From 922c51596fdeb042356bc6e0e5021f7d59a344ca Mon Sep 17 00:00:00 2001
From: Francis Dupont <fdupont@isc.org>
Date: Wed, 5 Feb 2025 16:16:17 +0100
Subject: [PATCH] [#3729] Added check for environ vs shlib

---
 compiler-checks/environ-in-shlib.cc |  5 +++++
 meson.build                         | 12 ++++++++++++
 src/lib/asiolink/meson.build        |  3 +--
 3 files changed, 18 insertions(+), 2 deletions(-)
 create mode 100644 compiler-checks/environ-in-shlib.cc

diff --git a/compiler-checks/environ-in-shlib.cc b/compiler-checks/environ-in-shlib.cc
new file mode 100644
index 0000000000..d50947a378
--- /dev/null
+++ b/compiler-checks/environ-in-shlib.cc
@@ -0,0 +1,5 @@
+extern char **environ;
+
+char** fn() {
+    return environ;
+}
diff --git a/meson.build b/meson.build
index 14cfb33e5d..a66738c211 100644
--- a/meson.build
+++ b/meson.build
@@ -269,6 +269,18 @@ result = cpp.run(
 )
 conf_data.set('HAVE_STREAM_TRUNCATED_ERROR', result.returncode() == 0)
 
+ENVIRON_SHLIB_FLAGS = []
+if cpp.has_link_argument('-Wl,--no-undefined')
+    result = cpp.links(
+        fs.read('compiler-checks/environ-in-shlib.cc'),
+        name: 'ENVIRON_SHLIB_FLAGS',
+        args: ['--shared', '-fPIC', '-Wl,--no-undefined'],
+    )
+    if not result
+        ENVIRON_SHLIB_FLAGS += ['b_lundef=false']
+    endif
+endif
+
 #### System-specific Variables
 
 SYSTEM = build_machine.system()
diff --git a/src/lib/asiolink/meson.build b/src/lib/asiolink/meson.build
index 6c271a2b56..6dbfa4928e 100644
--- a/src/lib/asiolink/meson.build
+++ b/src/lib/asiolink/meson.build
@@ -19,8 +19,7 @@ kea_asiolink_lib = library(
     install: true,
     install_dir: 'lib',
     link_with: LIBS_BUILT_SO_FAR,
-    # The only way to avoid on FreeBSD: ld: error: undefined symbol: environ
-    override_options: ['b_lundef=false'],
+    override_options: ENVIRON_SHLIB_FLAGS,
 )
 LIBS_BUILT_SO_FAR = [kea_asiolink_lib] + LIBS_BUILT_SO_FAR
 subdir('testutils')