@@ -26,7 +26,18 @@ typealias ProcessID = HANDLE
2626typealias ProcessID = Never
2727#endif
2828
29- #if os(Linux) && !SWT_NO_DYNAMIC_LINKING
29+ /// A platform-specific wrapper type for various types used by `posix_spawn()`.
30+ ///
31+ /// Darwin and Linux differ in their optionality for the `posix_spawn()` types
32+ /// we use, so we use this typealias to paper over the differences.
33+ #if SWT_TARGET_OS_APPLE || os(FreeBSD) || os(OpenBSD)
34+ fileprivate typealias P < T> = T ?
35+ #elseif os(Linux)
36+ fileprivate typealias P < T> = T
37+ #endif
38+
39+ #if !SWT_NO_DYNAMIC_LINKING
40+ #if os(Linux)
3041/// Close file descriptors above a given value when spawing a new process.
3142///
3243/// This symbol is provided because the underlying function was added to glibc
@@ -38,13 +49,30 @@ private let _posix_spawn_file_actions_addclosefrom_np = symbol(named: "posix_spa
3849}
3950#endif
4051
41- /// Spawn a process and wait for it to terminate.
52+ #if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD)
53+ /// Change the current directory in the new process.
54+ ///
55+ /// This symbol is provided because `posix_spawn_file_actions_addchdir()` and
56+ /// its non-portable equivalent `posix_spawn_file_actions_addchdir_np()` are not
57+ /// consistently available across all platforms that implement the
58+ /// `posix_spawn()` API.
59+ private let _posix_spawn_file_actions_addchdir = symbol ( named: " posix_spawn_file_actions_addchdir " ) . map {
60+ castCFunction ( at: $0, to: ( @convention( c) ( UnsafeMutablePointer < P < posix_spawn_file_actions_t > > , UnsafePointer < CChar > ) - > CInt) . self)
61+ } ?? symbol ( named: " posix_spawn_file_actions_addchdir_np " ) . map {
62+ castCFunction ( at: $0, to: ( @convention( c) ( UnsafeMutablePointer < P < posix_spawn_file_actions_t > > , UnsafePointer < CChar > ) - > CInt) . self)
63+ }
64+ #endif
65+ #endif
66+
67+ /// Spawn a child process.
4268///
4369/// - Parameters:
4470/// - executablePath: The path to the executable to spawn.
4571/// - arguments: The arguments to pass to the executable, not including the
4672/// executable path.
4773/// - environment: The environment block to pass to the executable.
74+ /// - currentDirectoryPath: The path to use as the executable's initial
75+ /// working directory.
4876/// - standardInput: If not `nil`, a file handle the child process should
4977/// inherit as its standard input stream. This file handle must be backed
5078/// by a file descriptor and be open for reading.
@@ -61,39 +89,33 @@ private let _posix_spawn_file_actions_addclosefrom_np = symbol(named: "posix_spa
6189/// eventually pass this value to ``wait(for:)`` to avoid leaking system
6290/// resources.
6391///
64- /// - Throws: Any error that prevented the process from spawning or its exit
65- /// condition from being read.
92+ /// - Throws: Any error that prevented the process from spawning.
6693func spawnExecutable(
6794 atPath executablePath: String ,
6895 arguments: [ String ] ,
6996 environment: [ String : String ] ,
97+ currentDirectoryPath: String ? = nil ,
7098 standardInput: borrowing FileHandle ? = nil ,
7199 standardOutput: borrowing FileHandle ? = nil ,
72100 standardError: borrowing FileHandle ? = nil ,
73101 additionalFileHandles: [ UnsafePointer < FileHandle > ] = [ ]
74102) throws -> ProcessID {
75- // Darwin and Linux differ in their optionality for the posix_spawn types we
76- // use, so use this typealias to paper over the differences.
77- #if SWT_TARGET_OS_APPLE || os(FreeBSD) || os(OpenBSD)
78- typealias P < T> = T ?
79- #elseif os(Linux)
80- typealias P < T> = T
81- #endif
82-
83103#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD)
84104 return try withUnsafeTemporaryAllocation ( of: P< posix_spawn_file_actions_t> . self , capacity: 1 ) { fileActions in
85105 let fileActions = fileActions. baseAddress!
86- guard 0 == posix_spawn_file_actions_init ( fileActions) else {
87- throw CError ( rawValue: swt_errno ( ) )
106+ let fileActionsInitialized = posix_spawn_file_actions_init ( fileActions)
107+ guard 0 == fileActionsInitialized else {
108+ throw CError ( rawValue: fileActionsInitialized)
88109 }
89110 defer {
90111 _ = posix_spawn_file_actions_destroy ( fileActions)
91112 }
92113
93114 return try withUnsafeTemporaryAllocation ( of: P< posix_spawnattr_t> . self , capacity: 1 ) { attrs in
94115 let attrs = attrs. baseAddress!
95- guard 0 == posix_spawnattr_init ( attrs) else {
96- throw CError ( rawValue: swt_errno ( ) )
116+ let attrsInitialized = posix_spawnattr_init ( attrs)
117+ guard 0 == attrsInitialized else {
118+ throw CError ( rawValue: attrsInitialized)
97119 }
98120 defer {
99121 _ = posix_spawnattr_destroy ( attrs)
@@ -116,6 +138,32 @@ func spawnExecutable(
116138 flags |= CShort ( POSIX_SPAWN_SETSIGDEF)
117139 }
118140
141+ // Set the current working directory (do this as early as possible, so
142+ // before inheriting or opening any file descriptors.)
143+ if let currentDirectoryPath {
144+ var chdirNeeded = true
145+
146+ #if !SWT_NO_DYNAMIC_LINKING
147+ if let _posix_spawn_file_actions_addchdir {
148+ chdirNeeded = false
149+ let directoryChanged = _posix_spawn_file_actions_addchdir ( fileActions, currentDirectoryPath)
150+ guard 0 == directoryChanged else {
151+ throw CError ( rawValue: directoryChanged)
152+ }
153+ }
154+ #endif
155+
156+ if chdirNeeded {
157+ // This platform does not support setting the current directory via
158+ // posix_spawn(), so set it here in the parent process and hope
159+ // another thread does not stomp on the change (as Foundation does.)
160+ // Platforms known to take this path: Amazon Linux 2, OpenBSD, QNX
161+ guard 0 == chdir ( currentDirectoryPath) else {
162+ throw CError ( rawValue: swt_errno ( ) )
163+ }
164+ }
165+ }
166+
119167 // Forward standard I/O streams and any explicitly added file handles.
120168 var highestFD = max ( STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO)
121169 func inherit( _ fileHandle: borrowing FileHandle , as standardFD: CInt ? = nil ) throws {
@@ -262,6 +310,7 @@ func spawnExecutable(
262310
263311 let commandLine = _escapeCommandLine ( CollectionOfOne ( executablePath) + arguments)
264312 let environ = environment. map { " \( $0. key) = \( $0. value) " } . joined ( separator: " \0 " ) + " \0 \0 "
313+ let currentDirectoryPath = currentDirectoryPath. map { Array ( $0. utf16) }
265314
266315 var flags = DWORD ( CREATE_NO_WINDOW | CREATE_UNICODE_ENVIRONMENT | EXTENDED_STARTUPINFO_PRESENT)
267316#if DEBUG
@@ -281,7 +330,7 @@ func spawnExecutable(
281330 true , // bInheritHandles
282331 flags,
283332 . init( mutating: environ) ,
284- nil ,
333+ currentDirectoryPath ,
285334 startupInfo. pointer ( to: \. StartupInfo) !,
286335 & processInfo
287336 ) else {
@@ -396,4 +445,32 @@ private func _escapeCommandLine(_ arguments: [String]) -> String {
396445 } . joined ( separator: " " )
397446}
398447#endif
448+
449+ /// Spawn a child process and wait for it to terminate.
450+ ///
451+ /// - Parameters:
452+ /// - executablePath: The path to the executable to spawn.
453+ /// - arguments: The arguments to pass to the executable, not including the
454+ /// executable path.
455+ /// - environment: The environment block to pass to the executable.
456+ /// - currentDirectoryPath: The path to use as the executable's initial
457+ /// working directory.
458+ ///
459+ /// - Returns: The exit status of the spawned process.
460+ ///
461+ /// - Throws: Any error that prevented the process from spawning or its exit
462+ /// condition from being read.
463+ ///
464+ /// This function is a convenience that spawns the given process and waits for
465+ /// it to terminate. It is primarily for use by other targets in this package
466+ /// such as its cross-import overlays.
467+ package func spawnExecutableAtPathAndWait(
468+ atPath executablePath: String ,
469+ arguments: [ String ] = [ ] ,
470+ environment: [ String : String ] = [ : ] ,
471+ currentDirectoryPath: String ? = nil
472+ ) async throws -> ExitStatus {
473+ let processID = try spawnExecutable ( atPath: executablePath, arguments: arguments, environment: environment, currentDirectoryPath: currentDirectoryPath)
474+ return try await wait ( for: processID)
475+ }
399476#endif
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