearFunc - function to clear data in response to /proc write
// Outputs:
//	None
// Returns:
//	true - initialized and callbacks will begin on user access to /proc
//	false - unable to create
//
// must be called in a preemptable context
//
boolean
SimpleProcInit(SIMPLE_PROC *pProc, const char* Name, IBA_PROC_NODE *ProcDir, 
		void *Context, IBA_PROC_FORMAT_FUNC FormatFunc,
		OPTIONAL SIMPLE_PROC_CLEAR_FUNC ClearFunc)
{
	IBA_PROC_NODE 		*entry;

	ASSERT(! pProc->Initialized);
	ASSERT(FormatFunc);
	ASSERT(Name);
	pProc->Context = Context;
	strncpy(pProc->Name, Name, SIMPLE_PROC_NAME_LEN-1);
	pProc->Name[SIMPLE_PROC_NAME_LEN-1] = '\0';
	pProc->ProcDir = ProcDir;
	pProc->FormatFunc = FormatFunc;
	pProc->ClearFunc = ClearFunc;
	
	entry = iba_create_proc_entry(pProc->Name,
				IBA_PROC_MODE_IFREG | IBA_PROC_MODE_IRUGOWUG,
				pProc->ProcDir);
	if (! entry)
	{
		MsgOut("Cannot create proc entry: %s\n", pProc->Name);
		return FALSE;
	}
	iba_set_proc_data(entry, pProc);
	iba_set_proc_read_func(entry, SimpleProcRead);
	iba_set_proc_write_func(entry, ClearFunc?SimpleProcWrite:NULL);
	pProc->Initialized = TRUE;
	return TRUE;
}

void
SimpleProcDestroy(SIMPLE_PROC *pProc)
{
	if (pProc->Initialized)
		iba_remove_proc_entry(pProc->Name, pProc->ProcDir);
	MemoryClear(pProc, sizeof(*pProc));
}