Commit 7089d582 authored by Daniel Verkamp's avatar Daniel Verkamp
Browse files

json_util: parse integer numbers directly 



Avoid a trip through floating-point numbers when parsing JSON numbers as
integers.

This will allow parsing 64-bit integers that cannot be represented in
double precision floating point.

Change-Id: Ic428c9f12e44e6dbee72f39a91ecb56ab30b365f
Signed-off-by: default avatarDaniel Verkamp <daniel.verkamp@intel.com>
Reviewed-on: https://review.gerrithub.io/364132


Reviewed-by: default avatarBen Walker <benjamin.walker@intel.com>
Tested-by: default avatarSPDK Automated Test System <sys_sgsw@intel.com>
parent d7134439

lib/json/json_util.c

+137 −15
Original line number Diff line number Diff line
@@ -92,6 +92,113 @@ spdk_json_strdup(const struct spdk_json_val *val) 
	return s;

}



struct spdk_json_num {

	bool negative;

	uint64_t significand;

	int64_t exponent;

};



static int

spdk_json_number_split(const struct spdk_json_val *val, struct spdk_json_num *num)

{

	const char *iter;

	size_t remaining;

	uint64_t *pval;

	uint64_t frac_digits = 0;

	uint64_t exponent_u64 = 0;

	bool exponent_negative = false;

	enum {

		NUM_STATE_INT,

		NUM_STATE_FRAC,

		NUM_STATE_EXP,

	} state;



	memset(num, 0, sizeof(*num));



	if (val->type != SPDK_JSON_VAL_NUMBER) {

		return -EINVAL;

	}



	remaining = val->len;

	if (remaining == 0) {

		return -EINVAL;

	}



	iter = val->start;

	if (*iter == '-') {

		num->negative = true;

		iter++;

		remaining--;

	}



	state = NUM_STATE_INT;

	pval = &num->significand;

	while (remaining--) {

		char c = *iter++;



		if (c == '.') {

			state = NUM_STATE_FRAC;

		} else if (c == 'e' || c == 'E') {

			state = NUM_STATE_EXP;

			pval = &exponent_u64;

		} else if (c == '-') {

			assert(state == NUM_STATE_EXP);

			exponent_negative = true;

		} else if (c == '+') {

			assert(state == NUM_STATE_EXP);

			/* exp_negative = false; */ /* already false by default */

		} else {

			uint64_t new_val;



			assert(c >= '0' && c <= '9');

			new_val = *pval * 10 + c - '0';

			if (new_val < *pval) {

				return -ERANGE;

			}



			if (state == NUM_STATE_FRAC) {

				frac_digits++;

			}



			*pval = new_val;

		}

	}



	if (exponent_negative) {

		if (exponent_u64 > 9223372036854775808ULL) { /* abs(INT64_MIN) */

			return -ERANGE;

		}

		num->exponent = (int64_t) - exponent_u64;

	} else {

		if (exponent_u64 > INT64_MAX) {

			return -ERANGE;

		}

		num->exponent = exponent_u64;

	}

	num->exponent -= frac_digits;



	/* Apply as much of the exponent as possible without overflow or truncation */

	if (num->exponent < 0) {

		while (num->exponent && num->significand >= 10 && num->significand % 10 == 0) {

			num->significand /= 10;

			num->exponent++;

		}

	} else { /* positive exponent */

		while (num->exponent) {

			uint64_t new_val = num->significand * 10;



			if (new_val < num->significand) {

				break;

			}



			num->significand = new_val;

			num->exponent--;

		}

	}



	return 0;

}



int

spdk_json_number_to_double(const struct spdk_json_val *val, double *num)

{
@@ -119,38 +226,53 @@ spdk_json_number_to_double(const struct spdk_json_val *val, double *num) 
int

spdk_json_number_to_int32(const struct spdk_json_val *val, int32_t *num)

{

	double dbl;

	struct spdk_json_num split_num;

	int rc;



	if (spdk_json_number_to_double(val, &dbl)) {

		return -1;

	rc = spdk_json_number_split(val, &split_num);

	if (rc) {

		return rc;

	}



	*num = (int32_t)dbl;

	if (dbl != (double)*num) {

		return -1;

	if (split_num.exponent) {

		return -ERANGE;

	}



	if (split_num.negative) {

		if (split_num.significand > 2147483648) { /* abs(INT32_MIN) */

			return -ERANGE;

		}

		*num = (int32_t) - (int64_t)split_num.significand;

		return 0;

	}



	/* positive */

	if (split_num.significand > INT32_MAX) {

		return -ERANGE;

	}

	*num = (int32_t)split_num.significand;

	return 0;

}



int

spdk_json_number_to_uint32(const struct spdk_json_val *val, uint32_t *num)

{

	double dbl;

	struct spdk_json_num split_num;

	int rc;



	if (spdk_json_number_to_double(val, &dbl)) {

		return -1;

	rc = spdk_json_number_split(val, &split_num);

	if (rc) {

		return rc;

	}



	if (dbl < 0) {

		return -1;

	if (split_num.exponent || split_num.negative) {

		return -ERANGE;

	}



	*num = (uint32_t)dbl;

	if (dbl != (double)*num) {

		return -1;

	if (split_num.significand > UINT32_MAX) {

		return -ERANGE;

	}



	*num = (uint32_t)split_num.significand;

	return 0;

}

test/lib/json/util/json_util_ut.c

+8 −1
Original line number Diff line number Diff line
@@ -383,7 +383,14 @@ test_decode_uint32(void) 
	v.len = 6;

	i = 0;

	CU_ASSERT(spdk_json_decode_uint32(&v, &i) == 0);

	CU_ASSERT(i == 4)

	CU_ASSERT(i == 4);



	/* valid negative exponent */

	v.start = "10e-1";

	v.len = 5;

	i = 0;

	CU_ASSERT(spdk_json_decode_uint32(&v, &i) == 0);

	CU_ASSERT(i == 1)

}



static void