implement pthread_getattr_np

this function is mainly (purely?) for obtaining stack address
information, but we also provide the detach state since it's easy to
do anyway.

1 files changed, 21 insertions, 0 deletions

diff --git a/src/thread/pthread_getattr_np.c b/src/thread/pthread_getattr_np.c
new file mode 100644
index 00000000..945242b7
--- /dev/null
+++ b/src/thread/pthread_getattr_np.c
@@ -0,0 +1,21 @@
+#include "pthread_impl.h"
+#include <sys/mman.h>
+
+int pthread_getattr_np(pthread_t t, pthread_attr_t *a)
+{
+	*a = (pthread_attr_t){0};
+	a->_a_detach = !!t->detached;
+	if (t->stack) {
+		a->_a_stackaddr = (uintptr_t)t->stack;
+		a->_a_stacksize = t->stack_size - DEFAULT_STACK_SIZE;
+	} else {
+		char *p = (void *)libc.auxv;
+		size_t l = PAGE_SIZE;
+		p += -(uintptr_t)p & PAGE_SIZE-1;
+		a->_a_stackaddr = (uintptr_t)p;
+		while (!posix_madvise(p-l-PAGE_SIZE, PAGE_SIZE, POSIX_MADV_NORMAL))
+			l += PAGE_SIZE;
+		a->_a_stacksize = l - DEFAULT_STACK_SIZE;
+	}
+	return 0;
+}