Centralize path-safe root joins and atomic file operations

2026-05-23 15:45:31 +00:00
parent 98649f4d81
commit 094b0d2532
11 changed files with 466 additions and 189 deletions
--- a/internal/fileops/fileops.go
+++ b/internal/fileops/fileops.go
@@ -0,0 +1,128 @@
+package fileops
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// WriteFileAtomic writes data to dst atomically via temp file + rename.
+func WriteFileAtomic(dst string, data []byte, perm os.FileMode) error {
+	if strings.TrimSpace(dst) == "" {
+		return fmt.Errorf("destination path is required")
+	}
+	if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
+		return fmt.Errorf("create destination directory: %w", err)
+	}
+
+	base := filepath.Base(dst)
+	tmp, err := os.CreateTemp(filepath.Dir(dst), "."+base+".tmp-*")
+	if err != nil {
+		return fmt.Errorf("create temp file: %w", err)
+	}
+	tmpPath := tmp.Name()
+	removeTmp := true
+	defer func() {
+		if removeTmp {
+			_ = os.Remove(tmpPath)
+		}
+	}()
+
+	if _, err := tmp.Write(data); err != nil {
+		_ = tmp.Close()
+		return fmt.Errorf("write temp file: %w", err)
+	}
+	if err := tmp.Sync(); err != nil {
+		_ = tmp.Close()
+		return fmt.Errorf("sync temp file: %w", err)
+	}
+	if err := tmp.Close(); err != nil {
+		return fmt.Errorf("close temp file: %w", err)
+	}
+	if err := os.Chmod(tmpPath, perm); err != nil {
+		return fmt.Errorf("set temp file permissions: %w", err)
+	}
+	if err := os.Rename(tmpPath, dst); err != nil {
+		return fmt.Errorf("install temp file: %w", err)
+	}
+	removeTmp = false
+	return nil
+}
+
+// CopyFileAtomic copies src to dst atomically via temp file + rename.
+func CopyFileAtomic(src, dst string, perm os.FileMode) error {
+	_, err := CopyFileAtomicWithChecksum(src, dst, perm)
+	return err
+}
+
+// CopyFileAtomicWithChecksum copies src to dst atomically and returns the SHA-256 checksum.
+func CopyFileAtomicWithChecksum(src, dst string, perm os.FileMode) (string, error) {
+	if strings.TrimSpace(src) == "" || strings.TrimSpace(dst) == "" {
+		return "", fmt.Errorf("source and destination paths are required")
+	}
+
+	in, err := os.Open(src)
+	if err != nil {
+		return "", fmt.Errorf("open source file: %w", err)
+	}
+	defer func() { _ = in.Close() }()
+
+	if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
+		return "", fmt.Errorf("create destination directory: %w", err)
+	}
+
+	base := filepath.Base(dst)
+	tmp, err := os.CreateTemp(filepath.Dir(dst), "."+base+".tmp-*")
+	if err != nil {
+		return "", fmt.Errorf("create temp file: %w", err)
+	}
+	tmpPath := tmp.Name()
+	removeTmp := true
+	defer func() {
+		if removeTmp {
+			_ = os.Remove(tmpPath)
+		}
+	}()
+
+	digest := sha256.New()
+	if _, err := io.Copy(io.MultiWriter(tmp, digest), in); err != nil {
+		_ = tmp.Close()
+		return "", fmt.Errorf("copy file: %w", err)
+	}
+	if err := tmp.Sync(); err != nil {
+		_ = tmp.Close()
+		return "", fmt.Errorf("sync temp file: %w", err)
+	}
+	if err := tmp.Close(); err != nil {
+		return "", fmt.Errorf("close temp file: %w", err)
+	}
+	if err := os.Chmod(tmpPath, perm); err != nil {
+		return "", fmt.Errorf("set temp file permissions: %w", err)
+	}
+	if err := os.Rename(tmpPath, dst); err != nil {
+		return "", fmt.Errorf("install temp file: %w", err)
+	}
+	removeTmp = false
+	return hex.EncodeToString(digest.Sum(nil)), nil
+}
+
+// InstallDownloadedTempFile installs a previously downloaded temp file at dst.
+func InstallDownloadedTempFile(tmpPath, dst string, perm os.FileMode) error {
+	if strings.TrimSpace(tmpPath) == "" || strings.TrimSpace(dst) == "" {
+		return fmt.Errorf("temp and destination paths are required")
+	}
+	if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
+		return fmt.Errorf("create destination directory: %w", err)
+	}
+	if err := os.Chmod(tmpPath, perm); err != nil {
+		return fmt.Errorf("set temp file permissions: %w", err)
+	}
+	if err := os.Rename(tmpPath, dst); err != nil {
+		return fmt.Errorf("install downloaded file: %w", err)
+	}
+	return nil
+}