mingw: forbid translating ERROR_SUCCESS to an errno value

Johannes Sixt pointed out that the `err_win_to_posix()` function
mishandles `ERROR_SUCCESS`: it maps it to `ENOSYS`.

The only purpose of this function is to map Win32 API errors to `errno`
ones, and there is actually no equivalent to `ERROR_SUCCESS`: the idea
of `errno` is that it will only be set in case of an error, and left
alone in case of success.

Therefore, as pointed out by Junio Hamano, it is a bug to call this
function when there was not even any error to map.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/compat/mingw.c b/compat/mingw.c
index 432adc1aed09153001b1aa607e3cee6beb5013fd..827065d96ded7650fadb7a2ccbeb2cf9652aed00 100644 (file)
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -114,6 +114,7 @@ int err_win_to_posix(DWORD winerr)
        case ERROR_SHARING_BUFFER_EXCEEDED: error = ENFILE; break;
        case ERROR_SHARING_VIOLATION: error = EACCES; break;
        case ERROR_STACK_OVERFLOW: error = ENOMEM; break;
+       case ERROR_SUCCESS: BUG("err_win_to_posix() called without an error!");
        case ERROR_SWAPERROR: error = ENOENT; break;
        case ERROR_TOO_MANY_MODULES: error = EMFILE; break;
        case ERROR_TOO_MANY_OPEN_FILES: error = EMFILE; break;