From 6028094e6bb94c562554d4abc7f0a702fcb1c2b8 Mon Sep 17 00:00:00 2001
From: Tonis Tiigi <tonistiigi@gmail.com>
Date: Thu, 30 Nov 2023 22:07:50 -0800
Subject: [PATCH] gitutil: find default remote by tracking branch

Using this command resolves remote based on remote
tracking branch of the curently selected branch and
should be more precise in case we can't predict if user
uses origin to mark upstream or their fork.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
---
 util/gitutil/gitutil.go      | 24 ++++++++++++++++++++++-
 util/gitutil/gitutil_test.go | 38 ++++++++++++++++++++++++++++++++++--
 util/gitutil/testutil.go     |  9 +++++++++
 3 files changed, 68 insertions(+), 3 deletions(-)

diff --git a/util/gitutil/gitutil.go b/util/gitutil/gitutil.go
index 22aa72ee..c781311e 100644
--- a/util/gitutil/gitutil.go
+++ b/util/gitutil/gitutil.go
@@ -78,7 +78,13 @@ func (c *Git) GitDir() (string, error) {
 }
 
 func (c *Git) RemoteURL() (string, error) {
-	// Try to get the remote URL from the origin remote first
+	// Try default remote based on remote tracking branch
+	if remote, err := c.currentRemote(); err == nil && remote != "" {
+		if ru, err := c.clean(c.run("remote", "get-url", remote)); err == nil && ru != "" {
+			return stripCredentials(ru), nil
+		}
+	}
+	// Next try to get the remote URL from the origin remote first
 	if ru, err := c.clean(c.run("remote", "get-url", "origin")); err == nil && ru != "" {
 		return stripCredentials(ru), nil
 	}
@@ -149,6 +155,22 @@ func (c *Git) clean(out string, err error) (string, error) {
 	return out, err
 }
 
+func (c *Git) currentRemote() (string, error) {
+	symref, err := c.clean(c.run("symbolic-ref", "-q", "HEAD"))
+	if err != nil {
+		return "", err
+	}
+	if symref == "" {
+		return "", nil
+	}
+	// git for-each-ref --format='%(upstream:remotename)'
+	remote, err := c.clean(c.run("for-each-ref", "--format=%(upstream:remotename)", symref))
+	if err != nil {
+		return "", err
+	}
+	return remote, nil
+}
+
 func IsUnknownRevision(err error) bool {
 	if err == nil {
 		return false
diff --git a/util/gitutil/gitutil_test.go b/util/gitutil/gitutil_test.go
index 991cd32e..06c6fa45 100644
--- a/util/gitutil/gitutil_test.go
+++ b/util/gitutil/gitutil_test.go
@@ -106,8 +106,9 @@ func TestGitDescribeTags(t *testing.T) {
 
 func TestGitRemoteURL(t *testing.T) {
 	type remote struct {
-		name string
-		url  string
+		name     string
+		url      string
+		tracking string
 	}
 
 	cases := []struct {
@@ -165,6 +166,36 @@ func TestGitRemoteURL(t *testing.T) {
 			},
 			fail: true,
 		},
+		{
+			name: "single tracking branch",
+			remotes: []remote{
+				{
+					name:     "foo",
+					url:      "https://github.com/tonistiigi/buildx.git",
+					tracking: "master",
+				},
+			},
+			expected: "https://github.com/tonistiigi/buildx.git",
+		},
+		{
+			name: "fork tracking branch",
+			remotes: []remote{
+				{
+					name: "origin",
+					url:  "git@github.com:crazy-max/buildx.git",
+				},
+				{
+					name:     "foobranch",
+					url:      "https://github.com/tonistiigi/buildx.git",
+					tracking: "master",
+				},
+				{
+					name: "crazymax",
+					url:  "git@github.com:crazy-max/buildx.git",
+				},
+			},
+			expected: "https://github.com/tonistiigi/buildx.git",
+		},
 	}
 	for _, tt := range cases {
 		tt := tt
@@ -177,6 +208,9 @@ func TestGitRemoteURL(t *testing.T) {
 			GitCommit(c, t, "initial commit")
 			for _, r := range tt.remotes {
 				GitSetRemote(c, t, r.name, r.url)
+				if r.tracking != "" {
+					GitSetMainUpstream(c, t, r.name, r.tracking)
+				}
 			}
 
 			ru, err := c.RemoteURL()
diff --git a/util/gitutil/testutil.go b/util/gitutil/testutil.go
index ea9dd058..d0de8970 100644
--- a/util/gitutil/testutil.go
+++ b/util/gitutil/testutil.go
@@ -52,6 +52,15 @@ func GitSetRemote(c *Git, tb testing.TB, name string, url string) {
 	require.NoError(tb, err)
 }
 
+func GitSetMainUpstream(c *Git, tb testing.TB, remote, target string) {
+	tb.Helper()
+	_, err := fakeGit(c, "fetch", "--depth", "1", remote, target)
+	require.NoError(tb, err)
+
+	_, err = fakeGit(c, "branch", "--set-upstream-to", remote+"/"+target, "main")
+	require.NoError(tb, err)
+}
+
 func Mktmp(tb testing.TB) string {
 	tb.Helper()
 	folder := tb.TempDir()