[Lldb-commits] [lldb] dbfdb13 - [lldb] [POSIX-DYLD] Update the cached exe path after attach

[Michał Górny via lldb-commits]

Author: Michał Górny
Date: 2020-12-17T09:31:22+01:00
New Revision: dbfdb139f75470a9abc78e7c9faf743fdd963c2d

URL: https://github.com/llvm/llvm-project/commit/dbfdb139f75470a9abc78e7c9faf743fdd963c2d
DIFF: https://github.com/llvm/llvm-project/commit/dbfdb139f75470a9abc78e7c9faf743fdd963c2d.diff

LOG: [lldb] [POSIX-DYLD] Update the cached exe path after attach

Fix the POSIX-DYLD plugin to update the cached executable path after
attaching.  Previously, the path was cached in DYLDRendezvous
constructor and not updated afterwards.  This meant that if LLDB was
attaching to a process (e.g. via connecting to lldb-server), the code
stored the empty path before DidAttach() resolved it.  The fix updates
the cached path in DidAttach().

This fixes a new instance of https://llvm.org/pr17880

Differential Revision: https://reviews.llvm.org/D92264

Added: 
    

Modified: 
    lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DYLDRendezvous.cpp
    lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DYLDRendezvous.h
    lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp
    lldb/test/API/commands/process/attach/TestProcessAttach.py
    lldb/test/API/commands/process/attach/main.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DYLDRendezvous.cpp b/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DYLDRendezvous.cpp
index 15b3805003a5..866acbddbdc8 100644
--- a/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DYLDRendezvous.cpp
+++ b/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DYLDRendezvous.cpp
@@ -94,12 +94,13 @@ DYLDRendezvous::DYLDRendezvous(Process *process)
     : m_process(process), m_rendezvous_addr(LLDB_INVALID_ADDRESS), m_current(),
       m_previous(), m_loaded_modules(), m_soentries(), m_added_soentries(),
       m_removed_soentries() {
-  Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
-
   m_thread_info.valid = false;
+  UpdateExecutablePath();
+}
 
-  // Cache a copy of the executable path
+void DYLDRendezvous::UpdateExecutablePath() {
   if (m_process) {
+    Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
     Module *exe_mod = m_process->GetTarget().GetExecutableModulePointer();
     if (exe_mod) {
       m_exe_file_spec = exe_mod->GetPlatformFileSpec();

diff  --git a/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DYLDRendezvous.h b/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DYLDRendezvous.h
index b028120eb0d4..3e88d88f407a 100644
--- a/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DYLDRendezvous.h
+++ b/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DYLDRendezvous.h
@@ -60,6 +60,9 @@ class DYLDRendezvous {
 
   DYLDRendezvous(lldb_private::Process *process);
 
+  /// Update the cached executable path.
+  void UpdateExecutablePath();
+
   /// Update the internal snapshot of runtime linker rendezvous and recompute
   /// the currently loaded modules.
   ///

diff  --git a/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp b/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp
index 01f746ada3ba..160faa74af23 100644
--- a/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp
+++ b/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp
@@ -102,6 +102,7 @@ void DynamicLoaderPOSIXDYLD::DidAttach() {
 
   ModuleSP executable_sp = GetTargetExecutable();
   ResolveExecutableModule(executable_sp);
+  m_rendezvous.UpdateExecutablePath();
 
   // find the main process load offset
   addr_t load_offset = ComputeLoadOffset();

diff  --git a/lldb/test/API/commands/process/attach/TestProcessAttach.py b/lldb/test/API/commands/process/attach/TestProcessAttach.py
index 5dfec5c76339..88429333edd3 100644
--- a/lldb/test/API/commands/process/attach/TestProcessAttach.py
+++ b/lldb/test/API/commands/process/attach/TestProcessAttach.py
@@ -20,6 +20,13 @@ class ProcessAttachTestCase(TestBase):
 
     NO_DEBUG_INFO_TESTCASE = True
 
+    def setUp(self):
+        # Call super's setUp().
+        TestBase.setUp(self)
+        # Find the line number to break for main.c.
+        self.line = line_number('main.cpp',
+                                '// Waiting to be attached...')
+
     @skipIfiOSSimulator
     def test_attach_to_process_by_id(self):
         """Test attach by process id"""
@@ -77,6 +84,28 @@ def test_attach_to_process_by_name(self):
         process = target.GetProcess()
         self.assertTrue(process, PROCESS_IS_VALID)
 
+    def test_attach_to_process_by_id_correct_executable_offset(self):
+        """
+        Test that after attaching to a process the executable offset
+        is determined correctly on FreeBSD.  This is a regression test
+        for dyld plugin getting the correct executable path,
+        and therefore being able to identify it in the module list.
+        """
+
+        self.build()
+        exe = self.getBuildArtifact(exe_name)
+
+        # In order to reproduce, we must spawn using a relative path
+        popen = self.spawnSubprocess(os.path.relpath(exe))
+
+        self.runCmd("process attach -p " + str(popen.pid))
+
+        # Make suer we did not attach to early
+        lldbutil.run_break_set_by_file_and_line(
+            self, "main.cpp", self.line, num_expected_locations=1, loc_exact=False)
+        self.runCmd("process continue")
+        self.expect("p g_val", substrs=["$0 = 12345"])
+
     def tearDown(self):
         # Destroy process before TestBase.tearDown()
         self.dbg.GetSelectedTarget().GetProcess().Destroy()

diff  --git a/lldb/test/API/commands/process/attach/main.cpp b/lldb/test/API/commands/process/attach/main.cpp
index 46ffacc0a840..a43ed8eac5b2 100644
--- a/lldb/test/API/commands/process/attach/main.cpp
+++ b/lldb/test/API/commands/process/attach/main.cpp
@@ -3,6 +3,8 @@
 #include <chrono>
 #include <thread>
 
+volatile int g_val = 12345;
+
 int main(int argc, char const *argv[]) {
     int temp;
     lldb_enable_attach();