cmd/go/internal/vcs: include Subversion VCS build information

The existing implementation lacks the Status function for retrieving VCS build
information for Subversion. As a consequence, binaries aren't stamped with the
Revision, CommitTime and Uncommitted information from SVN repositories.

This change provides the svnStatus function and retrieves the information by
running svn info and svn status commands.

Author: bsdcode

src/cmd/go/internal/vcs/vcs.go

@@ -498,6 +498,7 @@ var vcsSvn = &Cmd{
 	Scheme:     []string{"https", "http", "svn", "svn+ssh"},
 	PingCmd:    "info -- {scheme}://{repo}",
 	RemoteRepo: svnRemoteRepo,
+	Status:     svnStatus,
 }
 
 func svnRemoteRepo(vcsSvn *Cmd, rootDir string) (remoteRepo string, err error) {
@@ -530,6 +531,35 @@ func svnRemoteRepo(vcsSvn *Cmd, rootDir string) (remoteRepo string, err error) {
 	return strings.TrimSpace(out), nil
 }
 
+func svnStatus(vcsSvn *Cmd, rootDir string) (Status, error) {
+	out, err := vcsSvn.runOutputVerboseOnly(rootDir, "info --show-item last-changed-revision")
+	if err != nil {
+		return Status{}, err
+	}
+	rev := strings.TrimSpace(string(out))
+
+	out, err = vcsSvn.runOutputVerboseOnly(rootDir, "info --show-item last-changed-date")
+	if err != nil {
+		return Status{}, err
+	}
+	commitTime, err := time.Parse(time.RFC3339, strings.TrimSpace(string(out)))
+	if err != nil {
+		return Status{}, fmt.Errorf("unable to parse output of svn info: %v", err)
+	}
+
+	out, err = vcsSvn.runOutputVerboseOnly(rootDir, "status")
+	if err != nil {
+		return Status{}, err
+	}
+	uncommitted := len(out) > 0
+
+	return Status{
+		Revision:    rev,
+		CommitTime:  commitTime,
+		Uncommitted: uncommitted,
+	}, nil
+}
+
 // fossilRepoName is the name go get associates with a fossil repository. In the
 // real world the file can be named anything.
 const fossilRepoName = ".fossil"

src/cmd/go/testdata/script/version_buildvcs_svn.txt

@@ -0,0 +1,94 @@
+# This test checks that VCS information is stamped into Go binaries by default,
+# controlled with -buildvcs. This test focuses on Subversion specifics.
+# The Git test covers common functionality.
+
+[!exec:svn] skip
+[!exec:svnadmin] skip
+[short] skip
+env GOBIN=$WORK/gopath/bin
+env oldpath=$PATH
+cd repo/a
+
+# If there's no local repository, there's no VCS info.
+go install
+go version -m $GOBIN/a$GOEXE
+! stdout vcs.revision
+stdout '\s+mod\s+example.com/a\s+\(devel\)'
+rm $GOBIN/a$GOEXE
+
+# If there is a repository, but it can't be used for some reason,
+# there should be an error. It should hint about -buildvcs=false.
+cd ..
+mkdir .svn
+env PATH=$WORK${/}fakebin${:}$oldpath
+chmod 0755 $WORK/fakebin/svn
+! exec svn help
+cd a
+! go install
+stderr '^error obtaining VCS status: exit status 1\n\tUse -buildvcs=false to disable VCS stamping.$'
+rm $GOBIN/a$GOEXE
+cd ..
+env PATH=$oldpath
+rm .svn
+
+# Untagged repo.
+exec svnadmin create repo
+exec svn checkout file://$PWD/repo workingDir
+cd workingDir
+cp ../a/a.go .
+cp ../a/go.mod .
+cp ../README .
+exec svn status
+exec svn add a.go go.mod README
+exec svn commit -m 'initial commit'
+exec svn update
+go install
+go version -m $GOBIN/a$GOEXE
+stdout '^\tbuild\tvcs.revision=1$'
+stdout '^\tbuild\tvcs.modified=false$'
+stdout '^\tmod\texample.com/a\tv0.0.0-\d+-\d+\t+'
+rm $GOBIN/a$GOEXE
+
+# Building with -buildvcs=false suppresses the info.
+go install -buildvcs=false
+go version -m $GOBIN/a$GOEXE
+! stdout vcs.revision
+stdout '\s+mod\s+example.com/a\s+\(devel\)'
+rm $GOBIN/a$GOEXE
+
+# An untracked file is shown as uncommitted, even if it isn't part of the build.
+cp ../../outside/empty.txt extra.txt
+go install
+go version -m $GOBIN/a$GOEXE
+stdout '^\tbuild\tvcs.modified=true$'
+stdout '\s+mod\s+example.com/a\s+v0.0.0-\d+-\d+\+dirty\s+'
+rm extra.txt
+rm $GOBIN/a$GOEXE
+
+# An edited file is shown as uncommitted, even if it isn't part of the build.
+cp ../../outside/empty.txt README
+go install
+go version -m $GOBIN/a$GOEXE
+stdout '^\tbuild\tvcs.modified=true$'
+stdout '\s+mod\s+example.com/a\s+v0.0.0-\d+-\d+\+dirty\s+'
+exec svn revert README
+rm $GOBIN/a$GOEXE
+
+-- $WORK/fakebin/svn --
+#!/bin/sh
+exit 1
+-- $WORK/fakebin/svn.bat --
+exit 1
+-- repo/README --
+Far out in the uncharted backwaters of the unfashionable end of the western
+spiral arm of the Galaxy lies a small, unregarded yellow sun.
+-- repo/a/go.mod --
+module example.com/a
+
+go 1.18
+-- repo/a/a.go --
+package main
+
+func main() {}
+
+-- outside/empty.txt --