[PATCH] ntdll: qsort: comparator must not get the same pointer

[Marcus Meissner]

Hi,

ioquake runs qsort and uses *a==*b as a error assertion
(for two duplicate entries). The mergesort algorithm
in use calls the comparator with the same pointer.

Ciao, Marcus
---
 dlls/ntdll/misc.c         |    5 +++++
 dlls/ntdll/tests/string.c |    3 +++
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/dlls/ntdll/misc.c b/dlls/ntdll/misc.c
index eedef65..a78a3e4 100644
--- a/dlls/ntdll/misc.c
+++ b/dlls/ntdll/misc.c
@@ -272,6 +272,11 @@ NTDLL_mergesort( void *arr, void *barr, int elemsize, int(__cdecl *compar)(const
 
         for (k=left; k<=right; k++) {
             /*arr[k]=(barr[i]<barr[j])?barr[i++]:barr[j--];*/
+            if (i == j) {
+                memcpy(X(arr,k),X(barr,j),elemsize);
+                j--;
+                continue;
+            }
             if (compar(X(barr,i),X(barr,j))<0) {
                 memcpy(X(arr,k),X(barr,i),elemsize);
                 i++;
diff --git a/dlls/ntdll/tests/string.c b/dlls/ntdll/tests/string.c
index cd362ed..3f7236a 100644
--- a/dlls/ntdll/tests/string.c
+++ b/dlls/ntdll/tests/string.c
@@ -1145,16 +1145,19 @@ static void test_wcsrchr(void)
 
 static __cdecl int intcomparefunc(const void *a, const void*b)
 {
+	ok (a != b, "must never get the same pointer\n");
 	return (*(int*)a) - (*(int*)b);
 }
 
 static __cdecl int charcomparefunc(const void *a, const void*b)
 {
+	ok (a != b, "must never get the same pointer\n");
 	return (*(char*)a) - (*(char*)b);
 }
 
 static __cdecl int strcomparefunc(const void *a, const void*b)
 {
+	ok (a != b, "must never get the same pointer\n");
 	return lstrcmpA(*(char**)a,*(char**)b);
 }
 
-- 
1.6.4.2