[lldb] Implement CrashReason using UnixSignals

By adding signal codes to UnixSignals and adding a new function
where you can get a string with optional address and bounds.

Added signal codes to the Linux, FreeBSD and NetBSD signal sets.
I've checked the numbers against the relevant sources.

Each signal code has a code number, description and printing options.
By default you just get the descripton, you can opt into adding either
a fault address or bounds information.

Bounds signals we'll use the description, unless we have the bounds
values in which case we say whether it is an upper or lower bound
issue.

GetCrashReasonString remains in CrashReason because we need it to
be compiled only for platforms with siginfo_t. Ideally it would
move into NativeProcessProtocol, but that is also used
by NativeRegisterContextWindows, where there would be no siginfo_t.

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D146044

1 files changed, 63 insertions, 0 deletions

diff --git a/lldb/source/Target/UnixSignals.cpp b/lldb/source/Target/UnixSignals.cpp
index 02354be..d754537 100644
--- a/lldb/source/Target/UnixSignals.cpp
+++ b/lldb/source/Target/UnixSignals.cpp
@@ -13,6 +13,7 @@
 #include "lldb/Host/HostInfo.h"
 #include "lldb/Utility/ArchSpec.h"
 #include <optional>
+#include <sstream>
 
 using namespace lldb_private;
 using namespace llvm;
@@ -112,6 +113,16 @@ void UnixSignals::AddSignal(int signo, const char *name, bool default_suppress,
   ++m_version;
 }
 
+void UnixSignals::AddSignalCode(int signo, int code, const char *description,
+                                SignalCodePrintOption print_option) {
+  collection::iterator signal = m_signals.find(signo);
+  assert(signal != m_signals.end() &&
+         "Tried to add code to signal that does not exist.");
+  signal->second.m_codes.insert(
+      std::pair{code, SignalCode{ConstString(description), print_option}});
+  ++m_version;
+}
+
 void UnixSignals::RemoveSignal(int signo) {
   collection::iterator pos = m_signals.find(signo);
   if (pos != m_signals.end())
@@ -127,6 +138,58 @@ const char *UnixSignals::GetSignalAsCString(int signo) const {
     return pos->second.m_name.GetCString();
 }
 
+std::string
+UnixSignals::GetSignalDescription(int32_t signo, std::optional<int32_t> code,
+                                  std::optional<lldb::addr_t> addr,
+                                  std::optional<lldb::addr_t> lower,
+                                  std::optional<lldb::addr_t> upper) const {
+  std::string str;
+
+  collection::const_iterator pos = m_signals.find(signo);
+  if (pos != m_signals.end()) {
+    str = pos->second.m_name.GetCString();
+
+    if (code) {
+      std::map<int, SignalCode>::const_iterator cpos =
+          pos->second.m_codes.find(*code);
+      if (cpos != pos->second.m_codes.end()) {
+        const SignalCode &sc = cpos->second;
+        str += ": ";
+        if (sc.m_print_option != SignalCodePrintOption::Bounds)
+          str += sc.m_description.GetCString();
+
+        std::stringstream strm;
+        switch (sc.m_print_option) {
+        case SignalCodePrintOption::None:
+          break;
+        case SignalCodePrintOption::Address:
+          if (addr)
+            strm << " (fault address: 0x" << std::hex << *addr << ")";
+          break;
+        case SignalCodePrintOption::Bounds:
+          if (lower && upper && addr) {
+            if ((unsigned long)(*addr) < *lower)
+              strm << "lower bound violation ";
+            else
+              strm << "upper bound violation ";
+
+            strm << "(fault address: 0x" << std::hex << *addr;
+            strm << ", lower bound: 0x" << std::hex << *lower;
+            strm << ", upper bound: 0x" << std::hex << *upper;
+            strm << ")";
+          } else
+            strm << sc.m_description.GetCString();
+
+          break;
+        }
+        str += strm.str();
+      }
+    }
+  }
+
+  return str;
+}
+
 bool UnixSignals::SignalIsValid(int32_t signo) const {
   return m_signals.find(signo) != m_signals.end();
 }