[lldb] [Process/NetBSD] Copy watchpoints to newly-created threads

NetBSD ptrace interface does not populate watchpoints to newly-created
threads.  Solve this via copying the watchpoints from the current thread
when new thread is reported via TRAP_LWP.

Add a test that verifies that when the user does not have permissions
to set watchpoints on NetBSD, the 'watchpoint set' errors out gracefully
and thread monitoring does not crash on being unable to copy watchpoints
to new threads.

Differential Revision: https://reviews.llvm.org/D70023

2 files changed, 45 insertions, 0 deletions

diff --git a/lldb/test/Shell/Watchpoint/Inputs/thread-dbreg.c b/lldb/test/Shell/Watchpoint/Inputs/thread-dbreg.c
new file mode 100644
index 00000000000..14f3474789a
--- /dev/null
+++ b/lldb/test/Shell/Watchpoint/Inputs/thread-dbreg.c
@@ -0,0 +1,23 @@
+#include <pthread.h>
+
+int g_watchme = 0;
+
+void *thread_func(void *arg) {
+  /* watchpoint trigger from subthread */
+  g_watchme = 2;
+  return 0;
+}
+
+int main() {
+  pthread_t thread;
+  if (pthread_create(&thread, 0, thread_func, 0))
+    return 1;
+
+  /* watchpoint trigger from main thread */
+  g_watchme = 1;
+
+  if (pthread_join(thread, 0))
+    return 2;
+
+  return 0;
+}
diff --git a/lldb/test/Shell/Watchpoint/netbsd-nouserdbregs.test b/lldb/test/Shell/Watchpoint/netbsd-nouserdbregs.test
new file mode 100644
index 00000000000..884636c7cdf
--- /dev/null
+++ b/lldb/test/Shell/Watchpoint/netbsd-nouserdbregs.test
@@ -0,0 +1,22 @@
+# Check that 'watchpoint set' errors out gracefully when we can't set dbregs
+# and that new threads are monitored correctly even though we can't copy dbregs.
+
+# REQUIRES: system-netbsd && (target-x86 || target-x86_64) && !dbregs-set
+# RUN: %clang_host %p/Inputs/thread-dbreg.c -pthread -g -o %t.out
+# RUN: %lldb -b -o 'settings set interpreter.stop-command-source-on-error false' -s %s %t.out 2>&1 | FileCheck %s
+
+settings show interpreter.stop-command-source-on-error
+# CHECK: interpreter.stop-command-source-on-error (boolean) = false
+
+b main
+# CHECK: Breakpoint {{[0-9]+}}: where = {{.*}}`main
+b thread_func
+# CHECK: Breakpoint {{[0-9]+}}: where = {{.*}}`thread_func
+run
+# CHECK: stop reason = breakpoint
+watchpoint set variable g_watchme
+# CHECK: error: Watchpoint creation failed
+cont
+# CHECK: stop reason = breakpoint
+cont
+# CHECK: Process {{[0-9]+}} exited with status = 0