Skip to content

Implement Missing Command Line Quoting on Windows #2032

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

Merged
merged 1 commit into from
Mar 26, 2019
Merged

Implement Missing Command Line Quoting on Windows #2032

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
65 changes: 62 additions & 3 deletions Foundation/Process.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -102,6 +102,67 @@ private func processIsEqual(_ a : UnsafeRawPointer?, _ b : UnsafeRawPointer?) ->
return true
}

#if os(Windows)

private func quoteWindowsCommandLine(_ commandLine: [String]) -> String {
func quoteWindowsCommandArg(arg: String) -> String {
// Windows escaping, adapted from Daniel Colascione's "Everyone quotes
// command line arguments the wrong way" - Microsoft Developer Blog
if !arg.contains(where: {" \t\n\"".contains($0)}) {
return arg
}

// To escape the command line, we surround the argument with quotes. However
// the complication comes due to how the Windows command line parser treats
// backslashes (\) and quotes (")
//
// - \ is normally treated as a literal backslash
// - e.g. foo\bar\baz => foo\bar\baz
// - However, the sequence \" is treated as a literal "
// - e.g. foo\"bar => foo"bar
//
// But then what if we are given a path that ends with a \? Surrounding
// foo\bar\ with " would be "foo\bar\" which would be an unterminated string

// since it ends on a literal quote. To allow this case the parser treats:
//
// - \\" as \ followed by the " metachar
// - \\\" as \ followed by a literal "
// - In general:
// - 2n \ followed by " => n \ followed by the " metachar
// - 2n+1 \ followed by " => n \ followed by a literal "
var quoted = "\""
var unquoted = arg.unicodeScalars

while !unquoted.isEmpty {
guard let firstNonBackslash = unquoted.firstIndex(where: { $0 != "\\" }) else {
// String ends with a backslash e.g. foo\bar\, escape all the backslashes
// then add the metachar " below
let backslashCount = unquoted.count
quoted.append(String(repeating: "\\", count: backslashCount * 2))
break
}
let backslashCount = unquoted.distance(from: unquoted.startIndex, to: firstNonBackslash)
if (unquoted[firstNonBackslash] == "\"") {
// This is a string of \ followed by a " e.g. foo\"bar. Escape the
// backslashes and the quote
quoted.append(String(repeating: "\\", count: backslashCount * 2 + 1))
quoted.append(String(unquoted[firstNonBackslash]))
} else {
// These are just literal backslashes
quoted.append(String(repeating: "\\", count: backslashCount))
quoted.append(String(unquoted[firstNonBackslash]))
}
// Drop the backslashes and the following character
unquoted.removeFirst(backslashCount + 1)
}
quoted.append("\"")
return quoted
}
return commandLine.map(quoteWindowsCommandArg).joined(separator: " ")
}
#endif

open class Process: NSObject {
private static func setup() {
struct Once {
Expand Down Expand Up @@ -318,8 +379,6 @@ open class Process: NSObject {
}

#if os(Windows)
// TODO(compnerd) quote the commandline correctly
// https://blogs.msdn.microsoft.com/twistylittlepassagesallalike/2011/04/23/everyone-quotes-command-line-arguments-the-wrong-way/
var command: [String] = [launchPath]
if let arguments = self.arguments {
command.append(contentsOf: arguments)
Expand Down Expand Up @@ -412,7 +471,7 @@ open class Process: NSObject {
CFSocketCreateRunLoopSource(kCFAllocatorDefault, socket, 0)
CFRunLoopAddSource(managerThreadRunLoop?._cfRunLoop, source, kCFRunLoopDefaultMode)

try command.joined(separator: " ").withCString(encodedAs: UTF16.self) { wszCommandLine in
try quoteWindowsCommandLine(command).withCString(encodedAs: UTF16.self) { wszCommandLine in
try currentDirectoryURL.path.withCString(encodedAs: UTF16.self) { wszCurrentDirectory in
try szEnvironment.withCString(encodedAs: UTF16.self) { wszEnvironment in
if CreateProcessW(nil, UnsafeMutablePointer<WCHAR>(mutating: wszCommandLine),
Expand Down