Implement blackbox in Golang (#250)

* Initial release

pkg/box/boxutils.go

@@ -0,0 +1,224 @@
+package box
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"os/user"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
+
+	"github.com/StackExchange/blackbox/v2/pkg/makesafe"
+)
+
+// FileStatus returns the status of a file.
+func FileStatus(name string) (string, error) {
+	/*
+		DECRYPTED: File is decrypted and ready to edit (unknown if it has been edited).
+		ENCRYPTED: GPG file is newer than plaintext. Indicates recented edited then encrypted.
+		SHREDDED: Plaintext is missing.
+		GPGMISSING: The .gpg file is missing. Oops?
+		PLAINERROR: Can't access the plaintext file to determine status.
+		GPGERROR: Can't access .gpg file to determine status.
+	*/
+
+	p := name
+	e := p + ".gpg"
+	ps, perr := os.Stat(p)
+	es, eerr := os.Stat(e)
+	if perr == nil && eerr == nil {
+		if ps.ModTime().Before(es.ModTime()) {
+			return "ENCRYPTED", nil
+		}
+		return "DECRYPTED", nil
+	}
+
+	if os.IsNotExist(perr) && os.IsNotExist(eerr) {
+		return "BOTHMISSING", nil
+	}
+
+	if eerr != nil {
+		if os.IsNotExist(eerr) {
+			return "GPGMISSING", nil
+		}
+		return "GPGERROR", eerr
+	}
+
+	if perr != nil {
+		if os.IsNotExist(perr) {
+			return "SHREDDED", nil
+		}
+	}
+	return "PLAINERROR", perr
+}
+
+func anyGpg(names []string) error {
+	for _, name := range names {
+		if strings.HasSuffix(name, ".gpg") {
+			return fmt.Errorf(
+				"no not specify .gpg files. Specify %q not %q",
+				strings.TrimSuffix(name, ".gpg"), name)
+		}
+	}
+	return nil
+}
+
+// func isChanged(pname string) (bool, error) {
+// 	// if .gpg exists but not plainfile: unchanged
+// 	// if plaintext exists but not .gpg: changed
+// 	// if plainfile < .gpg: unchanged
+// 	// if plainfile > .gpg: don't know, need to try diff
+
+// 	// Gather info about the files:
+
+// 	pstat, perr := os.Stat(pname)
+// 	if perr != nil && (!os.IsNotExist(perr)) {
+// 		return false, fmt.Errorf("isChanged(%q) returned error: %w", pname, perr)
+// 	}
+// 	gname := pname + ".gpg"
+// 	gstat, gerr := os.Stat(gname)
+// 	if gerr != nil && (!os.IsNotExist(perr)) {
+// 		return false, fmt.Errorf("isChanged(%q) returned error: %w", gname, gerr)
+// 	}
+
+// 	pexists := perr == nil
+// 	gexists := gerr == nil
+
+// 	// Use the above rules:
+
+// 	// if .gpg exists but not plainfile: unchanged
+// 	if gexists && !pexists {
+// 		return false, nil
+// 	}
+
+// 	// if plaintext exists but not .gpg: changed
+// 	if pexists && !gexists {
+// 		return true, nil
+// 	}
+
+// 	// At this point we can conclude that both p and g exist.
+// 	//	Can't hurt to test that assertion.
+// 	if (!pexists) && (!gexists) {
+// 		return false, fmt.Errorf("Assertion failed. p and g should exist: pn=%q", pname)
+// 	}
+
+// 	pmodtime := pstat.ModTime()
+// 	gmodtime := gstat.ModTime()
+// 	// if plainfile < .gpg: unchanged
+// 	if pmodtime.Before(gmodtime) {
+// 		return false, nil
+// 	}
+// 	// if plainfile > .gpg: don't know, need to try diff
+// 	return false, fmt.Errorf("Can not know for sure. Try git diff?")
+// }
+
+func parseGroup(userinput string) (int, error) {
+	if userinput == "" {
+		return -1, fmt.Errorf("group spec is empty string")
+	}
+
+	// If it is a valid number, use it.
+	i, err := strconv.Atoi(userinput)
+	if err == nil {
+		return i, nil
+	}
+
+	// If not a number, look it up by name.
+	g, err := user.LookupGroup(userinput)
+	if err == nil {
+		i, err = strconv.Atoi(g.Gid)
+		return i, nil
+	}
+
+	// Give up.
+	return -1, err
+}
+
+// FindConfigDir tests various places until it finds the config dir.
+// If we can't determine the relative path, "" is returned.
+func FindConfigDir(reporoot, team string) (string, error) {
+
+	candidates := []string{}
+	if team != "" {
+		candidates = append(candidates, ".blackbox-"+team)
+	}
+	candidates = append(candidates, ".blackbox")
+	candidates = append(candidates, "keyrings/live")
+	logDebug.Printf("DEBUG: candidates = %q\n", candidates)
+
+	maxDirLevels := 30 // Prevent an infinite loop
+	relpath := "."
+	for i := 0; i < maxDirLevels; i++ {
+		// Does relpath contain any of our directory names?
+		for _, c := range candidates {
+			t := filepath.Join(relpath, c)
+			logDebug.Printf("Trying %q\n", t)
+			fi, err := os.Stat(t)
+			if err == nil && fi.IsDir() {
+				return t, nil
+			}
+			if err == nil {
+				return "", fmt.Errorf("path %q is not a directory: %w", t, err)
+			}
+			if !os.IsNotExist(err) {
+				return "", fmt.Errorf("dirExists access error: %w", err)
+			}
+		}
+
+		// If we are at the root, stop.
+		if abs, _ := filepath.Abs(relpath); abs == "/" {
+			break
+		}
+		// Try one directory up
+		relpath = filepath.Join("..", relpath)
+	}
+
+	return "", fmt.Errorf("No .blackbox (or equiv) directory found")
+}
+
+func gpgAgentNotice() {
+	// Is gpg-agent configured?
+	if os.Getenv("GPG_AGENT_INFO") != "" {
+		return
+	}
+	// Are we on macOS?
+	if runtime.GOOS == "darwin" {
+		// We assume the use of https://gpgtools.org, which
+		// uses the keychain.
+		return
+	}
+
+	// TODO(tlim): v1 verifies that "gpg-agent --version" outputs a version
+	// string that is 2.1.0 or higher.  It seems that 1.x is incompatible.
+
+	fmt.Println("WARNING: You probably want to run gpg-agent as")
+	fmt.Println("you will be asked for your passphrase many times.")
+	fmt.Println("Example: $ eval $(gpg-agent --daemon)")
+	fmt.Print("Press CTRL-C now to stop. ENTER to continue: ")
+	input := bufio.NewScanner(os.Stdin)
+	input.Scan()
+}
+
+func shouldWeOverwrite() {
+	fmt.Println()
+	fmt.Println("WARNING: This will overwrite any unencrypted files laying about.")
+	fmt.Print("Press CTRL-C now to stop. ENTER to continue: ")
+	input := bufio.NewScanner(os.Stdin)
+	input.Scan()
+}
+
+// PrettyCommitMessage generates a pretty commit message.
+func PrettyCommitMessage(verb string, files []string) string {
+	if len(files) == 0 {
+		// This use-case should probably be an error.
+		return verb + " (no files)"
+	}
+	rfiles := makesafe.RedactMany(files)
+	m, truncated := makesafe.FirstFewFlag(rfiles)
+	if truncated {
+		return verb + ": " + m
+	}
+	return verb + ": " + m
+}