Add apply-patch, basic revert and cherry-pick functionality (#17902)

This code adds a simple endpoint to apply patches to repositories and
branches on gitea. This is then used along with the conflicting checking
code in #18004 to provide a basic implementation of cherry-pick revert.

Now because the buttons necessary for cherry-pick and revert have 
required us to create a dropdown next to the Browse Source button
I've also implemented Create Branch and Create Tag operations.

Fix #3880 
Fix #17986 

Signed-off-by: Andrew Thornton <art27@cantab.net>

5 files changed, 422 insertions, 0 deletions

diff --git a/routers/api/v1/api.go b/routers/api/v1/api.go
index df00a852f2..6d8ab8ce98 100644
--- a/routers/api/v1/api.go
+++ b/routers/api/v1/api.go
@@ -975,6 +975,7 @@ func Routes(sessioner func(http.Handler) http.Handler) *web.Route {
 					m.Get("/tags/{sha}", context.RepoRefForAPI, repo.GetAnnotatedTag)
 					m.Get("/notes/{sha}", repo.GetNote)
 				}, reqRepoReader(unit.TypeCode))
+				m.Post("/diffpatch", reqRepoWriter(unit.TypeCode), reqToken(), bind(api.ApplyDiffPatchFileOptions{}), repo.ApplyDiffPatch)
 				m.Group("/contents", func() {
 					m.Get("", repo.GetContentsList)
 					m.Get("/*", repo.GetContents)
diff --git a/routers/api/v1/repo/patch.go b/routers/api/v1/repo/patch.go
new file mode 100644
index 0000000000..64a7a32d16
--- /dev/null
+++ b/routers/api/v1/repo/patch.go
@@ -0,0 +1,107 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package repo
+
+import (
+	"net/http"
+	"time"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/git"
+	api "code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/modules/web"
+	"code.gitea.io/gitea/services/repository/files"
+)
+
+// ApplyDiffPatch handles API call for applying a patch
+func ApplyDiffPatch(ctx *context.APIContext) {
+	// swagger:operation POST /repos/{owner}/{repo}/diffpatch repository repoApplyDiffPatch
+	// ---
+	// summary: Apply diff patch to repository
+	// consumes:
+	// - application/json
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// - name: body
+	//   in: body
+	//   required: true
+	//   schema:
+	//     "$ref": "#/definitions/UpdateFileOptions"
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/FileResponse"
+	apiOpts := web.GetForm(ctx).(*api.ApplyDiffPatchFileOptions)
+
+	opts := &files.ApplyDiffPatchOptions{
+		Content:   apiOpts.Content,
+		SHA:       apiOpts.SHA,
+		Message:   apiOpts.Message,
+		OldBranch: apiOpts.BranchName,
+		NewBranch: apiOpts.NewBranchName,
+		Committer: &files.IdentityOptions{
+			Name:  apiOpts.Committer.Name,
+			Email: apiOpts.Committer.Email,
+		},
+		Author: &files.IdentityOptions{
+			Name:  apiOpts.Author.Name,
+			Email: apiOpts.Author.Email,
+		},
+		Dates: &files.CommitDateOptions{
+			Author:    apiOpts.Dates.Author,
+			Committer: apiOpts.Dates.Committer,
+		},
+		Signoff: apiOpts.Signoff,
+	}
+	if opts.Dates.Author.IsZero() {
+		opts.Dates.Author = time.Now()
+	}
+	if opts.Dates.Committer.IsZero() {
+		opts.Dates.Committer = time.Now()
+	}
+
+	if opts.Message == "" {
+		opts.Message = "apply-patch"
+	}
+
+	if !canWriteFiles(ctx.Repo) {
+		ctx.Error(http.StatusInternalServerError, "ApplyPatch", models.ErrUserDoesNotHaveAccessToRepo{
+			UserID:   ctx.User.ID,
+			RepoName: ctx.Repo.Repository.LowerName,
+		})
+		return
+	}
+
+	fileResponse, err := files.ApplyDiffPatch(ctx, ctx.Repo.Repository, ctx.User, opts)
+	if err != nil {
+		if models.IsErrUserCannotCommit(err) || models.IsErrFilePathProtected(err) {
+			ctx.Error(http.StatusForbidden, "Access", err)
+			return
+		}
+		if models.IsErrBranchAlreadyExists(err) || models.IsErrFilenameInvalid(err) || models.IsErrSHADoesNotMatch(err) ||
+			models.IsErrFilePathInvalid(err) || models.IsErrRepoFileAlreadyExists(err) {
+			ctx.Error(http.StatusUnprocessableEntity, "Invalid", err)
+			return
+		}
+		if models.IsErrBranchDoesNotExist(err) || git.IsErrBranchNotExist(err) {
+			ctx.Error(http.StatusNotFound, "BranchDoesNotExist", err)
+			return
+		}
+		ctx.Error(http.StatusInternalServerError, "ApplyPatch", err)
+	} else {
+		ctx.JSON(http.StatusCreated, fileResponse)
+	}
+}
diff --git a/routers/web/repo/cherry_pick.go b/routers/web/repo/cherry_pick.go
new file mode 100644
index 0000000000..1b0d8452e2
--- /dev/null
+++ b/routers/web/repo/cherry_pick.go
@@ -0,0 +1,189 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package repo
+
+import (
+	"bytes"
+	"errors"
+	"strings"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/models/unit"
+	"code.gitea.io/gitea/modules/base"
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/util"
+	"code.gitea.io/gitea/modules/web"
+	"code.gitea.io/gitea/services/forms"
+	"code.gitea.io/gitea/services/repository/files"
+)
+
+var tplCherryPick base.TplName = "repo/editor/cherry_pick"
+
+// CherryPick handles cherrypick GETs
+func CherryPick(ctx *context.Context) {
+	ctx.Data["SHA"] = ctx.Params(":sha")
+	cherryPickCommit, err := ctx.Repo.GitRepo.GetCommit(ctx.Params(":sha"))
+	if err != nil {
+		if git.IsErrNotExist(err) {
+			ctx.NotFound("Missing Commit", err)
+			return
+		}
+		ctx.ServerError("GetCommit", err)
+		return
+	}
+
+	if ctx.FormString("cherry-pick-type") == "revert" {
+		ctx.Data["CherryPickType"] = "revert"
+		ctx.Data["commit_summary"] = "revert " + ctx.Params(":sha")
+		ctx.Data["commit_message"] = "revert " + cherryPickCommit.Message()
+	} else {
+		ctx.Data["CherryPickType"] = "cherry-pick"
+		splits := strings.SplitN(cherryPickCommit.Message(), "\n", 2)
+		ctx.Data["commit_summary"] = splits[0]
+		ctx.Data["commit_message"] = splits[1]
+	}
+
+	ctx.Data["RequireHighlightJS"] = true
+
+	canCommit := renderCommitRights(ctx)
+	ctx.Data["TreePath"] = "patch"
+
+	if canCommit {
+		ctx.Data["commit_choice"] = frmCommitChoiceDirect
+	} else {
+		ctx.Data["commit_choice"] = frmCommitChoiceNewBranch
+	}
+	ctx.Data["new_branch_name"] = GetUniquePatchBranchName(ctx)
+	ctx.Data["last_commit"] = ctx.Repo.CommitID
+	ctx.Data["LineWrapExtensions"] = strings.Join(setting.Repository.Editor.LineWrapExtensions, ",")
+	ctx.Data["BranchLink"] = ctx.Repo.RepoLink + "/src/" + ctx.Repo.BranchNameSubURL()
+
+	ctx.HTML(200, tplCherryPick)
+}
+
+// CherryPickPost handles cherrypick POSTs
+func CherryPickPost(ctx *context.Context) {
+	form := web.GetForm(ctx).(*forms.CherryPickForm)
+
+	sha := ctx.Params(":sha")
+	ctx.Data["SHA"] = sha
+	if form.Revert {
+		ctx.Data["CherryPickType"] = "revert"
+	} else {
+		ctx.Data["CherryPickType"] = "cherry-pick"
+	}
+
+	ctx.Data["RequireHighlightJS"] = true
+	canCommit := renderCommitRights(ctx)
+	branchName := ctx.Repo.BranchName
+	if form.CommitChoice == frmCommitChoiceNewBranch {
+		branchName = form.NewBranchName
+	}
+	ctx.Data["commit_summary"] = form.CommitSummary
+	ctx.Data["commit_message"] = form.CommitMessage
+	ctx.Data["commit_choice"] = form.CommitChoice
+	ctx.Data["new_branch_name"] = form.NewBranchName
+	ctx.Data["last_commit"] = ctx.Repo.CommitID
+	ctx.Data["LineWrapExtensions"] = strings.Join(setting.Repository.Editor.LineWrapExtensions, ",")
+	ctx.Data["BranchLink"] = ctx.Repo.RepoLink + "/src/" + ctx.Repo.BranchNameSubURL()
+
+	if ctx.HasError() {
+		ctx.HTML(200, tplCherryPick)
+		return
+	}
+
+	// Cannot commit to a an existing branch if user doesn't have rights
+	if branchName == ctx.Repo.BranchName && !canCommit {
+		ctx.Data["Err_NewBranchName"] = true
+		ctx.Data["commit_choice"] = frmCommitChoiceNewBranch
+		ctx.RenderWithErr(ctx.Tr("repo.editor.cannot_commit_to_protected_branch", branchName), tplCherryPick, &form)
+		return
+	}
+
+	message := strings.TrimSpace(form.CommitSummary)
+	if message == "" {
+		if form.Revert {
+			message = ctx.Tr("repo.commit.revert-header", sha)
+		} else {
+			message = ctx.Tr("repo.commit.cherry-pick-header", sha)
+		}
+	}
+
+	form.CommitMessage = strings.TrimSpace(form.CommitMessage)
+	if len(form.CommitMessage) > 0 {
+		message += "\n\n" + form.CommitMessage
+	}
+
+	opts := &files.ApplyDiffPatchOptions{
+		LastCommitID: form.LastCommit,
+		OldBranch:    ctx.Repo.BranchName,
+		NewBranch:    branchName,
+		Message:      message,
+	}
+
+	// First lets try the simple plain read-tree -m approach
+	opts.Content = sha
+	if _, err := files.CherryPick(ctx, ctx.Repo.Repository, ctx.User, form.Revert, opts); err != nil {
+		if models.IsErrBranchAlreadyExists(err) {
+			// User has specified a branch that already exists
+			branchErr := err.(models.ErrBranchAlreadyExists)
+			ctx.Data["Err_NewBranchName"] = true
+			ctx.RenderWithErr(ctx.Tr("repo.editor.branch_already_exists", branchErr.BranchName), tplCherryPick, &form)
+			return
+		} else if models.IsErrCommitIDDoesNotMatch(err) {
+			ctx.RenderWithErr(ctx.Tr("repo.editor.file_changed_while_editing", ctx.Repo.RepoLink+"/compare/"+form.LastCommit+"..."+ctx.Repo.CommitID), tplPatchFile, &form)
+			return
+		}
+		// Drop through to the apply technique
+
+		buf := &bytes.Buffer{}
+		if form.Revert {
+			if err := git.GetReverseRawDiff(ctx, ctx.Repo.Repository.RepoPath(), sha, buf); err != nil {
+				if git.IsErrNotExist(err) {
+					ctx.NotFound("GetRawDiff", errors.New("commit "+ctx.Params(":sha")+" does not exist."))
+					return
+				}
+				ctx.ServerError("GetRawDiff", err)
+				return
+			}
+		} else {
+			if err := git.GetRawDiff(ctx, ctx.Repo.Repository.RepoPath(), sha, git.RawDiffType("patch"), buf); err != nil {
+				if git.IsErrNotExist(err) {
+					ctx.NotFound("GetRawDiff", errors.New("commit "+ctx.Params(":sha")+" does not exist."))
+					return
+				}
+				ctx.ServerError("GetRawDiff", err)
+				return
+			}
+		}
+
+		opts.Content = buf.String()
+		ctx.Data["FileContent"] = opts.Content
+
+		if _, err := files.ApplyDiffPatch(ctx, ctx.Repo.Repository, ctx.User, opts); err != nil {
+			if models.IsErrBranchAlreadyExists(err) {
+				// User has specified a branch that already exists
+				branchErr := err.(models.ErrBranchAlreadyExists)
+				ctx.Data["Err_NewBranchName"] = true
+				ctx.RenderWithErr(ctx.Tr("repo.editor.branch_already_exists", branchErr.BranchName), tplCherryPick, &form)
+				return
+			} else if models.IsErrCommitIDDoesNotMatch(err) {
+				ctx.RenderWithErr(ctx.Tr("repo.editor.file_changed_while_editing", ctx.Repo.RepoLink+"/compare/"+form.LastCommit+"..."+ctx.Repo.CommitID), tplPatchFile, &form)
+				return
+			} else {
+				ctx.RenderWithErr(ctx.Tr("repo.editor.fail_to_apply_patch", err), tplPatchFile, &form)
+				return
+			}
+		}
+	}
+
+	if form.CommitChoice == frmCommitChoiceNewBranch && ctx.Repo.Repository.UnitEnabled(unit.TypePullRequests) {
+		ctx.Redirect(ctx.Repo.RepoLink + "/compare/" + util.PathEscapeSegments(ctx.Repo.BranchName) + "..." + util.PathEscapeSegments(form.NewBranchName))
+	} else {
+		ctx.Redirect(ctx.Repo.RepoLink + "/src/branch/" + util.PathEscapeSegments(branchName))
+	}
+}
diff --git a/routers/web/repo/patch.go b/routers/web/repo/patch.go
new file mode 100644
index 0000000000..b00065a6ee
--- /dev/null
+++ b/routers/web/repo/patch.go
@@ -0,0 +1,120 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package repo
+
+import (
+	"strings"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/models/unit"
+	"code.gitea.io/gitea/modules/base"
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/util"
+	"code.gitea.io/gitea/modules/web"
+	"code.gitea.io/gitea/services/forms"
+	"code.gitea.io/gitea/services/repository/files"
+)
+
+const (
+	tplPatchFile base.TplName = "repo/editor/patch"
+)
+
+// NewDiffPatch render create patch page
+func NewDiffPatch(ctx *context.Context) {
+	ctx.Data["RequireHighlightJS"] = true
+
+	canCommit := renderCommitRights(ctx)
+
+	ctx.Data["TreePath"] = "patch"
+
+	ctx.Data["commit_summary"] = ""
+	ctx.Data["commit_message"] = ""
+	if canCommit {
+		ctx.Data["commit_choice"] = frmCommitChoiceDirect
+	} else {
+		ctx.Data["commit_choice"] = frmCommitChoiceNewBranch
+	}
+	ctx.Data["new_branch_name"] = GetUniquePatchBranchName(ctx)
+	ctx.Data["last_commit"] = ctx.Repo.CommitID
+	ctx.Data["LineWrapExtensions"] = strings.Join(setting.Repository.Editor.LineWrapExtensions, ",")
+	ctx.Data["BranchLink"] = ctx.Repo.RepoLink + "/src/" + ctx.Repo.BranchNameSubURL()
+
+	ctx.HTML(200, tplPatchFile)
+}
+
+// NewDiffPatchPost response for sending patch page
+func NewDiffPatchPost(ctx *context.Context) {
+	form := web.GetForm(ctx).(*forms.EditRepoFileForm)
+
+	canCommit := renderCommitRights(ctx)
+	branchName := ctx.Repo.BranchName
+	if form.CommitChoice == frmCommitChoiceNewBranch {
+		branchName = form.NewBranchName
+	}
+	ctx.Data["RequireHighlightJS"] = true
+	ctx.Data["TreePath"] = "patch"
+	ctx.Data["BranchLink"] = ctx.Repo.RepoLink + "/src/" + ctx.Repo.BranchNameSubURL()
+	ctx.Data["FileContent"] = form.Content
+	ctx.Data["commit_summary"] = form.CommitSummary
+	ctx.Data["commit_message"] = form.CommitMessage
+	ctx.Data["commit_choice"] = form.CommitChoice
+	ctx.Data["new_branch_name"] = form.NewBranchName
+	ctx.Data["last_commit"] = ctx.Repo.CommitID
+	ctx.Data["LineWrapExtensions"] = strings.Join(setting.Repository.Editor.LineWrapExtensions, ",")
+
+	if ctx.HasError() {
+		ctx.HTML(200, tplPatchFile)
+		return
+	}
+
+	// Cannot commit to a an existing branch if user doesn't have rights
+	if branchName == ctx.Repo.BranchName && !canCommit {
+		ctx.Data["Err_NewBranchName"] = true
+		ctx.Data["commit_choice"] = frmCommitChoiceNewBranch
+		ctx.RenderWithErr(ctx.Tr("repo.editor.cannot_commit_to_protected_branch", branchName), tplEditFile, &form)
+		return
+	}
+
+	// CommitSummary is optional in the web form, if empty, give it a default message based on add or update
+	// `message` will be both the summary and message combined
+	message := strings.TrimSpace(form.CommitSummary)
+	if len(message) == 0 {
+		message = ctx.Tr("repo.editor.patch")
+	}
+
+	form.CommitMessage = strings.TrimSpace(form.CommitMessage)
+	if len(form.CommitMessage) > 0 {
+		message += "\n\n" + form.CommitMessage
+	}
+
+	if _, err := files.ApplyDiffPatch(ctx, ctx.Repo.Repository, ctx.User, &files.ApplyDiffPatchOptions{
+		LastCommitID: form.LastCommit,
+		OldBranch:    ctx.Repo.BranchName,
+		NewBranch:    branchName,
+		Message:      message,
+		Content:      strings.ReplaceAll(form.Content, "\r", ""),
+	}); err != nil {
+		if models.IsErrBranchAlreadyExists(err) {
+			// User has specified a branch that already exists
+			branchErr := err.(models.ErrBranchAlreadyExists)
+			ctx.Data["Err_NewBranchName"] = true
+			ctx.RenderWithErr(ctx.Tr("repo.editor.branch_already_exists", branchErr.BranchName), tplEditFile, &form)
+			return
+		} else if models.IsErrCommitIDDoesNotMatch(err) {
+			ctx.RenderWithErr(ctx.Tr("repo.editor.file_changed_while_editing", ctx.Repo.RepoLink+"/compare/"+form.LastCommit+"..."+ctx.Repo.CommitID), tplPatchFile, &form)
+			return
+		} else {
+			ctx.RenderWithErr(ctx.Tr("repo.editor.fail_to_apply_patch", err), tplPatchFile, &form)
+			return
+		}
+	}
+
+	if form.CommitChoice == frmCommitChoiceNewBranch && ctx.Repo.Repository.UnitEnabled(unit.TypePullRequests) {
+		ctx.Redirect(ctx.Repo.RepoLink + "/compare/" + util.PathEscapeSegments(ctx.Repo.BranchName) + "..." + util.PathEscapeSegments(form.NewBranchName))
+	} else {
+		ctx.Redirect(ctx.Repo.RepoLink + "/src/branch/" + util.PathEscapeSegments(branchName) + "/" + util.PathEscapeSegments(form.TreePath))
+	}
+}
diff --git a/routers/web/web.go b/routers/web/web.go
index 60a379aef8..52eca9a0a6 100644
--- a/routers/web/web.go
+++ b/routers/web/web.go
@@ -808,6 +808,10 @@ func RegisterRoutes(m *web.Route) {
 				m.Combo("/_upload/*", repo.MustBeAbleToUpload).
 					Get(repo.UploadFile).
 					Post(bindIgnErr(forms.UploadRepoFileForm{}), repo.UploadFilePost)
+				m.Combo("/_diffpatch/*").Get(repo.NewDiffPatch).
+					Post(bindIgnErr(forms.EditRepoFileForm{}), repo.NewDiffPatchPost)
+				m.Combo("/_cherrypick/{sha:([a-f0-9]{7,40})}/*").Get(repo.CherryPick).
+					Post(bindIgnErr(forms.CherryPickForm{}), repo.CherryPickPost)
 			}, context.RepoRefByType(context.RepoRefBranch), repo.MustBeEditable)
 			m.Group("", func() {
 				m.Post("/upload-file", repo.UploadFileToServer)
@@ -1029,6 +1033,7 @@ func RegisterRoutes(m *web.Route) {
 		m.Group("", func() {
 			m.Get("/graph", repo.Graph)
 			m.Get("/commit/{sha:([a-f0-9]{7,40})$}", repo.SetEditorconfigIfExists, repo.SetDiffViewStyle, repo.SetWhitespaceBehavior, repo.Diff)
+			m.Get("/cherry-pick/{sha:([a-f0-9]{7,40})$}", repo.SetEditorconfigIfExists, repo.CherryPick)
 		}, repo.MustBeNotEmpty, context.RepoRef(), reqRepoCodeReader)
 
 		m.Group("/src", func() {