kernel32: Revise GetLongPathNameA to avoid overriding the input on long names.

dlls/kernel32/path.c

@@ -292,6 +292,7 @@ DWORD WINAPI GetLongPathNameW( LPCWSTR shortpath, LPWSTR longpath, DWORD longlen
     BOOL                unixabsolute;
     WIN32_FIND_DATAW    wfd;
     HANDLE              goit;
+    BOOL                is_legal_8dot3;
 
     if (!shortpath)
     {
@@ -365,7 +366,7 @@ DWORD WINAPI GetLongPathNameW( LPCWSTR shortpath, LPWSTR longpath, DWORD longlen
             }
         }
 
-        /* Check if the file exists and use the existing file name */
+        /* Check if the file exists */
         goit = FindFirstFileW(tmplongpath, &wfd);
         if (goit == INVALID_HANDLE_VALUE)
         {
@@ -374,7 +375,12 @@ DWORD WINAPI GetLongPathNameW( LPCWSTR shortpath, LPWSTR longpath, DWORD longlen
             return 0;
         }
         FindClose(goit);
-        strcpyW(tmplongpath + lp, wfd.cFileName);
+
+        is_legal_8dot3 = FALSE;
+        CheckNameLegalDOS8Dot3W(tmplongpath + lp, NULL, 0, NULL, &is_legal_8dot3);
+        /* Use the existing file name if it's a short name */
+        if (is_legal_8dot3)
+            strcpyW(tmplongpath + lp, wfd.cFileName);
         lp += strlenW(tmplongpath + lp);
         sp += tmplen;
     }

dlls/kernel32/tests/path.c

@@ -868,7 +868,6 @@ static void test_PathNameA(CHAR *curdir, CHAR curDrive, CHAR otherDrive)
        "GetLongPathNameA returned '%s' instead of '%s'\n",tmpstr1,tmpstr);
     tmpstr[len] = tolower(tmpstr[len]);
     ok(GetLongPathNameA(tmpstr,tmpstr1,MAX_PATH),"GetLongPathNameA failed\n");
-    todo_wine
     ok(lstrcmpA(tmpstr,tmpstr1)==0,
        "GetLongPathNameA returned '%s' instead of '%s'\n",tmpstr1,tmpstr);
     sprintf(tmpstr,"%s/%s",SHORTDIR,SHORTFILE);