Fixed pointer subtraction for scale (#17986)

SakiTakamachi · SakiTakamachi · commit 7c9872e255b3 · 2025-03-14T09:00:00.000+09:00
Closes #17986
diff --git a/NEWS b/NEWS
@@ -2,6 +2,9 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? ????, PHP 8.4.6
 
+- BCMath:
+  . Fixed pointer subtraction for scale. (SakiTakamachi)
+
 - Core:
   . Fixed property hook backing value access in multi-level inheritance.
     (ilutov)
diff --git a/ext/bcmath/libbcmath/src/str2num.c b/ext/bcmath/libbcmath/src/str2num.c
@@ -180,7 +180,7 @@ bool bc_str2num(bc_num *num, const char *str, const char *end, size_t scale, siz
 			 */
 			if (str_scale > 0) {
 				const char *fractional_new_end = bc_skip_zero_reverse(fractional_end, fractional_ptr);
-				str_scale -= fractional_new_end - fractional_end;
+				str_scale -= fractional_end - fractional_new_end; /* fractional_end >= fractional_new_end */
 			}
 		}
 	} else {

Original file line number	Diff line number	Diff line change
`@@ -180,7 +180,7 @@ bool bc_str2num(bc_num num, const char str, const char *end, size_t scale, siz`
`180`	`180`	`*/`
`181`	`181`	`if (str_scale > 0) {`
`182`	`182`	`const char *fractional_new_end = bc_skip_zero_reverse(fractional_end, fractional_ptr);`
`183`		`- str_scale -= fractional_new_end - fractional_end;`
	`183`	`+ str_scale -= fractional_end - fractional_new_end; /* fractional_end >= fractional_new_end */`
`184`	`184`	`}`
`185`	`185`	`}`
`186`	`186`	`} else {`