Set gist visibility via Git push options (#215)

internal/hooks/pre_receive.go

@@ -0,0 +1,78 @@
+package hooks
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"os/exec"
+	"strings"
+)
+
+func PreReceive(in io.Reader, out, er io.Writer) error {
+	var err error
+	var disallowedFiles []string
+	var disallowedCommits []string
+
+	scanner := bufio.NewScanner(in)
+	for scanner.Scan() {
+		line := scanner.Text()
+		parts := strings.Split(line, " ")
+		if len(parts) < 3 {
+			_, _ = fmt.Fprintln(er, "Invalid input")
+			return fmt.Errorf("invalid input")
+		}
+
+		oldRev, newRev := parts[0], parts[1]
+
+		var changedFiles string
+		if oldRev == BaseHash {
+			// First commit
+			if changedFiles, err = getChangedFiles(newRev); err != nil {
+				_, _ = fmt.Fprintln(er, "Failed to get changed files")
+				return err
+			}
+		} else {
+			if changedFiles, err = getChangedFiles(fmt.Sprintf("%s..%s", oldRev, newRev)); err != nil {
+				_, _ = fmt.Fprintln(er, "Failed to get changed files")
+				return err
+			}
+		}
+
+		var currentCommit string
+		for _, file := range strings.Fields(changedFiles) {
+			if strings.HasPrefix(file, "/") {
+				currentCommit = file[1:]
+			}
+
+			if strings.Contains(file[1:], "/") {
+				disallowedFiles = append(disallowedFiles, file)
+				disallowedCommits = append(disallowedCommits, currentCommit[0:7])
+			}
+		}
+	}
+
+	if len(disallowedFiles) > 0 {
+		_, _ = fmt.Fprintln(out, "\nPushing files in directories is not allowed:")
+		for i := range disallowedFiles {
+			_, _ = fmt.Fprintf(out, "  %s (%s)\n", disallowedFiles[i], disallowedCommits[i])
+		}
+		_, _ = fmt.Fprintln(out)
+		return fmt.Errorf("pushing files in directories is not allowed: %s", disallowedFiles)
+	}
+
+	return nil
+}
+
+func getChangedFiles(rev string) (string, error) {
+	cmd := exec.Command("git", "log", "--name-only", "--format=/%H", "--diff-filter=AM", rev)
+
+	var out bytes.Buffer
+	cmd.Stdout = &out
+	err := cmd.Run()
+	if err != nil {
+		return "", err
+	}
+
+	return out.String(), nil
+}