Use of Threads under HPUX currently raise rb_eNotImpError ("ruby engine can initialize only in the main thread") since the STACKADDR_AVAILABLE is not available.

This brings basic support for the get_stack() under HPUX.

This patch also resolves issue under HPUX where signals usually cause the coredump since the stack size is too small.

Signed-off-by: Michal Rokos <rokos@nextsoft.cz>

diff --git a/thread_pthread.c b/thread_pthread.c
index e08f3de..66ef3a8 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -511,6 +511,14 @@ size_t pthread_get_stacksize_np(pthread_t);
 #define STACKADDR_AVAILABLE 1
 #elif defined HAVE_PTHREAD_GETTHRDS_NP
 #define STACKADDR_AVAILABLE 1
+#elif defined __ia64 && defined _HPUX_SOURCE
+#define STACKADDR_AVAILABLE 1
+/*
+ * Do not lower the thread's stack to PTHREAD_STACK_MIN,
+ * otherwise one would receive a 'sendsig: useracc failed.'
+ * and a coredump.
+ */
+#undef PTHREAD_STACK_MIN
 #endif
 
 #ifndef MAINSTACKADDR_AVAILABLE
@@ -582,6 +590,30 @@ get_stack(void **addr, size_t *size)
     *addr = thinfo.__pi_stackaddr;
     *size = thinfo.__pi_stacksize;
     STACK_DIR_UPPER((void)0, (void)(*addr = (char *)*addr + *size));
+#elif defined __ia64 && defined _HPUX_SOURCE
+    /*
+     * Although HP-UX defines _pthread_stack_info_np(), it cannot be
+     * used since it returns an error when the thread is not suspended.
+     * So lets use some other way to get the stack information...
+     */
+    pthread_attr_t attr;
+
+    /*
+     * Using value of sp is very rough... To make it more real,
+     * addr would need to be aligned to vps_pagesize.
+     * The vps_pagesize is 'Default user page size (kBytes)'
+     * and could be retrieved by gettune().
+     */
+    *addr = _Asm_get_sp();
+
+    /*
+     * As the PTHREAD_STACK_MIN is undefined and
+     * noone touches the default stacksize,
+     * it is just fine to use the default.
+     */
+    CHECK_ERR(pthread_attr_init(&attr));
+    CHECK_ERR(pthread_attr_getstacksize(&attr, size));
+    pthread_attr_destroy(&attr);
 #else
 #error STACKADDR_AVAILABLE is defined but not implemented.
 #endif