ext/bcmath: Fixed bug (bcpowmod() with mod = -1 returns 1 when it must be 0)

Author: Girgias

NEWS

@@ -7,6 +7,9 @@ PHP                                                                        NEWS
   . Fixed bug GH-12814 (max_execution_time reached too early on MacOS 14
     when running on Apple Silicon). (Manuel Kress)
 
+- BCMatch:
+  . Fixed bug (bcpowmod() with mod = -1 returns 1 when it must be 0). (Girgias)
+
 - Curl:
   . Fixed bug GH-14307 (Test curl_basic_024 fails with curl 8.8.0). (nielsdos)
 

ext/bcmath/libbcmath/src/raisemod.c

@@ -81,7 +81,7 @@ zend_result bc_raisemod (bc_num base, bc_num expo, bc_num mod, bc_num *result, i
 
   /* Do the calculation. */
   rscale = MAX(scale, power->n_scale);
-  if ( !bc_compare(modulus, BCG(_one_)) )
+  if ( !_bc_do_compare(modulus, BCG(_one_), false, false) )
     {
       bc_free_num (&temp);
       temp = bc_new_num (1, scale);

ext/bcmath/tests/bcpowmod_with_mod_1.phpt

@@ -0,0 +1,16 @@
+--TEST--
+bcpowmod() must return 0 when mod is +1 or -1
+--EXTENSIONS--
+bcmath
+--FILE--
+<?php
+var_dump(bcpowmod(5, 0, 1));
+var_dump(bcpowmod(5, 0, 1, 3));
+var_dump(bcpowmod(5, 0, -1));
+var_dump(bcpowmod(5, 0, -1, 3));
+?>
+--EXPECT--
+string(1) "0"
+string(5) "0.000"
+string(1) "0"
+string(5) "0.000"