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Fix process launch failure on FreeBSD after r365761 

Summary:
After rLLDB365761, and with `LLVM_ENABLE_ABI_BREAKING_CHECKS` enabled,
launching any process on FreeBSD crashes lldb with:

```
Expected<T> must be checked before access or destruction.
Expected<T> value was in success state. (Note: Expected<T> values in success mode must still be checked prior to being destroyed).
```

This is because `m_operation_thread` and `m_monitor_thread` were wrapped
in `llvm::Expected<>`, but this requires the objects to be correctly
initialized before accessing them.

To fix the crashes, use `llvm::Optional<>` for the members (as indicated
by labath), and use local variables to store the return values of
`LaunchThread` and `StartMonitoringChildProcess`.  Then, only assign to
the member variables after checking if the return values indicated
success.

Reviewers: devnexen, emaste, MaskRay, mgorny

Reviewed By: devnexen

Subscribers: jfb, labath, krytarowski, lldb-commits

Differential Revision: https://reviews.llvm.org/D68723

llvm-svn: 374444
This commit is contained in:
Dimitry Andric 2019-10-10 20:26:59 +00:00
parent 79f2432966
commit a42942e0ec
2 changed files with 32 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp
View File

@ -703,7 +703,7 @@ ProcessMonitor::ProcessMonitor(
const lldb_private::ProcessLaunchInfo & /* launch_info */,
lldb_private::Status &error)
: m_process(static_cast<ProcessFreeBSD *>(process)),
m_operation_thread(nullptr), m_monitor_thread(nullptr), m_pid(LLDB_INVALID_PROCESS_ID), m_terminal_fd(-1), m_operation(0) {
m_operation_thread(), m_monitor_thread(), m_pid(LLDB_INVALID_PROCESS_ID), m_terminal_fd(-1), m_operation(0) {
using namespace std::placeholders;
std::unique_ptr<LaunchArgs> args(
@ -730,20 +730,22 @@ ProcessMonitor::ProcessMonitor(
}
// Finally, start monitoring the child process for change in state.
m_monitor_thread = Host::StartMonitoringChildProcess(
llvm::Expected<lldb_private::HostThread> monitor_thread =
Host::StartMonitoringChildProcess(
std::bind(&ProcessMonitor::MonitorCallback, this, _1, _2, _3, _4),
GetPID(), true);
if (!m_monitor_thread->IsJoinable()) {
if (!monitor_thread || !monitor_thread->IsJoinable()) {
error.SetErrorToGenericError();
error.SetErrorString("Process launch failed.");
return;
}
m_monitor_thread = *monitor_thread;
}
ProcessMonitor::ProcessMonitor(ProcessFreeBSD *process, lldb::pid_t pid,
lldb_private::Status &error)
: m_process(static_cast<ProcessFreeBSD *>(process)),
m_operation_thread(nullptr), m_monitor_thread(nullptr), m_pid(pid), m_terminal_fd(-1), m_operation(0) {
m_operation_thread(), m_monitor_thread(), m_pid(pid), m_terminal_fd(-1), m_operation(0) {
using namespace std::placeholders;
sem_init(&m_operation_pending, 0, 0);
@ -768,14 +770,16 @@ ProcessMonitor::ProcessMonitor(ProcessFreeBSD *process, lldb::pid_t pid,
}
// Finally, start monitoring the child process for change in state.
m_monitor_thread = Host::StartMonitoringChildProcess(
llvm::Expected<lldb_private::HostThread> monitor_thread =
Host::StartMonitoringChildProcess(
std::bind(&ProcessMonitor::MonitorCallback, this, _1, _2, _3, _4),
GetPID(), true);
if (!m_monitor_thread->IsJoinable()) {
if (!monitor_thread || !monitor_thread->IsJoinable()) {
error.SetErrorToGenericError();
error.SetErrorString("Process attach failed.");
return;
}
m_monitor_thread = *monitor_thread;
}
ProcessMonitor::~ProcessMonitor() { StopMonitor(); }
@ -784,13 +788,15 @@ ProcessMonitor::~ProcessMonitor() { StopMonitor(); }
void ProcessMonitor::StartLaunchOpThread(LaunchArgs *args, Status &error) {
static const char *g_thread_name = "lldb.process.freebsd.operation";
if (m_operation_thread->IsJoinable())
if (m_operation_thread && m_operation_thread->IsJoinable())
return;
m_operation_thread =
ThreadLauncher::LaunchThread(g_thread_name, LaunchOpThread, args);
if (!m_operation_thread)
error = m_operation_thread.takeError();
llvm::Expected<lldb_private::HostThread> operation_thread =
ThreadLauncher::LaunchThread(g_thread_name, LaunchOpThread, args);
if (operation_thread)
m_operation_thread = *operation_thread;
else
error = operation_thread.takeError();
}
void *ProcessMonitor::LaunchOpThread(void *arg) {
@ -952,14 +958,15 @@ void ProcessMonitor::StartAttachOpThread(AttachArgs *args,
lldb_private::Status &error) {
static const char *g_thread_name = "lldb.process.freebsd.operation";
if (m_operation_thread->IsJoinable())
if (m_operation_thread && m_operation_thread->IsJoinable())
return;
m_operation_thread =
ThreadLauncher::LaunchThread(g_thread_name, AttachOpThread, args);
if (!m_operation_thread)
error = m_operation_thread.takeError();
llvm::Expected<lldb_private::HostThread> operation_thread =
ThreadLauncher::LaunchThread(g_thread_name, AttachOpThread, args);
if (operation_thread)
m_operation_thread = *operation_thread;
else
error = operation_thread.takeError();
}
void *ProcessMonitor::AttachOpThread(void *arg) {
@ -1374,7 +1381,7 @@ bool ProcessMonitor::DupDescriptor(const FileSpec &file_spec, int fd,
}
void ProcessMonitor::StopMonitoringChildProcess() {
if (m_monitor_thread->IsJoinable()) {
if (m_monitor_thread && m_monitor_thread->IsJoinable()) {
m_monitor_thread->Cancel();
m_monitor_thread->Join(nullptr);
m_monitor_thread->Reset();
@ -1412,10 +1419,9 @@ void ProcessMonitor::StopMonitor() {
bool ProcessMonitor::WaitForInitialTIDStop(lldb::tid_t tid) { return true; }
void ProcessMonitor::StopOpThread() {
if (!m_operation_thread->IsJoinable())
return;
m_operation_thread->Cancel();
m_operation_thread->Join(nullptr);
m_operation_thread->Reset();
if (m_operation_thread && m_operation_thread->IsJoinable()) {
m_operation_thread->Cancel();
m_operation_thread->Join(nullptr);
m_operation_thread->Reset();
}
}

4
lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h
View File

@ -183,8 +183,8 @@ public:
private:
ProcessFreeBSD *m_process;
llvm::Expected<lldb_private::HostThread> m_operation_thread;
llvm::Expected<lldb_private::HostThread> m_monitor_thread;
llvm::Optional<lldb_private::HostThread> m_operation_thread;
llvm::Optional<lldb_private::HostThread> m_monitor_thread;
lldb::pid_t m_pid;
int m_terminal_fd;