ProcessMonitor improvements for Linux.

-Remove tracing of fork/vfork until we add support for tracing inferiors' children on Linux.
-Add trace exec option for ptrace so that we don't receive legacy SIGTRAP signals on execve calls.
-Add handling of SIGCHLD sent by kernel (for now, deliver the signal to the inferior).

llvm-svn: 182153

1 files changed, 28 insertions, 3 deletions

diff --git a/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp b/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
index f7f7d8c6b73..bfb710dd3fb 100644
--- a/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
+++ b/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
@@ -1208,7 +1208,13 @@ ProcessMonitor::Launch(LaunchArgs *args)
     ptrace_opts |= PTRACE_O_TRACEEXIT;
 
     // Have the tracer trace threads which spawn in the inferior process.
-    ptrace_opts |= PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK | PTRACE_O_TRACECLONE;
+    // TODO: if we want to support tracing the inferiors' child, add the
+    // appropriate ptrace flags here (PTRACE_O_TRACEFORK, PTRACE_O_TRACEVFORK)
+    ptrace_opts |= PTRACE_O_TRACECLONE;
+
+    // Have the tracer notify us before execve returns
+    // (needed to disable legacy SIGTRAP generation)
+    ptrace_opts |= PTRACE_O_TRACEEXEC;
 
     if (PTRACE(PTRACE_SETOPTIONS, pid, NULL, (void*)ptrace_opts, 0) < 0)
     {
@@ -1390,8 +1396,11 @@ ProcessMonitor::MonitorSIGTRAP(ProcessMonitor *monitor,
         assert(false && "Unexpected SIGTRAP code!");
         break;
 
-    case (SIGTRAP | (PTRACE_EVENT_FORK << 8)):
-    case (SIGTRAP | (PTRACE_EVENT_VFORK << 8)):
+    // TODO: these two cases are required if we want to support tracing
+    // of the inferiors' children
+    // case (SIGTRAP | (PTRACE_EVENT_FORK << 8)):
+    // case (SIGTRAP | (PTRACE_EVENT_VFORK << 8)):
+
     case (SIGTRAP | (PTRACE_EVENT_CLONE << 8)):
     {
         unsigned long tid = 0;
@@ -1401,6 +1410,11 @@ ProcessMonitor::MonitorSIGTRAP(ProcessMonitor *monitor,
         break;
     }
 
+    case (SIGTRAP | (PTRACE_EVENT_EXEC << 8)):
+        // Don't follow the child by default and resume
+        monitor->Resume(pid, SIGCONT);
+        break;
+
     case (SIGTRAP | (PTRACE_EVENT_EXIT << 8)):
     {
         // The inferior process is about to exit.  Maintain the process in a
@@ -1478,6 +1492,17 @@ ProcessMonitor::MonitorSignal(ProcessMonitor *monitor,
         return ProcessMessage::Crash(pid, reason, signo, fault_addr);
     }
 
+    if (signo == SIGCHLD) {
+        assert(monitor);
+        // TODO: Implement tracing of inferiors' children
+        // If we fail to deliver the signal then create a message with the signal
+        if (!monitor->Resume(pid, signo)) {
+            assert(0 && "SIGCHLD delivery failed");
+            message = ProcessMessage::Signal(pid, signo);
+        }
+        return message;
+    }
+
     // Everything else is "normal" and does not require any special action on
     // our part.
     return ProcessMessage::Signal(pid, signo);