[libc] Let wrappergen pick LLVM libc mangled name from aliasee file.

[sivachandra]

Summary

Along the way, made a change to run tool unittests when the target
"check-libc" is run by introducing a libc testsuite for tool unittests.

[michaelrj]

LGTM

libc/test/utils/tools/CMakeLists.txt

-add_custom_target(libc-tool-util-tests)
+add_libc_testsuite(libc-tool-unittests)
 
 function(add_libc_tool_unittest target_name)
 
   cmake_parse_arguments(
     "LIBC_TOOL_UNITTEST"
     "" # No optional arguments
     "" # Single value arguments
     "SRCS;DEPENDS;ARGS" # Multi-value arguments
function(add_libc_tool_unittest target_name)
   )
 
   add_custom_command(
     TARGET ${target_name}
     POST_BUILD
     COMMAND $<TARGET_FILE:${target_name}> 
             ${LIBC_TOOL_UNITTEST_ARGS}
   )
-  add_dependencies(libc-tool-util-tests ${target_name})
+  add_dependencies(libc-tool-unittests ${target_name})
 
   target_compile_options(${target_name} PUBLIC -fno-rtti)
   target_link_libraries(${target_name} PRIVATE LLVMSupport)
 endfunction()
 
 add_subdirectory(WrapperGen)

libc/test/utils/tools/WrapperGen/CMakeLists.txt

-add_libc_tool_unittest( wrappergen_test
+add_libc_tool_unittest(
+  wrappergen_test
   SRCS 
     wrappergen_test.cpp   
   ARGS
     --path=${LIBC_SOURCE_DIR}
     --tool=${CMAKE_BINARY_DIR}/bin/libc-wrappergen
     --api=${LIBC_SOURCE_DIR}/test/utils/tools/WrapperGen/testapi.td
 )
 
 add_dependencies(wrappergen_test libc-wrappergen)

libc/test/utils/tools/WrapperGen/wrappergen_test.cpp

 //===-- Unittests for WrapperGen ------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/FileUtilities.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Program.h"
 #include "llvm/Support/raw_ostream.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include <unistd.h>
 
 llvm::cl::opt<std::string>
TEST_F(WrapperGenTest, RunWrapperGenOnStrlenWithAliasee) {
   ASSERT_EQ(STDOutOutput, "extern \"C\" size_t strlen(const char * __arg0) "
                           "__attribute__((alias(\"STRLEN_ALIAS\")));\n");
   // TODO:(michaelrj) Figure out how to make this output comparison
   // less brittle. Currently it's just comparing the output of the program
   // to an exact string, this means that even a small formatting change
   // would break this test.
 }
 
+TEST_F(WrapperGenTest, DeclStrlenAliasUsingAliaseeFile) {
+  llvm::Optional<llvm::StringRef> Redirects[] = {
+      llvm::None, llvm::StringRef(STDOutFile.get().TmpName),
+      llvm::StringRef(STDErrFile.get().TmpName)};
+
+  const char *AliaseeFileContent = "abc\nxyz__llvm_libcSTRLEN_ALIAS\nijk\n";
+  llvm::SmallVector<char> AliaseeFilePath;
+  auto AliaseeFileCreateError = llvm::sys::fs::createUniqueFile(
+      "libc-wrappergen-test-aliasee-file-%%-%%-%%-%%.txt", AliaseeFilePath);
+  ASSERT_FALSE(AliaseeFileCreateError);
+  auto AliaseeFileWriteError = llvm::writeFileAtomically(
+      "libc-wrappergen-temp-test-aliasee-file-%%-%%-%%-%%.txt",
+      llvm::StringRef(AliaseeFilePath.data()),
+      llvm::StringRef(AliaseeFileContent));
+  ASSERT_FALSE(AliaseeFileWriteError);
+
+  llvm::StringRef ArgV[] = {ProgPath,
+                            llvm::StringRef(IncludeArg),
+                            llvm::StringRef(APIArg),
+                            "--aliasee-file",
+                            llvm::StringRef(AliaseeFilePath.data()),
+                            "--name",
+                            "strlen"};
+
+  int ExitCode =
+      llvm::sys::ExecuteAndWait(ProgPath, ArgV, llvm::None, Redirects);
+
+  EXPECT_EQ(ExitCode, 0);
+
+  auto STDErrOrError = llvm::MemoryBuffer::getFile(STDErrFile.get().TmpName);
+  std::string STDErrOutput = STDErrOrError.get()->getBuffer().str();
+
+  ASSERT_EQ(STDErrOutput, "");
+
+  auto STDOutOrError = llvm::MemoryBuffer::getFile(STDOutFile.get().TmpName);
+  std::string STDOutOutput = STDOutOrError.get()->getBuffer().str();
+
+  ASSERT_EQ(STDOutOutput,
+            "extern \"C\" size_t strlen(const char * __arg0) "
+            "__attribute__((alias(\"xyz__llvm_libcSTRLEN_ALIAS\")));\n");
+}
+
+/////////////////////////////////////////////////////////////////////
 /////////////////////////////////////////////////////////////////////
 // BAD INPUT TESTS
 // all of the tests after this point are testing inputs that should
 // return errors
 /////////////////////////////////////////////////////////////////////
 
 TEST_F(WrapperGenTest,
        RunWrapperGenOnStrlenWithAliaseeAndAliaseeFileWhichIsError) {
ASSERT_EQ(STDErrOutput, ("error: Unable to read the aliasee file " +
                            BadAliaseeFileName + "\n")
                               .str());
 
   auto STDOutOrError = llvm::MemoryBuffer::getFile(STDOutFile.get().TmpName);
   std::string STDOutOutput = STDOutOrError.get()->getBuffer().str();
 
   ASSERT_EQ(STDOutOutput, "");
 }
+
+TEST_F(WrapperGenTest, RunWithAliaseeFileMissingLLVMLibcName) {
+  llvm::Optional<llvm::StringRef> Redirects[] = {
+      llvm::None, llvm::StringRef(STDOutFile.get().TmpName),
+      llvm::StringRef(STDErrFile.get().TmpName)};
+
+  llvm::SmallVector<char> AliaseeFilePath;
+  auto AliaseeFileCreateError = llvm::sys::fs::createUniqueFile(
+      "libc-wrappergen-test-aliasee-file-%%-%%-%%-%%.txt", AliaseeFilePath);
+  ASSERT_FALSE(AliaseeFileCreateError);
+
+  llvm::StringRef ArgV[] = {ProgPath,
+                            llvm::StringRef(IncludeArg),
+                            llvm::StringRef(APIArg),
+                            "--aliasee-file",
+                            llvm::StringRef(AliaseeFilePath.data()),
+                            "--name",
+                            "strlen"};
+
+  int ExitCode =
+      llvm::sys::ExecuteAndWait(ProgPath, ArgV, llvm::None, Redirects);
+
+  EXPECT_NE(ExitCode, 0);
+
+  auto STDErrOrError = llvm::MemoryBuffer::getFile(STDErrFile.get().TmpName);
+  std::string STDErrOutput = STDErrOrError.get()->getBuffer().str();
+
+  ASSERT_EQ(STDErrOutput, ("error: Did not find an LLVM libc mangled name in " +
+                           AliaseeFilePath + "\n")
+                              .str());
+}

libc/utils/tools/WrapperGen/Main.cpp

 
 static std::string GetAliaseeName() {
   if (AliaseeString.size() > 0)
     return AliaseeString;
 
   auto ErrorOrBuf = llvm::MemoryBuffer::getFile(AliaseeFile);
   if (!ErrorOrBuf)
     llvm::PrintFatalError("Unable to read the aliasee file " + AliaseeFile);
-  return std::string(ErrorOrBuf.get()->getBuffer().trim());
+  llvm::StringRef FileContent = ErrorOrBuf.get()->getBuffer().trim();
+  llvm::SmallVector<llvm::StringRef> Lines;
+  FileContent.split(Lines, '\n');
+  for (llvm::StringRef L : Lines) {
+    if (L.contains("__llvm_libc"))
+      return std::string(L);
+  }
+  llvm::PrintFatalError("Did not find an LLVM libc mangled name in " +
+                        AliaseeFile);
+  return std::string();
 }
 
 static bool WrapperGenMain(llvm::raw_ostream &OS, llvm::RecordKeeper &Records) {
   if (!AliaseeString.empty() && !AliaseeFile.empty()) {
     llvm::PrintFatalError("The options 'aliasee' and 'aliasee-file' cannot "
                           "be specified simultaniously.");
   }