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cmd/go/internal/modfetch/codehost: work around an apparent bug in 'git fetch --unshallow'

When 'git fetch' is passed the '--unshallow' flag, it assumes that the
local and remote refs are equal.¹ However, we were fetching an
expanded set of refs explicitly in the same command, violating that
assumption.

Now we first expand the set of refs, then unshallow the repo in a
separate fetch. Empirically, this seems to work, whereas the opposite
order does not.

¹4c86140027/transport.c (L1303-L1309)

Fixes #34266

Change-Id: Ie97eb7c1223f944003a1e31d0ec9e69aad0efc0d
Reviewed-on: https://go-review.googlesource.com/c/go/+/196961
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
This commit is contained in:
Bryan C. Mills 2019-09-16 09:39:10 -04:00
parent 47d27a87f9
commit 1804bbab62
2 changed files with 35 additions and 53 deletions

View File

@ -265,13 +265,6 @@ func (r *gitRepo) findRef(hash string) (ref string, ok bool) {
return "", false
}
func unshallow(gitDir string) []string {
if _, err := os.Stat(filepath.Join(gitDir, "shallow")); err == nil {
return []string{"--unshallow"}
}
return []string{}
}
// minHashDigits is the minimum number of digits to require
// before accepting a hex digit sequence as potentially identifying
// a specific commit in a git repo. (Of course, users can always
@ -421,29 +414,27 @@ func (r *gitRepo) stat(rev string) (*RevInfo, error) {
// fetchRefsLocked requires that r.mu remain locked for the duration of the call.
func (r *gitRepo) fetchRefsLocked() error {
if r.fetchLevel < fetchAll {
if err := r.fetchUnshallow("refs/heads/*:refs/heads/*", "refs/tags/*:refs/tags/*"); err != nil {
// NOTE: To work around a bug affecting Git clients up to at least 2.23.0
// (2019-08-16), we must first expand the set of local refs, and only then
// unshallow the repository as a separate fetch operation. (See
// golang.org/issue/34266 and
// https://github.com/git/git/blob/4c86140027f4a0d2caaa3ab4bd8bfc5ce3c11c8a/transport.c#L1303-L1309.)
if _, err := Run(r.dir, "git", "fetch", "-f", r.remote, "refs/heads/*:refs/heads/*", "refs/tags/*:refs/tags/*"); err != nil {
return err
}
if _, err := os.Stat(filepath.Join(r.dir, "shallow")); err == nil {
if _, err := Run(r.dir, "git", "fetch", "--unshallow", "-f", r.remote); err != nil {
return err
}
}
r.fetchLevel = fetchAll
}
return nil
}
func (r *gitRepo) fetchUnshallow(refSpecs ...string) error {
// To work around a protocol version 2 bug that breaks --unshallow,
// add -c protocol.version=0.
// TODO(rsc): The bug is believed to be server-side, meaning only
// on Google's Git servers. Once the servers are fixed, drop the
// protocol.version=0. See Google-internal bug b/110495752.
var protoFlag []string
unshallowFlag := unshallow(r.dir)
if len(unshallowFlag) > 0 {
protoFlag = []string{"-c", "protocol.version=0"}
}
_, err := Run(r.dir, "git", protoFlag, "fetch", unshallowFlag, "-f", r.remote, refSpecs)
return err
}
// statLocal returns a RevInfo describing rev in the local git repository.
// It uses version as info.Version.
func (r *gitRepo) statLocal(version, rev string) (*RevInfo, error) {
@ -563,39 +554,10 @@ func (r *gitRepo) ReadFileRevs(revs []string, file string, maxSize int64) (map[s
}
defer unlock()
var refs []string
var protoFlag []string
var unshallowFlag []string
for _, tag := range redo {
refs = append(refs, "refs/tags/"+tag+":refs/tags/"+tag)
}
if len(refs) > 1 {
unshallowFlag = unshallow(r.dir)
if len(unshallowFlag) > 0 {
// To work around a protocol version 2 bug that breaks --unshallow,
// add -c protocol.version=0.
// TODO(rsc): The bug is believed to be server-side, meaning only
// on Google's Git servers. Once the servers are fixed, drop the
// protocol.version=0. See Google-internal bug b/110495752.
protoFlag = []string{"-c", "protocol.version=0"}
}
}
if _, err := Run(r.dir, "git", protoFlag, "fetch", unshallowFlag, "-f", r.remote, refs); err != nil {
if err := r.fetchRefsLocked(); err != nil {
return nil, err
}
// TODO(bcmills): after the 1.11 freeze, replace the block above with:
// if r.fetchLevel <= fetchSome {
// r.fetchLevel = fetchSome
// var refs []string
// for _, tag := range redo {
// refs = append(refs, "refs/tags/"+tag+":refs/tags/"+tag)
// }
// if _, err := Run(r.dir, "git", "fetch", "--update-shallow", "-f", r.remote, refs); err != nil {
// return nil, err
// }
// }
if _, err := r.readFileRevs(redo, file, files); err != nil {
return nil, err
}

View File

@ -0,0 +1,20 @@
# Regression test for golang.org/issue/34092: with an empty module cache,
# 'GOPROXY=direct go get golang.org/x/tools/gopls@master' did not correctly
# resolve the pseudo-version for its dependency on golang.org/x/tools.
[short] skip
[!net] skip
[!exec:git] skip
env GO111MODULE=on
env GOPROXY=direct
env GOSUMDB=off
go list -m cloud.google.com/go@master
! stdout 'v0.0.0-'
-- go.mod --
module example.com
go 1.14
-- go.sum --