big update: added reactions, groups, media share

server/internal/media/local.go

@@ -0,0 +1,95 @@
+package media
+
+import (
+	"context"
+	"errors"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+// Local stores objects as files under a base directory.
+type Local struct {
+	dir string
+}
+
+// NewLocal creates a Local store rooted at dir, creating it if needed.
+func NewLocal(dir string) (*Local, error) {
+	if err := os.MkdirAll(dir, 0o750); err != nil {
+		return nil, err
+	}
+	return &Local{dir: dir}, nil
+}
+
+func (l *Local) resolve(key string) (string, error) {
+	clean := filepath.Clean(filepath.Join(l.dir, key))
+	if !hasPrefix(clean, l.dir) {
+		return "", errors.New("media: invalid storage key")
+	}
+	return clean, nil
+}
+
+// Save writes the stream to disk atomically under the base directory.
+func (l *Local) Save(_ context.Context, key string, r io.Reader) error {
+	path, err := l.resolve(key)
+	if err != nil {
+		return err
+	}
+	if err := os.MkdirAll(filepath.Dir(path), 0o750); err != nil {
+		return err
+	}
+	tmp, err := os.CreateTemp(filepath.Dir(path), ".upload-*")
+	if err != nil {
+		return err
+	}
+	defer os.Remove(tmp.Name())
+
+	if _, err := io.Copy(tmp, r); err != nil {
+		tmp.Close()
+		return err
+	}
+	if err := tmp.Close(); err != nil {
+		return err
+	}
+	return os.Rename(tmp.Name(), path)
+}
+
+// Open returns a reader for the object or ErrNotFound.
+func (l *Local) Open(_ context.Context, key string) (io.ReadCloser, error) {
+	path, err := l.resolve(key)
+	if err != nil {
+		return nil, err
+	}
+	f, err := os.Open(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, ErrNotFound
+		}
+		return nil, err
+	}
+	return f, nil
+}
+
+// Delete removes the object; missing objects are not an error.
+func (l *Local) Delete(_ context.Context, key string) error {
+	path, err := l.resolve(key)
+	if err != nil {
+		return err
+	}
+	if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	return nil
+}
+
+func hasPrefix(p, dir string) bool {
+	rel, err := filepath.Rel(dir, p)
+	if err != nil {
+		return false
+	}
+	return rel != ".." && !startsWithDotDot(rel)
+}
+
+func startsWithDotDot(rel string) bool {
+	return len(rel) >= 3 && rel[0] == '.' && rel[1] == '.' && (rel[2] == '/' || rel[2] == '\\')
+}