Fix OpenBSD build. (#4108)

Also in case fiber context stack creation via mmap is enabled, adding MAP_STACK flag for this platform.

config.m4

@@ -350,6 +350,7 @@ if test "$PHP_SWOOLE" != "no"; then
     AC_CHECK_LIB(pthread, pthread_spin_lock, AC_DEFINE(HAVE_SPINLOCK, 1, [have pthread_spin_lock]))
     AC_CHECK_LIB(pthread, pthread_mutex_timedlock, AC_DEFINE(HAVE_MUTEX_TIMEDLOCK, 1, [have pthread_mutex_timedlock]))
     AC_CHECK_LIB(pthread, pthread_barrier_init, AC_DEFINE(HAVE_PTHREAD_BARRIER, 1, [have pthread_barrier_init]))
+    AC_CHECK_LIB(pthread, pthread_mutexattr_setpshared, AC_DEFINE(HAVE_PTHREAD_MUTEXATTR_SETPSHARED, 1, [have pthread_mutexattr_setpshared]))
     AC_CHECK_LIB(pthread, pthread_mutexattr_setrobust, AC_DEFINE(HAVE_PTHREAD_MUTEXATTR_SETROBUST, 1, [have pthread_mutexattr_setrobust]))
     AC_CHECK_LIB(pthread, pthread_mutex_consistent, AC_DEFINE(HAVE_PTHREAD_MUTEX_CONSISTENT, 1, [have pthread_mutex_consistent]))
     AC_CHECK_LIB(pcre, pcre_compile, AC_DEFINE(HAVE_PCRE, 1, [have pcre]))

src/coroutine/context.cc

@@ -15,19 +15,18 @@
 */
 
 #include "swoole_coroutine_context.h"
-#if __linux__
+#ifdef SW_CONTEXT_PROTECT_STACK_PAGE
 #include <sys/mman.h>
+#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
+#define MAP_ANONYMOUS MAP_ANON
+#endif
 #endif
 
 #ifndef SW_USE_THREAD_CONTEXT
 
 #define MAGIC_STRING "swoole_coroutine#5652a7fb2b38be"
 #define START_OFFSET (64 * 1024)
 
-#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
-#define MAP_ANONYMOUS MAP_ANON
-#endif
-
 namespace swoole {
 namespace coroutine {
 
@@ -36,7 +35,13 @@ Context::Context(size_t stack_size, const coroutine_func_t &fn, void *private_da
     end_ = false;
 
 #ifdef SW_CONTEXT_PROTECT_STACK_PAGE
-    stack_ = (char *) ::mmap(0, stack_size_, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    int mapflags = MAP_PRIVATE | MAP_ANONYMOUS;
+#ifdef __OpenBSD__
+    // no-op for Linux and NetBSD, not to enable on FreeBSD as the semantic differs.
+    // However necessary on OpenBSD.
+    mapflags |= MAP_STACK;
+#endif
+    stack_ = (char *) ::mmap(0, stack_size_, PROT_READ | PROT_WRITE, mapflags, -1, 0);
 #else
     stack_ = (char *) sw_malloc(stack_size_);
 #endif

src/lock/mutex.cc

@@ -40,7 +40,11 @@ Mutex::Mutex(int flags) : Lock() {
     pthread_mutexattr_init(&impl->attr_);
 
     if (flags & PROCESS_SHARED) {
+#ifdef HAVE_PTHREAD_MUTEXATTR_SETROBUST
         pthread_mutexattr_setpshared(&impl->attr_, PTHREAD_PROCESS_SHARED);
+#else
+        swWarn("PTHREAD_MUTEX_PSHARED is not supported");
+#endif
     }
 
     if (flags & ROBUST) {