From 61d1d92aa4785090213e89566e01e342f60d9b92 Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Fri, 4 Oct 2019 08:09:30 -0700 Subject: msvc: work around a bug in GetEnvironmentVariable() The return value of that function is 0 both for variables that are unset, as well as for variables whose values are empty. To discern those two cases, one has to call `GetLastError()`, whose return value is `ERROR_ENVVAR_NOT_FOUND` and `ERROR_SUCCESS`, respectively. Except that it is not actually set to `ERROR_SUCCESS` in the latter case, apparently, but the last error value seems to be simply unchanged. To work around this, let's just re-set the last error value just before inspecting the environment variable. This fixes a problem that triggers failures in t3301-notes.sh (where we try to override config settings by passing empty values for certain environment variables). This problem is hidden in the MINGW build by the fact that older MSVC runtimes (such as the one used by MINGW builds) have a `calloc()` that re-sets the last error value in case of success, while newer runtimes set the error value only if `NULL` is returned by that function. Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- compat/mingw.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'compat') diff --git a/compat/mingw.c b/compat/mingw.c index 4891789771..7d8cb814ba 100644 --- a/compat/mingw.c +++ b/compat/mingw.c @@ -1661,6 +1661,8 @@ char *mingw_getenv(const char *name) if (!w_key) die("Out of memory, (tried to allocate %u wchar_t's)", len_key); xutftowcs(w_key, name, len_key); + /* GetEnvironmentVariableW() only sets the last error upon failure */ + SetLastError(ERROR_SUCCESS); len_value = GetEnvironmentVariableW(w_key, w_value, ARRAY_SIZE(w_value)); if (!len_value && GetLastError() == ERROR_ENVVAR_NOT_FOUND) { free(w_key); -- cgit v1.2.3