[lld/mac] Implement -application_extension

[int3]

lgtm

lld/MachO/Options.td

692

lld/test/MachO/application-extension.s

47

[int3]

lld/test/MachO/application-extension.s

20

nit: s/.so/.dylib/

[thakis]

Thanks!

lld/test/MachO/application-extension.s

20

Hm, I thought it's custom to call -dylibs .dylib and -bundles .so?

[int3]

lld/test/MachO/application-extension.s

20

oh is it? alright then

lld/MachO/Config.h

public:
   bool matchGlob(llvm::StringRef symbolName) const;
   bool match(llvm::StringRef symbolName) const;
 };
 
 struct Configuration {
   Symbol *entry = nullptr;
   bool hasReexports = false;
   bool allLoad = false;
+  bool applicationExtension = false;
   bool archMultiple = false;
   bool exportDynamic = false;
   bool forceLoadObjC = false;
   bool forceLoadSwift = false;
   bool staticLink = false;
   bool implicitDylibs = false;
   bool isPic = false;
   bool headerPadMaxInstallNames = false;

lld/MachO/Driver.cpp

config->ltoNewPassManager =
       args.hasFlag(OPT_no_lto_legacy_pass_manager, OPT_lto_legacy_pass_manager,
                    LLVM_ENABLE_NEW_PASS_MANAGER);
   config->ltoo = args::getInteger(args, OPT_lto_O, 2);
   if (config->ltoo > 3)
     error("--lto-O: invalid optimization level: " + Twine(config->ltoo));
   config->runtimePaths = args::getStrings(args, OPT_rpath);
   config->allLoad = args.hasArg(OPT_all_load);
   config->archMultiple = args.hasArg(OPT_arch_multiple);
+  config->applicationExtension = args.hasFlag(
+      OPT_application_extension, OPT_no_application_extension, false);
   config->exportDynamic = args.hasArg(OPT_export_dynamic);
   config->forceLoadObjC = args.hasArg(OPT_ObjC);
   config->forceLoadSwift = args.hasArg(OPT_force_load_swift_libs);
   config->deadStripDylibs = args.hasArg(OPT_dead_strip_dylibs);
   config->demangle = args.hasArg(OPT_demangle);
   config->implicitDylibs = !args.hasArg(OPT_no_implicit_dylibs);
   config->emitFunctionStarts =
       args.hasFlag(OPT_function_starts, OPT_no_function_starts, true);

lld/MachO/InputFiles.h

public:
   // implemented in the bundle. When used like this, it is very similar
   // to a Dylib, so we re-used the same class to represent it.
   bool isBundleLoader;
 
 private:
   bool handleLDSymbol(StringRef originalName);
   void handleLDPreviousSymbol(StringRef name, StringRef originalName);
   void handleLDInstallNameSymbol(StringRef name, StringRef originalName);
+  void checkAppExtensionSafety(bool dylibIsAppExtensionSafe) const;
 };
 
 // .a file
 class ArchiveFile final : public InputFile {
 public:
   explicit ArchiveFile(std::unique_ptr<llvm::object::Archive> &&file);
   static bool classof(const InputFile *f) { return f->kind() == ArchiveKind; }
   void fetch(const llvm::object::Archive::Symbol &sym);

lld/MachO/InputFiles.cpp

if (config->printEachFile)
     message(toString(this));
   inputFiles.insert(this);
 
   deadStrippable = hdr->flags & MH_DEAD_STRIPPABLE_DYLIB;
 
   if (!checkCompatibility(this))
     return;
 
+  checkAppExtensionSafety(hdr->flags & MH_APP_EXTENSION_SAFE);
+
   for (auto *cmd : findCommands<rpath_command>(hdr, LC_RPATH)) {
     StringRef rpath{reinterpret_cast<const char *>(cmd) + cmd->path};
     rpaths.push_back(rpath);
   }
 
   // Initialize symbols.
   exportingFile = isImplicitlyLinked(installName) ? this : this->umbrella;
   if (const load_command *cmd = findCommand(hdr, LC_DYLD_INFO_ONLY)) {
DylibFile::DylibFile(const InterfaceFile &interface, DylibFile *umbrella,
 
   if (!is_contained(skipPlatformChecks, installName) &&
       !is_contained(interface.targets(), config->platformInfo.target)) {
     error(toString(this) + " is incompatible with " +
           std::string(config->platformInfo.target));
     return;
   }
 
+  checkAppExtensionSafety(interface.isApplicationExtensionSafe());
+
   exportingFile = isImplicitlyLinked(installName) ? this : umbrella;
   auto addSymbol = [&](const Twine &name) -> void {
     symbols.push_back(symtab->addDylib(saver.save(name), exportingFile,
                                        /*isWeakDef=*/false,
                                        /*isTlv=*/false));
   };
   // TODO(compnerd) filter out symbols based on the target platform
   // TODO: handle weak defs, thread locals
void DylibFile::handleLDInstallNameSymbol(StringRef name,
   std::tie(condition, installName) = name.split('$');
   VersionTuple version;
   if (!condition.consume_front("os") || version.tryParse(condition))
     warn("failed to parse os version, symbol '" + originalName + "' ignored");
   else if (version == config->platformInfo.minimum)
     this->installName = saver.save(installName);
 }
 
+void DylibFile::checkAppExtensionSafety(bool dylibIsAppExtensionSafe) const {
+  if (config->applicationExtension && !dylibIsAppExtensionSafe)
+    warn("using '-application_extension' with unsafe dylib: " + toString(this));
+}
+
 ArchiveFile::ArchiveFile(std::unique_ptr<object::Archive> &&f)
     : InputFile(ArchiveKind, f->getMemoryBufferRef()), file(std::move(f)) {
   for (const object::Archive::Symbol &sym : file->symbols())
     symtab->addLazy(sym.getName(), this, sym);
 }
 
 void ArchiveFile::fetch(const object::Archive::Symbol &sym) {
   object::Archive::Child c =

lld/MachO/Options.td

def segment_order : Separate<["-"], "segment_order">,
     HelpText<"With -preload, specify layout sequence of colon-separated <segments>">,
     Flags<[HelpHidden]>,
     Group<grp_rare>;
 def allow_heap_execute : Flag<["-"], "allow_heap_execute">,
     HelpText<"On i386, allow any page to execute code">,
     Flags<[HelpHidden]>,
     Group<grp_rare>;
 def application_extension : Flag<["-"], "application_extension">,
-    HelpText<"Designate the linker output as safe for use in an application extension">,
-    Flags<[HelpHidden]>,
+    HelpText<"Mark output as safe for use in an application extension, and validate that linked dylibs are safe">,
     Group<grp_rare>;
 def no_application_extension : Flag<["-"], "no_application_extension">,
-    HelpText<"Designate the linker output as unsafe for use in an application extension">,
-    Flags<[HelpHidden]>,
+    HelpText<"Disable application extension functionality (default)">,
     Group<grp_rare>;
 def fatal_warnings : Flag<["-"], "fatal_warnings">,
     HelpText<"Treat warnings as errors">,
     Group<grp_rare>;
 def no_eh_labels : Flag<["-"], "no_eh_labels">,
     HelpText<"In -r mode, suppress .eh labels in the __eh_frame section">,
     Flags<[HelpHidden]>,
     Group<grp_rare>;

lld/MachO/SyntheticSections.cpp

if (config->outputType == MH_DYLIB && !config->hasReexports)
     hdr->flags |= MH_NO_REEXPORTED_DYLIBS;
 
   if (config->markDeadStrippableDylib)
     hdr->flags |= MH_DEAD_STRIPPABLE_DYLIB;
 
   if (config->outputType == MH_EXECUTE && config->isPic)
     hdr->flags |= MH_PIE;
 
+  if (config->outputType == MH_DYLIB && config->applicationExtension)
+    hdr->flags |= MH_APP_EXTENSION_SAFE;
+
   if (in.exports->hasWeakSymbol || in.weakBinding->hasNonWeakDefinition())
     hdr->flags |= MH_WEAK_DEFINES;
 
   if (in.exports->hasWeakSymbol || in.weakBinding->hasEntry())
     hdr->flags |= MH_BINDS_TO_WEAK;
 
   for (const OutputSegment *seg : outputSegments) {
     for (const OutputSection *osec : seg->getSections()) {

lld/test/MachO/application-extension.s

+# REQUIRES: aarch64
+
+## --no-leading-lines is needed for .tbd files.
+# RUN: rm -rf %t; split-file --no-leading-lines %s %t
+
+# RUN: llvm-mc -filetype=obj -triple=arm64-apple-macos -o %t/foo.o %t/foo.s
+# RUN: llvm-mc -filetype=obj -triple=arm64-apple-macos -o %t/bar.o %t/bar.s
+
+## MH_APP_EXTENSION_SAFE is only set on dylibs, and only if requested.
+# RUN: %lld -arch arm64 -dylib -o %t/foo.dylib %t/foo.o
+# RUN: llvm-otool -hv %t/foo.dylib | FileCheck --check-prefix=NOAPPEXT %s
+# RUN: %lld -arch arm64 -dylib -o %t/foo-appext.dylib %t/foo.o \
+# RUN:     -application_extension
+# RUN: llvm-otool -hv %t/foo-appext.dylib | FileCheck --check-prefix=APPEXT %s
+# RUN: %lld -arch arm64 -dylib -o %t/foo-noappext.dylib %t/foo.o \
+# RUN:     -application_extension -no_application_extension
+# RUN: llvm-otool -hv %t/foo-noappext.dylib \
+# RUN:     | FileCheck --check-prefix=NOAPPEXT %s
+# RUN: %lld -arch arm64 -bundle -o %t/foo.so %t/foo.o \
+# RUN:     -application_extension
+# RUN: llvm-otool -hv %t/foo.so | FileCheck --check-prefix=NOAPPEXT %s
+
+# APPEXT: APP_EXTENSION_SAFE
+# NOAPPEXT-NOT: APP_EXTENSION_SAFE
+
+## The warning is emitted for all target types.
+# RUN: %lld -arch arm64 -dylib -o %t/bar.dylib %t/bar.o \
+# RUN:     -application_extension %t/foo-appext.dylib
+# RUN: %lld -arch arm64 -dylib -o %t/bar.dylib %t/bar.o \
+# RUN:     -application_extension -L %t -ltbd-appext
+# RUN: not %lld -arch arm64 -dylib -o %t/bar.dylib %t/bar.o \
+# RUN:     -application_extension %t/foo-noappext.dylib \
+# RUN:     2>&1 | FileCheck --check-prefix=WARN %s
+# RUN: not %lld -arch arm64 -dylib -o %t/bar.dylib %t/bar.o \
+# RUN:     -application_extension -L %t -ltbd-noappext \
+# RUN:     2>&1 | FileCheck --check-prefix=WARN %s
+# RUN: not %lld -arch arm64 -bundle -o %t/bar.so %t/bar.o \
+# RUN:     -application_extension %t/foo-noappext.dylib \
+# RUN:     2>&1 | FileCheck --check-prefix=WARN %s
+# RUN: not %lld -arch arm64 -bundle -o %t/bar.so %t/bar.o \
+# RUN:     -application_extension -L %t -ltbd-noappext \
+# RUN:     2>&1 | FileCheck --check-prefix=WARN %s
+
+# WARN: using '-application_extension' with unsafe dylib:
+
+## Test we warn on dylibs loaded indirectly via reexports.
+# RUN: not %lld -arch arm64 -dylib -o %t/bar.dylib %t/bar.o \
+# RUN:     -application_extension -L %t -lbaz-noappext-reexport \
+# RUN:     -u _baz 2>&1 | FileCheck --check-prefix=WARN %s
+
+#--- foo.s
+.globl _foo
+.p2align 2
+_foo:
+  ret
+
+#--- libtbd-appext.tbd
+--- !tapi-tbd
+tbd-version: 4
+targets: [ arm64-macos ]
+uuids:
+  - target: arm64-macos
+    value:  2E994C7F-3F03-3A07-879C-55690D22BEDA
+install-name:     '/usr/lib/libtbd-appext.dylib'
+exports:
+  - targets:      [ arm64-macos ]
+    symbols:      [ _foo ]
+...
+
+#--- libtbd-noappext.tbd
+--- !tapi-tbd
+tbd-version: 4
+targets: [ arm64-macos ]
+flags: [ not_app_extension_safe ]
+uuids:
+  - target: arm64-macos
+    value:  2E994C7F-3F03-3A07-879C-55690D22BEDA
+install-name:     '/usr/lib/libtbd-noappext.dylib'
+exports:
+  - targets:      [ arm64-macos ]
+    symbols:      [ _foo ]
+...
+
+#--- bar.s
+.globl _bar
+.p2align 2
+_bar:
+  ret
+
+#--- libbaz-noappext-reexport.tbd
+--- !tapi-tbd
+tbd-version:      4
+targets:          [ arm64-macos ]
+uuids:
+  - target:       arm64-macos
+    value:        00000000-0000-0000-0000-000000000001
+install-name:     '/usr/lib/libbaz.dylib'
+reexported-libraries:
+  - targets:      [ arm64-macos ]
+    libraries:    [ '/usr/lib/libbaz-noappext-reexport.dylib']
+--- !tapi-tbd
+tbd-version:      4
+targets:          [ arm64-macos ]
+flags: [ not_app_extension_safe ]
+uuids:
+  - target:       arm64-macos
+    value:        00000000-0000-0000-0000-000000000003
+install-name:     '/usr/lib/libbaz-noappext-reexport.dylib'
+parent-umbrella:
+  - targets:      [ arm64-macos ]
+    umbrella:     baz
+exports:
+  - targets:      [ arm64-macos ]
+    symbols:      [ _baz ]
+...