[Lldb-commits] [lldb] [lldb] Log to system log instead of stderr from Host::SystemLog (PR #83366)

[Jonas Devlieghere via lldb-commits]

https://github.com/JDevlieghere created https://github.com/llvm/llvm-project/pull/83366

Currently, calls to Host::SystemLog print to stderr on all host platforms except Darwin. This severely limits its value on the command line, where we don't want to overload the user with log messages. Switch to using the syslog function on POSIX systems to send messages to the system logger instead of stdout.

On Darwin systems this sends the log message to os_log, which matches what we do today. Nevertheless I kept the current implementation that uses os_log directly as it gives us more freedom.

I'm not sure if there's an equivalent on Windows, so I kept the existing behavior of logging to stderr.

>From 06942859d49640470785796659678cf0d4207e6e Mon Sep 17 00:00:00 2001
From: Jonas Devlieghere <jonas at devlieghere.com>
Date: Wed, 28 Feb 2024 18:12:45 -0800
Subject: [PATCH] [lldb] Log to system log instead of stderr from
 Host::SystemLog

Currently, calls to Host::SystemLog print to stderr on all host
platforms except Darwin. This severely limits its value on the command
line, where we don't want to overload the user with log messages. Switch
to using the syslog function on POSIX systems to send messages to the
system logger instead of stdout.

On Darwin systems this sends the log message to os_log, which matches
what we do today. Nevertheless I kept the current implementation that
uses os_log directly as it gives us more freedom.

I'm not sure if there's an equivalent on Windows, so I kept the existing
behavior of logging to stderr.
---
 lldb/source/Host/common/Host.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lldb/source/Host/common/Host.cpp b/lldb/source/Host/common/Host.cpp
index f4cec97f5af633..1af01ef5025bc4 100644
--- a/lldb/source/Host/common/Host.cpp
+++ b/lldb/source/Host/common/Host.cpp
@@ -89,8 +89,17 @@ using namespace lldb;
 using namespace lldb_private;
 
 #if !defined(__APPLE__)
+#if !defined(_WIN32)
+#include <syslog.h>
+void Host::SystemLog(llvm::StringRef message) {
+  openlog("lldb", LOG_CONS | LOG_PID | LOG_NDELAY, LOG_USER);
+  syslog(LOG_INFO, "%s", message.data());
+  closelog();
+}
+#else
 void Host::SystemLog(llvm::StringRef message) { llvm::errs() << message; }
 #endif
+#endif
 
 #if !defined(__APPLE__) && !defined(_WIN32)
 static thread_result_t