/********************************************************/

/*  ntapi: Native API core library                      */

/*  Copyright (C) 2013--2021  SysDeer Technologies, LLC */

/*  Released under GPLv2 and GPLv3; see COPYING.NTAPI.  */

/********************************************************/

#include <psxtypes/psxtypes.h>

#include <pemagine/pemagine.h>

#include <ntapi/nt_object.h>

#include <ntapi/nt_crc32.h>

#include <ntapi/ntapi.h>

#include "ntapi_impl.h"

struct callback_ctx {

	void *			import_table;

	ntapi_hashed_symbol *	hash_table;

	uint32_t		hash_table_array_size;

};

static int __process_exported_symbol(

	const void *				base,

	struct pe_raw_export_hdr *		exp_hdr,

	struct pe_export_sym *			exp_item,

	enum pe_callback_reason			reason,

	void *					context)

{

	uint32_t		hash_value;

	struct callback_ctx *	ctx;

	ntapi_hashed_symbol *	hashed_symbol;

	uintptr_t *		fnptr;

	/* unused params */

	(void)base;

	(void)exp_hdr;

	/* binary search variables */

	uint32_t	lower;

	uint32_t	upper;

	uint32_t	idx;

	if (reason != PE_CALLBACK_REASON_ITEM)

		return 1;

	ctx = (struct callback_ctx *)context;

	hash_value = __ntapi_tt_mbstr_crc32(exp_item->name);

	/* zero-based array, binary search, idx < upper is guaranteed */

	lower  = 0;

	upper  = ctx->hash_table_array_size;

	/* binary search */

	while (lower < upper) {

		idx		= (lower + upper) / 2;

		hashed_symbol	= (ntapi_hashed_symbol *)

					((uintptr_t)ctx->hash_table

					+ idx * sizeof(ntapi_hashed_symbol));

		if (hash_value == hashed_symbol->crc32_hash) {

			fnptr = (uintptr_t *)(

				(uintptr_t)ctx->import_table

				+ (sizeof(uintptr_t)

					* hashed_symbol->ordinal));

			*fnptr = (uintptr_t)exp_item->addr;

			return 1;

		}

		else {

			if (hash_value > hashed_symbol->crc32_hash)

				lower = idx + 1;

			else

				upper = idx;

		}

	}

	return 1;

}

int32_t __cdecl __ntapi_tt_populate_hashed_import_table(

    __in 	void *			image_base,

    __in	void *			import_table,

    __in	ntapi_hashed_symbol *	hash_table,

    __in	uint32_t		hash_table_array_size)

{

	struct pe_export_sym	exp_item;

	struct callback_ctx	ctx;

	ctx.import_table		= import_table;

	ctx.hash_table			= hash_table;

	ctx.hash_table_array_size	= hash_table_array_size;

	pe_enum_image_exports(

		image_base,

		&__process_exported_symbol,

		&exp_item,

		&ctx;;

	return 0;

}