[llvm] [clang] Fix handling of adding a file with the same name as an existing dir to VFS (PR #94461)

[via llvm-commits]

https://github.com/jensmassberg updated https://github.com/llvm/llvm-project/pull/94461

>From 161365c534f4b5fb196c716544350790c86b061e Mon Sep 17 00:00:00 2001
From: jensmassberg <massberg at google.com>
Date: Wed, 5 Jun 2024 13:19:38 +0200
Subject: [PATCH 1/2] [clang] Fix handling of adding a file with the same name
 as an existing dir to VFS

---
 llvm/lib/Support/VirtualFileSystem.cpp           | 4 ++++
 llvm/unittests/Support/VirtualFileSystemTest.cpp | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/llvm/lib/Support/VirtualFileSystem.cpp b/llvm/lib/Support/VirtualFileSystem.cpp
index fcefdef992be..defe7a7f45f4 100644
--- a/llvm/lib/Support/VirtualFileSystem.cpp
+++ b/llvm/lib/Support/VirtualFileSystem.cpp
@@ -893,6 +893,10 @@ bool InMemoryFileSystem::addFile(const Twine &P, time_t ModificationTime,
     }
 
     if (auto *NewDir = dyn_cast<detail::InMemoryDirectory>(Node)) {
+      // Trying to insert a file in place of a directory.
+      if (I == E)
+        return false;
+
       Dir = NewDir;
     } else {
       assert((isa<detail::InMemoryFile>(Node) ||
diff --git a/llvm/unittests/Support/VirtualFileSystemTest.cpp b/llvm/unittests/Support/VirtualFileSystemTest.cpp
index e9fd9671ea6a..d12fd0ae2d50 100644
--- a/llvm/unittests/Support/VirtualFileSystemTest.cpp
+++ b/llvm/unittests/Support/VirtualFileSystemTest.cpp
@@ -1138,6 +1138,8 @@ TEST_F(InMemoryFileSystemTest, DuplicatedFile) {
   ASSERT_FALSE(FS.addFile("/a/b", 0, MemoryBuffer::getMemBuffer("a")));
   ASSERT_TRUE(FS.addFile("/a", 0, MemoryBuffer::getMemBuffer("a")));
   ASSERT_FALSE(FS.addFile("/a", 0, MemoryBuffer::getMemBuffer("b")));
+  ASSERT_TRUE(FS.addFile("/b/c/d", 0, MemoryBuffer::getMemBuffer("a")));
+  ASSERT_FALSE(FS.addFile("/b/c", 0, MemoryBuffer::getMemBuffer("a")));
 }
 
 TEST_F(InMemoryFileSystemTest, DirectoryIteration) {

>From 27152fdceb4aaae11254d74c207e3c8da078756e Mon Sep 17 00:00:00 2001
From: jensmassberg <massberg at google.com>
Date: Wed, 5 Jun 2024 13:19:38 +0200
Subject: [PATCH 2/2] [clang] Fix handling of adding a file with the same name
 as an existing dir to VFS

---
 llvm/lib/Support/VirtualFileSystem.cpp        | 61 ++++++++++---------
 .../Support/VirtualFileSystemTest.cpp         |  5 ++
 2 files changed, 36 insertions(+), 30 deletions(-)

diff --git a/llvm/lib/Support/VirtualFileSystem.cpp b/llvm/lib/Support/VirtualFileSystem.cpp
index fcefdef992be..7360901f2962 100644
--- a/llvm/lib/Support/VirtualFileSystem.cpp
+++ b/llvm/lib/Support/VirtualFileSystem.cpp
@@ -867,21 +867,16 @@ bool InMemoryFileSystem::addFile(const Twine &P, time_t ModificationTime,
   // Any intermediate directories we create should be accessible by
   // the owner, even if Perms says otherwise for the final path.
   const auto NewDirectoryPerms = ResolvedPerms | sys::fs::owner_all;
+
+  StringRef Name = *I;
   while (true) {
-    StringRef Name = *I;
-    detail::InMemoryNode *Node = Dir->getChild(Name);
+    Name = *I;
     ++I;
+    if (I == E)
+      break;
+    detail::InMemoryNode *Node = Dir->getChild(Name);
     if (!Node) {
-      if (I == E) {
-        // End of the path.
-        Dir->addChild(
-            Name, MakeNode({Dir->getUniqueID(), Path, Name, ModificationTime,
-                            std::move(Buffer), ResolvedUser, ResolvedGroup,
-                            ResolvedType, ResolvedPerms}));
-        return true;
-      }
-
-      // Create a new directory. Use the path up to here.
+      // This isn't the last element, so we create a new directory.
       Status Stat(
           StringRef(Path.str().begin(), Name.end() - Path.str().begin()),
           getDirectoryID(Dir->getUniqueID(), Name),
@@ -891,27 +886,33 @@ bool InMemoryFileSystem::addFile(const Twine &P, time_t ModificationTime,
           Name, std::make_unique<detail::InMemoryDirectory>(std::move(Stat))));
       continue;
     }
+    // Creating file under another file.
+    if (!isa<detail::InMemoryDirectory>(Node))
+      return false;
+    Dir = cast<detail::InMemoryDirectory>(Node);
+  }
+  detail::InMemoryNode *Node = Dir->getChild(Name);
+  if (!Node) {
+    Dir->addChild(Name,
+                  MakeNode({Dir->getUniqueID(), Path, Name, ModificationTime,
+                            std::move(Buffer), ResolvedUser, ResolvedGroup,
+                            ResolvedType, ResolvedPerms}));
+    return true;
+  }
+  if (isa<detail::InMemoryDirectory>(Node))
+    return ResolvedType == sys::fs::file_type::directory_file;
 
-    if (auto *NewDir = dyn_cast<detail::InMemoryDirectory>(Node)) {
-      Dir = NewDir;
-    } else {
-      assert((isa<detail::InMemoryFile>(Node) ||
-              isa<detail::InMemoryHardLink>(Node)) &&
-             "Must be either file, hardlink or directory!");
-
-      // Trying to insert a directory in place of a file.
-      if (I != E)
-        return false;
+  assert((isa<detail::InMemoryFile>(Node) ||
+          isa<detail::InMemoryHardLink>(Node)) &&
+         "Must be either file, hardlink or directory!");
 
-      // Return false only if the new file is different from the existing one.
-      if (auto Link = dyn_cast<detail::InMemoryHardLink>(Node)) {
-        return Link->getResolvedFile().getBuffer()->getBuffer() ==
-               Buffer->getBuffer();
-      }
-      return cast<detail::InMemoryFile>(Node)->getBuffer()->getBuffer() ==
-             Buffer->getBuffer();
-    }
+  // Return false only if the new file is different from the existing one.
+  if (auto *Link = dyn_cast<detail::InMemoryHardLink>(Node)) {
+    return Link->getResolvedFile().getBuffer()->getBuffer() ==
+           Buffer->getBuffer();
   }
+  return cast<detail::InMemoryFile>(Node)->getBuffer()->getBuffer() ==
+         Buffer->getBuffer();
 }
 
 bool InMemoryFileSystem::addFile(const Twine &P, time_t ModificationTime,
diff --git a/llvm/unittests/Support/VirtualFileSystemTest.cpp b/llvm/unittests/Support/VirtualFileSystemTest.cpp
index e9fd9671ea6a..9e9b4fbcdedd 100644
--- a/llvm/unittests/Support/VirtualFileSystemTest.cpp
+++ b/llvm/unittests/Support/VirtualFileSystemTest.cpp
@@ -1138,6 +1138,11 @@ TEST_F(InMemoryFileSystemTest, DuplicatedFile) {
   ASSERT_FALSE(FS.addFile("/a/b", 0, MemoryBuffer::getMemBuffer("a")));
   ASSERT_TRUE(FS.addFile("/a", 0, MemoryBuffer::getMemBuffer("a")));
   ASSERT_FALSE(FS.addFile("/a", 0, MemoryBuffer::getMemBuffer("b")));
+  ASSERT_TRUE(FS.addFile("/b/c/d", 0, MemoryBuffer::getMemBuffer("a")));
+  ASSERT_FALSE(FS.addFile("/b/c", 0, MemoryBuffer::getMemBuffer("a")));
+  ASSERT_TRUE(FS.addFile(
+      "/b/c", 0, MemoryBuffer::getMemBuffer(""), /*User=*/std::nullopt,
+      /*Group=*/std::nullopt, sys::fs::file_type::directory_file));
 }
 
 TEST_F(InMemoryFileSystemTest, DirectoryIteration) {