Blame src/hash/ntapi_tt_populate_hashed_import_table.c

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/********************************************************/
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/*  ntapi: Native API core library                      */
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/*  Copyright (C) 2013--2021  SysDeer Technologies, LLC */
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/*  Released under GPLv2 and GPLv3; see COPYING.NTAPI.  */
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/********************************************************/
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#include <psxtypes/psxtypes.h>
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#include <pemagine/pemagine.h>
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#include <ntapi/nt_object.h>
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#include <ntapi/nt_crc32.h>
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#include <ntapi/ntapi.h>
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#include "ntapi_impl.h"
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struct callback_ctx {
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	void *			import_table;
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	ntapi_hashed_symbol *	hash_table;
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	uint32_t		hash_table_array_size;
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};
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static int __process_exported_symbol(
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	const void *				base,
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	struct pe_raw_export_hdr *		exp_hdr,
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	struct pe_export_sym *			exp_item,
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	enum pe_callback_reason			reason,
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	void *					context)
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{
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	uint32_t		hash_value;
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	struct callback_ctx *	ctx;
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	ntapi_hashed_symbol *	hashed_symbol;
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	uintptr_t *		fnptr;
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	/* unused params */
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	(void)base;
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	(void)exp_hdr;
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	/* binary search variables */
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	uint32_t	lower;
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	uint32_t	upper;
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	uint32_t	idx;
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	if (reason != PE_CALLBACK_REASON_ITEM)
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		return 1;
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	ctx = (struct callback_ctx *)context;
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	hash_value = __ntapi_tt_mbstr_crc32(exp_item->name);
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	/* zero-based array, binary search, idx < upper is guaranteed */
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	lower  = 0;
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	upper  = ctx->hash_table_array_size;
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	/* binary search */
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	while (lower < upper) {
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		idx		= (lower + upper) / 2;
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		hashed_symbol	= (ntapi_hashed_symbol *)
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					((uintptr_t)ctx->hash_table
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					+ idx * sizeof(ntapi_hashed_symbol));
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		if (hash_value == hashed_symbol->crc32_hash) {
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			fnptr = (uintptr_t *)(
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				(uintptr_t)ctx->import_table
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				+ (sizeof(uintptr_t)
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					* hashed_symbol->ordinal));
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			*fnptr = (uintptr_t)exp_item->addr;
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			return 1;
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		}
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		else {
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			if (hash_value > hashed_symbol->crc32_hash)
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				lower = idx + 1;
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			else
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				upper = idx;
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		}
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	}
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	return 1;
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}
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int32_t __cdecl __ntapi_tt_populate_hashed_import_table(
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    __in 	void *			image_base,
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    __in	void *			import_table,
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    __in	ntapi_hashed_symbol *	hash_table,
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    __in	uint32_t		hash_table_array_size)
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{
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	struct pe_export_sym	exp_item;
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	struct callback_ctx	ctx;
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	ctx.import_table		= import_table;
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	ctx.hash_table			= hash_table;
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	ctx.hash_table_array_size	= hash_table_array_size;
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	pe_enum_image_exports(
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		image_base,
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		&__process_exported_symbol,
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		&exp_item,
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		&ctx;;
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	return 0;
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}