Add entrypoints to the runtime that exposes metadata necessary for reflection tests on Linux (#32339)

Author: augusto2112

include/swift/Remote/MetadataReader.h

@@ -509,6 +509,7 @@ class MetadataReader {
     if (!meta || meta->getKind() != MetadataKind::Class)
       return None;
 
+#if SWIFT_OBJC_INTEROP
     // The following algorithm only works on the non-fragile Apple runtime.
 
     // Grab the RO-data pointer.  This part is not ABI.
@@ -524,6 +525,23 @@ class MetadataReader {
       return None;
 
     return start;
+#else
+    // All swift class instances start with an isa pointer,
+    // followed by the retain counts (which are the size of a long long).
+    size_t isaAndRetainCountSize = sizeof(StoredSize) + sizeof(long long);
+    size_t start = isaAndRetainCountSize;
+
+    auto classMeta = cast<TargetClassMetadata<Runtime>>(meta);
+    while (classMeta->Superclass) {
+      classMeta = cast<TargetClassMetadata<Runtime>>(
+          readMetadata(classMeta->Superclass));
+
+      // Subtract the size contribution of the isa and retain counts from 
+      // the super class.
+      start += classMeta->InstanceSize - isaAndRetainCountSize;
+    }
+    return start;
+#endif
   }
 
   /// Given a pointer to the metadata, attempt to read the value

include/swift/SwiftRemoteMirror/SwiftRemoteMirror.h

@@ -80,6 +80,11 @@ void
 swift_reflection_addReflectionInfo(SwiftReflectionContextRef ContextRef,
                                    swift_reflection_info_t Info);
 
+/// Add reflection sections from a loaded Swift image.
+SWIFT_REMOTE_MIRROR_LINKAGE
+void swift_reflection_addReflectionMappingInfo(
+    SwiftReflectionContextRef ContextRef, swift_reflection_mapping_info_t Info);
+
 /// Add reflection information from a loaded Swift image.
 /// Returns true on success, false if the image's memory couldn't be read.
 SWIFT_REMOTE_MIRROR_LINKAGE

include/swift/SwiftRemoteMirror/SwiftRemoteMirrorTypes.h

@@ -48,11 +48,23 @@ typedef struct swift_reflection_section {
   void *End;
 } swift_reflection_section_t;
 
+/// Represents the remote address and size of an image's section
+typedef struct swift_remote_reflection_section {
+    uintptr_t StartAddress;
+    uintptr_t Size;
+} swift_remote_reflection_section_t;
+
 typedef struct swift_reflection_section_pair {
   swift_reflection_section_t section;
   swift_reflection_ptr_t offset; ///< DEPRECATED. Must be zero
 } swift_reflection_section_pair_t;
 
+/// Represents the mapping between an image sections's local and remote addresses
+typedef struct swift_reflection_section_mapping {
+  swift_reflection_section_t local_section;
+  swift_remote_reflection_section_t remote_section;
+} swift_reflection_section_mapping_t;
+
 /// Represents the set of Swift reflection sections of an image.
 /// Not all sections may be present.
 ///
@@ -71,6 +83,16 @@ typedef struct swift_reflection_info {
   swift_reflection_ptr_t RemoteStartAddress;
 } swift_reflection_info_t;
 
+/// Represents the set of Swift reflection sections of an image,
+typedef struct swift_reflection_mapping_info {
+  swift_reflection_section_mapping_t field;
+  swift_reflection_section_mapping_t associated_types;
+  swift_reflection_section_mapping_t builtin_types;
+  swift_reflection_section_mapping_t capture;
+  swift_reflection_section_mapping_t type_references;
+  swift_reflection_section_mapping_t reflection_strings;
+} swift_reflection_mapping_info_t;
+
 /// The layout kind of a Swift type.
 typedef enum swift_layout_kind {
   // Nothing is known about the size or contents of this value.

stdlib/private/CMakeLists.txt

@@ -23,8 +23,10 @@ if(SWIFT_BUILD_SDK_OVERLAY)
 
   if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     add_subdirectory(StdlibUnittestFoundationExtras)
-    if (SWIFT_INCLUDE_TESTS)
-      add_subdirectory(SwiftReflectionTest)
-    endif()
+  endif()
+  # Currently SwiftReflectionTest cannot be built on Windows, due to 
+  # dependencies on POSIX symbols 
+  if (SWIFT_INCLUDE_TESTS AND (NOT CMAKE_SYSTEM_NAME STREQUAL "Windows"))
+    add_subdirectory(SwiftReflectionTest)
   endif()
 endif()

stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift

@@ -16,11 +16,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-// FIXME: Make this work with Linux
-
-import MachO
-import Darwin
-
 let RequestInstanceKind = "k"
 let RequestInstanceAddress = "i"
 let RequestReflectionInfos = "r"
@@ -31,56 +26,10 @@ let RequestStringLength = "l"
 let RequestDone = "d"
 let RequestPointerSize = "p"
 
-internal func debugLog(_ message: @autoclosure () -> String) {
-#if DEBUG_LOG
-  fputs("Child: \(message())\n", stderr)
-  fflush(stderr)
-#endif
-}
-
-public enum InstanceKind : UInt8 {
-  case None
-  case Object
-  case Existential
-  case ErrorExistential
-  case Closure
-  case Enum
-  case EnumValue
-}
-
-/// Represents a section in a loaded image in this process.
-internal struct Section {
-  /// The absolute start address of the section's data in this address space.
-  let startAddress: UnsafeRawPointer
-
-  /// The size of the section in bytes.
-  let size: UInt
-}
 
-/// Holds the addresses and sizes of sections related to reflection
-internal struct ReflectionInfo : Sequence {
-  /// The name of the loaded image
-  internal let imageName: String
-
-  /// Reflection metadata sections
-  internal let fieldmd: Section?
-  internal let assocty: Section?
-  internal let builtin: Section?
-  internal let capture: Section?
-  internal let typeref: Section?
-  internal let reflstr: Section?
-
-  internal func makeIterator() -> AnyIterator<Section?> {
-    return AnyIterator([
-      fieldmd,
-      assocty,
-      builtin,
-      capture,
-      typeref,
-      reflstr
-    ].makeIterator())
-  }
-}
+#if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
+import MachO
+import Darwin
 
 #if arch(x86_64) || arch(arm64)
 typealias MachHeader = mach_header_64
@@ -105,6 +54,36 @@ internal func getSectionInfo(_ name: String,
   return Section(startAddress: nonNullAddress, size: size)
 }
 
+/// Get the TEXT segment location and size for a loaded image.
+///
+/// - Parameter i: The index of the loaded image as reported by Dyld.
+/// - Returns: The image name, address, and size.
+internal func getAddressInfoForImage(atIndex i: UInt32) ->
+        (name: String, address: UnsafeMutablePointer<UInt8>?, size: UInt) {
+  debugLog("BEGIN \(#function)"); defer { debugLog("END \(#function)") }
+  let header = unsafeBitCast(_dyld_get_image_header(i),
+          to: UnsafePointer<MachHeader>.self)
+  let name = String(validatingUTF8: _dyld_get_image_name(i)!)!
+  var size: UInt = 0
+  let address = getsegmentdata(header, "__TEXT", &size)
+  return (name, address, size)
+}
+
+/// Send all loadedimages loaded in the current process.
+internal func sendImages() {
+  debugLog("BEGIN \(#function)"); defer { debugLog("END \(#function)") }
+  let infos = (0..<getImageCount()).map(getAddressInfoForImage)
+
+  debugLog("\(infos.count) reflection info bundles.")
+  precondition(infos.count >= 1)
+  sendValue(infos.count)
+  for (name, address, size) in infos {
+    debugLog("Sending info for \(name)")
+    sendValue(address)
+    sendValue(size)
+  }
+}
+
 /// Get the Swift Reflection section locations for a loaded image.
 ///
 /// An image of interest must have the following sections in the __TEXT
@@ -140,19 +119,100 @@ internal func getReflectionInfoForImage(atIndex i: UInt32) -> ReflectionInfo? {
                         reflstr: reflstr)
 }
 
-/// Get the TEXT segment location and size for a loaded image.
-///
-/// - Parameter i: The index of the loaded image as reported by Dyld.
-/// - Returns: The image name, address, and size.
-internal func getAddressInfoForImage(atIndex i: UInt32) ->
-  (name: String, address: UnsafeMutablePointer<UInt8>?, size: UInt) {
-  debugLog("BEGIN \(#function)"); defer { debugLog("END \(#function)") }
-  let header = unsafeBitCast(_dyld_get_image_header(i),
-    to: UnsafePointer<MachHeader>.self)
-  let name = String(validatingUTF8: _dyld_get_image_name(i)!)!
-  var size: UInt = 0
-  let address = getsegmentdata(header, "__TEXT", &size)
-  return (name, address, size)
+internal func getImageCount() -> UInt32 {
+  return _dyld_image_count()
+}
+
+let rtldDefault = UnsafeMutableRawPointer(bitPattern: Int(-2))
+#elseif !os(Windows)
+import SwiftShims
+import Glibc
+
+let rtldDefault: UnsafeMutableRawPointer? = nil
+
+extension Section {
+  init(range: MetadataSectionRange) {
+    self.startAddress = UnsafeRawPointer(bitPattern: range.start)!
+    self.size = UInt(range.length)
+  }
+}
+
+internal func getReflectionInfoForImage(atIndex i: UInt32) -> ReflectionInfo? {
+  return _getMetadataSection(UInt(i)).map { rawPointer in
+    let name = _getMetadataSectionName(rawPointer)
+    let metadataSection = rawPointer.bindMemory(to: MetadataSections.self, capacity: 1).pointee
+    return ReflectionInfo(imageName: String(validatingUTF8: name)!,
+            fieldmd: Section(range: metadataSection.swift5_fieldmd),
+            assocty: Section(range: metadataSection.swift5_assocty),
+            builtin: Section(range: metadataSection.swift5_builtin),
+            capture: Section(range: metadataSection.swift5_capture),
+            typeref: Section(range: metadataSection.swift5_typeref),
+            reflstr: Section(range: metadataSection.swift5_reflstr))
+  }
+}
+
+internal func getImageCount() -> UInt32 {
+  return UInt32(_getMetadataSectionCount())
+}
+
+internal func sendImages() {
+  preconditionFailure("Should only be called in macOS!")
+}
+
+
+#else // os(Linux)
+#error("SwiftReflectionTest does not currently support this OS.")
+#endif
+
+internal func debugLog(_ message: @autoclosure () -> String) {
+#if DEBUG_LOG
+  fputs("Child: \(message())\n", stderr)
+  fflush(stderr)
+#endif
+}
+
+public enum InstanceKind: UInt8 {
+  case None
+  case Object
+  case Existential
+  case ErrorExistential
+  case Closure
+  case Enum
+  case EnumValue
+}
+
+/// Represents a section in a loaded image in this process.
+internal struct Section {
+  /// The absolute start address of the section's data in this address space.
+  let startAddress: UnsafeRawPointer
+
+  /// The size of the section in bytes.
+  let size: UInt
+}
+
+/// Holds the addresses and sizes of sections related to reflection.
+internal struct ReflectionInfo : Sequence {
+  /// The name of the loaded image.
+  internal let imageName: String
+
+  /// Reflection metadata sections.
+  internal let fieldmd: Section?
+  internal let assocty: Section?
+  internal let builtin: Section?
+  internal let capture: Section?
+  internal let typeref: Section?
+  internal let reflstr: Section?
+
+  internal func makeIterator() -> AnyIterator<Section?> {
+    return AnyIterator([
+      fieldmd,
+      assocty,
+      builtin,
+      capture,
+      typeref,
+      reflstr
+    ].makeIterator())
+  }
 }
 
 internal func sendBytes<T>(from address: UnsafePointer<T>, count: Int) {
@@ -197,7 +257,7 @@ internal func readUInt() -> UInt {
 /// process.
 internal func sendReflectionInfos() {
   debugLog("BEGIN \(#function)"); defer { debugLog("END \(#function)") }
-  let infos = (0..<_dyld_image_count()).compactMap(getReflectionInfoForImage)
+  let infos = (0..<getImageCount()).compactMap(getReflectionInfoForImage)
 
   var numInfos = infos.count
   debugLog("\(numInfos) reflection info bundles.")
@@ -212,21 +272,6 @@ internal func sendReflectionInfos() {
   }
 }
 
-/// Send all loadedimages loaded in the current process.
-internal func sendImages() {
-  debugLog("BEGIN \(#function)"); defer { debugLog("END \(#function)") }
-  let infos = (0..<_dyld_image_count()).map(getAddressInfoForImage)
-
-  debugLog("\(infos.count) reflection info bundles.")
-  precondition(infos.count >= 1)
-  sendValue(infos.count)
-  for (name, address, size) in infos {
-    debugLog("Sending info for \(name)")
-    sendValue(address)
-    sendValue(size)
-  }
-}
-
 internal func printErrnoAndExit() {
   debugLog("BEGIN \(#function)"); defer { debugLog("END \(#function)") }
   let errorCString = strerror(errno)!
@@ -261,8 +306,7 @@ internal func sendSymbolAddress() {
   debugLog("BEGIN \(#function)"); defer { debugLog("END \(#function)") }
   let name = readLine()!
   name.withCString {
-    let handle = UnsafeMutableRawPointer(bitPattern: Int(-2))!
-    let symbol = dlsym(handle, $0)
+    let symbol = dlsym(rtldDefault, $0)
     let symbolAddress = unsafeBitCast(symbol, to: UInt.self)
     sendValue(symbolAddress)
   }