shellenum.go

package main

import (
	"fmt"
	"os"
	"path/filepath"
	"syscall"
	"unsafe"

	"github.com/go-ole/go-ole"
	"golang.org/x/sys/windows"
)

// ---------------- Shell 目录枚举（IShellFolder::EnumObjects） ----------------
// 与资源管理器同款枚举路径。对 OneDrive 等"云占位目录"（reparse tag 0x9000xxxx1A），
// Win32 FindFirstFile（os.ReadDir）枚举会触发 OneDrive 下载目录全部内容；
// 而 shell API 枚举走 OneDrive 的虚拟化路径，只返回元数据，不触发下载。

const (
	shcontFolders       = 0x20 // SHCONTF_FOLDERS
	shcontNonFolders    = 0x40 // SHCONTF_NONFOLDERS
	shcontIncludeHidden = 0x80 // SHCONTF_INCLUDEHIDDEN

	sfgaoFolder     = 0x20000000 // SFGAO_FOLDER
	sfgaoStream     = 0x04000000 // SFGAO_STREAM
	sfgaoFilesystem = 0x40000000 // SFGAO_FILESYSTEM

	shgdnForParsing = 0x8000 // SHGDN_FORPARSING
)

var (
	shellILCombine         = syscall.NewLazyDLL("shell32.dll").NewProc("ILCombine")
	shellGetPathFromIDList = syscall.NewLazyDLL("shell32.dll").NewProc("SHGetPathFromIDListW")
)

// isReparseDir 检测目录是否为 reparse point（OneDrive 云占位目录、符号链接、junction 等）。
// 用 FindFirstFile 读属性（Go os.Lstat 的 REPARSE 位会被 OneDrive/cldflt 隐藏）；
// 单次 FindFirstFile 只取目录自身属性、不枚举内容，不会触发云盘下载。
func isReparseDir(path string) bool {
	var fd windows.Win32finddata
	p, _ := windows.UTF16PtrFromString(path)
	h, err := windows.FindFirstFile(p, &fd)
	if err != nil {
		return false
	}
	windows.FindClose(h)
	return fd.FileAttributes&windows.FILE_ATTRIBUTE_DIRECTORY != 0 &&
		fd.FileAttributes&windows.FILE_ATTRIBUTE_REPARSE_POINT != 0
}

// listDirShell 用 IShellFolder::EnumObjects 枚举目录（资源管理器同款）。
// 失败返回 error，由调用方回退 os.ReadDir。
func listDirShell(path string) ([]FileEntry, error) {
	leave := shellCOMEnter()
	defer leave()

	p, _ := syscall.UTF16PtrFromString(path)
	var absPidl uintptr
	hr, _, _ := shellParseDisplayName.Call(uintptr(unsafe.Pointer(p)), 0, uintptr(unsafe.Pointer(&absPidl)), 0, 0)
	if absPidl != 0 {
		defer procCoTaskMemFree.Call(absPidl)
	}
	if hr != 0 || absPidl == 0 {
		return nil, fmt.Errorf("SHParseDisplayName 失败：0x%08x", uint32(hr))
	}

	iidFolder, _ := ole.CLSIDFromString("{000214E6-0000-0000-C000-000000000046}")
	var parentFolder uintptr
	var childPidl uintptr
	hr, _, _ = shellBindToParent.Call(absPidl, uintptr(unsafe.Pointer(iidFolder)), uintptr(unsafe.Pointer(&parentFolder)), uintptr(unsafe.Pointer(&childPidl)))
	if parentFolder != 0 {
		defer callComVtable(parentFolder, 2)
	}
	if hr != 0 || childPidl == 0 {
		return nil, fmt.Errorf("SHBindToParent 失败：0x%08x", uint32(hr))
	}

	// BindToObject 绑定目标目录自身的 IShellFolder —— vtable 索引 5。
	// 注意：不能直接 EnumObjects(parentFolder)（那是父目录的内容）；
	// 且 OneDrive 等云盘路径被 shell 扩展接管为虚拟命名空间，
	// 必须经 BindToObject 落到目标节点（云端视图，只读元数据不触发下载）。
	var folder uintptr
	hr = callComVtable(parentFolder, 5, childPidl, 0, uintptr(unsafe.Pointer(iidFolder)), uintptr(unsafe.Pointer(&folder)))
	if folder != 0 {
		defer callComVtable(folder, 2)
	}
	if hr != 0 {
		return nil, fmt.Errorf("BindToObject 失败：0x%08x", uint32(hr))
	}

	// IShellFolder::EnumObjects(hwnd, grfFlags, ppenumIDList) —— vtable 索引 4
	var enum uintptr
	hr = callComVtable(folder, 4, 0, shcontFolders|shcontNonFolders|shcontIncludeHidden, uintptr(unsafe.Pointer(&enum)))
	if enum != 0 {
		defer callComVtable(enum, 2)
	}
	if hr != 0 {
		return nil, fmt.Errorf("EnumObjects 失败：0x%08x", uint32(hr))
	}

	entries := []FileEntry{}
	for {
		// IEnumIDList::Next(celt, rgelt, pceltFetched) —— vtable 索引 3
		var pidl uintptr
		var fetched uint32
		hr = callComVtable(enum, 3, 1, uintptr(unsafe.Pointer(&pidl)), uintptr(unsafe.Pointer(&fetched)))
		if hr != 0 || fetched == 0 || pidl == 0 {
			if pidl != 0 {
				procCoTaskMemFree.Call(pidl)
			}
			break
		}
		// IShellFolder::GetAttributesOf —— vtable 索引 9：云端未下载条目本地无实体，
		// 目录标志只能从 shell 属性获取
		var sfgao uint32 = sfgaoFolder | sfgaoStream | sfgaoFilesystem
		hrAttr := callComVtable(folder, 9, 1, uintptr(unsafe.Pointer(&pidl)), uintptr(unsafe.Pointer(&sfgao)))
		shellIsDir := hrAttr == 0 && sfgao&sfgaoFolder != 0

		full, ok := shellPidlToPath(folder, absPidl, pidl)
		procCoTaskMemFree.Call(pidl)
		if !ok {
			continue
		}
		e := FileEntry{
			Name:        filepath.Base(full),
			Path:        full,
			IsDir:       shellIsDir,
			Size:        -1,
			ModTime:     "未知",
			ModTimeUnix: 0,
		}
		// 元数据用 Lstat 获取（占位符属性本地可用，不触发云盘下载）；
		// 云端未下载条目本地无实体，Lstat 失败时保留 shell 属性判断
		if fi, err := os.Lstat(full); err == nil {
			e.IsDir = fi.IsDir()
			e.ModTime = fi.ModTime().Format("2006-01-02 15:04")
			e.ModTimeUnix = fi.ModTime().Unix()
			if !fi.IsDir() {
				e.Size = fi.Size()
			}
		}
		if e.IsDir {
			e.IconType = "folder"
		} else {
			e.IconType = iconType(full)
		}
		e.Icon = getSystemIcon(full, e.IsDir)
		entries = append(entries, e)
	}
	return entries, nil
}

// shellStrret STRRET 结构（x64 布局必须与 C 一致：uType 4 + pad 4 + union 264 = 272 字节，
// 否则 shell 写入 cStr[260] 会写穿 Go 栈缓冲）
// union：STRRET_WSTR=0 → 前 8 字节为动态宽字符串指针；STRRET_OFFSET=1 → pidl 内 ANSI 偏移
// （仅 SHGDN_INFOLDER 使用，FORPARSING 不返回，不支持）；STRRET_CSTR=2 → 内嵌 ANSI 数组
type shellStrret struct {
	uType uint32
	_     uint32
	union [264]byte
}

// shellStrretToString 解析 STRRET 为字符串（STRRET_WSTR 调用方负责 CoTaskMemFree，此处代释）
func shellStrretToString(s *shellStrret) string {
	switch s.uType {
	case 0:
		pOleStr := *(*uintptr)(unsafe.Pointer(&s.union[0]))
		str := utf16PtrToString(pOleStr)
		procCoTaskMemFree.Call(pOleStr)
		return str
	case 1:
		return "" // STRRET_OFFSET：仅 SHGDN_INFOLDER 产生，本路径（FORPARSING）不会出现
	case 2:
		// STRRET_CSTR：结构内嵌 ANSI 数组，上限 260（MAX_PATH）防越界
		base := unsafe.Pointer(&s.union[0])
		var buf []byte
		for i := uint32(0); i < 260; i++ {
			c := *(*byte)(unsafe.Add(base, uintptr(i)))
			if c == 0 {
				break
			}
			buf = append(buf, c)
		}
		return string(buf)
	}
	return ""
}

// shellPidlToPath 组合父绝对 PIDL 与子相对 PIDL，转文件系统路径。
// 先用 SHGetPathFromIDListW（MAX_PATH 限制）；超长路径回退
// GetDisplayNameOf(SHGDN_FORPARSING)（动态分配，不受长度限制）。
func shellPidlToPath(folder, parent, child uintptr) (string, bool) {
	abs, _, _ := shellILCombine.Call(parent, child)
	if abs != 0 {
		defer procCoTaskMemFree.Call(abs)
		var buf [windows.MAX_PATH]uint16
		if r, _, _ := shellGetPathFromIDList.Call(abs, uintptr(unsafe.Pointer(&buf[0]))); r != 0 {
			return syscall.UTF16ToString(buf[:]), true
		}
	}
	// 超长路径回退：IShellFolder::GetDisplayNameOf —— vtable 索引 11
	var sr shellStrret
	hr := callComVtable(folder, 11, child, shgdnForParsing, uintptr(unsafe.Pointer(&sr)))
	if hr != 0 {
		return "", false
	}
	s := shellStrretToString(&sr)
	return s, s != ""
}