[ELF] Don't set the executable bit for relocatable or shared files

[phosek]

Summary

These are not executable files so they shouldn't be marked as such.

[ruiu]

So is true for .so, isn't it?

[phosek]

True, that's a good point.

[grimar]

+1 to testcase request.

ELF/Writer.cpp

1838

I believe LLD style avoids using ternary operator where possible.
So I see this code better as:

unsigned Flags = FileOutputBuffer::F_executable;
if (Config->Relocatable || Config->Shared)
  Flags = 0;

[ruiu]

ELF/Writer.cpp

1838

Yeah, sort of. I learned this style from Go. I'd prefer defaulting to 0 and re-setting F_executable though.

[phosek]

Test added.

[ruiu]

LGTM with this fix.

ELF/Writer.cpp

1837

Please remove !Config->Shared as other linkers set X bit to shared libraries.

ELF/Writer.cpp

 // Open a result file.
 template <class ELFT> void Writer<ELFT>::openFile() {
   if (!Config->Is64 && FileSize > UINT32_MAX) {
     error("output file too large: " + Twine(FileSize) + " bytes");
     return;
   }
 
   unlinkAsync(Config->OutputFile);
+  unsigned Flags = 0;
+  if (!Config->Relocatable && !Config->Shared)
+    Flags = FileOutputBuffer::F_executable;
   Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
-      FileOutputBuffer::create(Config->OutputFile, FileSize,
-                               FileOutputBuffer::F_executable);
+      FileOutputBuffer::create(Config->OutputFile, FileSize, Flags);
 
   if (!BufferOrErr)
     error("failed to open " + Config->OutputFile + ": " +
           llvm::toString(BufferOrErr.takeError()));
   else
     Buffer = std::move(*BufferOrErr);
 }
 

test/ELF/file-access.s

+# REQUIRES: x86, gnustat
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: ld.lld -r %t.o -o %t1.o
+# RUN: stat -c %%A %t1.o | FileCheck --check-prefix=CHECK-RELOC %s
+# CHECK-RELOC: -rw-r--r--
+# RUN: ld.lld -shared %t.o -o %t2.so
+# RUN: stat -c %%A %t2.so | FileCheck --check-prefix=CHECK-SHARED %s
+# CHECK-SHARED: -rw-r--r--
+# RUN: ld.lld %t.o -o %t3
+# RUN: stat -c %%A %t3 | FileCheck --check-prefix=CHECK-EXEC %s
+# CHECK-EXEC: -rwxr-xr-x
+
+.global _start
+_start:
+  nop

test/lit.cfg.py

 
 tar_executable = lit.util.which('tar', config.environment['PATH'])
 if tar_executable:
     tar_version = subprocess.Popen(
         [tar_executable, '--version'], stdout=subprocess.PIPE, env={'LANG': 'C'})
     if 'GNU tar' in tar_version.stdout.read().decode():
         config.available_features.add('gnutar')
     tar_version.wait()
+
+stat_executable = lit.util.which('stat', config.environment['PATH'])
+if stat_executable:
+    stat_version = subprocess.Popen(
+        [stat_executable, '--version'], stdout=subprocess.PIPE, env={'LANG': 'C'})
+    if 'GNU coreutils' in stat_version.stdout.read().decode():
+        config.available_features.add('gnustat')
+    stat_version.wait()