From a45fa01387fd15b4bf8291cf02931cecac86c3a4 Mon Sep 17 00:00:00 2001
From: Ben Gamari <ben@smart-cactus.org>
Date: Fri, 2 Apr 2021 10:51:53 -0400
Subject: rts: Fix usage of pthread_setname_np

Previously we used this non-portable function unconditionally, breaking
FreeBSD.

Fixes #19637.
---
 configure.ac          | 68 ++++++++++++++++++++++++++++++++++++++++++++-------
 rts/posix/OSThreads.c |  8 ++++--
 2 files changed, 65 insertions(+), 11 deletions(-)

diff --git a/configure.ac b/configure.ac
index bcda0b1ffb..383aeaa99f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1214,20 +1214,70 @@ AC_CHECK_FUNC(pthread_create,
 AC_DEFINE_UNQUOTED([NEED_PTHREAD_LIB], [$need_lpthread],
     [Define 1 if we need to link code using pthreads with -lpthread])
 
+dnl Setting thread names
+dnl ~~~~~~~~~~~~~~~~~~~~
+dnl The portability situation here is complicated:
+dnl
+dnl * FreeBSD supports pthread_set_name_np in <pthread_np.h>
+dnl * glibc supports pthread_setname_np
+dnl * Darwin supports pthread_setname_np but does not take a
+dnl   pthread_t argument.
+dnl
+AC_CHECK_HEADERS([pthread_np.h])
+
 dnl ** pthread_setname_np is a recent addition to glibc, and OS X has
 dnl    a different single-argument version.
 AC_CHECK_LIB(pthread, pthread_setname_np)
-AC_MSG_CHECKING(for pthread_setname_np)
-AC_LINK_IFELSE([AC_LANG_PROGRAM(
-[[
-#define _GNU_SOURCE
-#include <pthread.h>
-]],
-[[pthread_setname_np(pthread_self(), "name");]])],
+
+AC_MSG_CHECKING([for pthread_setname_np (Darwin)])
+AC_LINK_IFELSE([
+  AC_LANG_PROGRAM(
+    [[
+    #include <pthread.h>
+    ]],
+    [[pthread_setname_np("name");]]
+  )],
+  [
+    AC_MSG_RESULT(yes)
+    AC_DEFINE([HAVE_PTHREAD_SETNAME_NP_DARWIN], [1],
+      [Define to 1 if you have the Darwin version of pthread_setname_np])
+  ],
+  AC_MSG_RESULT(no)
+)
+
+dnl glibc
+AC_MSG_CHECKING([for pthread_setname_np (glibc)])
+AC_LINK_IFELSE([
+  AC_LANG_PROGRAM(
+    [[
+    #define _GNU_SOURCE
+    #include <pthread.h>
+    ]],
+    [[pthread_setname_np(pthread_self(), "name");]]
+  )],
+  [
     AC_MSG_RESULT(yes)
     AC_DEFINE([HAVE_PTHREAD_SETNAME_NP], [1],
-      [Define to 1 if you have the glibc version of pthread_setname_np]),
-    AC_MSG_RESULT(no)
+      [Define to 1 if you have the glibc version of pthread_setname_np])
+  ],
+  AC_MSG_RESULT(no)
+)
+
+dnl FreeBSD
+AC_MSG_CHECKING([for pthread_set_name_np])
+AC_LINK_IFELSE([
+  AC_LANG_PROGRAM(
+    [[
+    #include <pthread_np.h>
+    ]],
+    [[pthread_setname_np(pthread_self(), "name");]]
+  )],
+  [
+    AC_MSG_RESULT(yes)
+    AC_DEFINE([HAVE_PTHREAD_SET_NAME_NP], [1],
+      [Define to 1 if you have pthread_set_name_np])
+  ],
+  AC_MSG_RESULT(no)
 )
 
 dnl ** check for eventfd which is needed by the I/O manager
diff --git a/rts/posix/OSThreads.c b/rts/posix/OSThreads.c
index 200a4ccdad..b815894a9f 100644
--- a/rts/posix/OSThreads.c
+++ b/rts/posix/OSThreads.c
@@ -30,7 +30,7 @@
 
 #if defined(HAVE_PTHREAD_H)
 #include <pthread.h>
-#if defined(freebsd_HOST_OS)
+#if defined(HAVE_PTHREAD_NP_H)
 #include <pthread_np.h>
 #endif
 #endif
@@ -153,8 +153,12 @@ createOSThread (OSThreadId* pId, char *name STG_UNUSED,
   int result = pthread_create(pId, NULL, startProc, param);
   if (!result) {
     pthread_detach(*pId);
-#if defined(HAVE_PTHREAD_SETNAME_NP)
+#if defined(HAVE_PTHREAD_SET_NAME_NP)
+    pthread_set_name_np(*pId, name);
+#elif defined(HAVE_PTHREAD_SETNAME_NP)
     pthread_setname_np(*pId, name);
+#elif defined(HAVE_PTHREAD_SETNAME_NP_DARWIN)
+    pthread_setname_np(name);
 #endif
   }
   return result;
-- 
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