Fix verifyCommits error when push a new branch (#26664)

> ### Description
> If a new branch is pushed, and the repository has a rule that would
require signed commits for the new branch, the commit is rejected with a
500 error regardless of whether it's signed.
> 
> When pushing a new branch, the "old" commit is the empty ID
(0000000000000000000000000000000000000000). verifyCommits has no
provision for this and passes an invalid commit range to git rev-list.
Prior to 1.19 this wasn't an issue because only pre-existing individual
branches could be protected.
> 
> I was able to reproduce with
[try.gitea.io/CraigTest/test](https://try.gitea.io/CraigTest/test),
which is set up with a blanket rule to require commits on all branches.


Fix #25565
Very thanks to @Craig-Holmquist-NTI for reporting the bug and suggesting
an valid solution!

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

routers/private/hook_verification.go

@@ -28,23 +28,31 @@ func verifyCommits(oldCommitID, newCommitID string, repo *git.Repository, env []
 		_ = stdoutWriter.Close()
 	}()
 
+	var command *git.Command
+	if oldCommitID == git.EmptySHA {
+		// When creating a new branch, the oldCommitID is empty, by using "newCommitID --not --all":
+		// List commits that are reachable by following the newCommitID, exclude "all" existing heads/tags commits
+		// So, it only lists the new commits received, doesn't list the commits already present in the receiving repository
+		command = git.NewCommand(repo.Ctx, "rev-list").AddDynamicArguments(newCommitID).AddArguments("--not", "--all")
+	} else {
+		command = git.NewCommand(repo.Ctx, "rev-list").AddDynamicArguments(oldCommitID + "..." + newCommitID)
+	}
 	// This is safe as force pushes are already forbidden
-	err = git.NewCommand(repo.Ctx, "rev-list").AddDynamicArguments(oldCommitID + "..." + newCommitID).
-		Run(&git.RunOpts{
-			Env:    env,
-			Dir:    repo.Path,
-			Stdout: stdoutWriter,
-			PipelineFunc: func(ctx context.Context, cancel context.CancelFunc) error {
-				_ = stdoutWriter.Close()
-				err := readAndVerifyCommitsFromShaReader(stdoutReader, repo, env)
-				if err != nil {
-					log.Error("%v", err)
-					cancel()
-				}
-				_ = stdoutReader.Close()
-				return err
-			},
-		})
+	err = command.Run(&git.RunOpts{
+		Env:    env,
+		Dir:    repo.Path,
+		Stdout: stdoutWriter,
+		PipelineFunc: func(ctx context.Context, cancel context.CancelFunc) error {
+			_ = stdoutWriter.Close()
+			err := readAndVerifyCommitsFromShaReader(stdoutReader, repo, env)
+			if err != nil {
+				log.Error("%v", err)
+				cancel()
+			}
+			_ = stdoutReader.Close()
+			return err
+		},
+	})
 	if err != nil && !isErrUnverifiedCommit(err) {
 		log.Error("Unable to check commits from %s to %s in %s: %v", oldCommitID, newCommitID, repo.Path, err)
 	}

routers/private/hook_verification_test.go

@@ -0,0 +1,43 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package private
+
+import (
+	"context"
+	"testing"
+
+	"code.gitea.io/gitea/models/unittest"
+	"code.gitea.io/gitea/modules/git"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var testReposDir = "tests/repos/"
+
+func TestVerifyCommits(t *testing.T) {
+	unittest.PrepareTestEnv(t)
+
+	gitRepo, err := git.OpenRepository(context.Background(), testReposDir+"repo1_hook_verification")
+	defer gitRepo.Close()
+	assert.NoError(t, err)
+
+	testCases := []struct {
+		base, head string
+		verified   bool
+	}{
+		{"72920278f2f999e3005801e5d5b8ab8139d3641c", "d766f2917716d45be24bfa968b8409544941be32", true},
+		{git.EmptySHA, "93eac826f6188f34646cea81bf426aa5ba7d3bfe", true}, // New branch with verified commit
+		{"9779d17a04f1e2640583d35703c62460b2d86e0a", "72920278f2f999e3005801e5d5b8ab8139d3641c", false},
+		{git.EmptySHA, "9ce3f779ae33f31fce17fac3c512047b75d7498b", false}, // New branch with unverified commit
+	}
+
+	for _, tc := range testCases {
+		err = verifyCommits(tc.base, tc.head, gitRepo, nil)
+		if tc.verified {
+			assert.NoError(t, err)
+		} else {
+			assert.Error(t, err)
+		}
+	}
+}

routers/private/main_test.go

@@ -0,0 +1,17 @@
+// Copyright 2017 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package private
+
+import (
+	"path/filepath"
+	"testing"
+
+	"code.gitea.io/gitea/models/unittest"
+)
+
+func TestMain(m *testing.M) {
+	unittest.MainTest(m, &unittest.TestOptions{
+		GiteaRootPath: filepath.Join("..", ".."),
+	})
+}

routers/private/tests/repos/repo1_hook_verification/HEAD

@@ -0,0 +1 @@
+ref: refs/heads/main

routers/private/tests/repos/repo1_hook_verification/config

@@ -0,0 +1,6 @@
+[core]
+	repositoryformatversion = 0
+	filemode = false
+	bare = true
+	symlinks = false
+	ignorecase = true

routers/private/tests/repos/repo1_hook_verification/info/refs

@@ -0,0 +1 @@
+d766f2917716d45be24bfa968b8409544941be32	refs/heads/main

routers/private/tests/repos/repo1_hook_verification/logs/HEAD

@@ -0,0 +1 @@
+0000000000000000000000000000000000000000 d766f2917716d45be24bfa968b8409544941be32 Gitea <gitea@fake.local> 1693148474 +0800	push

routers/private/tests/repos/repo1_hook_verification/logs/refs/heads/main

@@ -0,0 +1 @@
+0000000000000000000000000000000000000000 d766f2917716d45be24bfa968b8409544941be32 Gitea <gitea@fake.local> 1693148474 +0800	push

routers/private/tests/repos/repo1_hook_verification/objects/72/920278f2f999e3005801e5d5b8ab8139d3641c

@@ -0,0 +1,2 @@
+x
<01><>K
+1]<5D><14><0B><><EFBFBD>A<EFBFBD>S<EFBFBD><53>$<1D>"32oo<6F><06><>W<EFBFBD><57><EFBFBD><EFBFBD>{<7B>!<21><>`<60><>JC%<25>.<2E>$<07>r]sѱe$<24>m<EFBFBD><6D>M<EFBFBD><4D>)<29><><EFBFBD>(O`<60>btl<>E[:;4<12><>H<>1_<31><5F><EFBFBD>ray<61><79><EFBFBD>l<EFBFBD><6C><EFBFBD><EFBFBD>~<7E><>E<EFBFBD>L@c<><02>Xv<58>M<EFBFBD><4D>":<3A>MۃG<DB83>_}<7D>?<3F>

routers/private/tests/repos/repo1_hook_verification/objects/97/79d17a04f1e2640583d35703c62460b2d86e0a

@@ -0,0 +1,2 @@
+x
<01><>1
+!ES{<7B><>AwGGa	9E<39>QgW<10><><EFBFBD>#<23>A<EFBFBD><0F><><EFBFBD><EFBFBD>Z<18>/<2F><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>p<EFBFBD><70>(<28>(<28><><EFBFBD><EFBFBD>Bh<42>ۼ&<26><11><14><><EFBFBD>:pLY`<60><><EFBFBD>U<EFBFBD><55>-<2D>z<EFBFBD><7A><EFBFBD><1A><>\<5C><>ZM:<3A><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>xJ/<2F>G}
:<3A>3

routers/private/tests/repos/repo1_hook_verification/objects/cb/a4c30c196a0e03e7bdf6eeb8393d14b9d073aa

@@ -0,0 +1,3 @@
+x
<01><>A
+<EFBFBD>0E]<5D><14>$<24>L<EFBFBD><0C>x<EFBFBD>L2<4C>]<5D><><EFBFBD>
+<EFBFBD><EFBFBD><EFBFBD>

routers/private/tests/repos/repo1_hook_verification/objects/d7/66f2917716d45be24bfa968b8409544941be32

@@ -0,0 +1,3 @@
+x
<01><>ˮ<EFBFBD>FE3<45>+zn%44<34>!%Qx<51><78>ۀ
s<>A<EFBFBD>`8<><38><EFBFBD><EFBFBD>{<7B><>2IM<49>j<EFBFBD><6A><EFBFBD><EFBFBD><EFBFBD>d<EFBFBD><64>f<06><><EFBFBD>2<EFBFBD><32><EFBFBD>"<22>$<24>e<EFBFBD><65>
+-(<28> <20><04>!<21><>J"<22>a<EFBFBD><17>@<40>Ba<42><61>Ho3<6F><33>V<EFBFBD><56><04><$<24>/)<29>$J<>JD<04>B<EFBFBD><42>H<EFBFBD><1F><><EFBFBD>{<7B>#<23>RR<52><52>O<EFBFBD><4F>nf<6E><66>F<EFBFBD><46>O<EFBFBD><4F>
+<EFBFBD>q[<5B><>2<EFBFBD>̇~<7E><><EFBFBD><EFBFBD><7F><EFBFBD>zjj<6A><6A><EFBFBD><EFBFBD>L<EFBFBD><4C><EFBFBD><EFBFBD>}prm<72>Fqh<71><68>`@ث<><D8AB><EFBFBD><EFBFBD><EFBFBD><EFBFBD>՘f<D598>?3<>[7<><37><EFBFBD><EFBFBD><EFBFBD><EFBFBD>)	^<5E><>u<EFBFBD>ֿ,<2C><><EFBFBD>l7<6C>z<EFBFBD><06>r|&<10>Ou4<75><34>9<EFBFBD>:<3A><>Qj<51><6A><EFBFBD><15><>1x<31><78><EFBFBD>6<EFBFBD>Q<EFBFBD><51><EFBFBD><EFBFBD>%<25><>t<><74>s<EFBFBD><73><EFBFBD>V<EFBFBD>|(<1C>V<EFBFBD><56>,aL,<2C><>G~<7E><><16><><EFBFBD><EFBFBD><EFBFBD>r<1D><><EFBFBD><EFBFBD>@<40>`<60><><EFBFBD>$[!	Xˊep<><70><1E>[8	o<><6F>(<28><><EFBFBD>k<EFBFBD>Z<EFBFBD>γy<CEB3>eй<65><D0B9><EFBFBD><05>Y<EFBFBD><59>k<EFBFBD>d<64><7F>6<EFBFBD>3<EFBFBD>;3<><06>	R<>iދdY<64>Dk91V]/C<>#<23><>&<26><>po<70>F<EFBFBD>b<EFBFBD><62><EFBFBD>}<7D><><EFBFBD><EFBFBD><EFBFBD>uW&]+m xaqd<71>I<EFBFBD>X<EFBFBD><58>3

routers/private/tests/repos/repo1_hook_verification/objects/info/packs

@@ -0,0 +1 @@
+