From 5437a4c5e90886c6688da90eaf70617d50e64895 Mon Sep 17 00:00:00 2001
From: Ben Langmuir <blangmuir@apple.com>
Date: Tue, 25 Apr 2023 11:04:06 -0700
Subject: [llvm][vfs] Avoid silent fallback to process-wide working directory

In createPhysicalFileSystem, preserve the per-instance working
directory, even after the first call to getcwd fails.

rdar://108213753

Differential Revision: https://reviews.llvm.org/D149173
---
 llvm/lib/Support/VirtualFileSystem.cpp | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

(limited to 'llvm/lib/Support/VirtualFileSystem.cpp')

diff --git a/llvm/lib/Support/VirtualFileSystem.cpp b/llvm/lib/Support/VirtualFileSystem.cpp
index a167e0a76795..bcf5389db6a0 100644
--- a/llvm/lib/Support/VirtualFileSystem.cpp
+++ b/llvm/lib/Support/VirtualFileSystem.cpp
@@ -257,12 +257,12 @@ public:
   explicit RealFileSystem(bool LinkCWDToProcess) {
     if (!LinkCWDToProcess) {
       SmallString<128> PWD, RealPWD;
-      if (llvm::sys::fs::current_path(PWD))
-        return; // Awful, but nothing to do here.
-      if (llvm::sys::fs::real_path(PWD, RealPWD))
-        WD = {PWD, PWD};
+      if (std::error_code EC = llvm::sys::fs::current_path(PWD))
+        WD = EC;
+      else if (llvm::sys::fs::real_path(PWD, RealPWD))
+        WD = WorkingDirectory{PWD, PWD};
       else
-        WD = {PWD, RealPWD};
+        WD = WorkingDirectory{PWD, RealPWD};
     }
   }
 
@@ -284,10 +284,10 @@ private:
   // If this FS has its own working dir, use it to make Path absolute.
   // The returned twine is safe to use as long as both Storage and Path live.
   Twine adjustPath(const Twine &Path, SmallVectorImpl<char> &Storage) const {
-    if (!WD)
+    if (!WD || !*WD)
       return Path;
     Path.toVector(Storage);
-    sys::fs::make_absolute(WD->Resolved, Storage);
+    sys::fs::make_absolute(WD->get().Resolved, Storage);
     return Storage;
   }
 
@@ -297,7 +297,7 @@ private:
     // The current working directory, with links resolved. (readlink .).
     SmallString<128> Resolved;
   };
-  std::optional<WorkingDirectory> WD;
+  std::optional<llvm::ErrorOr<WorkingDirectory>> WD;
 };
 
 } // namespace
@@ -323,8 +323,10 @@ RealFileSystem::openFileForRead(const Twine &Name) {
 }
 
 llvm::ErrorOr<std::string> RealFileSystem::getCurrentWorkingDirectory() const {
+  if (WD && *WD)
+    return std::string(WD->get().Specified.str());
   if (WD)
-    return std::string(WD->Specified.str());
+    return WD->getError();
 
   SmallString<128> Dir;
   if (std::error_code EC = llvm::sys::fs::current_path(Dir))
@@ -345,7 +347,7 @@ std::error_code RealFileSystem::setCurrentWorkingDirectory(const Twine &Path) {
     return std::make_error_code(std::errc::not_a_directory);
   if (auto Err = llvm::sys::fs::real_path(Absolute, Resolved))
     return Err;
-  WD = {Absolute, Resolved};
+  WD = WorkingDirectory{Absolute, Resolved};
   return std::error_code();
 }
 
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