Regression, calls to !git_error_last() not updated after commit 3618a2a

[jdavid]

This is a regression in libgit2 v1.8.0
Error introduced in commit 3618a2a
It shows up with Windows (winhttp).
Found in pygit2's test suite, see https://ci.appveyor.com/project/jdavid/pygit2/builds/49513776
It currently blocks the release of pygit2, see libgit2/pygit2#1285

Commit 3618a2a introduces this change:

@@ -184,6 +189,9 @@ const git_error *git_error_last(void)
        if ((threadstate = git_threadstate_get()) == NULL)
                return &tlsdata_error;
 
+       if (!threadstate->last_error)
+               return &no_error;
+
        return threadstate->last_error;
 }

But winhttp.c is not updated:

static int certificate_check(winhttp_stream *s, int valid)
{
    [...]

    if (error < 0 && !git_error_last())    <----
        git_error_set(GIT_ERROR_HTTP, "user cancelled certificate check");

Here since commit 3618a2a !git_error_last() always evaluates to false.

To find out where the issue is I made my fork of libgit2 and reverted the change introduced in commit 3618a2a. The result is that the tests pass, see https://ci.appveyor.com/project/jdavid/pygit2/builds/49705963

Of course I think the proper fix would be to update winhttp.c

A git grep shows that this same error happens in other places in libgit2:

$ git --no-pager grep "\!git_error_last()"
src/libgit2/transports/ssh_libssh2.c:		if (!git_error_last())
src/libgit2/transports/winhttp.c:		if (!git_error_last())
src/libgit2/transports/winhttp.c:	if (error < 0 && !git_error_last())
src/libgit2/transports/winhttp.c:				if (!git_error_last())
src/util/fs_path.c:			if (!git_error_last())

Reproduction steps

Error found in pygit2 CI (AppVeyor), see https://ci.appveyor.com/project/jdavid/pygit2/builds/49513776/job/v4dw1jrduwk69k20

Expected behavior

The test should pass.

Actual behavior

The test fails.

Version of libgit2 (release number or SHA1)

Error introduced in commit 3618a2a

Operating system(s) tested

Windows.

[ethomson]

Thanks for the report — does https://github.com/libgit2/libgit2/compare/ethomson/cb_err?expand=1 resolve this?

[jdavid]

Yes it works, https://ci.appveyor.com/project/jdavid/pygit2/build/job/f1db6c5b80900n6q

[ethomson]

We'll ship a v1.8.1 🔜