[compiler-rt][libFuzzer] Add support for capturing SIGTRAP exits. (#149120)

Swift's FatalError raises a SIGTRAP, which currently causes the fuzzer
to exit without writing out the crashing input.

rdar://142975522

GitOrigin-RevId: 33cc58f46f0c163d4bea2c7212b3830b3adf99b3

FuzzerDriver.cpp

diff --git a/FuzzerDriver.cpp b/FuzzerDriver.cpp
index 40322e2..ad3a65a 100644
--- a/FuzzerDriver.cpp
+++ b/FuzzerDriver.cpp
@@ -834,6 +834,7 @@
   Options.HandleInt = Flags.handle_int;
   Options.HandleSegv = Flags.handle_segv;
   Options.HandleTerm = Flags.handle_term;
+  Options.HandleTrap = Flags.handle_trap;
   Options.HandleXfsz = Flags.handle_xfsz;
   Options.HandleUsr1 = Flags.handle_usr1;
   Options.HandleUsr2 = Flags.handle_usr2;

FuzzerFlags.def

diff --git a/FuzzerFlags.def b/FuzzerFlags.def
index b88458a..96282b8 100644
--- a/FuzzerFlags.def
+++ b/FuzzerFlags.def
@@ -152,6 +152,7 @@
 FUZZER_FLAG_INT(handle_fpe, 1, "If 1, try to intercept SIGFPE.")
 FUZZER_FLAG_INT(handle_int, 1, "If 1, try to intercept SIGINT.")
 FUZZER_FLAG_INT(handle_term, 1, "If 1, try to intercept SIGTERM.")
+FUZZER_FLAG_INT(handle_trap, 1, "If 1, try to intercept SIGTRAP.")
 FUZZER_FLAG_INT(handle_xfsz, 1, "If 1, try to intercept SIGXFSZ.")
 FUZZER_FLAG_INT(handle_usr1, 1, "If 1, try to intercept SIGUSR1.")
 FUZZER_FLAG_INT(handle_usr2, 1, "If 1, try to intercept SIGUSR2.")

FuzzerOptions.h

diff --git a/FuzzerOptions.h b/FuzzerOptions.h
index 72e2561..6478b63 100644
--- a/FuzzerOptions.h
+++ b/FuzzerOptions.h
@@ -82,6 +82,7 @@
   bool HandleInt = false;
   bool HandleSegv = false;
   bool HandleTerm = false;
+  bool HandleTrap = false;
   bool HandleXfsz = false;
   bool HandleUsr1 = false;
   bool HandleUsr2 = false;

FuzzerUtilFuchsia.cpp

diff --git a/FuzzerUtilFuchsia.cpp b/FuzzerUtilFuchsia.cpp
index 735d155..7f065c7 100644
--- a/FuzzerUtilFuchsia.cpp
+++ b/FuzzerUtilFuchsia.cpp
@@ -410,7 +410,7 @@
 
   // Early exit if no crash handler needed.
   if (!Options.HandleSegv && !Options.HandleBus && !Options.HandleIll &&
-      !Options.HandleFpe && !Options.HandleAbrt)
+      !Options.HandleFpe && !Options.HandleAbrt && !Options.HandleTrap)
     return;
 
   // Set up the crash handler and wait until it is ready before proceeding.

FuzzerUtilPosix.cpp

diff --git a/FuzzerUtilPosix.cpp b/FuzzerUtilPosix.cpp
index 392c1e5..ae22ecf 100644
--- a/FuzzerUtilPosix.cpp
+++ b/FuzzerUtilPosix.cpp
@@ -132,6 +132,8 @@
     SetSigaction(SIGILL, CrashHandler);
   if (Options.HandleFpe)
     SetSigaction(SIGFPE, CrashHandler);
+  if (Options.HandleTrap)
+    SetSigaction(SIGTRAP, CrashHandler);
   if (Options.HandleXfsz)
     SetSigaction(SIGXFSZ, FileSizeExceedHandler);
   if (Options.HandleUsr1)