Files
Commilitia-Drop/desktop/platform/download.go
T
admin f21fa5b5e8 cdrop — 跨 OS 剪贴板与文件传输服务
Commilitia Drop:自托管的跨设备剪贴板同步与点对点文件传输。

- 后端 Go(chi / SQLite WAL / SSE Hub / WebRTC signaling + 状态机 / Relay ring buffer),编译进单个 distroless 镜像(前端 go:embed)。
- 前端 React + TanStack Router + Zustand,自实现 SSE + WebRTC P2P,NAT 受阻时回退服务端中继;聚珍(Juzhen)CJK 综合排版。
- 桌面端 Wails v2(macOS / Windows),瘦客户端复用 web。
- 鉴权 OIDC PKCE(自建 Casdoor 等),refresh_token 信封加密存系统密钥库;iOS Shortcut 用 HS256 scoped token。

架构文档与变更记录见 docs 分支(PROJECT_BRIEF / FRONTEND_DESIGN / CHANGELOG)。

本次为公开发布初始提交:完整开发历史(含部署细节)留存于私有归档,公开仓库自此干净起步。
2026-06-15 21:38:28 +08:00

113 lines
3.5 KiB
Go

package platform
import (
"fmt"
"os"
"os/exec"
"path/filepath"
"runtime"
"strings"
)
// SaveDownload writes a received file's bytes into dir (empty → system Downloads),
// returning the absolute path written. The name comes from a transfer peer (U2,
// untrusted), so it is sanitized to a bare filename before use — no path
// components survive, so a crafted name like "../../x" cannot escape dir. On a
// name collision a " (n)" suffix is appended rather than overwriting. After a
// successful write the file is best-effort revealed in the OS file manager.
//
// If the configured dir is unwritable (deleted, no permission, read-only), the
// write is retried into the system Downloads dir before giving up — the WebView
// has no usable download fallback (WKWebView ignores blob a[download]), so a
// received file must never be silently lost to a bad setting. The returned path
// reflects where the file actually landed, so the UI can show it.
func SaveDownload(dir, name string, data []byte) (string, error) {
if dir == "" {
dir = DefaultDownloadDir()
}
path, err := writeInto(dir, name, data)
if err == nil {
return path, nil
}
if def := DefaultDownloadDir(); def != dir {
if p, ferr := writeInto(def, name, data); ferr == nil {
return p, nil
}
}
return "", err // report the original (configured-dir) failure
}
// writeInto sanitizes the name, resolves a non-colliding path under dir, writes
// the bytes, and reveals the result. Returns the absolute path written.
func writeInto(dir, name string, data []byte) (string, error) {
if err := os.MkdirAll(dir, 0o755); err != nil {
return "", err
}
safe := sanitizeFileName(name)
if safe == "" {
safe = "cdrop-download"
}
target := uniquePath(dir, safe)
if err := os.WriteFile(target, data, 0o644); err != nil {
return "", err
}
revealInFileManager(target)
return target, nil
}
// sanitizeFileName reduces a peer-supplied name to a single safe filename:
// directory components are dropped (path-traversal defense), control chars are
// removed, and characters reserved by common filesystems are replaced with "_".
func sanitizeFileName(name string) string {
name = filepath.Base(filepath.FromSlash(name)) // strip any directory parts
name = strings.TrimSpace(name)
if name == "." || name == ".." {
return ""
}
var b strings.Builder
for _, r := range name {
switch {
case r < 0x20:
continue // control characters
case strings.ContainsRune(`/\:*?"<>|`, r):
b.WriteRune('_') // filesystem-reserved
default:
b.WriteRune(r)
}
}
out := strings.TrimSpace(b.String())
if len(out) > 200 {
out = strings.TrimSpace(out[:200])
}
return out
}
// uniquePath returns dir/name, or dir/"name (n).ext" with the lowest n that does
// not yet exist, so a repeated transfer never silently overwrites a prior file.
func uniquePath(dir, name string) string {
target := filepath.Join(dir, name)
if _, err := os.Stat(target); os.IsNotExist(err) {
return target
}
ext := filepath.Ext(name)
stem := strings.TrimSuffix(name, ext)
for i := 1; ; i += 1 {
cand := filepath.Join(dir, fmt.Sprintf("%s (%d)%s", stem, i, ext))
if _, err := os.Stat(cand); os.IsNotExist(err) {
return cand
}
}
}
// revealInFileManager opens the OS file manager with the saved file selected.
// Best-effort: the save already succeeded, so any error here is ignored.
func revealInFileManager(path string) {
switch runtime.GOOS {
case "darwin":
_ = exec.Command("open", "-R", path).Start()
case "windows":
_ = exec.Command("explorer", "/select,"+path).Start()
}
}