6.0: Fix WASI support (#825)

* Add explicit include of `wasi/libc-environ.h` (#786)

This is necessary to get the `__wasilibc_get_environ` function
declaration.

(cherry picked from commit 243066f)

* Add explicit void type parameter to C functions without parameters (#775)

C functions with `()` as parameter list can take any number of
parameters. But WebAssembly requires static signature information for
every function call, so we need to explicitly specify `(void)` to
indicate that the function takes no parameters.

(cherry picked from commit 8f34f38)

* Exclude EREMOTE definition for WASI platform (#778)

WASI does not define the EREMOTE error code.

(cherry picked from commit 6bb5ff7)

* Throw `.featureUnsupported` when attempting to create temp files on WASI (#779)

WASI does not have temp directory concept, and does not provide mktemp
family of functions, so attempting to create a temporary file should be
considered a feature unsupported.

(cherry picked from commit fb11420)

* Fix `operatingSystemVersion` on WASI (#782)

The `operatingSystemVersion` property type is a tuple but the it was
returning an `OperatingSystemVersion` instance on unknown platforms.

(cherry picked from commit a8f1225)

* Guard out extended or fs attributes related code on WASI (#784)

This commit guards out the extended attributes and file system
attributes related code on WASI as WASI does not support these
features. Just return nothing or ignore the set request.

(cherry picked from commit fab7195)

* Guard out user/group related code on WASI (#783)

* Guard out user/group related code on WASI

This change guards out the user/group related code on WASI, as WASI does
not have the concept of users or groups.

* Throw explicit unsupported error if trying to set user or group on WASI

Instead of implicitly ignoring user-given values, we should throw
exception to make it clear that those values cannot be set on WASI.

(cherry picked from commit 0b3974d)

* Skip sticky-bit check in `isDeletableFile` on WASI (#785)

WASI does not surface the sticky bit and getuid, so we cannot check
whether the file is actually deletable before attempting to delete it.

(cherry picked from commit e90b6c3)

* Implement `_copyRegularFile` for WASI without `sendfile` (#787)

WASI doesn't have `sendfile`, so we need to implement the copy in user
space with `read` and `write`. It's not as efficient as `sendfile`, but
it's the best we can do.

(cherry picked from commit 2a6afeb)

* Port `LockedState` and `_ThreadLocal` to WASI without any locking (#780)

(cherry picked from commit aa68eeb)

* Add WASI platform conditions for libc imports and word size (#776)

* Add `import WASILibc` statements to libc import chains

* Declare wasm32 arch as 32-bit environment

* Switch to _pointerBitWidth for architecture checks

This change switches the architecture checks in Data.swift to use the
_pointerBitWidth instead of the arch() checks for consistency with newer
platforms.

(cherry picked from commit c82d167)

* Enable wasi-libc emulation features (#777)

* Enable wasi-libc emulation features

Those features require explicit macro definitions to be enabled, so add
them to the package definition. Only affects WASI builds.

* Prefer `TARGET_OS_WASI` over `__wasi__`

And explain why we need definition checks for `signal.h` and `sys/mman.h`

(cherry picked from commit c86692f)

---------

Co-authored-by: Yuta Saito <[email protected]>

Author: MaxDesiatov

CMakeLists.txt

@@ -116,6 +116,14 @@ foreach(version ${_SwiftFoundation_versions})
     endforeach()
 endforeach()
 
+# wasi-libc emulation feature flags
+set(_SwiftFoundation_wasi_libc_flags)
+if(CMAKE_SYSTEM_NAME STREQUAL "WASI")
+    list(APPEND _SwiftFoundation_wasi_libc_flags
+        "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xcc -D_WASI_EMULATED_SIGNAL>"
+        "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xcc -D_WASI_EMULATED_MMAN>")
+endif()
+
 include(GNUInstallDirs)
 include(SwiftFoundationSwiftSupport)
 

Package.swift

@@ -70,6 +70,11 @@ var dependencies: [Package.Dependency] {
     }
 }
 
+let wasiLibcCSettings: [CSetting] = [
+    .define("_WASI_EMULATED_SIGNAL", .when(platforms: [.wasi])),
+    .define("_WASI_EMULATED_MMAN", .when(platforms: [.wasi])),
+]
+
 let package = Package(
     name: "FoundationPreview",
     platforms: [.macOS("13.3"), .iOS("16.4"), .tvOS("16.4"), .watchOS("9.4")],
@@ -91,15 +96,23 @@ let package = Package(
             path: "Sources/Foundation"),
 
         // _FoundationCShims (Internal)
-        .target(name: "_FoundationCShims",
-                cSettings: [.define("_CRT_SECURE_NO_WARNINGS",
-                                    .when(platforms: [.windows]))]),
+        .target(
+            name: "_FoundationCShims",
+            cSettings: [
+                .define("_CRT_SECURE_NO_WARNINGS", .when(platforms: [.windows]))
+            ] + wasiLibcCSettings
+        ),
 
         // TestSupport (Internal)
-        .target(name: "TestSupport", dependencies: [
-            "FoundationEssentials",
-            "FoundationInternationalization",
-        ], swiftSettings: availabilityMacros + concurrencyChecking),
+        .target(
+            name: "TestSupport",
+            dependencies: [
+                "FoundationEssentials",
+                "FoundationInternationalization",
+            ],
+            cSettings: wasiLibcCSettings,
+            swiftSettings: availabilityMacros + concurrencyChecking
+        ),
 
         // FoundationEssentials
         .target(
@@ -130,11 +143,14 @@ let package = Package(
           ],
           cSettings: [
             .define("_GNU_SOURCE", .when(platforms: [.linux]))
-          ],
+          ] + wasiLibcCSettings,
           swiftSettings: [
             .enableExperimentalFeature("VariadicGenerics"),
             .enableExperimentalFeature("AccessLevelOnImport")
-          ] + availabilityMacros + concurrencyChecking
+          ] + availabilityMacros + concurrencyChecking,
+          linkerSettings: [
+            .linkedLibrary("wasi-emulated-getpid", .when(platforms: [.wasi])),
+          ]
         ),
         .testTarget(
             name: "FoundationEssentialsTests",
@@ -166,6 +182,7 @@ let package = Package(
                 "CMakeLists.txt",
                 "Predicate/CMakeLists.txt"
             ],
+            cSettings: wasiLibcCSettings,
             swiftSettings: [
                 .enableExperimentalFeature("AccessLevelOnImport")
             ] + availabilityMacros + concurrencyChecking

Sources/FoundationEssentials/CMakeLists.txt

@@ -65,6 +65,7 @@ target_compile_options(FoundationEssentials PRIVATE
     "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -enable-experimental-feature -Xfrontend StrictConcurrency>"
     "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -enable-upcoming-feature -Xfrontend InferSendableFromCaptures>")
 target_compile_options(FoundationEssentials PRIVATE ${_SwiftFoundation_availability_macros})
+target_compile_options(FoundationEssentials PRIVATE ${_SwiftFoundation_wasi_libc_flags})
 target_compile_options(FoundationEssentials PRIVATE -package-name "SwiftFoundation")
 
 target_link_libraries(FoundationEssentials PUBLIC

Sources/FoundationEssentials/Calendar/Calendar.swift

@@ -20,6 +20,8 @@ import Glibc
 import Musl
 #elseif canImport(CRT)
 import CRT
+#elseif os(WASI)
+import WASILibc
 #endif
 
 #if FOUNDATION_FRAMEWORK

Sources/FoundationEssentials/Calendar/Calendar_Gregorian.swift

@@ -20,6 +20,8 @@ import Glibc
 import Musl
 #elseif canImport(CRT)
 import CRT
+#elseif os(WASI)
+import WASILibc
 #endif
 
 

Sources/FoundationEssentials/Data/Data+Reading.swift

@@ -27,6 +27,8 @@ import Musl
 #elseif os(Windows)
 import CRT
 import WinSDK
+#elseif os(WASI)
+import WASILibc
 #endif
 
 func _fgetxattr(_ fd: Int32, _ name: UnsafePointer<CChar>!, _ value: UnsafeMutableRawPointer!, _ size: Int, _ position: UInt32, _ options: Int32) -> Int {

Sources/FoundationEssentials/Data/Data+Writing.swift

@@ -29,6 +29,8 @@ import Musl
 #elseif os(Windows)
 import CRT
 import WinSDK
+#elseif os(WASI)
+import WASILibc
 #endif
 
 #if !NO_FILESYSTEM
@@ -129,6 +131,10 @@ private func cleanupTemporaryDirectory(at inPath: String?) {
 
 /// Caller is responsible for calling `close` on the `Int32` file descriptor.
 private func createTemporaryFile(at destinationPath: String, inPath: PathOrURL, prefix: String, options: Data.WritingOptions) throws -> (Int32, String) {
+#if os(WASI)
+    // WASI does not have temp directories
+    throw CocoaError(.featureUnsupported)
+#else
     var directoryPath = destinationPath
     if !directoryPath.isEmpty && directoryPath.last! != "/" {
         directoryPath.append("/")
@@ -183,6 +189,7 @@ private func createTemporaryFile(at destinationPath: String, inPath: PathOrURL,
             }
         }
     } while true
+#endif // os(WASI)
 }
 
 /// Returns `(file descriptor, temporary file path, temporary directory path)`
@@ -516,6 +523,7 @@ private func writeToFileAux(path inPath: PathOrURL, buffer: UnsafeRawBufferPoint
 
                 cleanupTemporaryDirectory(at: temporaryDirectoryPath)
 
+#if !os(WASI) // WASI does not support fchmod for now
                 if let mode {
                     // Try to change the mode if the path has not changed. Do our best, but don't report an error.
 #if FOUNDATION_FRAMEWORK
@@ -539,6 +547,7 @@ private func writeToFileAux(path inPath: PathOrURL, buffer: UnsafeRawBufferPoint
                     fchmod(fd, mode)
 #endif
                 }
+#endif // os(WASI)
             }
         }
     }

Sources/FoundationEssentials/Data/Data.swift

@@ -76,6 +76,8 @@ import Glibc
 import Musl
 #elseif canImport(ucrt)
 import ucrt
+#elseif canImport(WASILibc)
+import WASILibc
 #endif
 
 #if os(Windows)
@@ -580,11 +582,11 @@ public struct Data : Equatable, Hashable, RandomAccessCollection, MutableCollect
     @usableFromInline
     @frozen
     internal struct InlineData : Sendable {
-#if arch(x86_64) || arch(arm64) || arch(s390x) || arch(powerpc64) || arch(powerpc64le)
+#if _pointerBitWidth(_64)
         @usableFromInline typealias Buffer = (UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8,
                                               UInt8, UInt8, UInt8, UInt8, UInt8, UInt8) //len  //enum
         @usableFromInline var bytes: Buffer
-#elseif arch(i386) || arch(arm) || arch(arm64_32)
+#elseif _pointerBitWidth(_32)
         @usableFromInline typealias Buffer = (UInt8, UInt8, UInt8, UInt8,
                                               UInt8, UInt8) //len  //enum
         @usableFromInline var bytes: Buffer
@@ -615,9 +617,9 @@ public struct Data : Equatable, Hashable, RandomAccessCollection, MutableCollect
         @inlinable // This is @inlinable as a trivial initializer.
         init(count: Int = 0) {
             assert(count <= MemoryLayout<Buffer>.size)
-#if arch(x86_64) || arch(arm64) || arch(s390x) || arch(powerpc64) || arch(powerpc64le)
+#if _pointerBitWidth(_64)
             bytes = (UInt8(0), UInt8(0), UInt8(0), UInt8(0), UInt8(0), UInt8(0), UInt8(0), UInt8(0), UInt8(0), UInt8(0), UInt8(0), UInt8(0), UInt8(0), UInt8(0))
-#elseif arch(i386) || arch(arm) || arch(arm64_32)
+#elseif _pointerBitWidth(_32)
             bytes = (UInt8(0), UInt8(0), UInt8(0), UInt8(0), UInt8(0), UInt8(0))
 #else
     #error ("Unsupported architecture: initialization for Buffer is required for this architecture")
@@ -802,9 +804,9 @@ public struct Data : Equatable, Hashable, RandomAccessCollection, MutableCollect
         }
     }
 
-#if arch(x86_64) || arch(arm64) || arch(s390x) || arch(powerpc64) || arch(powerpc64le)
+#if _pointerBitWidth(_64)
     @usableFromInline internal typealias HalfInt = Int32
-#elseif arch(i386) || arch(arm) || arch(arm64_32)
+#elseif _pointerBitWidth(_32)
     @usableFromInline internal typealias HalfInt = Int16
 #else
     #error ("Unsupported architecture: a definition of half of the pointer sized Int needs to be defined for this architecture")

Sources/FoundationEssentials/Date.swift

@@ -20,6 +20,8 @@ import Glibc
 import Musl
 #elseif canImport(WinSDK)
 import WinSDK
+#elseif os(WASI)
+import WASILibc
 #endif
 
 #if !FOUNDATION_FRAMEWORK

Sources/FoundationEssentials/Decimal/Decimal+Math.swift

@@ -20,6 +20,8 @@ import Glibc
 import Musl
 #elseif canImport(CRT)
 import CRT
+#elseif os(WASI)
+import WASILibc
 #endif
 
 private let powerOfTen: [Decimal.VariableLengthInteger] = [

Sources/FoundationEssentials/Error/CocoaError+FilePath.swift

@@ -24,6 +24,8 @@ import Musl
 #elseif os(Windows)
 import CRT
 import WinSDK
+#elseif os(WASI)
+import WASILibc
 #endif
 
 extension CocoaError.Code {

Sources/FoundationEssentials/Error/ErrorCodes+POSIX.swift

@@ -21,6 +21,8 @@
 #elseif os(Windows)
 import CRT
 import WinSDK
+#elseif os(WASI)
+import WASILibc
 #endif
 
 #if FOUNDATION_FRAMEWORK
@@ -467,11 +469,13 @@ extension POSIXError {
         return .ESTALE
     }
 
+    #if !os(WASI)
     /// Too many levels of remote in path.
     public static var EREMOTE: POSIXErrorCode {
         return .EREMOTE
     }
     #endif
+    #endif
 
     #if canImport(Darwin)
     /// RPC struct is bad.

Sources/FoundationEssentials/FileManager/FileManager+Basics.swift

@@ -21,6 +21,8 @@ import Musl
 #elseif os(Windows)
 import CRT
 import WinSDK
+#elseif os(WASI)
+import WASILibc
 #endif
 
 #if os(Windows)

Sources/FoundationEssentials/FileManager/FileManager+Directories.swift

@@ -28,6 +28,8 @@ import Musl
 #elseif os(Windows)
 import CRT
 import WinSDK
+#elseif os(WASI)
+import WASILibc
 #endif
 
 internal import _FoundationCShims

Sources/FoundationEssentials/FileManager/FileManager+Files.swift

@@ -29,6 +29,9 @@ internal import _FoundationCShims
 #elseif os(Windows)
 import CRT
 import WinSDK
+#elseif os(WASI)
+internal import _FoundationCShims
+import WASILibc
 #endif
 
 extension Date {
@@ -471,7 +474,7 @@ extension _FileManagerImpl {
             parent = fileManager.currentDirectoryPath
         }
 
-#if os(Windows)
+#if os(Windows) || os(WASI)
         return fileManager.isWritableFile(atPath: parent) && fileManager.isWritableFile(atPath: path)
 #else
         guard fileManager.isWritableFile(atPath: parent),
@@ -494,7 +497,7 @@ extension _FileManagerImpl {
 #endif
     }
 
-#if !os(Windows)
+#if !os(Windows) && !os(WASI)
     private func _extendedAttribute(_ key: UnsafePointer<CChar>, at path: UnsafePointer<CChar>, followSymlinks: Bool) throws -> Data? {
         #if canImport(Darwin)
         var size = getxattr(path, key, nil, 0, 0, followSymlinks ? 0 : XATTR_NOFOLLOW)
@@ -648,10 +651,11 @@ extension _FileManagerImpl {
 
             var attributes = statAtPath.fileAttributes
             try? Self._catInfo(for: URL(filePath: path, directoryHint: .isDirectory), statInfo: statAtPath, into: &attributes)
-            
+            #if !os(WASI) // WASI does not support extended attributes
             if let extendedAttrs = try? _extendedAttributes(at: fsRep, followSymlinks: false) {
                 attributes[._extendedAttributes] = extendedAttrs
             }
+            #endif
 
             #if !targetEnvironment(simulator) && FOUNDATION_FRAMEWORK
             if statAtPath.isRegular || statAtPath.isDirectory {
@@ -713,6 +717,9 @@ extension _FileManagerImpl {
                 ]
             }
         }
+#elseif os(WASI)
+        // WASI does not support file system attributes
+        return [:]
 #else
         try fileManager.withFileSystemRepresentation(for: path) { rep in
             guard let rep else {
@@ -928,19 +935,29 @@ extension _FileManagerImpl {
             let groupID = _readFileAttributePrimitive(attributes[.groupOwnerAccountID], as: UInt.self)
 
             if user != nil || userID != nil || group != nil || groupID != nil {
+                #if os(WASI)
+                // WASI does not have the concept of users or groups
+                throw CocoaError.errorWithFilePath(.featureUnsupported, path)
+                #else
                 // Bias toward userID & groupID - try to prevent round trips to getpwnam if possible.
                 var leaveUnchanged: UInt32 { UInt32(bitPattern: -1) }
                 let rawUserID = userID.flatMap(uid_t.init) ?? user.flatMap(Self._userAccountNameToNumber) ?? leaveUnchanged
                 let rawGroupID = groupID.flatMap(gid_t.init) ?? group.flatMap(Self._groupAccountNameToNumber) ?? leaveUnchanged
                 if chown(fileSystemRepresentation, rawUserID, rawGroupID) != 0 {
                     throw CocoaError.errorWithFilePath(path, errno: errno, reading: false)
                 }
+                #endif
             }
 
             try Self._setCatInfoAttributes(attributes, path: path)
 
             if let extendedAttrs = attributes[.init("NSFileExtendedAttributes")] as? [String : Data] {
+                #if os(WASI)
+                // WASI does not support extended attributes
+                throw CocoaError.errorWithFilePath(.featureUnsupported, path)
+                #else
                 try Self._setAttributes(extendedAttrs, at: fileSystemRepresentation, followSymLinks: false)
+                #endif
             }
 
             if let date = attributes[.modificationDate] as? Date {

Sources/FoundationEssentials/FileManager/FileManager+SymbolicLinks.swift

@@ -23,6 +23,8 @@ import Musl
 import CRT
 import WinSDK
 internal import _FoundationCShims
+#elseif os(WASI)
+import WASILibc
 #endif
 
 extension _FileManagerImpl {

Sources/FoundationEssentials/FileManager/FileManager+Utilities.swift

@@ -34,6 +34,8 @@ internal import _FoundationCShims
 #elseif os(Windows)
 import CRT
 import WinSDK
+#elseif os(WASI)
+import WASILibc
 #endif
 
 #if os(Windows)
@@ -176,7 +178,7 @@ extension _FileManagerImpl {
         #endif
     }
 
-#if !os(Windows)
+#if !os(Windows) && !os(WASI)
     static func _setAttribute(_ key: UnsafePointer<CChar>, value: Data, at path: UnsafePointer<CChar>, followSymLinks: Bool) throws {
         try value.withUnsafeBytes { buffer in
             #if canImport(Darwin)
@@ -274,7 +276,7 @@ extension _FileManagerImpl {
     }
     #endif
 
-#if !os(Windows)
+#if !os(Windows) && !os(WASI)
     static func _userAccountNameToNumber(_ name: String) -> uid_t? {
         name.withCString { ptr in
             getpwnam(ptr)?.pointee.pw_uid

Sources/FoundationEssentials/FileManager/FileOperations.swift

@@ -21,6 +21,8 @@ import Musl
 #elseif os(Windows)
 import CRT
 import WinSDK
+#elseif os(WASI)
+import WASILibc
 #endif
 
 #if FOUNDATION_FRAMEWORK
@@ -866,12 +868,14 @@ enum _FileOperations {
         }
         defer { close(dstfd) }
 
+        #if !os(WASI) // WASI doesn't have fchmod for now
         // Set the file permissions using fchmod() instead of when open()ing to avoid umask() issues
         let permissions = fileInfo.st_mode & ~S_IFMT
         guard fchmod(dstfd, permissions) == 0 else {
             try delegate.throwIfNecessary(errno, String(cString: srcPtr), String(cString: dstPtr))
             return
         }
+        #endif
 
         if fileInfo.st_size == 0 {
             // no copying required
@@ -882,12 +886,31 @@ enum _FileOperations {
         let chunkSize: Int = Int(fileInfo.st_blksize)
         var current: off_t = 0
 
+        #if os(WASI)
+        // WASI doesn't have sendfile, so we need to do it in user space with read/write
+        try withUnsafeTemporaryAllocation(of: UInt8.self, capacity: chunkSize) { buffer in
+            while current < total {
+                let readSize = Swift.min(total - Int(current), chunkSize)
+                let bytesRead = read(srcfd, buffer.baseAddress, readSize)
+                guard bytesRead >= 0 else {
+                    try delegate.throwIfNecessary(errno, String(cString: srcPtr), String(cString: dstPtr))
+                    return
+                }
+                guard write(dstfd, buffer.baseAddress, bytesRead) == bytesRead else {
+                    try delegate.throwIfNecessary(errno, String(cString: srcPtr), String(cString: dstPtr))
+                    return
+                }
+                current += off_t(bytesRead)
+            }
+        }
+        #else
         while current < total {
             guard sendfile(dstfd, srcfd, &current, Swift.min(total - Int(current), chunkSize)) != -1 else {
                 try delegate.throwIfNecessary(errno, String(cString: srcPtr), String(cString: dstPtr))
                 return
             }
         }
+        #endif
     }
     #endif
 

Sources/FoundationEssentials/Formatting/BinaryInteger+NumericStringRepresentation.swift

@@ -20,6 +20,8 @@ import Glibc
 import Musl
 #elseif os(Windows)
 import CRT
+#elseif os(WASI)
+import WASILibc
 #endif
 
 // MARK: - BinaryInteger + Numeric string representation

Sources/FoundationEssentials/LockedState.swift

@@ -35,6 +35,9 @@ package struct LockedState<State> {
         typealias Primitive = pthread_mutex_t
 #elseif canImport(WinSDK)
         typealias Primitive = SRWLOCK
+#elseif os(WASI)
+        // WASI is single-threaded, so we don't need a lock.
+        typealias Primitive = Void
 #endif
 
         typealias PlatformLock = UnsafeMutablePointer<Primitive>
@@ -47,6 +50,8 @@ package struct LockedState<State> {
             pthread_mutex_init(platformLock, nil)
 #elseif canImport(WinSDK)
             InitializeSRWLock(platformLock)
+#elseif os(WASI)
+            // no-op
 #endif
         }
 
@@ -64,6 +69,8 @@ package struct LockedState<State> {
             pthread_mutex_lock(platformLock)
 #elseif canImport(WinSDK)
             AcquireSRWLockExclusive(platformLock)
+#elseif os(WASI)
+            // no-op
 #endif
         }
 
@@ -74,6 +81,8 @@ package struct LockedState<State> {
             pthread_mutex_unlock(platformLock)
 #elseif canImport(WinSDK)
             ReleaseSRWLockExclusive(platformLock)
+#elseif os(WASI)
+            // no-op
 #endif
         }
     }

Sources/FoundationEssentials/Platform.swift

@@ -114,7 +114,7 @@ private let _cachedUGIDs: (uid_t, gid_t) = {
 }()
 #endif
 
-#if !os(Windows)
+#if !os(Windows) && !os(WASI)
 extension Platform {
     private static var ROOT_USER: UInt32 { 0 }
     static func getUGIDs(allowEffectiveRootUID: Bool = true) -> (uid: UInt32, gid: UInt32) {
@@ -175,7 +175,7 @@ extension Platform {
         // FIXME: bionic implements this as `return 0;` and does not expose the
         // function via headers. We should be able to shim this and use the call
         // if it is available.
-#if !os(Android)
+#if !os(Android) && !os(WASI)
         guard issetugid() == 0 else { return nil }
 #endif
         if let value = getenv(name) {

Sources/FoundationEssentials/ProcessInfo/ProcessInfo.swift

@@ -23,6 +23,8 @@ import Glibc
 import Musl
 #elseif os(Windows)
 import WinSDK
+#elseif os(WASI)
+import WASILibc
 #endif
 
 #if !NO_PROCESS
@@ -391,7 +393,7 @@ extension _ProcessInfo {
             patch: Int(osVersionInfo.dwBuildNumber)
         )
 #else
-        return OperatingSystemVersion(majorVersion: -1, minorVersion: 0, patchVersion: 0)
+        return (major: -1, minor: 0, patch: 0)
 #endif
     }
 

Sources/FoundationEssentials/PropertyList/OpenStepPlist.swift

@@ -16,6 +16,8 @@ import Darwin
 import Bionic
 #elseif canImport(Glibc)
 import Glibc
+#elseif os(WASI)
+import WASILibc
 #elseif canImport(Musl)
 import Musl
 #endif

Sources/FoundationEssentials/String/String+Path.swift

@@ -20,6 +20,8 @@ import Glibc
 import Musl
 #elseif os(Windows)
 import WinSDK
+#elseif os(WASI)
+import WASILibc
 #endif
 
 internal import _FoundationCShims
@@ -452,6 +454,7 @@ extension String {
             return envVar.standardizingPath
         }
 
+        #if !os(WASI) // WASI does not have user concept
         // Next, attempt to find the home directory via getpwnam/getpwuid
         var pass: UnsafeMutablePointer<passwd>?
         if let user {
@@ -465,6 +468,7 @@ extension String {
         if let dir = pass?.pointee.pw_dir {
             return String(cString: dir).standardizingPath
         }
+        #endif
 
         // Fallback to HOME for the current user if possible
         if user == nil, let home = getenv("HOME") {

Sources/FoundationEssentials/_ThreadLocal.swift

@@ -32,6 +32,8 @@ struct _ThreadLocal {
     fileprivate typealias PlatformKey = tss_t
 #elseif canImport(WinSDK)
     fileprivate typealias PlatformKey = DWORD
+#elseif os(WASI)
+    fileprivate typealias PlatformKey = UnsafeMutablePointer<UnsafeMutableRawPointer?>
 #endif
 
     struct Key<Value> {
@@ -48,6 +50,8 @@ struct _ThreadLocal {
             self.key = key
 #elseif canImport(WinSDK)
             key = FlsAlloc(nil)
+#elseif os(WASI)
+            key = UnsafeMutablePointer<UnsafeMutableRawPointer?>.allocate(capacity: 1)
 #endif
         }
     }
@@ -60,6 +64,8 @@ struct _ThreadLocal {
             tss_get(key)
 #elseif canImport(WinSDK)
             FlsGetValue(key)
+#elseif os(WASI)
+            key.pointee
 #endif
         }
 
@@ -70,6 +76,8 @@ struct _ThreadLocal {
             tss_set(key, newValue)
 #elseif canImport(WinSDK)
             FlsSetValue(key, newValue)
+#elseif os(WASI)
+            key.pointee = newValue
 #endif
         }
     }

Sources/FoundationInternationalization/CMakeLists.txt

@@ -33,6 +33,7 @@ target_compile_options(FoundationInternationalization PRIVATE
     "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -enable-experimental-feature -Xfrontend StrictConcurrency>"
     "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -enable-upcoming-feature -Xfrontend InferSendableFromCaptures>")
 target_compile_options(FoundationInternationalization PRIVATE ${_SwiftFoundation_availability_macros})
+target_compile_options(FoundationInternationalization PRIVATE ${_SwiftFoundation_wasi_libc_flags})
 target_compile_options(FoundationInternationalization PRIVATE -package-name "SwiftFoundation")
 
 target_link_libraries(FoundationInternationalization PUBLIC

Sources/FoundationInternationalization/Calendar/Calendar_ICU.swift

@@ -24,6 +24,8 @@ import Musl
 import CRT
 #elseif canImport(Darwin)
 import Darwin
+#elseif os(WASI)
+import WASILibc
 #endif
 
 internal import _FoundationICU

Sources/FoundationInternationalization/Formatting/Duration+Formatting.swift

@@ -24,6 +24,8 @@ import Glibc
 import Musl
 #elseif os(Windows)
 import CRT
+#elseif os(WASI)
+import WASILibc
 #endif
 
 @available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)

Sources/_FoundationCShims/include/_CStdlib.h

@@ -60,7 +60,21 @@
 #endif
 
 #if __has_include(<signal.h>)
-#include <signal.h>
+/// Guard against including `signal.h` on WASI. The `signal.h` header file
+/// itself is available in wasi-libc, but it's just a stub that doesn't actually
+/// do anything. And also including it requires a special macro definition
+/// (`_WASI_EMULATED_SIGNAL`) and it causes compilation errors without the macro.
+# if !TARGET_OS_WASI || defined(_WASI_EMULATED_SIGNAL)
+#  include <signal.h>
+# endif
+#endif
+
+#if __has_include(<sys/mman.h>)
+/// Similar to `signal.h`, guard against including `sys/mman.h` on WASI unless
+/// `_WASI_EMULATED_MMAN` is enabled.
+# if !TARGET_OS_WASI || defined(_WASI_EMULATED_MMAN)
+#  include <sys/mman.h>
+# endif
 #endif
 
 #if __has_include(<stdalign.h>)

Sources/_FoundationCShims/include/platform_shims.h

@@ -31,19 +31,19 @@
 #include <security.h>
 #endif
 
-INTERNAL char * _Nullable * _Nullable _platform_shims_get_environ();
+INTERNAL char * _Nullable * _Nullable _platform_shims_get_environ(void);
 
-INTERNAL void _platform_shims_lock_environ();
-INTERNAL void _platform_shims_unlock_environ();
+INTERNAL void _platform_shims_lock_environ(void);
+INTERNAL void _platform_shims_unlock_environ(void);
 
 #if __has_include(<mach/vm_page_size.h>)
 #include <mach/vm_page_size.h>
-INTERNAL vm_size_t _platform_shims_vm_size();
+INTERNAL vm_size_t _platform_shims_vm_size(void);
 #endif
 
 #if __has_include(<mach/mach.h>)
 #include <mach/mach.h>
-INTERNAL mach_port_t _platform_mach_task_self();
+INTERNAL mach_port_t _platform_mach_task_self(void);
 #endif
 
 #if __has_include(<libkern/OSThermalNotification.h>)
@@ -65,7 +65,7 @@ typedef enum {
 } _platform_shims_OSThermalPressureLevel;
 
 
-INTERNAL const char * _Nonnull _platform_shims_kOSThermalNotificationPressureLevelName();
+INTERNAL const char * _Nonnull _platform_shims_kOSThermalNotificationPressureLevelName(void);
 #endif
 
 #endif /* CSHIMS_PLATFORM_SHIMS */

Sources/_FoundationCShims/platform_shims.c

@@ -21,21 +21,25 @@
 extern char **environ;
 #endif
 
+#if __wasi__
+#include <wasi/libc-environ.h> // for __wasilibc_get_environ
+#endif
+
 #if __has_include(<libc_private.h>)
 #import <libc_private.h>
-void _platform_shims_lock_environ() {
+void _platform_shims_lock_environ(void) {
     environ_lock_np();
 }
 
-void _platform_shims_unlock_environ() {
+void _platform_shims_unlock_environ(void) {
     environ_unlock_np();
 }
 #else
-void _platform_shims_lock_environ() { /* noop */ }
-void _platform_shims_unlock_environ() { /* noop */ }
+void _platform_shims_lock_environ(void) { /* noop */ }
+void _platform_shims_unlock_environ(void) { /* noop */ }
 #endif
 
-char ** _platform_shims_get_environ() {
+char ** _platform_shims_get_environ(void) {
 #if __has_include(<crt_externs.h>)
     return *_NSGetEnviron();
 #elif defined(_WIN32)
@@ -48,20 +52,20 @@ char ** _platform_shims_get_environ() {
 }
 
 #if __has_include(<libkern/OSThermalNotification.h>)
-const char * _platform_shims_kOSThermalNotificationPressureLevelName() {
+const char * _platform_shims_kOSThermalNotificationPressureLevelName(void) {
     return kOSThermalNotificationPressureLevelName;
 }
 #endif
 
 #if __has_include(<mach/vm_page_size.h>)
-vm_size_t _platform_shims_vm_size() {
+vm_size_t _platform_shims_vm_size(void) {
     // This shim exists because vm_page_size is not marked const, and therefore looks like global mutable state to Swift.
     return vm_page_size;
 }
 #endif
 
 #if __has_include(<mach/mach.h>)
-mach_port_t _platform_mach_task_self() {
+mach_port_t _platform_mach_task_self(void) {
     // This shim exists because mach_task_self_ is not marked const, and therefore looks like global mutable state to Swift.
     return mach_task_self();
 }