Implement "embedded" command to extract static resources (#9982)

* draft

* Implement extract command

* Fix nits and force args on extract

* Add !bindata stub, support Windows, fmt

* fix vendored flag

* Remove leading slash for matching

* Add docs

* Fix typos

* Add embedded view command

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

2 files changed, 362 insertions, 0 deletions

diff --git a/cmd/embedded.go b/cmd/embedded.go
new file mode 100644
index 0000000000..363b85c066
--- /dev/null
+++ b/cmd/embedded.go
@@ -0,0 +1,332 @@
+// Copyright 2020 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.
+
+// +build bindata
+
+package cmd
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/options"
+	"code.gitea.io/gitea/modules/public"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/templates"
+
+	"github.com/gobwas/glob"
+	"github.com/urfave/cli"
+)
+
+// Cmdembedded represents the available extract sub-command.
+var (
+	Cmdembedded = cli.Command{
+		Name:        "embedded",
+		Usage:       "Extract embedded resources",
+		Description: "A command for extracting embedded resources, like templates and images",
+		Subcommands: []cli.Command{
+			subcmdList,
+			subcmdView,
+			subcmdExtract,
+		},
+	}
+
+	subcmdList = cli.Command{
+		Name:   "list",
+		Usage:  "List files matching the given pattern",
+		Action: runList,
+		Flags: []cli.Flag{
+			cli.BoolFlag{
+				Name:  "include-vendored,vendor",
+				Usage: "Include files under public/vendor as well",
+			},
+		},
+	}
+
+	subcmdView = cli.Command{
+		Name:   "view",
+		Usage:  "View a file matching the given pattern",
+		Action: runView,
+		Flags: []cli.Flag{
+			cli.BoolFlag{
+				Name:  "include-vendored,vendor",
+				Usage: "Include files under public/vendor as well",
+			},
+		},
+	}
+
+	subcmdExtract = cli.Command{
+		Name:   "extract",
+		Usage:  "Extract resources",
+		Action: runExtract,
+		Flags: []cli.Flag{
+			cli.BoolFlag{
+				Name:  "include-vendored,vendor",
+				Usage: "Include files under public/vendor as well",
+			},
+			cli.BoolFlag{
+				Name:  "overwrite",
+				Usage: "Overwrite files if they already exist",
+			},
+			cli.BoolFlag{
+				Name:  "rename",
+				Usage: "Rename files as {name}.bak if they already exist (overwrites previous .bak)",
+			},
+			cli.BoolFlag{
+				Name:  "custom",
+				Usage: "Extract to the 'custom' directory as per app.ini",
+			},
+			cli.StringFlag{
+				Name:  "destination,dest-dir",
+				Usage: "Extract to the specified directory",
+			},
+		},
+	}
+
+	sections map[string]*section
+	assets   []asset
+)
+
+type section struct {
+	Path  string
+	Names func() []string
+	IsDir func(string) (bool, error)
+	Asset func(string) ([]byte, error)
+}
+
+type asset struct {
+	Section *section
+	Name    string
+	Path    string
+}
+
+func initEmbeddedExtractor(c *cli.Context) error {
+
+	// Silence the console logger
+	log.DelNamedLogger("console")
+	log.DelNamedLogger(log.DEFAULT)
+
+	// Read configuration file
+	setting.NewContext()
+
+	pats, err := getPatterns(c.Args())
+	if err != nil {
+		return err
+	}
+	sections := make(map[string]*section, 3)
+
+	sections["public"] = &section{Path: "public", Names: public.AssetNames, IsDir: public.AssetIsDir, Asset: public.Asset}
+	sections["options"] = &section{Path: "options", Names: options.AssetNames, IsDir: options.AssetIsDir, Asset: options.Asset}
+	sections["templates"] = &section{Path: "templates", Names: templates.AssetNames, IsDir: templates.AssetIsDir, Asset: templates.Asset}
+
+	for _, sec := range sections {
+		assets = append(assets, buildAssetList(sec, pats, c)...)
+	}
+
+	// Sort assets
+	sort.SliceStable(assets, func(i, j int) bool {
+		return assets[i].Path < assets[j].Path
+	})
+
+	return nil
+}
+
+func runList(c *cli.Context) error {
+	if err := runListDo(c); err != nil {
+		fmt.Fprintf(os.Stderr, "%v\n", err)
+		return err
+	}
+	return nil
+}
+
+func runView(c *cli.Context) error {
+	if err := runViewDo(c); err != nil {
+		fmt.Fprintf(os.Stderr, "%v\n", err)
+		return err
+	}
+	return nil
+}
+
+func runExtract(c *cli.Context) error {
+	if err := runExtractDo(c); err != nil {
+		fmt.Fprintf(os.Stderr, "%v\n", err)
+		return err
+	}
+	return nil
+}
+
+func runListDo(c *cli.Context) error {
+	if err := initEmbeddedExtractor(c); err != nil {
+		return err
+	}
+
+	for _, a := range assets {
+		fmt.Println(a.Path)
+	}
+
+	return nil
+}
+
+func runViewDo(c *cli.Context) error {
+	if err := initEmbeddedExtractor(c); err != nil {
+		return err
+	}
+
+	if len(assets) == 0 {
+		return fmt.Errorf("No files matched the given pattern")
+	} else if len(assets) > 1 {
+		return fmt.Errorf("Too many files matched the given pattern; try to be more specific")
+	}
+
+	data, err := assets[0].Section.Asset(assets[0].Name)
+	if err != nil {
+		return fmt.Errorf("%s: %v", assets[0].Path, err)
+	}
+
+	if _, err = os.Stdout.Write(data); err != nil {
+		return fmt.Errorf("%s: %v", assets[0].Path, err)
+	}
+
+	return nil
+}
+
+func runExtractDo(c *cli.Context) error {
+	if err := initEmbeddedExtractor(c); err != nil {
+		return err
+	}
+
+	if len(c.Args()) == 0 {
+		return fmt.Errorf("A list of pattern of files to extract is mandatory (e.g. '**' for all)")
+	}
+
+	destdir := "."
+
+	if c.IsSet("destination") {
+		destdir = c.String("destination")
+	} else if c.Bool("custom") {
+		destdir = setting.CustomPath
+		fmt.Println("Using app.ini at", setting.CustomConf)
+	}
+
+	fi, err := os.Stat(destdir)
+	if errors.Is(err, os.ErrNotExist) {
+		// In case Windows users attempt to provide a forward-slash path
+		wdestdir := filepath.FromSlash(destdir)
+		if wfi, werr := os.Stat(wdestdir); werr == nil {
+			destdir = wdestdir
+			fi = wfi
+			err = nil
+		}
+	}
+	if err != nil {
+		return fmt.Errorf("%s: %s", destdir, err)
+	} else if !fi.IsDir() {
+		return fmt.Errorf("%s is not a directory.", destdir)
+	}
+
+	fmt.Printf("Extracting to %s:\n", destdir)
+
+	overwrite := c.Bool("overwrite")
+	rename := c.Bool("rename")
+
+	for _, a := range assets {
+		if err := extractAsset(destdir, a, overwrite, rename); err != nil {
+			// Non-fatal error
+			fmt.Fprintf(os.Stderr, "%s: %v", a.Path, err)
+		}
+	}
+
+	return nil
+}
+
+func extractAsset(d string, a asset, overwrite, rename bool) error {
+	dest := filepath.Join(d, filepath.FromSlash(a.Path))
+	dir := filepath.Dir(dest)
+
+	data, err := a.Section.Asset(a.Name)
+	if err != nil {
+		return fmt.Errorf("%s: %v", a.Path, err)
+	}
+
+	if err := os.MkdirAll(dir, os.ModePerm); err != nil {
+		return fmt.Errorf("%s: %v", dir, err)
+	}
+
+	perms := os.ModePerm & 0666
+
+	fi, err := os.Lstat(dest)
+	if err != nil {
+		if !errors.Is(err, os.ErrNotExist) {
+			return fmt.Errorf("%s: %v", dest, err)
+		}
+	} else if !overwrite && !rename {
+		fmt.Printf("%s already exists; skipped.\n", dest)
+		return nil
+	} else if !fi.Mode().IsRegular() {
+		return fmt.Errorf("%s already exists, but it's not a regular file", dest)
+	} else if rename {
+		if err := os.Rename(dest, dest+".bak"); err != nil {
+			return fmt.Errorf("Error creating backup for %s: %v", dest, err)
+		}
+		// Attempt to respect file permissions mask (even if user:group will be set anew)
+		perms = fi.Mode()
+	}
+
+	file, err := os.OpenFile(dest, os.O_WRONLY|os.O_TRUNC|os.O_CREATE, perms)
+	if err != nil {
+		return fmt.Errorf("%s: %v", dest, err)
+	}
+	defer file.Close()
+
+	if _, err = file.Write(data); err != nil {
+		return fmt.Errorf("%s: %v", dest, err)
+	}
+
+	fmt.Println(dest)
+
+	return nil
+}
+
+func buildAssetList(sec *section, globs []glob.Glob, c *cli.Context) []asset {
+	var results = make([]asset, 0, 64)
+	for _, name := range sec.Names() {
+		if isdir, err := sec.IsDir(name); !isdir && err == nil {
+			if sec.Path == "public" &&
+				strings.HasPrefix(name, "vendor/") &&
+				!c.Bool("include-vendored") {
+				continue
+			}
+			matchName := sec.Path + "/" + name
+			for _, g := range globs {
+				if g.Match(matchName) {
+					results = append(results, asset{Section: sec,
+						Name: name,
+						Path: sec.Path + "/" + name})
+					break
+				}
+			}
+		}
+	}
+	return results
+}
+
+func getPatterns(args []string) ([]glob.Glob, error) {
+	if len(args) == 0 {
+		args = []string{"**"}
+	}
+	pat := make([]glob.Glob, len(args))
+	for i := range args {
+		if g, err := glob.Compile(args[i], '/'); err != nil {
+			return nil, fmt.Errorf("'%s': Invalid glob pattern: %v", args[i], err)
+		} else {
+			pat[i] = g
+		}
+	}
+	return pat, nil
+}
diff --git a/cmd/embedded_stub.go b/cmd/embedded_stub.go
new file mode 100644
index 0000000000..1f9af7b86b
--- /dev/null
+++ b/cmd/embedded_stub.go
@@ -0,0 +1,30 @@
+// Copyright 2020 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.
+
+// +build !bindata
+
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/urfave/cli"
+)
+
+// Cmdembedded represents the available extract sub-command.
+var (
+	Cmdembedded = cli.Command{
+		Name:        "embedded",
+		Usage:       "Extract embedded resources",
+		Description: "A command for extracting embedded resources, like templates and images",
+		Action:      extractorNotImplemented,
+	}
+)
+
+func extractorNotImplemented(c *cli.Context) error {
+	err := fmt.Errorf("Sorry: the 'embedded' subcommand is not available in builds without bindata")
+	fmt.Fprintf(os.Stderr, "%s\n", err)
+	return err
+}