[PATCH 5/8] add the functions for mtx_t

[Jens Gustedt <Jens.Gustedt@inria.fr>]

This is straightforward encapsulation of the corresponding
pthread_mutex_t functions.
---
 src/thread/mtx_destroy.c   |    5 +++++
 src/thread/mtx_init.c      |   10 ++++++++++
 src/thread/mtx_lock.c      |   13 +++++++++++++
 src/thread/mtx_timedlock.c |   18 ++++++++++++++++++
 src/thread/mtx_trylock.c   |   21 +++++++++++++++++++++
 src/thread/mtx_unlock.c    |    9 +++++++++
 6 files changed, 76 insertions(+)
 create mode 100644 src/thread/mtx_destroy.c
 create mode 100644 src/thread/mtx_init.c
 create mode 100644 src/thread/mtx_lock.c
 create mode 100644 src/thread/mtx_timedlock.c
 create mode 100644 src/thread/mtx_trylock.c
 create mode 100644 src/thread/mtx_unlock.c

diff --git a/src/thread/mtx_destroy.c b/src/thread/mtx_destroy.c
new file mode 100644
index 0000000..482b781
--- /dev/null
+++ b/src/thread/mtx_destroy.c
@@ -0,0 +1,5 @@
+#include <threads.h>
+
+void (mtx_destroy)(mtx_t *mtx) {
+	/* empty */
+}
diff --git a/src/thread/mtx_init.c b/src/thread/mtx_init.c
new file mode 100644
index 0000000..a197898
--- /dev/null
+++ b/src/thread/mtx_init.c
@@ -0,0 +1,10 @@
+#include "pthread_impl.h"
+#include <threads.h>
+
+int mtx_init(mtx_t * m, int type)
+{
+	*m = (mtx_t) {
+		._m_type = ((type&mtx_recursive) ? PTHREAD_MUTEX_RECURSIVE : PTHREAD_MUTEX_NORMAL),
+	};
+	return thrd_success;
+}
diff --git a/src/thread/mtx_lock.c b/src/thread/mtx_lock.c
new file mode 100644
index 0000000..4d5d75e
--- /dev/null
+++ b/src/thread/mtx_lock.c
@@ -0,0 +1,13 @@
+#include "pthread_impl.h"
+#include <threads.h>
+
+int mtx_lock(mtx_t *m)
+{
+	if (m->_m_type == PTHREAD_MUTEX_NORMAL && !a_cas(&m->_m_lock, 0, EBUSY))
+		return thrd_success;
+	/* Calling mtx_timedlock with a null pointer is an
+	   extension. Such a call is convenient, here, since it avoids
+	   to repeat the case analysis that is already done for
+	   mtx_timedlock. */
+	return mtx_timedlock(m, 0);
+}
diff --git a/src/thread/mtx_timedlock.c b/src/thread/mtx_timedlock.c
new file mode 100644
index 0000000..08359d8
--- /dev/null
+++ b/src/thread/mtx_timedlock.c
@@ -0,0 +1,18 @@
+#include <threads.h>
+#include <errno.h>
+
+int __pthread_mutex_timedlock(mtx_t *restrict m, const struct timespec *restrict ts);
+
+int mtx_timedlock(mtx_t *restrict mutex, const struct timespec *restrict ts) {
+	int ret = __pthread_mutex_timedlock(mutex, ts);
+	switch (ret) {
+	/* May also return EINVAL or EAGAIN. EAGAIN is
+	   specially tricky since C11 doesn't define how many recursive
+	   calls can be done. (this *isn't* the maximum amount of nested
+	   calls!) This implementation here deals this with a counter and
+	   detects overflow, so this is definitively UB. */
+	default:        return thrd_error;
+	case 0:         return thrd_success;
+	case ETIMEDOUT: return thrd_timedout;
+	}
+}
diff --git a/src/thread/mtx_trylock.c b/src/thread/mtx_trylock.c
new file mode 100644
index 0000000..4f55796
--- /dev/null
+++ b/src/thread/mtx_trylock.c
@@ -0,0 +1,21 @@
+#include "pthread_impl.h"
+#include <threads.h>
+
+int __pthread_mutex_trylock(pthread_mutex_t *restrict m);
+
+int mtx_trylock(mtx_t *restrict m) {
+	if (m->_m_type == PTHREAD_MUTEX_NORMAL)
+		return (a_cas(&m->_m_lock, 0, EBUSY) & EBUSY) ? thrd_busy : thrd_success;
+
+	int ret = __pthread_mutex_trylock(m);
+	switch (ret) {
+	/* In case of UB may also return EINVAL or EAGAIN. EAGAIN is
+	   specially tricky since C11 doesn't define how many recursive
+	   calls can be done. (this *isn't* the maximum amount of nested
+	   calls!) This implementation here deals this with a counter and
+	   detects overflow, so this is definitively UB. */
+	default:    return thrd_error;
+	case 0:     return thrd_success;
+	case EBUSY: return thrd_busy;
+	}
+}
diff --git a/src/thread/mtx_unlock.c b/src/thread/mtx_unlock.c
new file mode 100644
index 0000000..e673cd5
--- /dev/null
+++ b/src/thread/mtx_unlock.c
@@ -0,0 +1,9 @@
+#include <threads.h>
+
+int __pthread_mutex_unlock(mtx_t *);
+
+int (mtx_unlock)(mtx_t *mtx) {
+	int ret = __pthread_mutex_unlock(mtx);
+	/* In case of UB may also return EPERM. */
+	return ret ? thrd_error : thrd_success;
+}
-- 
1.7.10.4