kernelbase: Don't return ERROR_INSUFFICIENT_BUFFER from GetEnvironmentVariableW.

dlls/kernel32/tests/environ.c

@@ -106,9 +106,12 @@ static void test_GetSetEnvironmentVariableA(void)
        GetLastError());
 
     /* Try to retrieve the environment variable we just set */
+    SetLastError(0xdeadbeef);
     ret_size = GetEnvironmentVariableA(name, NULL, 0);
     ok(ret_size == strlen(value) + 1,
        "should return length with terminating 0 ret_size=%d\n", ret_size);
+    ok(GetLastError() == 0xdeadbeef,
+       "should not fail with zero size but GetLastError=%d\n", GetLastError());
 
     lstrcpyA(buf, "foo");
     ret_size = GetEnvironmentVariableA(name, buf, lstrlenA(value));
@@ -208,10 +211,13 @@ static void test_GetSetEnvironmentVariableW(void)
        GetLastError());
 
     /* Try to retrieve the environment variable we just set */
+    SetLastError(0xdeadbeef);
     ret_size = GetEnvironmentVariableW(name, NULL, 0);
     ok(ret_size == lstrlenW(value) + 1,
        "should return length with terminating 0 ret_size=%d\n",
        ret_size);
+    ok(GetLastError() == 0xdeadbeef,
+       "should not fail with zero size but GetLastError=%d\n", GetLastError());
 
     lstrcpyW(buf, fooW);
     ret_size = GetEnvironmentVariableW(name, buf, lstrlenW(value));

dlls/kernelbase/process.c

@@ -1395,7 +1395,8 @@ DWORD WINAPI DECLSPEC_HOTPATCH GetEnvironmentVariableW( LPCWSTR name, LPWSTR val
 
     status = RtlQueryEnvironmentVariable_U( NULL, &us_name, &us_value );
     len = us_value.Length / sizeof(WCHAR);
-    if (!set_ntstatus( status )) return (status == STATUS_BUFFER_TOO_SMALL) ? len + 1 : 0;
+    if (status == STATUS_BUFFER_TOO_SMALL) return len + 1;
+    if (!set_ntstatus( status )) return 0;
     if (size) val[len] = 0;
     return len;
 }