76 lines
3.1 KiB
TypeScript
76 lines
3.1 KiB
TypeScript
/** Filesystem path guards shared by sidebar APIs that access a session workspace. */
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import { realpath } from 'node:fs/promises'
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import { basename, dirname, join } from 'node:path'
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import { isWithin, requireAbsolute } from './fs-tree.ts'
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import { SidebarError } from './wire.ts'
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/** Resolve a path and convert filesystem resolution failures to an API error. */
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async function resolveRealPath(path: string, label: string): Promise<string> {
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try {
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return await realpath(path)
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} catch (error) {
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throw new SidebarError('fs-error', `cannot resolve ${label} "${path}": ${error instanceof Error ? error.message : String(error)}`, 400)
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}
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}
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/** Reject a resolved path whose real filesystem target escapes the workspace. */
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function assertWithinWorkspace(workspace: string, target: string): void {
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if (!isWithin(workspace, target)) {
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throw new SidebarError('forbidden', `path "${target}" is outside workspace`, 403)
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}
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}
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/**
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* Resolve an existing workspace path through symlinks and enforce containment.
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*
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* @param cwd - Session workspace directory.
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* @param target - Client-supplied absolute path.
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* @returns The canonical absolute path used for the filesystem operation.
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*/
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export async function ensureWorkspacePath(cwd: string, target: string): Promise<string> {
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const absolute = requireAbsolute(target)
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const [realCwd, realTarget] = await Promise.all([
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resolveRealPath(cwd, 'workspace'),
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resolveRealPath(absolute, 'target'),
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])
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assertWithinWorkspace(realCwd, realTarget)
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return realTarget
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}
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/**
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* Validate a write destination, including destinations that do not exist yet.
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* Existing targets are resolved to catch symlinks; missing targets are checked
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* against the nearest existing ancestor before the caller creates or renames.
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* The returned path is rebuilt from that canonical ancestor, so an existing
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* symlink is never left in the path passed to the write operation.
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*
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* @param cwd - Session workspace directory.
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* @param target - Client-supplied absolute destination path.
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* @returns A canonical path for an existing target or its nearest existing ancestor.
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*/
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export async function ensureWorkspaceWritePath(cwd: string, target: string): Promise<string> {
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const absolute = requireAbsolute(target)
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const realCwd = await resolveRealPath(cwd, 'workspace')
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let existingPath = absolute
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const missingSegments: string[] = []
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for (;;) {
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try {
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const realTarget = await realpath(existingPath)
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assertWithinWorkspace(realCwd, realTarget)
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return missingSegments.reduce((path, segment) => join(path, segment), realTarget)
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} catch (error) {
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if ((error as NodeJS.ErrnoException).code !== 'ENOENT') {
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if (error instanceof SidebarError) throw error
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throw new SidebarError('fs-error', `cannot resolve target "${existingPath}": ${error instanceof Error ? error.message : String(error)}`, 400)
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}
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const parent = dirname(existingPath)
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if (parent === existingPath) {
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throw new SidebarError('fs-error', `cannot resolve target "${absolute}"`, 400)
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}
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missingSegments.unshift(basename(existingPath))
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existingPath = parent
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}
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}
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}
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