path: root/compat/mingw.c
diff options
authorJohannes Schindelin <>2019-11-30 10:36:39 (GMT)
committerJunio C Hamano <>2019-11-30 22:09:09 (GMT)
commit4d0375ca24f6e317e94705e74c89f33c66c35107 (patch)
tree826ebb0e549e0794f5d63e06deaae59dcb88b1d0 /compat/mingw.c
parentac33519ddfa818f420b4ef5a09b4a7b3ac8adeb8 (diff)
mingw: do set `errno` correctly when trying to restrict handle inheritance
In 9a780a384de (mingw: spawned processes need to inherit only standard handles, 2019-11-22), we taught the Windows-specific part to restrict which file handles are passed on to the spawned processes. Since this logic seemed to be a bit fragile across Windows versions (we _still_ support Windows Vista in Git for Windows, for example), a fall-back was added to try spawning the process again, this time without restricting which file handles are to be inherited by the spawned process. In the common case (i.e. when the process could not be spawned for reasons _other_ than the file handle inheritance), the fall-back attempt would still fail, of course. Crucially, one thing we missed in that code path was to set `errno` appropriately. This should have been caught by t0061.2 which expected `errno` to be `ENOENT` after trying to start a process for a non-existing executable, but `errno` was set to `ENOENT` prior to the `CreateProcessW()` call: while looking for the config settings for trace2, Git tries to access `xdg_config` and `user_config` via `access_or_die()`, and as neither of those config files exists when running the test case (because in Git's test suite, `HOME` points to the test directory), the `errno` has the expected value, but for the wrong reasons. Let's fix that by making sure that `errno` is set correctly. It even appears that `errno` was set in the _wrong_ case previously: `CreateProcessW()` returns non-zero upon success, but `errno` was set only in the non-zero case. It would be nice if we could somehow fix t0061 to make sure that this does not regress again. One approach that seemed like it should work, but did not, was to set `errno` to 0 in the test helper that is used by t0061.2. However, when `mingw_spawnvpe()` wants to see whether the file in question is a script, it calls `parse_interpreter()`, which in turn tries to `open()` the file. Obviously, this call fails, and sets `errno` to `ENOENT`, deep inside the call chain started from that test helper. Instead, we force re-set `errno` at the beginning of the function `mingw_spawnve_fd()`, which _should_ be safe given that callers of that function will want to look at `errno` if -1 was returned. And if that `errno` is 0 ("No error"), regression tests like t0061.2 will kick in. Reported-by: Johannes Sixt <> Signed-off-by: Johannes Schindelin <> Acked-by: Johannes Sixt <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'compat/mingw.c')
1 files changed, 5 insertions, 1 deletions
diff --git a/compat/mingw.c b/compat/mingw.c
index 2b6eca2..432adc1 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -1423,6 +1423,9 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
const char *(*quote_arg)(const char *arg) =
is_msys2_sh(*argv) ? quote_arg_msys2 : quote_arg_msvc;
+ /* Make sure to override previous errors, if any */
+ errno = 0;
if (restrict_handle_inheritance < 0)
restrict_handle_inheritance = core_restrict_inherited_handles;
@@ -1580,8 +1583,9 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
ret = CreateProcessW(*wcmd ? wcmd : NULL, wargs, NULL, NULL,
TRUE, flags, wenvblk, dir ? wdir : NULL,
&si.StartupInfo, &pi);
- if (ret && buf.len) {
+ if (!ret)
errno = err_win_to_posix(GetLastError());
+ if (ret && buf.len) {
warning("failed to restrict file handles (%ld)\n\n%s",
err, buf.buf);