[lldb] Show signal number description

[da-viper]

show information about the signal when the user presses process handle <unix-signal> i.e

(lldb) process handle SIGWINCH 
NAME         PASS   STOP   NOTIFY  DESCRIPTION
===========  =====  =====  ======  ===================
SIGWINCH     true   false  false   window size changes

Wanted to use the existing GetSignalDescription but it is expected behaviour to return the signal name if no signal code is passed. It is used in stop info.

llvm-project/lldb/source/Target/StopInfo.cpp

Lines 1192 to 1195 in 65c895d

	std::string signal_name =
	unix_signals->GetSignalDescription(m_value, m_code);
	if (signal_name.size())
	strm << signal_name;

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Ebuka Ezike (da-viper)

Changes

show information about the signal when the user presses process handle <unix-signal> i.e

(lldb) process handle SIGWINCH 
NAME         PASS   STOP   NOTIFY  DESCRIPTION
===========  =====  =====  ======  ===================
SIGWINCH     true   false  false   window size changes

Wanted to use the existing GetSignalDescription but it is expected behaviour to return the signal name if no signal code is passed. It is used in stop info.

llvm-project/lldb/source/Target/StopInfo.cpp

Lines 1192 to 1195 in 65c895d

	std::string signal_name =
	unix_signals->GetSignalDescription(m_value, m_code);
	if (signal_name.size())
	strm << signal_name;

---

Full diff: https://github.com/llvm/llvm-project/pull/164176.diff

4 Files Affected:

• (modified) lldb/include/lldb/Target/UnixSignals.h (+2)
• (modified) lldb/source/Commands/CommandObjectProcess.cpp (+10-3)
• (modified) lldb/source/Target/UnixSignals.cpp (+7)
• (modified) lldb/unittests/Signals/UnixSignalsTest.cpp (+12)

diff --git a/lldb/include/lldb/Target/UnixSignals.h b/lldb/include/lldb/Target/UnixSignals.h
index a1807d69f329b..590e4d1aa5208 100644
--- a/lldb/include/lldb/Target/UnixSignals.h
+++ b/lldb/include/lldb/Target/UnixSignals.h
@@ -31,6 +31,8 @@ class UnixSignals {
 
   llvm::StringRef GetSignalAsStringRef(int32_t signo) const;
 
+  llvm::StringRef GetSignalNumberDescription(int32_t signo) const;
+
   std::string
   GetSignalDescription(int32_t signo,
                        std::optional<int32_t> code = std::nullopt,
diff --git a/lldb/source/Commands/CommandObjectProcess.cpp b/lldb/source/Commands/CommandObjectProcess.cpp
index 7d326404a5503..1dc9d12580cbe 100644
--- a/lldb/source/Commands/CommandObjectProcess.cpp
+++ b/lldb/source/Commands/CommandObjectProcess.cpp
@@ -1603,8 +1603,8 @@ class CommandObjectProcessHandle : public CommandObjectParsed {
   Options *GetOptions() override { return &m_options; }
 
   void PrintSignalHeader(Stream &str) {
-    str.Printf("NAME         PASS   STOP   NOTIFY\n");
-    str.Printf("===========  =====  =====  ======\n");
+    str.Printf("NAME         PASS   STOP   NOTIFY  DESCRIPTION\n");
+    str.Printf("===========  =====  =====  ======  ===================\n");
   }
 
   void PrintSignal(Stream &str, int32_t signo, llvm::StringRef sig_name,
@@ -1616,8 +1616,15 @@ class CommandObjectProcessHandle : public CommandObjectParsed {
     str.Format("{0, -11}  ", sig_name);
     if (signals_sp->GetSignalInfo(signo, suppress, stop, notify)) {
       bool pass = !suppress;
-      str.Printf("%s  %s  %s", (pass ? "true " : "false"),
+      str.Printf("%s  %s  %s  ", (pass ? "true " : "false"),
                  (stop ? "true " : "false"), (notify ? "true " : "false"));
+
+      llvm::StringRef sig_description =
+          signals_sp->GetSignalNumberDescription(signo);
+      if (!sig_description.empty()) {
+        str.PutCString(" ");
+        str.PutCString(sig_description);
+      }
     }
     str.Printf("\n");
   }
diff --git a/lldb/source/Target/UnixSignals.cpp b/lldb/source/Target/UnixSignals.cpp
index 6113c6648817c..881431f4631e5 100644
--- a/lldb/source/Target/UnixSignals.cpp
+++ b/lldb/source/Target/UnixSignals.cpp
@@ -137,6 +137,13 @@ llvm::StringRef UnixSignals::GetSignalAsStringRef(int32_t signo) const {
   return pos->second.m_name;
 }
 
+llvm::StringRef UnixSignals::GetSignalNumberDescription(int32_t signo) const {
+  const auto pos = m_signals.find(signo);
+  if (pos == m_signals.end())
+    return {};
+  return pos->second.m_description;
+}
+
 std::string UnixSignals::GetSignalDescription(
     int32_t signo, std::optional<int32_t> code,
     std::optional<lldb::addr_t> addr, std::optional<lldb::addr_t> lower,
diff --git a/lldb/unittests/Signals/UnixSignalsTest.cpp b/lldb/unittests/Signals/UnixSignalsTest.cpp
index 582e441556067..3bd4aedd600a3 100644
--- a/lldb/unittests/Signals/UnixSignalsTest.cpp
+++ b/lldb/unittests/Signals/UnixSignalsTest.cpp
@@ -148,6 +148,18 @@ TEST(UnixSignalsTest, GetAsString) {
             signals.GetSignalDescription(16, 3, 0x1233, 0x1234, 0x5678));
 }
 
+TEST(UnixSignalsTest, GetNumberDescription) {
+  TestSignals signals;
+
+  ASSERT_EQ("DESC2", signals.GetSignalNumberDescription(2));
+  ASSERT_EQ("DESC4", signals.GetSignalNumberDescription(4));
+  ASSERT_EQ("DESC8", signals.GetSignalNumberDescription(8));
+  ASSERT_EQ("DESC16", signals.GetSignalNumberDescription(16));
+
+  // Unknown signal number.
+  ASSERT_EQ("", signals.GetSignalNumberDescription(100));
+}
+
 TEST(UnixSignalsTest, VersionChange) {
   TestSignals signals;
 

[DavidSpickett]

This is a good idea, one less reason to leave the debugger.

Took me a while to figure out exactly why you couldn't use the existing method, but that's not because you didn't say so, it's because we have too much overlapping terminology in the existing code.

It's like GetSignalDescription is the __repr__ of the signal, and so should try as hard as it can to return something, sometimes just the name. You specifically want the description part of the information instead.

It's not for this PR but it feels like GetSignalDescription should be GetSignalAsString or FormatSignal or whatever, and GetSignalAsStringRef should be GetSignalName to match your new method.

Too many things say "signal" when they mean just the signal number but also other things say signal when they mean the whole signal struct.

If you want to have a go at improving that, please do.

Your new method does what it says though so it's ok. If you do change the other names, it could be "GetSignalDescription" as you'd have liked it to be.

[JDevlieghere]

LGTM modulo David's whitespace comment.

[DavidSpickett]

LGTM. This is a neat improvement.