[unittests] Preserve LD_LIBRARY_PATH in crash recovery test

[miyuki]

Summary

We need to preserve the LD_LIBRARY_PATH environment variable when
spawning a child process (certain setups rely on non-standard paths
for e.g. libstdc++). In order to achieve this, set
LLVM_CRC_UNIXCRCRETURNCODE in the parent process instead of creating
the child's environment from scratch.

[aganea]

Thanks for the fix @miyuki ! Just being curious, what happens without this patch? I'm also wondering why isn't it a problem in the ProgramTest.cpp, since it also spawn child processes? (I actually copied some of this code from there)

[miyuki]

In our case, the child process fails to find the correct version of libstdc++ and exits with return code 1, ASSERT_EQ(-2, RetCode) fails.

[MaskRay]

llvm/unittests/Support/CrashRecoveryTest.cpp

178

Perhaps ExecuteAndWait should have a mode to append environment variables. In the absence of that feature,

llvm/utils/not/not.cpp

#ifdef _WIN32
    SetEnvironmentVariableA("...);
#else
    setenv(...);
#endif

[aganea]

llvm/unittests/Support/CrashRecoveryTest.cpp

178

Agreed. In that case @miyuki would this work?
Replacing:

std::vector<StringRef> EnvTable;
EnvTable.push_back("LLVM_CRC_UNIXCRCRETURNCODE=1");

by:

setenv("LLVM_CRC_UNIXCRCRETURNCODE", "1", 0);

[miyuki]

Use setenv in the parent process

[miyuki]

llvm/unittests/Support/CrashRecoveryTest.cpp

178

Yes, this works in our environment.

[aganea]

Great! Thanks for the fix!

llvm/unittests/Support/CrashRecoveryTest.cpp

TEST(CrashRecoveryTest, UnixCRCReturnCode) {
   }
 
   std::string Executable =
       sys::fs::getMainExecutable(TestMainArgv0, &CrashTestStringArg1);
   StringRef argv[] = {
       Executable, "--gtest_filter=CrashRecoveryTest.UnixCRCReturnCode"};
 
   // Add LLVM_CRC_UNIXCRCRETURNCODE to the environment of the child process.
-  std::vector<StringRef> EnvTable;
-  EnvTable.push_back("LLVM_CRC_UNIXCRCRETURNCODE=1");
+  int Res = setenv("LLVM_CRC_UNIXCRCRETURNCODE", "1", 0);
+  ASSERT_EQ(Res, 0);
 
   std::string Error;
   bool ExecutionFailed;
-  int RetCode = ExecuteAndWait(Executable, argv, makeArrayRef(EnvTable), {}, 0, 0, &Error,
+  int RetCode = ExecuteAndWait(Executable, argv, {}, {}, 0, 0, &Error,
                                &ExecutionFailed);
   ASSERT_EQ(-2, RetCode);
 }
 #endif