Skip to content

fix(security): use atomic temp-dir swap for cache updates [DEVA11Y-482] #21

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
sunny-se wants to merge 1 commit into
base: main
Choose a base branch
from
+24 −17
Open

fix(security): use atomic temp-dir swap for cache updates [DEVA11Y-482] #21

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
41 changes: 24 additions & 17 deletions Plugins/BrowserStackAccessibilityLint/BrowserStackAccessibilityLint.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -199,33 +199,40 @@ private struct BrowserStackCLIDownloader {
return BrowserStackCLIArtifact(version: info.version, executableURL: expectedExecutableURL)
}

if fileManager.fileExists(atPath: versionDirectory.path) {
try fileManager.removeItem(at: versionDirectory)
}
try fileManager.createDirectory(at: versionDirectory, withIntermediateDirectories: true)

Diagnostics.remark("BrowserStackAccessibilityLint: Downloading CLI \(info.version)...")

// Download into a temporary directory to avoid TOCTOU races
let tempDirectory = cacheRoot.appendingPathComponent(".download-\(UUID().uuidString)", isDirectory: true)
try fileManager.createDirectory(at: tempDirectory, withIntermediateDirectories: true)
defer { try? fileManager.removeItem(at: tempDirectory) }

#if os(Windows)
let archiveURL = versionDirectory.appendingPathComponent("browserstack-cli.zip")
let archiveURL = tempDirectory.appendingPathComponent("browserstack-cli.zip")
try await download(from: info.resolvedURL, to: archiveURL)
Diagnostics.remark("BrowserStackAccessibilityLint: Extracting CLI \(info.version)...")
try unzip(archive: archiveURL, into: versionDirectory)
try unzip(archive: archiveURL, into: tempDirectory)
try? fileManager.removeItem(at: archiveURL)
#else
try extractWithBsdtar(from: info.resolvedURL, into: versionDirectory)
try extractWithBsdtar(from: info.resolvedURL, into: tempDirectory)
#endif

let locatedBinary = try locateExecutable(in: versionDirectory, preferredName: executableName)
let finalBinaryURL: URL
if locatedBinary.lastPathComponent == executableName {
finalBinaryURL = locatedBinary
} else {
finalBinaryURL = expectedExecutableURL
if fileManager.fileExists(atPath: finalBinaryURL.path) {
try fileManager.removeItem(at: finalBinaryURL)
let locatedBinary = try locateExecutable(in: tempDirectory, preferredName: executableName)

// Atomically swap: remove old version dir, move temp into place
if fileManager.fileExists(atPath: versionDirectory.path) {
try fileManager.removeItem(at: versionDirectory)
}
try fileManager.moveItem(at: tempDirectory, to: versionDirectory)

let finalBinaryURL = versionDirectory.appendingPathComponent(locatedBinary.lastPathComponent, isDirectory: false)
if locatedBinary.lastPathComponent != executableName {
let expectedURL = versionDirectory.appendingPathComponent(executableName, isDirectory: false)
if fileManager.fileExists(atPath: expectedURL.path) {
try fileManager.removeItem(at: expectedURL)
}
try fileManager.moveItem(at: locatedBinary, to: finalBinaryURL)
try fileManager.moveItem(at: finalBinaryURL, to: expectedURL)
try ensureExecutablePermissions(at: expectedURL)
return BrowserStackCLIArtifact(version: info.version, executableURL: expectedURL)
}

try ensureExecutablePermissions(at: finalBinaryURL)
Expand Down
Loading