Refactor git command package to improve security and maintainability (#22678)

This PR follows #21535 (and replace #22592)

## Review without space diff

https://github.com/go-gitea/gitea/pull/22678/files?diff=split&w=1

## Purpose of this PR

1. Make git module command completely safe (risky user inputs won't be
passed as argument option anymore)
2. Avoid low-level mistakes like
https://github.com/go-gitea/gitea/pull/22098#discussion_r1045234918
3. Remove deprecated and dirty `CmdArgCheck` function, hide the `CmdArg`
type
4. Simplify code when using git command

## The main idea of this PR

* Move the `git.CmdArg` to the `internal` package, then no other package
except `git` could use it. Then developers could never do
`AddArguments(git.CmdArg(userInput))` any more.
* Introduce `git.ToTrustedCmdArgs`, it's for user-provided and already
trusted arguments. It's only used in a few cases, for example: use git
arguments from config file, help unit test with some arguments.
* Introduce `AddOptionValues` and `AddOptionFormat`, they make code more
clear and simple:
    * Before: `AddArguments("-m").AddDynamicArguments(message)`
    * After: `AddOptionValues("-m", message)`
    * -
* Before: `AddArguments(git.CmdArg(fmt.Sprintf("--author='%s <%s>'",
sig.Name, sig.Email)))`
* After: `AddOptionFormat("--author='%s <%s>'", sig.Name, sig.Email)`

## FAQ

### Why these changes were not done in #21535 ?

#21535 is mainly a search&replace, it did its best to not change too
much logic.

Making the framework better needs a lot of changes, so this separate PR
is needed as the second step.


### The naming of `AddOptionXxx`

According to git's manual, the `--xxx` part is called `option`.

### How can it guarantee that `internal.CmdArg` won't be not misused?

Go's specification guarantees that. Trying to access other package's
internal package causes compilation error.

And, `golangci-lint` also denies the git/internal package. Only the
`git/command.go` can use it carefully.

### There is still a `ToTrustedCmdArgs`, will it still allow developers
to make mistakes and pass untrusted arguments?

Generally speaking, no. Because when using `ToTrustedCmdArgs`, the code
will be very complex (see the changes for examples). Then developers and
reviewers can know that something might be unreasonable.

### Why there was a `CmdArgCheck` and why it's removed?

At the moment of #21535, to reduce unnecessary changes, `CmdArgCheck`
was introduced as a hacky patch. Now, almost all code could be written
as `cmd := NewCommand(); cmd.AddXxx(...)`, then there is no need for
`CmdArgCheck` anymore.


### Why many codes for `signArg == ""` is deleted?

Because in the old code, `signArg` could never be empty string, it's
either `-S[key-id]` or `--no-gpg-sign`. So the `signArg == ""` is just
dead code.

---------

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

3 files changed, 12 insertions, 12 deletions

diff --git a/tests/integration/git_helper_for_declarative_test.go b/tests/integration/git_helper_for_declarative_test.go
index 9e3ff9c44..1e9978309 100644
--- a/tests/integration/git_helper_for_declarative_test.go
+++ b/tests/integration/git_helper_for_declarative_test.go
@@ -154,16 +154,16 @@ func doGitAddRemote(dstPath, remoteName string, u *url.URL) func(*testing.T) {
 	}
 }
 
-func doGitPushTestRepository(dstPath string, args ...git.CmdArg) func(*testing.T) {
+func doGitPushTestRepository(dstPath string, args ...string) func(*testing.T) {
 	return func(t *testing.T) {
-		_, _, err := git.NewCommand(git.DefaultContext, append([]git.CmdArg{"push", "-u"}, args...)...).RunStdString(&git.RunOpts{Dir: dstPath})
+		_, _, err := git.NewCommand(git.DefaultContext, "push", "-u").AddArguments(git.ToTrustedCmdArgs(args)...).RunStdString(&git.RunOpts{Dir: dstPath})
 		assert.NoError(t, err)
 	}
 }
 
-func doGitPushTestRepositoryFail(dstPath string, args ...git.CmdArg) func(*testing.T) {
+func doGitPushTestRepositoryFail(dstPath string, args ...string) func(*testing.T) {
 	return func(t *testing.T) {
-		_, _, err := git.NewCommand(git.DefaultContext, append([]git.CmdArg{"push"}, args...)...).RunStdString(&git.RunOpts{Dir: dstPath})
+		_, _, err := git.NewCommand(git.DefaultContext, "push").AddArguments(git.ToTrustedCmdArgs(args)...).RunStdString(&git.RunOpts{Dir: dstPath})
 		assert.Error(t, err)
 	}
 }
@@ -175,23 +175,23 @@ func doGitCreateBranch(dstPath, branch string) func(*testing.T) {
 	}
 }
 
-func doGitCheckoutBranch(dstPath string, args ...git.CmdArg) func(*testing.T) {
+func doGitCheckoutBranch(dstPath string, args ...string) func(*testing.T) {
 	return func(t *testing.T) {
-		_, _, err := git.NewCommandNoGlobals(append(append(git.AllowLFSFiltersArgs(), "checkout"), args...)...).RunStdString(&git.RunOpts{Dir: dstPath})
+		_, _, err := git.NewCommandContextNoGlobals(git.DefaultContext, git.AllowLFSFiltersArgs()...).AddArguments("checkout").AddArguments(git.ToTrustedCmdArgs(args)...).RunStdString(&git.RunOpts{Dir: dstPath})
 		assert.NoError(t, err)
 	}
 }
 
-func doGitMerge(dstPath string, args ...git.CmdArg) func(*testing.T) {
+func doGitMerge(dstPath string, args ...string) func(*testing.T) {
 	return func(t *testing.T) {
-		_, _, err := git.NewCommand(git.DefaultContext, append([]git.CmdArg{"merge"}, args...)...).RunStdString(&git.RunOpts{Dir: dstPath})
+		_, _, err := git.NewCommand(git.DefaultContext, "merge").AddArguments(git.ToTrustedCmdArgs(args)...).RunStdString(&git.RunOpts{Dir: dstPath})
 		assert.NoError(t, err)
 	}
 }
 
-func doGitPull(dstPath string, args ...git.CmdArg) func(*testing.T) {
+func doGitPull(dstPath string, args ...string) func(*testing.T) {
 	return func(t *testing.T) {
-		_, _, err := git.NewCommandNoGlobals(append(append(git.AllowLFSFiltersArgs(), "pull"), args...)...).RunStdString(&git.RunOpts{Dir: dstPath})
+		_, _, err := git.NewCommandContextNoGlobals(git.DefaultContext, git.AllowLFSFiltersArgs()...).AddArguments("pull").AddArguments(git.ToTrustedCmdArgs(args)...).RunStdString(&git.RunOpts{Dir: dstPath})
 		assert.NoError(t, err)
 	}
 }
diff --git a/tests/integration/git_test.go b/tests/integration/git_test.go
index a11bad21b..420a8676b 100644
--- a/tests/integration/git_test.go
+++ b/tests/integration/git_test.go
@@ -509,7 +509,7 @@ func doCreatePRAndSetManuallyMerged(ctx, baseCtx APITestContext, dstPath, baseBr
 		}))
 
 		t.Run("CreateHeadBranch", doGitCreateBranch(dstPath, headBranch))
-		t.Run("PushToHeadBranch", doGitPushTestRepository(dstPath, "origin", git.CmdArgCheck(headBranch)))
+		t.Run("PushToHeadBranch", doGitPushTestRepository(dstPath, "origin", headBranch))
 		t.Run("CreateEmptyPullRequest", func(t *testing.T) {
 			pr, err = doAPICreatePullRequest(ctx, baseCtx.Username, baseCtx.Reponame, baseBranch, headBranch)(t)
 			assert.NoError(t, err)
diff --git a/tests/integration/pull_merge_test.go b/tests/integration/pull_merge_test.go
index e80822a75..090a27c39 100644
--- a/tests/integration/pull_merge_test.go
+++ b/tests/integration/pull_merge_test.go
@@ -287,7 +287,7 @@ func TestCantMergeUnrelated(t *testing.T) {
 		assert.NoError(t, err)
 		sha := strings.TrimSpace(stdout.String())
 
-		_, _, err = git.NewCommand(git.DefaultContext, "update-index", "--add", "--replace", "--cacheinfo", "100644", git.CmdArgCheck(sha), "somewher-over-the-rainbow").RunStdString(&git.RunOpts{Dir: path})
+		_, _, err = git.NewCommand(git.DefaultContext, "update-index", "--add", "--replace", "--cacheinfo").AddDynamicArguments("100644", sha, "somewher-over-the-rainbow").RunStdString(&git.RunOpts{Dir: path})
 		assert.NoError(t, err)
 
 		treeSha, _, err := git.NewCommand(git.DefaultContext, "write-tree").RunStdString(&git.RunOpts{Dir: path})