[Freestanding] Remove uses of stat() and dlsym().

We shouldn't be using stat() or dlsym() in the freestanding
runtime.

rdar://111214571
rdar://106555012

Author: al45tair

CMakeLists.txt

@@ -585,6 +585,11 @@ option(SWIFT_THREADING_PACKAGE
    Valid package names are 'pthreads', 'darwin', 'linux', 'win32', 'c11', 'none'
    or the empty string for the SDK default.")
 
+option(SWIFT_THREADING_HAS_DLSYM
+  "Enable the use of the dlsym() function.  This gets used to provide TSan
+   support on some platforms."
+  TRUE)
+
 #
 # End of user-configurable options.
 #

cmake/modules/AddSwiftUnittests.cmake

@@ -47,12 +47,19 @@ function(add_swift_unittest test_dirname)
   endif()
 
   # some headers switch their inline implementations based on
-  # SWIFT_STDLIB_SINGLE_THREADED_CONCURRENCY and
+  # SWIFT_STDLIB_SINGLE_THREADED_CONCURRENCY, SWIFT_STDLIB_HAS_DLSYM and
   # SWIFT_THREADING_PACKAGE definitions
   if(SWIFT_STDLIB_SINGLE_THREADED_CONCURRENCY)
     target_compile_definitions("${test_dirname}" PRIVATE
       SWIFT_STDLIB_SINGLE_THREADED_CONCURRENCY)
   endif()
+  if(SWIFT_STDLIB_HAS_DLSYM)
+    target_compile_definitions("${test_dirname}" PRIVATE
+      "SWIFT_STDLIB_HAS_DLSYM=1")
+  else()
+    target_compile_definitions("${test_dirname}" PRIVATE
+      "SWIFT_STDLIB_HAS_DLSYM=0")
+  endif()
 
   string(TOUPPER "${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_THREADING_PACKAGE}" _threading_package)
   target_compile_definitions("${test_dirname}" PRIVATE

include/swift/Threading/ThreadSanitizer.h

@@ -24,7 +24,10 @@
 
 namespace swift {
 
-#if defined(_WIN32) || defined(__wasi__) || !__has_include(<dlfcn.h>)
+#if SWIFT_THREADING_NONE                                                \
+  || defined(_WIN32) || defined(__wasi__)                               \
+  || !__has_include(<dlfcn.h>)                                          \
+  || (defined(SWIFT_STDLIB_HAS_DLSYM) && !SWIFT_STDLIB_HAS_DLSYM)
 
 #define SWIFT_THREADING_TSAN_SUPPORT 0
 
@@ -35,6 +38,7 @@ template <typename T> T *acquire(T *ptr) { return ptr; }
 template <typename T> T *release(T *ptr) { return ptr; }
 
 } // namespace tsan
+
 #else
 
 #define SWIFT_THREADING_TSAN_SUPPORT 1

lib/Threading/ThreadSanitizer.cpp

@@ -23,6 +23,8 @@
 
 #include "swift/shims/Visibility.h"
 
+#include <dlfcn.h>
+
 #include <cstdio>
 
 namespace swift {
@@ -32,9 +34,6 @@ SWIFT_THREADING_EXPORT bool _swift_tsan_enabled = false;
 SWIFT_THREADING_EXPORT void (*_swift_tsan_acquire)(const void *) = nullptr;
 SWIFT_THREADING_EXPORT void (*_swift_tsan_release)(const void *) = nullptr;
 
-#if __has_include(<dlfcn.h>)
-#include <dlfcn.h>
-
 // The TSan library code will call this function when it starts up
 extern "C" SWIFT_ATTRIBUTE_FOR_EXPORTS
 void __tsan_on_initialize() {
@@ -53,7 +52,6 @@ void __tsan_on_initialize() {
     next_init();
   }
 }
-#endif // __has_include(<dlfcn.h>)
 
 } // namespace threading_impl
 } // namespace swift

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -323,6 +323,16 @@ function(_add_target_variant_c_compile_flags)
     list(APPEND result "-DSWIFT_STDLIB_HAS_DLADDR")
   endif()
 
+  if(SWIFT_STDLIB_HAS_DLSYM)
+    list(APPEND result "-DSWIFT_STDLIB_HAS_DLSYM=1")
+  else()
+    list(APPEND result "-DSWIFT_STDLIB_HAS_DLSYM=0")
+  endif()
+
+  if(SWIFT_STDLIB_HAS_FILESYSTEM)
+    list(APPEND result "-DSWIFT_STDLIB_HAS_FILESYSTEM")
+  endif()
+
   if(SWIFT_RUNTIME_STATIC_IMAGE_INSPECTION)
     list(APPEND result "-DSWIFT_RUNTIME_STATIC_IMAGE_INSPECTION")
   endif()

stdlib/cmake/modules/StdlibOptions.cmake

@@ -135,7 +135,15 @@ option(SWIFT_STDLIB_BUILD_PRIVATE
        TRUE)
 
 option(SWIFT_STDLIB_HAS_DLADDR
-       "Build stdlib assuming the runtime environment runtime environment provides dladdr API."
+       "Build stdlib assuming the runtime environment provides the dladdr API."
+       TRUE)
+
+option(SWIFT_STDLIB_HAS_DLSYM
+       "Build stdlib assuming the runtime environment provides the dlsym API."
+       TRUE)
+
+option(SWIFT_STDLIB_HAS_FILESYSTEM
+       "Build stdlib assuming the runtime environment has a filesystem."
        TRUE)
 
 option(SWIFT_RUNTIME_STATIC_IMAGE_INSPECTION

utils/build-presets.ini

@@ -2550,6 +2550,8 @@ swift-enable-reflection=0
 swift-stdlib-reflection-metadata=debugger-only
 swift-stdlib-stable-abi=0
 swift-stdlib-has-dladdr=0
+swift-stdlib-has-dlsym=0
+swift-stdlib-has-filesystem=0
 swift-stdlib-supports-backtrace-reporting=0
 swift-stdlib-has-darwin-libmalloc=0
 swift-stdlib-has-asl=0

utils/build-script-impl

@@ -206,6 +206,8 @@ KNOWN_SETTINGS=(
     swift-enable-reflection                       "1"               "whether to support reflection and mirrors"
     swift-stdlib-reflection-metadata              "enabled"         "whether to build stdlib with runtime metadata (valid options are 'enabled', 'disabled' and 'debugger-only')"
     swift-stdlib-has-dladdr                       "1"               "whether to build stdlib assuming the runtime environment provides dladdr API"
+    swift-stdlib-has-dlsym                        "1"               "whether to build stdlib assuming the runtime environment provides the dlsym API"
+    swift-stdlib-has-filesystem                   "1"               "whether to build stdlib assuming the runtime environment provides a filesystem"
     swift-stdlib-supports-backtrace-reporting     ""                "whether to build stdlib assuming the runtime environment provides the backtrace(3) API, if not set defaults to true on all platforms except for Cygwin, Haiku and wasm"
     swift-runtime-static-image-inspection         "0"               "whether to build stdlib assuming the runtime environment only supports a single runtime image with Swift code"
     swift-threading-package                       ""                "override the threading package for the host build; this is either a single package or a semicolon-separated list of sdk:package pairs.  Valid packages are empty string (no override), 'pthreads', 'darwin', 'linux', 'win32', 'c11', 'none'"
@@ -1940,6 +1942,8 @@ for host in "${ALL_HOSTS[@]}"; do
                     -DSWIFT_STDLIB_SINGLE_THREADED_CONCURRENCY:BOOL=$(true_false "${SWIFT_STDLIB_SINGLE_THREADED_CONCURRENCY}")
                     -DSWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS:BOOL=$(true_false "${SWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS}")
                     -DSWIFT_STDLIB_HAS_DLADDR:BOOL=$(true_false "${SWIFT_STDLIB_HAS_DLADDR}")
+                    -DSWIFT_STDLIB_HAS_DLSYM:BOOL=$(true_false "${SWIFT_STDLIB_HAS_DLSYM}")
+                    -DSWIFT_STDLIB_HAS_FILESYSTEM:BOOL=$(true_false "${SWIFT_STDLIB_HAS_FILESYSTEM}")
                     -DSWIFT_RUNTIME_STATIC_IMAGE_INSPECTION:BOOL=$(true_false "${SWIFT_RUNTIME_STATIC_IMAGE_INSPECTION}")
                     -DSWIFT_STDLIB_OS_VERSIONING:BOOL=$(true_false "${SWIFT_STDLIB_OS_VERSIONING}")
                     -DSWIFT_STDLIB_HAS_COMMANDLINE:BOOL=$(true_false "${SWIFT_STDLIB_HAS_COMMANDLINE}")