From d830c410638577e1759bcccfdec5f17907973bb0 Mon Sep 17 00:00:00 2001
From: Thad House <ThadHouse@users.noreply.github.com>
Date: Fri, 12 Dec 2025 19:39:26 -0800
Subject: [PATCH] [wpinet] Add option to use directly linked Avahi from cmake
 (#8469)

---
 .clang-tidy                                  |  3 +++
 CMakeLists.txt                               |  1 +
 wpinet/CMakeLists.txt                        | 15 ++++++++++++
 wpinet/src/main/native/linux/AvahiClient.cpp |  4 ++++
 wpinet/src/main/native/linux/AvahiClient.hpp | 24 ++++++++++++++++++--
 5 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/.clang-tidy b/.clang-tidy
index 33d48c6044..1c902d5b9e 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -68,4 +68,7 @@ Checks:
   modernize-use-override,
   modernize-use-using,
   readability-braces-around-statements'
+CheckOptions:
+  - key: modernize-use-using.IgnoreExternC
+    value: 'true'
 FormatStyle: file
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e9118a6fe1..d2408b0c36 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -96,6 +96,7 @@ option(WITH_BENCHMARK "Build the benchmark project" ON)
 option(USE_SYSTEM_FMTLIB "Use system fmtlib" OFF)
 option(USE_SYSTEM_LIBUV "Use system libuv" OFF)
 option(USE_SYSTEM_EIGEN "Use system eigen" OFF)
+option(USE_LINKED_AVAHI "Use directly linked Avahi instead of loading at runtime" OFF)
 
 # Options for location of OpenCV Java.
 set(OPENCV_JAVA_INSTALL_DIR "" CACHE PATH "Location to search for the OpenCV jar file")
diff --git a/wpinet/CMakeLists.txt b/wpinet/CMakeLists.txt
index b4b5a62d65..af645178e3 100644
--- a/wpinet/CMakeLists.txt
+++ b/wpinet/CMakeLists.txt
@@ -128,6 +128,21 @@ target_compile_features(wpinet PUBLIC cxx_std_20)
 wpilib_target_warnings(wpinet)
 target_link_libraries(wpinet PUBLIC wpiutil)
 
+if(USE_LINKED_AVAHI)
+    find_library(AVAHI_COMMON REQUIRED NAMES avahi-common)
+    if(AVAHI_COMMON)
+        message(STATUS "Found avahi common: ${AVAHI_COMMON}")
+    endif()
+
+    find_library(AVAHI_CLIENT REQUIRED NAMES avahi-client)
+    if(AVAHI_CLIENT)
+        message(STATUS "Found avahi client: ${AVAHI_CLIENT}")
+    endif()
+
+    target_link_libraries(wpinet PUBLIC ${AVAHI_COMMON} ${AVAHI_CLIENT})
+    target_compile_definitions(wpinet PRIVATE DIRECT_LINK_AVAHI)
+endif()
+
 if(NOT USE_SYSTEM_LIBUV)
     target_sources(wpinet PRIVATE ${uv_native_src})
     install(
diff --git a/wpinet/src/main/native/linux/AvahiClient.cpp b/wpinet/src/main/native/linux/AvahiClient.cpp
index 7eee1c0020..a9a19bcd58 100644
--- a/wpinet/src/main/native/linux/AvahiClient.cpp
+++ b/wpinet/src/main/native/linux/AvahiClient.cpp
@@ -11,6 +11,9 @@
 
 using namespace wpi::net;
 
+#ifdef DIRECT_LINK_AVAHI
+#define AvahiFunctionLoad(snake_name) snake_name = &::avahi_##snake_name
+#else
 #define AvahiFunctionLoad(snake_name)                                          \
   do {                                                                         \
     snake_name =                                                               \
@@ -19,6 +22,7 @@ using namespace wpi::net;
       return;                                                                  \
     }                                                                          \
   } while (false)
+#endif
 
 AvahiFunctionTable::AvahiFunctionTable() {
   void* lib = dlopen("libavahi-common.so.3", RTLD_LAZY);
diff --git a/wpinet/src/main/native/linux/AvahiClient.hpp b/wpinet/src/main/native/linux/AvahiClient.hpp
index ede5276411..15fb3d836c 100644
--- a/wpinet/src/main/native/linux/AvahiClient.hpp
+++ b/wpinet/src/main/native/linux/AvahiClient.hpp
@@ -8,6 +8,20 @@
 
 #include <memory>
 
+#ifdef DIRECT_LINK_AVAHI
+#include "avahi-client/client.h"
+#include "avahi-client/lookup.h"
+#include "avahi-client/publish.h"
+#include "avahi-common/address.h"
+#include "avahi-common/alternative.h"
+#include "avahi-common/domain.h"
+#include "avahi-common/error.h"
+#include "avahi-common/malloc.h"
+#include "avahi-common/strlst.h"
+#include "avahi-common/thread-watch.h"
+
+#else
+
 /***
   This file is part of avahi.
   avahi is free software; you can redistribute it and/or modify it
@@ -24,6 +38,8 @@
   USA.
 ***/
 
+extern "C" {
+
 typedef struct AvahiPoll AvahiPoll;
 
 typedef enum {
@@ -223,6 +239,10 @@ enum {
   AVAHI_ERR_MAX = -54
 };
 
+}  // extern "C"
+
+#endif
+
 namespace wpi::net {
 class AvahiFunctionTable {
  public:
@@ -235,8 +255,8 @@ class AvahiFunctionTable {
   AvahiFunction(threaded_poll_get, const AvahiPoll*, (AvahiThreadedPoll*));
   AvahiFunction(threaded_poll_start, int, (AvahiThreadedPoll*));
   AvahiFunction(threaded_poll_stop, int, (AvahiThreadedPoll*));
-  AvahiFunction(threaded_poll_lock, int, (AvahiThreadedPoll*));
-  AvahiFunction(threaded_poll_unlock, int, (AvahiThreadedPoll*));
+  AvahiFunction(threaded_poll_lock, void, (AvahiThreadedPoll*));
+  AvahiFunction(threaded_poll_unlock, void, (AvahiThreadedPoll*));
 
   AvahiFunction(client_new, AvahiClient*,
                 (const AvahiPoll* poll_api, AvahiClientFlags flags,