The return value of round returns the scale before removing unnecessary zeros, and uses that.

Author: SakiTakamachi

ext/bcmath/bcmath.c

@@ -807,8 +807,8 @@ PHP_FUNCTION(bcround)
 		goto cleanup;
 	}
 
-	bc_round(num, precision, mode, &result);
-	RETVAL_NEW_STR(bc_num2str_ex(result, result->n_scale));
+	size_t scale = bc_round(num, precision, mode, &result);
+	RETVAL_NEW_STR(bc_num2str_ex(result, scale));
 
 	cleanup: {
 		bc_free_num(&num);
@@ -1799,9 +1799,9 @@ PHP_METHOD(BcMath_Number, round)
 	bcmath_number_obj_t *intern = get_bcmath_number_from_zval(ZEND_THIS);
 
 	bc_num ret = NULL;
-	bc_round(intern->num, precision, rounding_mode, &ret);
+	size_t scale = bc_round(intern->num, precision, rounding_mode, &ret);
 
-	bcmath_number_obj_t *new_intern = bcmath_number_new_obj(ret, ret->n_scale);
+	bcmath_number_obj_t *new_intern = bcmath_number_new_obj(ret, scale);
 	RETURN_OBJ(&new_intern->std);
 }
 

ext/bcmath/libbcmath/src/bcmath.h

@@ -157,7 +157,7 @@ bool bc_divmod(bc_num num1, bc_num num2, bc_num *quo, bc_num *rem, size_t scale)
 
 bc_num bc_floor_or_ceil(bc_num num, bool is_floor);
 
-void bc_round(bc_num num, zend_long places, zend_long mode, bc_num *result);
+size_t bc_round(bc_num num, zend_long places, zend_long mode, bc_num *result);
 
 typedef enum {
 	OK,

ext/bcmath/libbcmath/src/round.c

@@ -18,7 +18,7 @@
 #include "private.h"
 #include <stddef.h>
 
-void bc_round(bc_num num, zend_long precision, zend_long mode, bc_num *result)
+size_t bc_round(bc_num num, zend_long precision, zend_long mode, bc_num *result)
 {
 	/* clear result */
 	bc_free_num(result);
@@ -43,19 +43,19 @@ void bc_round(bc_num num, zend_long precision, zend_long mode, bc_num *result)
 			case PHP_ROUND_HALF_ODD:
 			case PHP_ROUND_TOWARD_ZERO:
 				*result = bc_copy_num(BCG(_zero_));
-				return;
+				return 0;
 
 			case PHP_ROUND_CEILING:
 				if (num->n_sign == MINUS) {
 					*result = bc_copy_num(BCG(_zero_));
-					return;
+					return 0;
 				}
 				break;
 
 			case PHP_ROUND_FLOOR:
 				if (num->n_sign == PLUS) {
 					*result = bc_copy_num(BCG(_zero_));
-					return;
+					return 0;
 				}
 				break;
 
@@ -67,7 +67,7 @@ void bc_round(bc_num num, zend_long precision, zend_long mode, bc_num *result)
 
 		if (bc_is_zero(num)) {
 			*result = bc_copy_num(BCG(_zero_));
-			return;
+			return 0;
 		}
 
 		/* If precision is -3, it becomes 1000. */
@@ -78,7 +78,7 @@ void bc_round(bc_num num, zend_long precision, zend_long mode, bc_num *result)
 		}
 		(*result)->n_value[0] = 1;
 		(*result)->n_sign = num->n_sign;
-		return;
+		return 0;
 	}
 
 	/* Just like bcadd('1', '1', 4) becomes '2.0000', it pads with zeros at the end if necessary. */
@@ -90,7 +90,7 @@ void bc_round(bc_num num, zend_long precision, zend_long mode, bc_num *result)
 			(*result)->n_sign = num->n_sign;
 			memcpy((*result)->n_value, num->n_value, num->n_len + num->n_scale);
 		}
-		return;
+		return precision;
 	}
 
 	/*
@@ -222,8 +222,10 @@ void bc_round(bc_num num, zend_long precision, zend_long mode, bc_num *result)
 	}
 
 check_zero:
+	size_t scale = (*result)->n_scale;
 	if (bc_is_zero(*result)) {
 		(*result)->n_sign = PLUS;
 		(*result)->n_scale = 0;
 	}
+	return scale;
 }