[dsymutil] Fix crash in the Reproducer/FileCollector when TMPDIR is empty

[JDevlieghere]

Summary

Fix a crash in dsymutil caused by the Reproducer/FileCollector when TMPDIR is empty.

rdar://102170986

[goncharov]

llvm/test/tools/dsymutil/X86/reproducer.test

17

unfortunately this still crashes if run in CI where you can't write anywhere. I wonder what tmpdir defaults to if empty? root of fs?

llvm/lib/Support/FileCollector.cpp

static bool isCaseSensitivePath(StringRef Path) {
   // default.
   UpperDest = Path.upper();
   if (!sys::fs::real_path(UpperDest, RealDest) && Path.equals(RealDest))
     return false;
   return true;
 }
 
 FileCollector::FileCollector(std::string Root, std::string OverlayRoot)
-    : Root(std::move(Root)), OverlayRoot(std::move(OverlayRoot)) {
+    : Root(Root), OverlayRoot(OverlayRoot) {
+  assert(sys::path::is_absolute(Root) && "Root not absolute");
+  assert(sys::path::is_absolute(OverlayRoot) && "OverlayRoot not absolute");
 }
 
 void FileCollector::PathCanonicalizer::updateWithRealPath(
     SmallVectorImpl<char> &Path) {
   StringRef SrcPath(Path.begin(), Path.size());
   StringRef Filename = sys::path::filename(SrcPath);
   StringRef Directory = sys::path::parent_path(SrcPath);
 

llvm/test/tools/dsymutil/X86/reproducer.test

 # UNSUPPORTED: system-windows
 # This test is unsupported on windows because it creates paths
 # longer than MAX_PATH
 
 # Recreate the folder structure in a temp directory we can remove later.
 RUN: rm -rf %t
 RUN: mkdir -p %t/Inputs
 RUN: cp %p/../Inputs/basic.macho.x86_64 %t/Inputs
 RUN: cp %p/../Inputs/basic1.macho.x86_64.o %t/Inputs
 RUN: cp %p/../Inputs/basic2.macho.x86_64.o %t/Inputs
 RUN: cp %p/../Inputs/basic3.macho.x86_64.o %t/Inputs
 
 # Verify all the files are present.
 RUN: dsymutil -f -o - -oso-prepend-path=%t %t/Inputs/basic.macho.x86_64 | llvm-dwarfdump -a - | FileCheck %s
 
+# Make sure we don't crash with an empty TMPDIR.
+RUN: env TMPDIR="" dsymutil -o -f %t.generate -oso-prepend-path=%t %t/Inputs/basic.macho.x86_64 2>&1
+
 # Create a reproducer.
 RUN: env DSYMUTIL_REPRODUCER_PATH=%t.repro dsymutil -gen-reproducer -f -o %t.generate -oso-prepend-path=%t %t/Inputs/basic.macho.x86_64 2>&1 | FileCheck %s --check-prefixes=REPRODUCER
 RUN: llvm-dwarfdump -a %t.generate | FileCheck %s
 
 # Remove the input files and verify that was successful.
 RUN: rm -rf %t
 RUN: not dsymutil -f -o %t.error -oso-prepend-path=%t %t/Inputs/basic.macho.x86_64 2>&1 | FileCheck %s --check-prefix=ERROR
 

llvm/tools/dsymutil/Reproducer.cpp

 static std::string createReproducerDir(std::error_code &EC) {
   SmallString<128> Root;
   if (const char *Path = getenv("DSYMUTIL_REPRODUCER_PATH")) {
     Root.assign(Path);
     EC = sys::fs::create_directory(Root);
   } else {
     EC = sys::fs::createUniqueDirectory("dsymutil", Root);
   }
+  sys::fs::make_absolute(Root);
   return EC ? "" : std::string(Root);
 }
 
 Reproducer::Reproducer() : VFS(vfs::getRealFileSystem()) {}
 Reproducer::~Reproducer() = default;
 
 ReproducerGenerate::ReproducerGenerate(std::error_code &EC, int Argc,
                                        char **Argv, bool GenerateOnExit)