test(fs): compare Windows DACL access policy

ReplaceFileW preserves ACLs by merging security information, which may reserialize auto-inheritance state and duplicate equivalent ACEs. Compare the final ordered, de-duplicated ACE policy instead of requiring byte-identical self-relative descriptor buffers.

Update the host-independent binding assertion to expect the namespaced absolute paths that the Win32 boundary actually receives, and align the package and bilingual RFC contracts with the semantic DACL guarantee.
This commit is contained in:
Tianyi Cui
2026-07-19 13:25:15 +08:00
parent 0f8d0082e4
commit a6b8ce456a
5 changed files with 30 additions and 7 deletions
@@ -10,9 +10,9 @@ On Windows, creating the staging directory and temp file under the target's pare
## Decision
`dsh-fs-local` reads an existing target's DACL with `GetFileSecurityW`, applies it to the empty temp file with inheritance protected before writing content, and publishes the closed temp with `ReplaceFileW`. The protected staging descriptor prevents the temp directory's inherited entries from broadening access; `ReplaceFileW` preserves the original target security descriptor and other replacement metadata. New files have no prior descriptor to preserve and continue to inherit the destination directory's DACL.
`dsh-fs-local` reads an existing target's DACL with `GetFileSecurityW`, applies it to the empty temp file with inheritance protected before writing content, and publishes the closed temp with `ReplaceFileW`. The protected staging descriptor prevents the temp directory's inherited entries from broadening access; `ReplaceFileW` preserves the original target access policy and other replacement metadata. Its ACL merge may reserialize auto-inheritance state or duplicate equivalent ACEs, so self-relative descriptor buffers are not a stable equality contract. New files have no prior descriptor to preserve and continue to inherit the destination directory's DACL.
Native Windows coverage protects a target DACL, inspects the written staging file, and compares the final replacement descriptor. Host-independent binding tests cover Win32 error translation and every native call boundary.
Native Windows coverage protects a target DACL, inspects the written staging file, and compares the final replacement's ordered, de-duplicated ACE policy. Host-independent binding tests cover Win32 error translation and every native call boundary.
## Alternatives considered
@@ -10,9 +10,9 @@ Status: implemented
## 决策
`dsh-fs-local` 通过 `GetFileSecurityW` 读取现有目标文件的 DACL,在写入内容前将其以禁止继承的形式应用到空临时文件,并通过 `ReplaceFileW` 发布已关闭的临时文件。受保护的暂存安全描述符可防止暂存目录中的继承条目扩大访问权限;`ReplaceFileW` 会保留原目标文件的安全描述符及其他替换元数据。新建文件没有既有描述符需要保留,因此仍继承目标目录的 DACL。
`dsh-fs-local` 通过 `GetFileSecurityW` 读取现有目标文件的 DACL,在写入内容前将其以禁止继承的形式应用到空临时文件,并通过 `ReplaceFileW` 发布已关闭的临时文件。受保护的暂存安全描述符可防止暂存目录中的继承条目扩大访问权限;`ReplaceFileW` 会保留原目标文件的访问策略及其他替换元数据。其 ACL 合并过程可能重新序列化自动继承状态或复制等价 ACE,因此不能把自相对安全描述符缓冲区的逐字节相等作为稳定契约。新建文件没有既有描述符需要保留,因此仍继承目标目录的 DACL。
Windows 原生覆盖率测试会保护目标文件的 DACL、检查写入完成的暂存文件,并对比最终替换文件的描述符。与宿主平台无关的绑定测试覆盖 Win32 错误转换以及每个原生调用边界。
Windows 原生覆盖率测试会保护目标文件的 DACL、检查写入完成的暂存文件,并对比最终替换文件中保持顺序且去重后的 ACE 策略。与宿主平台无关的绑定测试覆盖 Win32 错误转换以及每个原生调用边界。
## 备选方案
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@@ -16,7 +16,7 @@ await ctx.plugin(LocalFileSystem, { cwd: process.cwd() })
- **`stat` / `lstat`** — return target metadata or `undefined` when absent. `stat` reports `FsInfo` for an already resolved target (`version` = an opaque token derived from bigint `dev:ino:size:mtimeNs:ctimeNs`, `type` of `file`/`directory`/`other`, byte `size`); path-shaped `lstat` reports `FsPathInfo` without following the final symlink and can therefore return `symlink`. Both check cancellation before and after their asynchronous metadata probe, so an abort that lands in flight reports `FS_ABORTED` rather than stale absence.
- **`readText` / `streamText`** — UTF-8 only. `readText` reads the whole file; `streamText` streams it in chunks (cross-chunk decoding) so a huge file never has to be held whole in memory. Both reject invalid UTF-8 and NUL-byte binary samples (`FS_NOT_TEXT`) and non-regular targets. The `read` tool (`@deepseek-ai/dsh-tool-fs`) decides which to call by size and owns the line windowing.
- **`listDir`** — lists one directory level in stable `name.localeCompare()` order. Each entry carries the child basename, type, resolved child target (`displayPath` under the listed directory, `targetKey` as the realpath identity), and cheap stat metadata (`version`, plus `size` for regular files). It never opens or decodes file contents. Missing targets report `FS_NOT_FOUND`, file/special-file targets report `FS_NOT_DIRECTORY`, aborted calls report `FS_ABORTED`, permission failures report `FS_PERMISSION_DENIED`, and other listing or child metadata I/O failures report `FS_IO_ERROR`. Broken/disappeared children are returned as `other` without metadata, but permission/IO failures while resolving a child fail the whole listing with a structured `FsError`.
- **`writeText`** — atomic: writes to a temp file opened exclusively (`wx`, `0o600`) inside a randomly-named private staging dir (`0o700`) next to the target, fsyncs, then renames over the target. An existing file's mode is preserved, while new files default to `0o600`; on Windows a new file inherits the destination directory's DACL, while replacement copies the target DACL onto the empty temp before writing and publishes through `ReplaceFileW` so the original descriptor survives ([Windows DACL preservation RFC](../../../docs/rfc/implemented/bug-fix/2026-07-19-windows-atomic-write-dacl-preservation.md)). The `expected` guard is OPTIONAL: omitting it unconditionally creates-or-overwrites; `createIfAbsent` creates a missing target and rejects an existing one (`FS_NOT_OBSERVED`); `replaceIfVersion` replaces only at the observed version (a missing target or mismatch is `FS_STALE_VERSION`).
- **`writeText`** — atomic: writes to a temp file opened exclusively (`wx`, `0o600`) inside a randomly-named private staging dir (`0o700`) next to the target, fsyncs, then renames over the target. An existing file's mode is preserved, while new files default to `0o600`; on Windows a new file inherits the destination directory's DACL, while replacement copies the target DACL onto the empty temp before writing and publishes through `ReplaceFileW` so the original access policy survives ([Windows DACL preservation RFC](../../../docs/rfc/implemented/bug-fix/2026-07-19-windows-atomic-write-dacl-preservation.md)). The `expected` guard is OPTIONAL: omitting it unconditionally creates-or-overwrites; `createIfAbsent` creates a missing target and rejects an existing one (`FS_NOT_OBSERVED`); `replaceIfVersion` replaces only at the observed version (a missing target or mismatch is `FS_STALE_VERSION`).
- **`editText`** — atomic literal read-modify-write over the same primitive, serialized per target by a mutation lock. The `expected` guard is OPTIONAL: when supplied it verifies the version BEFORE literal matching (a stale edit reports `FS_STALE_VERSION`, never `FS_EDIT_NOT_FOUND`/`FS_AMBIGUOUS_EDIT` against newer content); omitting it edits the current content unconditionally. A missing target reports `FS_STALE_VERSION` either way. LF-normalizes for matching, restores the file's dominant CRLF/LF style, and rejects empty `oldString` / zero matches (`FS_EDIT_NOT_FOUND`) or ambiguous multi-matches without `replace_all` (`FS_AMBIGUOUS_EDIT`).
The package-root SDK surface is the default/named `LocalFileSystem` class plus `Config`. Raw I/O lives in `src/fsio.ts` (Cordis-free, independently unit-tested); `src/index.ts` is the thin service wiring.
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@@ -372,6 +372,28 @@ describe('streamWholeText', () => {
// bits, so mode assertions are POSIX-only; native DACL preservation is asserted separately.
const posixModes = process.platform !== 'win32'
function daclAcePolicy(descriptor: Buffer): string[] {
const daclOffset = descriptor.readUInt32LE(16)
if (daclOffset === 0) return []
const aceCount = descriptor.readUInt16LE(daclOffset + 4)
const policy: string[] = []
const seen = new Set<string>()
let offset = daclOffset + 8
for (let index = 0; index < aceCount; index++) {
const size = descriptor.readUInt16LE(offset + 2)
const ace = Buffer.from(descriptor.subarray(offset, offset + size))
// INHERITED_ACE records provenance, not the entry's access policy.
ace.writeUInt8(ace.readUInt8(1) & ~0x10, 1)
const key = ace.toString('hex')
if (!seen.has(key)) {
seen.add(key)
policy.push(key)
}
offset += size
}
return policy
}
describe('writeFileAtomic — temp-file safety', () => {
it('writes through a private staging dir and owner-only temp file', async () => {
const file = join(dir, 'a.txt')
@@ -409,7 +431,7 @@ describe('writeFileAtomic — temp-file safety', () => {
})
expect(await readFile(file, 'utf8')).toBe('new')
expect(await readFileDaclWin32(file)).toEqual(expectedDacl)
expect(daclAcePolicy(await readFileDaclWin32(file))).toEqual(daclAcePolicy(expectedDacl))
})
it('copies a Windows target DACL before content and publishes through secure replacement', async () => {
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@@ -1,5 +1,6 @@
/** Host-independent binding tests for the Win32 DACL and replacement helpers. */
import { toNamespacedPath } from 'node:path'
import { afterEach, describe, expect, it, vi } from 'vitest'
type GetFileSecurityW = (
@@ -92,7 +93,7 @@ describe('Windows file-security helpers', () => {
await copyFileDaclWin32('source', 'temp')
expect(native.installed).toEqual([descriptor])
await replaceFileWin32('target', 'temp')
expect(native.replacements).toEqual([['target', 'temp']])
expect(native.replacements).toEqual([[toNamespacedPath('target'), toNamespacedPath('temp')]])
})
it('maps descriptor-size probe failures to Node-style codes', async () => {