commit d144087c963d8189bb4aeaa7800dcb9f93ac84db
author Jonas Devlieghere <jonas@devlieghere.com> Fri Apr 03 09:18:47 2020 -0700
committer Jonas Devlieghere <jonas@devlieghere.com> Fri Apr 03 09:29:22 2020 -0700
tree ee64e6c0071c6c5387663acffc8df87920406fe4
parent 63bfb3a81ba2aef8d0444b58aafc868af38a623c

[lldb/Support] Treat empty FileSpec as an invalid file.

LLDB relies on empty FileSpecs being invalid files, for example, they
don't exists. Currently this assumption does not always hold during
reproducer replay, because we pass the result of GetPath to the VFS.
This is an empty string, which the VFS converts to an absolute directory
by prepending the current working directory, before looking it up in the
YAML mapping. This means that an empty FileSpec will exist when the
current working directory does. This breaks at least one test
(TestAddDsymCommand.py) when ran from replay.

This patch special cases empty FileSpecs and returns a sensible result
before calling GetPath and forwarding the call.

Differential revision: https://reviews.llvm.org/D77351

lldb/source/Host/common/FileSystem.cpp

diff --git a/lldb/source/Host/common/FileSystem.cpp b/lldb/source/Host/common/FileSystem.cpp
index dcfa594..7e33eeb 100644
--- a/lldb/source/Host/common/FileSystem.cpp
+++ b/lldb/source/Host/common/FileSystem.cpp
@@ -87,6 +87,11 @@
 
 vfs::directory_iterator FileSystem::DirBegin(const FileSpec &file_spec,
                                              std::error_code &ec) {
+  if (!file_spec) {
+    ec = std::error_code(static_cast<int>(errc::no_such_file_or_directory),
+                         std::system_category());
+    return {};
+  }
   return DirBegin(file_spec.GetPath(), ec);
 }
 
@@ -97,6 +102,9 @@
 
 llvm::ErrorOr<vfs::Status>
 FileSystem::GetStatus(const FileSpec &file_spec) const {
+  if (!file_spec)
+    return std::error_code(static_cast<int>(errc::no_such_file_or_directory),
+                           std::system_category());
   return GetStatus(file_spec.GetPath());
 }
 
@@ -106,6 +114,8 @@
 
 sys::TimePoint<>
 FileSystem::GetModificationTime(const FileSpec &file_spec) const {
+  if (!file_spec)
+    return sys::TimePoint<>();
   return GetModificationTime(file_spec.GetPath());
 }
 
@@ -117,6 +127,8 @@
 }
 
 uint64_t FileSystem::GetByteSize(const FileSpec &file_spec) const {
+  if (!file_spec)
+    return 0;
   return GetByteSize(file_spec.GetPath());
 }
 
@@ -133,6 +145,8 @@
 
 uint32_t FileSystem::GetPermissions(const FileSpec &file_spec,
                                     std::error_code &ec) const {
+  if (!file_spec)
+    return sys::fs::perms::perms_not_known;
   return GetPermissions(file_spec.GetPath(), ec);
 }
 
@@ -154,7 +168,7 @@
 bool FileSystem::Exists(const Twine &path) const { return m_fs->exists(path); }
 
 bool FileSystem::Exists(const FileSpec &file_spec) const {
-  return Exists(file_spec.GetPath());
+  return file_spec && Exists(file_spec.GetPath());
 }
 
 bool FileSystem::Readable(const Twine &path) const {
@@ -162,7 +176,7 @@
 }
 
 bool FileSystem::Readable(const FileSpec &file_spec) const {
-  return Readable(file_spec.GetPath());
+  return file_spec && Readable(file_spec.GetPath());
 }
 
 bool FileSystem::IsDirectory(const Twine &path) const {
@@ -173,7 +187,7 @@
 }
 
 bool FileSystem::IsDirectory(const FileSpec &file_spec) const {
-  return IsDirectory(file_spec.GetPath());
+  return file_spec && IsDirectory(file_spec.GetPath());
 }
 
 bool FileSystem::IsLocal(const Twine &path) const {
@@ -183,7 +197,7 @@
 }
 
 bool FileSystem::IsLocal(const FileSpec &file_spec) const {
-  return IsLocal(file_spec.GetPath());
+  return file_spec && IsLocal(file_spec.GetPath());
 }
 
 void FileSystem::EnumerateDirectory(Twine path, bool find_directories,
@@ -261,6 +275,9 @@
 }
 
 void FileSystem::Resolve(FileSpec &file_spec) {
+  if (!file_spec)
+    return;
+
   // Extract path from the FileSpec.
   SmallString<128> path;
   file_spec.GetPath(path);

lldb/unittests/Host/FileSystemTest.cpp

diff --git a/lldb/unittests/Host/FileSystemTest.cpp b/lldb/unittests/Host/FileSystemTest.cpp
index d8db2c1..f31c5c4 100644
--- a/lldb/unittests/Host/FileSystemTest.cpp
+++ b/lldb/unittests/Host/FileSystemTest.cpp
@@ -303,3 +303,29 @@
   EXPECT_EQ(code.value(), ENOENT);
 }
 
+TEST(FileSystemTest, EmptyTest) {
+  FileSpec spec;
+  FileSystem fs;
+
+  {
+    std::error_code ec;
+    fs.DirBegin(spec, ec);
+    EXPECT_EQ(ec.category(), std::system_category());
+    EXPECT_EQ(ec.value(), ENOENT);
+  }
+
+  {
+    llvm::ErrorOr<vfs::Status> status = fs.GetStatus(spec);
+    ASSERT_FALSE(status);
+    EXPECT_EQ(status.getError().category(), std::system_category());
+    EXPECT_EQ(status.getError().value(), ENOENT);
+  }
+
+  EXPECT_EQ(sys::TimePoint<>(), fs.GetModificationTime(spec));
+  EXPECT_EQ(static_cast<uint64_t>(0), fs.GetByteSize(spec));
+  EXPECT_EQ(llvm::sys::fs::perms::perms_not_known, fs.GetPermissions(spec));
+  EXPECT_FALSE(fs.Exists(spec));
+  EXPECT_FALSE(fs.Readable(spec));
+  EXPECT_FALSE(fs.IsDirectory(spec));
+  EXPECT_FALSE(fs.IsLocal(spec));
+}