Drop read/write/close LibcShims and use the platform APIs directly from the SwiftPrivate module

stdlib/private/CMakeLists.txt

@@ -1,7 +1,3 @@
-if(SWIFT_BUILD_STDLIB OR SWIFT_BUILD_SDK_OVERLAY)
-  add_subdirectory(SwiftPrivate)
-endif()
-
 if(SWIFT_BUILD_SDK_OVERLAY)
   # SwiftPrivateThreadExtras makes use of Darwin/Glibc, which is part of the
   # SDK overlay. It can't be built separately from the SDK overlay.
@@ -11,6 +7,7 @@ if(SWIFT_BUILD_SDK_OVERLAY)
 endif()
 
 if(SWIFT_BUILD_SDK_OVERLAY OR SWIFT_BUILD_TEST_SUPPORT_MODULES)
+  add_subdirectory(SwiftPrivate)
   add_subdirectory(RuntimeUnittest)
   add_subdirectory(StdlibUnicodeUnittest)
   add_subdirectory(StdlibCollectionUnittest)

stdlib/private/SwiftPrivate/CMakeLists.txt

@@ -15,6 +15,16 @@ add_swift_target_library(swiftSwiftPrivate ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} I
   GYB_SOURCES
     AtomicInt.swift.gyb
 
+  SWIFT_MODULE_DEPENDS_OSX Darwin
+  SWIFT_MODULE_DEPENDS_IOS Darwin
+  SWIFT_MODULE_DEPENDS_TVOS Darwin
+  SWIFT_MODULE_DEPENDS_WATCHOS Darwin
+  SWIFT_MODULE_DEPENDS_FREESTANDING "${SWIFT_FREESTANDING_TEST_DEPENDENCIES}"
+  SWIFT_MODULE_DEPENDS_LINUX Glibc
+  SWIFT_MODULE_DEPENDS_FREEBSD Glibc
+  SWIFT_MODULE_DEPENDS_OPENBSD Glibc
+  SWIFT_MODULE_DEPENDS_CYGWIN Glibc
+  SWIFT_MODULE_DEPENDS_HAIKU Glibc
   SWIFT_MODULE_DEPENDS_WINDOWS CRT WinSDK
   SWIFT_COMPILE_FLAGS ${swift_swiftprivate_compile_flags} ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
   INSTALL_IN_COMPONENT stdlib-experimental

stdlib/private/SwiftPrivate/IO.swift

@@ -13,7 +13,13 @@
 import Swift
 import SwiftShims
 
-#if os(Windows)
+#if canImport(Darwin)
+import Darwin
+let (platform_read, platform_write, platform_close) = (read, write, close)
+#elseif canImport(Glibc)
+import Glibc
+let (platform_read, platform_write, platform_close) = (read, write, close)
+#elseif os(Windows)
 import CRT
 import WinSDK
 #endif
@@ -119,11 +125,11 @@ public struct _FDInputStream {
       }
     }
     let fd = self.fd
-    let readResult: __swift_ssize_t = _buffer.withUnsafeMutableBufferPointer {
+    let readResult: Int = _buffer.withUnsafeMutableBufferPointer {
       (_buffer) in
       let addr = _buffer.baseAddress! + self._bufferUsed
       let size = bufferFree
-      return _swift_stdlib_read(fd, addr, size)
+      return platform_read(fd, addr, size)
     }
     if readResult == 0 {
       isEOF = true
@@ -139,7 +145,7 @@ public struct _FDInputStream {
     if isClosed {
       return
     }
-    let result = _swift_stdlib_close(fd)
+    let result = platform_close(fd)
     if result < 0 {
       fatalError("close() returned an error")
     }
@@ -207,7 +213,7 @@ public struct _FDOutputStream : TextOutputStream {
       var writtenBytes = 0
       let bufferSize = utf8CStr.count - 1
       while writtenBytes != bufferSize {
-        let result = _swift_stdlib_write(
+        let result = platform_write(
           self.fd, UnsafeRawPointer(utf8CStr.baseAddress! + Int(writtenBytes)),
           bufferSize - writtenBytes)
         if result < 0 {
@@ -222,7 +228,7 @@ public struct _FDOutputStream : TextOutputStream {
     if isClosed {
       return
     }
-    let result = _swift_stdlib_close(fd)
+    let result = platform_close(fd)
     if result < 0 {
       fatalError("close() returned an error")
     }

stdlib/public/SwiftShims/LibcShims.h

@@ -45,14 +45,6 @@ static inline void _swift_stdlib_free(void *_Nullable ptr) {
   free(ptr);
 }
 
-// <unistd.h>
-SWIFT_RUNTIME_STDLIB_SPI
-__swift_ssize_t _swift_stdlib_read(int fd, void *buf, __swift_size_t nbyte);
-SWIFT_RUNTIME_STDLIB_SPI
-__swift_ssize_t _swift_stdlib_write(int fd, const void *buf, __swift_size_t nbyte);
-SWIFT_RUNTIME_STDLIB_SPI
-int _swift_stdlib_close(int fd);
-
 // String handling <string.h>
 SWIFT_READONLY
 static inline __swift_size_t _swift_stdlib_strlen(const char *s) {

stdlib/public/stubs/LibcShims.cpp

@@ -22,12 +22,6 @@
 #endif
 
 #include <stdio.h>
-#include <sys/types.h>
-#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__)) || defined(__wasi__)
-#include <unistd.h>
-#endif
-
-#include <type_traits>
 
 #include "../SwiftShims/LibcShims.h"
 
@@ -37,32 +31,3 @@ __swift_size_t _swift_stdlib_fwrite_stdout(const void *ptr,
                                                   __swift_size_t nitems) {
     return fwrite(ptr, size, nitems, stdout);
 }
-
-SWIFT_RUNTIME_STDLIB_SPI
-__swift_ssize_t
-_swift_stdlib_read(int fd, void *buf, __swift_size_t nbyte) {
-#if defined(_WIN32)
-  return _read(fd, buf, nbyte);
-#else
-  return read(fd, buf, nbyte);
-#endif
-}
-
-SWIFT_RUNTIME_STDLIB_SPI
-__swift_ssize_t
-_swift_stdlib_write(int fd, const void *buf, __swift_size_t nbyte) {
-#if defined(_WIN32)
-  return _write(fd, buf, nbyte);
-#else
-  return write(fd, buf, nbyte);
-#endif
-}
-
-SWIFT_RUNTIME_STDLIB_SPI
-int _swift_stdlib_close(int fd) {
-#if defined(_WIN32)
-  return _close(fd);
-#else
-  return close(fd);
-#endif
-}