build fixes for GNU/kFreeBSD (#6992)

Summary:
Upstream https://salsa.debian.org/mariadb-team/mariadb-10.4/-/blob/master/debian/patches/rocksdb-kfreebsd.patch
by jrtc27.

Fixes https://github.com/facebook/rocksdb/issues/5223.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6992

Reviewed By: zhichao-cao

Differential Revision: D22084150

Pulled By: ajkr

fbshipit-source-id: 1822311ba16f112a15065b2180ce89d36af9cafc

CMakeLists.txt

@@ -95,7 +95,7 @@ if(MSVC)
   option(WITH_XPRESS "build with windows built in compression" OFF)
   include(${CMAKE_CURRENT_SOURCE_DIR}/thirdparty.inc)
 else()
-  if(CMAKE_SYSTEM_NAME MATCHES "FreeBSD")
+  if(CMAKE_SYSTEM_NAME MATCHES "FreeBSD" AND NOT CMAKE_SYSTEM_NAME MATCHES "kFreeBSD")
     # FreeBSD has jemalloc as default malloc
     # but it does not have all the jemalloc files in include/...
     set(WITH_JEMALLOC ON)
@@ -448,6 +448,8 @@ elseif(CMAKE_SYSTEM_NAME MATCHES "Linux")
   add_definitions(-DOS_LINUX)
 elseif(CMAKE_SYSTEM_NAME MATCHES "SunOS")
   add_definitions(-DOS_SOLARIS)
+elseif(CMAKE_SYSTEM_NAME MATCHES "kFreeBSD")
+  add_definitions(-DOS_GNU_KFREEBSD)
 elseif(CMAKE_SYSTEM_NAME MATCHES "FreeBSD")
   add_definitions(-DOS_FREEBSD)
 elseif(CMAKE_SYSTEM_NAME MATCHES "NetBSD")

build_tools/build_detect_platform

@@ -192,6 +192,17 @@ EOF
         PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -lpthread"
         # PORT_FILES=port/freebsd/freebsd_specific.cc
         ;;
+    GNU/kFreeBSD)
+        PLATFORM=OS_GNU_KFREEBSD
+        COMMON_FLAGS="$COMMON_FLAGS -DOS_GNU_KFREEBSD"
+        if [ -z "$USE_CLANG" ]; then
+            COMMON_FLAGS="$COMMON_FLAGS -fno-builtin-memcmp"
+        else
+            PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -latomic"
+        fi
+        PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -lpthread -lrt"
+        # PORT_FILES=port/gnu_kfreebsd/gnu_kfreebsd_specific.cc
+        ;;
     NetBSD)
         PLATFORM=OS_NETBSD
         COMMON_FLAGS="$COMMON_FLAGS -fno-builtin-memcmp -D_REENTRANT -DOS_NETBSD"

env/env_posix.cc

@@ -41,7 +41,7 @@
 #include <time.h>
 #include <algorithm>
 // Get nano time includes
-#if defined(OS_LINUX) || defined(OS_FREEBSD)
+#if defined(OS_LINUX) || defined(OS_FREEBSD) || defined(OS_GNU_KFREEBSD)
 #elif defined(__MACH__)
 #include <Availability.h>
 #include <mach/clock.h>
@@ -249,7 +249,8 @@ class PosixEnv : public CompositeEnvWrapper {
   }
 
   uint64_t NowNanos() override {
-#if defined(OS_LINUX) || defined(OS_FREEBSD) || defined(OS_AIX)
+#if defined(OS_LINUX) || defined(OS_FREEBSD) || defined(OS_GNU_KFREEBSD) || \
+    defined(OS_AIX)
     struct timespec ts;
     clock_gettime(CLOCK_MONOTONIC, &ts);
     return static_cast<uint64_t>(ts.tv_sec) * 1000000000 + ts.tv_nsec;
@@ -269,8 +270,8 @@ class PosixEnv : public CompositeEnvWrapper {
   }
 
   uint64_t NowCPUNanos() override {
-#if defined(OS_LINUX) || defined(OS_FREEBSD) || defined(OS_AIX) || \
-    (defined(__MACH__) && defined(__MAC_10_12))
+#if defined(OS_LINUX) || defined(OS_FREEBSD) || defined(OS_GNU_KFREEBSD) || \
+    defined(OS_AIX) || (defined(__MACH__) && defined(__MAC_10_12))
     struct timespec ts;
     clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts);
     return static_cast<uint64_t>(ts.tv_sec) * 1000000000 + ts.tv_nsec;

port/stack_trace.cc

@@ -36,7 +36,7 @@ namespace port {
 
 namespace {
 
-#if defined(OS_LINUX) || defined(OS_FREEBSD)
+#if defined(OS_LINUX) || defined(OS_FREEBSD) || defined(OS_GNU_KFREEBSD)
 const char* GetExecutableName() {
   static char name[1024];