in source/shared/core_stmt.cpp [1882:2032]
void adjustDecimalPrecision(_Inout_ zval* param_z, _In_ SQLSMALLINT decimal_digits)
{
char* value = Z_STRVAL_P(param_z);
int value_len = Z_STRLEN_P(param_z);
// If the length is greater than maxDecimalStrLen, do not convert the string
// 6 is derived from: 1 for the decimal point; 1 for sign of the number; 1 for 'e' or 'E' (scientific notation);
// 1 for sign of scientific exponent; 2 for length of scientific exponent
const int MAX_DECIMAL_STRLEN = SQL_SERVER_DECIMAL_MAXIMUM_PRECISION + 6;
if (value_len > MAX_DECIMAL_STRLEN) {
return;
}
// If std::stold() succeeds, 'index' is the position of the first character after the numerical value
long double d = 0;
size_t index;
try {
d = std::stold(std::string(value), &index);
}
catch (const std::logic_error& ) {
return; // invalid input caused the conversion to throw an exception
}
if (index < value_len) {
return; // the input contains something else apart from the numerical value
}
// Navigate to the first digit or the decimal point
short is_negative = (d < 0) ? 1 : 0;
char *src = value + is_negative;
while (*src != DECIMAL_POINT && !isdigit(static_cast<unsigned int>(*src))) {
src++;
}
// Check if the value is in scientific notation
char *exp = strchr(src, 'E');
if (exp == NULL) {
exp = strchr(src, 'e');
}
// Find the decimal point
char *pt = strchr(src, DECIMAL_POINT);
char buffer[50] = " "; // A buffer with 2 blank spaces, as leeway
int offset = 1 + is_negative; // The position to start copying the original numerical value
if (exp == NULL) {
if (pt == NULL) {
return; // decimal point not found
}
int src_length = strnlen_s(src);
int num_decimals = src_length - (pt - src) - 1;
if (num_decimals <= decimal_digits) {
return; // no need to adjust number of decimals
}
memcpy_s(buffer + offset, src_length, src, src_length);
round_up_decimal_numbers(buffer, (pt - src) + offset, decimal_digits, offset, src_length + offset);
}
else {
int power = atoi(exp+1);
if (abs(power) > SQL_SERVER_DECIMAL_MAXIMUM_PRECISION) {
return; // Out of range, so let the server handle this
}
int num_decimals = 0;
if (power == 0) {
// Simply chop off the exp part
int length = (exp - src);
memcpy_s(buffer + offset, length, src, length);
if (pt != NULL) {
// Adjust decimal places only if decimal point is found and number of decimals more than decimal_digits
num_decimals = exp - pt - 1;
if (num_decimals > decimal_digits) {
round_up_decimal_numbers(buffer, (pt - src) + offset, decimal_digits, offset, length + offset);
}
}
} else {
int oldpos = 0;
if (pt == NULL) {
oldpos = exp - src; // Decimal point not found, use the exp sign
}
else {
oldpos = pt - src;
num_decimals = exp - pt - 1;
if (power > 0 && num_decimals <= power) {
return; // The result will be a whole number, do nothing and return
}
}
// Derive the new position for the decimal point in the buffer
int newpos = oldpos + power;
if (power > 0) {
newpos = newpos + offset;
if (num_decimals == 0) {
memset(buffer + offset + oldpos, '0', power); // Fill parts of the buffer with zeroes first
}
else {
buffer[newpos] = DECIMAL_POINT;
}
}
else {
// The negative "power" part shows exactly how many places to move the decimal point.
// Whether to pad zeroes depending on the original position of the decimal point pos.
if (newpos <= 0) {
// If newpos is negative or zero, pad zeroes (size of '0.' + places to move) in the buffer
short numzeroes = 2 + abs(newpos);
memset(buffer + offset, '0', numzeroes);
newpos = offset + 1; // The new decimal position should be offset + '0'
buffer[newpos] = DECIMAL_POINT; // Replace that '0' with the decimal point
offset = numzeroes + offset; // Short offset now in the buffer
}
else {
newpos = newpos + offset;
buffer[newpos] = DECIMAL_POINT;
}
}
// Start copying the content to the buffer until the exp sign or one more digit after decimal_digits
char *p = src;
int idx = offset;
int lastpos = newpos + decimal_digits + 1;
while (p != exp && idx <= lastpos) {
if (*p == DECIMAL_POINT) {
p++;
continue;
}
if (buffer[idx] == DECIMAL_POINT) {
idx++;
}
buffer[idx++] = *p;
p++;
}
// Round up is required only when number of decimals is more than decimal_digits
num_decimals = idx - newpos - 1;
if (num_decimals > decimal_digits) {
round_up_decimal_numbers(buffer, newpos, decimal_digits, offset, idx);
}
}
}
// Set the minus sign if negative
if (is_negative) {
buffer[0] = '-';
}
zend_string* zstr = zend_string_init(buffer, strnlen_s(buffer), 0);
zend_string_release(Z_STR_P(param_z));
ZVAL_NEW_STR(param_z, zstr);
}