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>

1 files changed, 9 insertions, 9 deletions

diff --git a/modules/git/commit.go b/modules/git/commit.go
index 14710de612..1f6289ed02 100644
--- a/modules/git/commit.go
+++ b/modules/git/commit.go
@@ -9,7 +9,6 @@ import (
 	"bytes"
 	"context"
 	"errors"
-	"fmt"
 	"io"
 	"os/exec"
 	"strconv"
@@ -91,8 +90,8 @@ func AddChanges(repoPath string, all bool, files ...string) error {
 }
 
 // AddChangesWithArgs marks local changes to be ready for commit.
-func AddChangesWithArgs(repoPath string, globalArgs []CmdArg, all bool, files ...string) error {
-	cmd := NewCommandNoGlobals(append(globalArgs, "add")...)
+func AddChangesWithArgs(repoPath string, globalArgs TrustedCmdArgs, all bool, files ...string) error {
+	cmd := NewCommandContextNoGlobals(DefaultContext, globalArgs...).AddArguments("add")
 	if all {
 		cmd.AddArguments("--all")
 	}
@@ -111,17 +110,18 @@ type CommitChangesOptions struct {
 // CommitChanges commits local changes with given committer, author and message.
 // If author is nil, it will be the same as committer.
 func CommitChanges(repoPath string, opts CommitChangesOptions) error {
-	cargs := make([]CmdArg, len(globalCommandArgs))
+	cargs := make(TrustedCmdArgs, len(globalCommandArgs))
 	copy(cargs, globalCommandArgs)
 	return CommitChangesWithArgs(repoPath, cargs, opts)
 }
 
 // CommitChangesWithArgs commits local changes with given committer, author and message.
 // If author is nil, it will be the same as committer.
-func CommitChangesWithArgs(repoPath string, args []CmdArg, opts CommitChangesOptions) error {
-	cmd := NewCommandNoGlobals(args...)
+func CommitChangesWithArgs(repoPath string, args TrustedCmdArgs, opts CommitChangesOptions) error {
+	cmd := NewCommandContextNoGlobals(DefaultContext, args...)
 	if opts.Committer != nil {
-		cmd.AddArguments("-c", CmdArg("user.name="+opts.Committer.Name), "-c", CmdArg("user.email="+opts.Committer.Email))
+		cmd.AddOptionValues("-c", "user.name="+opts.Committer.Name)
+		cmd.AddOptionValues("-c", "user.email="+opts.Committer.Email)
 	}
 	cmd.AddArguments("commit")
 
@@ -129,9 +129,9 @@ func CommitChangesWithArgs(repoPath string, args []CmdArg, opts CommitChangesOpt
 		opts.Author = opts.Committer
 	}
 	if opts.Author != nil {
-		cmd.AddArguments(CmdArg(fmt.Sprintf("--author='%s <%s>'", opts.Author.Name, opts.Author.Email)))
+		cmd.AddOptionFormat("--author='%s <%s>'", opts.Author.Name, opts.Author.Email)
 	}
-	cmd.AddArguments("-m").AddDynamicArguments(opts.Message)
+	cmd.AddOptionValues("-m", opts.Message)
 
 	_, _, err := cmd.RunStdString(&RunOpts{Dir: repoPath})
 	// No stderr but exit status 1 means nothing to commit.