Patch-Source: https://github.com/lpereira/lwan/commit/870a8aa013544b944db15abf484690b5fb0b88be
From 870a8aa013544b944db15abf484690b5fb0b88be Mon Sep 17 00:00:00 2001
From: Leandro Pereira <leandro@hardinfo.org>
Date: Wed, 9 Oct 2019 22:03:06 -0700
Subject: [PATCH] Only provide gettid() implementation if not available in libc

Newer glibc provides a wrapper for this syscall now.
---
 CMakeLists.txt                      | 1 +
 src/cmake/lwan-build-config.h.cmake | 1 +
 src/lib/missing.c                   | 6 +++++-
 src/lib/missing/sys/types.h         | 4 +++-
 4 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8266609..7028963 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -85,6 +85,7 @@ check_function_exists(readahead HAS_READAHEAD)
 check_function_exists(mkostemp HAS_MKOSTEMP)
 check_function_exists(clock_gettime HAS_CLOCK_GETTIME)
 check_function_exists(pthread_barrier_init HAS_PTHREADBARRIER)
+check_function_exists(gettid HAVE_GETTID)
 
 if (NOT HAS_CLOCK_GETTIME AND ${CMAKE_SYSTEM_NAME} MATCHES "Linux")
 	list(APPEND ADDITIONAL_LIBRARIES rt)
diff --git a/src/cmake/lwan-build-config.h.cmake b/src/cmake/lwan-build-config.h.cmake
index 4708ed5..3d80c20 100644
--- a/src/cmake/lwan-build-config.h.cmake
+++ b/src/cmake/lwan-build-config.h.cmake
@@ -30,6 +30,7 @@
 #cmakedefine HAS_READAHEAD
 #cmakedefine HAS_REALLOCARRAY
 #cmakedefine HAS_MKOSTEMP
+#cmakedefine HAVE_GETTID
 
 /* Compiler builtins for specific CPU instruction support */
 #cmakedefine HAVE_BUILTIN_CLZLL
diff --git a/src/lib/missing.c b/src/lib/missing.c
index 22dddaa..c3b5a4b 100644
--- a/src/lib/missing.c
+++ b/src/lib/missing.c
@@ -351,13 +351,17 @@ proc_pidpath(pid_t pid, void *buffer, size_t buffersize)
 #endif
 
 #if defined(__linux__)
+
+#if !defined(HAVE_GETTID)
 #include <sys/syscall.h>
 
-long
+pid_t
 gettid(void)
 {
-    return syscall(SYS_gettid);
+    return (pid_t)syscall(SYS_gettid);
 }
+#endif
+
 #elif defined(__FreeBSD__)
 #include <sys/thr.h>
 
diff --git a/src/lib/missing/sys/types.h b/src/lib/missing/sys/types.h
index f178de8..cdc0658 100644
--- a/src/lib/missing/sys/types.h
+++ b/src/lib/missing/sys/types.h
@@ -22,6 +22,8 @@
 #ifndef MISSING_SYS_TYPES_H
 #define MISSING_SYS_TYPES_H
 
-long gettid(void);
+#ifndef HAVE_GETTID
+pid_t gettid(void);
+#endif
 
 #endif