cmd/go/internal/vcweb: set GIT_PROTOCOL in the git CGI handler

This works around a bug in 'git http-backend' that was fixed in
Git 2.34.0,¹ and will hopefully allow the tests in
cmd/go/internal/modfetch/codehost to pass reliably using older
Git releases (I tested with 2.30.2).

¹https://github.com/git/git/commit/ff6a37c99e3343633c53f56789afcc8f8165d276

Fixes #56881.

Change-Id: Icd2e4d252d5f712685d146f34e11922dd0c41ff0
Reviewed-on: https://go-review.googlesource.com/c/go/+/549795
Reviewed-by: Michael Matloob <matloob@golang.org>
Auto-Submit: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Bryan Mills <bcmills@google.com>

diff --git a/src/cmd/go/internal/modfetch/codehost/git_test.go b/src/cmd/go/internal/modfetch/codehost/git_test.go
index 328ab5bf58eef8fec3d5295706a48e127bb75047..dba9935b5820b51a18224367456aa485fc76ff38 100644 (file)
--- a/src/cmd/go/internal/modfetch/codehost/git_test.go
+++ b/src/cmd/go/internal/modfetch/codehost/git_test.go
@@ -280,9 +280,6 @@ func TestLatest(t *testing.T) {
                                t.Fatal(err)
                        }
                        if !reflect.DeepEqual(info, tt.info) {
-                               if !reflect.DeepEqual(info.Tags, tt.info.Tags) {
-                                       testenv.SkipFlaky(t, 56881)
-                               }
                                t.Errorf("Latest: incorrect info\nhave %+v (origin %+v)\nwant %+v (origin %+v)", info, info.Origin, tt.info, tt.info.Origin)
                        }
                }
@@ -661,9 +658,6 @@ func TestStat(t *testing.T) {
                        }
                        info.Origin = nil // TestLatest and ../../../testdata/script/reuse_git.txt test Origin well enough
                        if !reflect.DeepEqual(info, tt.info) {
-                               if !reflect.DeepEqual(info.Tags, tt.info.Tags) {
-                                       testenv.SkipFlaky(t, 56881)
-                               }
                                t.Errorf("Stat: incorrect info\nhave %+v\nwant %+v", *info, *tt.info)
                        }
                }

diff --git a/src/cmd/go/internal/vcweb/git.go b/src/cmd/go/internal/vcweb/git.go
index 316c2382ba2b352eae62fee0e3a0661011badfac..d1e0563bede03378562ca3105c5472b97107ef2f 100644 (file)
--- a/src/cmd/go/internal/vcweb/git.go
+++ b/src/cmd/go/internal/vcweb/git.go
@@ -37,16 +37,35 @@ func (h *gitHandler) Handler(dir string, env []string, logger *log.Logger) (http
                return nil, ServerNotInstalledError{name: "git"}
        }
 
-       handler := &cgi.Handler{
-               Path:   h.gitPath,
-               Logger: logger,
-               Args:   []string{"http-backend"},
-               Dir:    dir,
-               Env: append(slices.Clip(env),
-                       "GIT_PROJECT_ROOT="+dir,
-                       "GIT_HTTP_EXPORT_ALL=1",
-               ),
-       }
+       baseEnv := append(slices.Clip(env),
+               "GIT_PROJECT_ROOT="+dir,
+               "GIT_HTTP_EXPORT_ALL=1",
+       )
+
+       handler := http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+               // The Git client sends the requested Git protocol version as a
+               // "Git-Protocol" HTTP request header, which the CGI host then converts
+               // to an environment variable (HTTP_GIT_PROTOCOL).
+               //
+               // However, versions of Git older that 2.34.0 don't recognize the
+               // HTTP_GIT_PROTOCOL variable, and instead need that value to be set in the
+               // GIT_PROTOCOL variable. We do so here so that vcweb can work reliably
+               // with older Git releases. (As of the time of writing, the Go project's
+               // builders were on Git version 2.30.2.)
+               env := slices.Clip(baseEnv)
+               if p := req.Header.Get("Git-Protocol"); p != "" {
+                       env = append(env, "GIT_PROTOCOL="+p)
+               }
+
+               h := &cgi.Handler{
+                       Path:   h.gitPath,
+                       Logger: logger,
+                       Args:   []string{"http-backend"},
+                       Dir:    dir,
+                       Env:    env,
+               }
+               h.ServeHTTP(w, req)
+       })
 
        return handler, nil
 }