implement a subset of match filters for the qfProcessInfo and qsProcessInfo packets (#168)

## Purpose
Properly implement a subset of match filters for the `qfProcessInfo` and
`qsProcessInfo` packets.

fixes #167
fixes #171 

## Overview
* Fix the `Handle_qfProcessInfo` implementation to parse the incoming
string; it was mistakenly using the full argument string `args` instead
of the individual argument string `arg`.
* Decode the hex-encoded process name string to match against in
`Handle_qfProcessInfo`. It was incorrectly not decoded before.
* Fix `PlatformSessionImplBase::updateProcesses` to clear the process
list before enumerating/matching.
* Without this fix, the process list keeps growing with redundant
entries.
* Implement `PlatformSessionImplBase::processMatch` to perform the
actual matching against the values provided with the `qfProcessInfo`
packet. They were previously ignored (and noted in a TODO).
* When matching against the process name, try matching against both the
process name in the `ProcessInfo` structure and the base thread name for
the process.
* This matching is necessary on Linux and Android because the process
name is the fully qualified path name to the executable, but the match
name is just the base name (e.g. "/home/user/a.out" vs "a.out") which
matches the primary thread name.
* This change was the most targeted fix that didn't disrupt other
behavior and break other test cases that rely on `ProcessInfo.name`
being the fully qualified executable file name.
* Add TODOs for the remaining missing functionality. The test coverage
on this code path appears to be incomplete.
* Enable the
`TestProcessAttach.ProcessAttachTestCase.test_attach_to_process_by_name`
test case on Linux and Android.

## Background
The `qfProcessInfo` and `qsProcessInfo` packets are and LLDB platform
extension and are used together to enumerate processes on the target.
They are documented
[here](https://lldb.llvm.org/resources/lldbgdbremote.html#qfprocessinfo-qsprocessinfo-platform-extension).

## Validation
Ranually run the `test_attach_to_process_by_name` test case on Android
and Linux to confirm it passes.

Author: andrurogerz

Headers/DebugServer2/GDBRemote/PlatformSessionImpl.h

@@ -49,6 +49,10 @@ class PlatformSessionImplBase : public DummySessionDelegateImpl {
 
 private:
   void updateProcesses(ProcessInfoMatch const &match) const;
+  static bool processMatch(ProcessInfoMatch const &match,
+                           ds2::ProcessInfo const &info);
+  static bool nameMatch(ProcessInfoMatch const &match,
+                        std::string const &name);
 };
 
 using PlatformSessionImpl =

Sources/GDBRemote/PlatformSessionImpl.cpp

@@ -139,13 +139,72 @@ ErrorCode PlatformSessionImplBase::onLaunchDebugServer(Session &session,
 
 void PlatformSessionImplBase::updateProcesses(
     ProcessInfoMatch const &match) const {
-  // TODO(fjricci) we should only add processes that match "match"
+  _processIterationState.vals.clear();
   Platform::EnumerateProcesses(
       true, UserId(), [&](ds2::ProcessInfo const &info) {
-        _processIterationState.vals.push_back(info.pid);
+        if (processMatch(match, info))
+          _processIterationState.vals.push_back(info.pid);
       });
 
   _processIterationState.it = _processIterationState.vals.begin();
 }
+
+bool PlatformSessionImplBase::processMatch(ProcessInfoMatch const &match,
+                                           ds2::ProcessInfo const &info) {
+  // Allow matching against the process info name, which is the full executable
+  // file path on Linux, or the name of the primary thread.
+  if (!match.name.empty() &&
+      !nameMatch(match, info.name) &&
+      !nameMatch(match, Platform::GetThreadName(info.pid, info.pid)))
+    return false;
+
+  if (match.pid != 0 && info.pid != match.pid)
+      return false;
+
+#if !defined(OS_WIN32)
+  if (match.parentPid != 0 && info.parentPid != match.parentPid)
+      return false;
+
+  if (match.effectiveUid != 0 && info.effectiveUid != match.effectiveUid)
+    return false;
+
+  if (match.effectiveGid != 0 && info.effectiveGid != match.effectiveGid)
+    return false;
+#endif
+
+  if (match.realGid != 0 && info.realGid != match.realGid)
+      return false;
+
+  if (match.realUid != 0 && info.realUid != match.realUid)
+      return false;
+
+  // TODO(andrurogerz): account for match.triple
+  return true;
+}
+
+bool PlatformSessionImplBase::nameMatch(ProcessInfoMatch const &match,
+                                        std::string const &name) {
+  if (match.nameMatch == "equals")
+    return name.compare(match.name) == 0;
+
+  if (match.nameMatch == "starts_with")
+    return name.size() >= match.name.size() &&
+           name.compare(0, match.name.size(), match.name) == 0;
+
+  if (match.nameMatch == "ends_with")
+    return name.size() >= match.name.size() &&
+           name.compare(name.size() - match.name.size(),
+                        match.name.size(),
+                        match.name) == 0;
+
+  if (match.nameMatch == "contains")
+    return name.rfind(match.name) != std::string::npos;
+
+  if (match.nameMatch == "regex")
+    // TODO(andrurogerz): match against "regex"
+    DS2LOG(Error, "name_match:regex is not currently supported");
+
+  return true;
+}
 } // namespace GDBRemote
 } // namespace ds2

Sources/GDBRemote/Session.cpp

@@ -2495,15 +2495,15 @@ void Session::Handle_qfProcessInfo(ProtocolInterpreter::Handler const &,
 
   ParseList(args, ';', [&](std::string const &arg) {
     std::string key, value;
-    size_t colon = args.find(':');
+    size_t colon = arg.find(':');
     if (colon == std::string::npos)
       return;
 
-    key = args.substr(0, colon);
-    value = args.substr(colon + 1);
+    key = arg.substr(0, colon);
+    value = arg.substr(colon + 1);
 
     if (key == "name") {
-      match.name = value;
+      match.name = HexToString(value);
     } else if (key == "name_match") {
       match.nameMatch = value;
     } else if (key == "pid") {

Support/Testing/Excluded/ds2/android-x86_64.excluded

@@ -108,7 +108,6 @@ TestNonStop.LldbGdbServerTestCase.test_vCont_then_partial_stop_run_both_llgs
 TestNonStop.LldbGdbServerTestCase.test_vCont_then_stop_llgs
 TestNonStop.LldbGdbServerTestCase.test_vCtrlC_llgs
 TestProcessAttach.ProcessAttachTestCase.test_attach_to_process_by_id_correct_executable_offset
-TestProcessAttach.ProcessAttachTestCase.test_attach_to_process_by_name
 TestRegistersIterator.RegistersIteratorTestCase.test_iter_registers_dwarf
 TestRegistersIterator.RegistersIteratorTestCase.test_iter_registers_dwo
 TestReportData.AsanTestReportDataCase.test_dwo

Support/Testing/Excluded/ds2/linux-i686.excluded

@@ -169,7 +169,6 @@ TestNoreturnUnwind.NoreturnUnwind.test_dwo
 TestPlatformCommand.PlatformCommandTestCase.test_shell
 TestPrintfAfterUp.Radar9531204TestCase.test_expr_commands_dwarf
 TestPrintfAfterUp.Radar9531204TestCase.test_expr_commands_dwo
-TestProcessAttach.ProcessAttachTestCase.test_attach_to_process_by_name
 TestRegistersIterator.RegistersIteratorTestCase.test_iter_registers_dwarf
 TestRegistersIterator.RegistersIteratorTestCase.test_iter_registers_dwo
 TestReturnValue.ReturnValueTestCase.test_with_python_dwarf

Support/Testing/Excluded/ds2/linux-x86_64.excluded

@@ -164,7 +164,6 @@ TestNoreturnUnwind.NoreturnUnwind.test_dwarf
 TestNoreturnUnwind.NoreturnUnwind.test_dwo
 TestPrintfAfterUp.Radar9531204TestCase.test_expr_commands_dwarf
 TestPrintfAfterUp.Radar9531204TestCase.test_expr_commands_dwo
-TestProcessAttach.ProcessAttachTestCase.test_attach_to_process_by_name
 TestProcessSaveCoreMinidump.ProcessSaveCoreMinidumpTestCase.test_save_linux_mini_dump_default_options_dwarf
 TestProcessSaveCoreMinidump.ProcessSaveCoreMinidumpTestCase.test_save_linux_mini_dump_default_options_dwarf
 TestProcessSaveCoreMinidump.ProcessSaveCoreMinidumpTestCase.test_save_linux_mini_dump_default_options_dwo