From 87a714861c5746d990b44b6e0839f082d7068f81 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Tue, 11 Apr 2023 18:05:25 -0400
Subject: lock: Add wrappers for POSIX synchronization primitives

---
 Makefile   |  3 ++-
 src/lock.h | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.c |  1 +
 3 files changed, 87 insertions(+), 1 deletion(-)
 create mode 100644 src/lock.h

diff --git a/Makefile b/Makefile
index aa8617e..20b4d07 100644
--- a/Makefile
+++ b/Makefile
@@ -55,7 +55,8 @@ LOCAL_CPPFLAGS := \
     -D_LARGEFILE64_SOURCE \
     -D_FILE_OFFSET_BITS=64 \
     -D_TIME_BITS=64 \
-    -DBFS_VERSION=\"$(VERSION)\"
+    -DBFS_VERSION=\"$(VERSION)\" \
+    -pthread
 
 LOCAL_CFLAGS := -std=c17
 LOCAL_LDFLAGS :=
diff --git a/src/lock.h b/src/lock.h
new file mode 100644
index 0000000..2ca7876
--- /dev/null
+++ b/src/lock.h
@@ -0,0 +1,84 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+/**
+ * Wrappers for POSIX synchronization primitives.
+ */
+
+#ifndef BFS_LOCK_H
+#define BFS_LOCK_H
+
+#include "diag.h"
+#include <errno.h>
+#include <pthread.h>
+
+#define lock_verify(expr, cond) \
+	bfs_verify((errno = (expr), (cond)), "%s: %s", #expr, strerror(errno))
+
+/**
+ * Wrapper for pthread_mutex_init().
+ *
+ * @return
+ *         0 on success, -1 on error.
+ */
+#define mutex_init(mutex, attr) \
+	((errno = pthread_mutex_init(mutex, attr)) ? -1 : 0)
+
+/**
+ * Wrapper for pthread_mutex_lock().
+ */
+#define mutex_lock(mutex) \
+	lock_verify(pthread_mutex_lock(mutex), errno == 0)
+
+/**
+ * Wrapper for pthread_mutex_trylock().
+ *
+ * @return
+ *         Whether the mutex was locked.
+ */
+#define mutex_trylock(mutex) \
+	(lock_verify(pthread_mutex_trylock(mutex), errno == 0 || errno == EBUSY), errno == 0)
+
+/**
+ * Wrapper for pthread_mutex_unlock().
+ */
+#define mutex_unlock(mutex) \
+	lock_verify(pthread_mutex_unlock(mutex), errno == 0)
+
+/**
+ * Wrapper for pthread_mutex_destroy().
+ */
+#define mutex_destroy(mutex) \
+	lock_verify(pthread_mutex_destroy(mutex), errno == 0)
+
+/**
+ * Wrapper for pthread_cond_init().
+ */
+#define cond_init(cond, attr) \
+	((errno = pthread_cond_init(cond, attr)) ? -1 : 0)
+
+/**
+ * Wrapper for pthread_cond_wait().
+ */
+#define cond_wait(cond, mutex) \
+	lock_verify(pthread_cond_wait(cond, mutex), errno == 0)
+
+/**
+ * Wrapper for pthread_cond_signal().
+ */
+#define cond_signal(cond) \
+	lock_verify(pthread_cond_signal(cond), errno == 0)
+
+/**
+ * Wrapper for pthread_cond_broadcast().
+ */
+#define cond_broadcast(cond) \
+	lock_verify(pthread_cond_broadcast(cond), errno == 0)
+
+/**
+ * Wrapper for pthread_cond_destroy().
+ */
+#define cond_destroy(cond) \
+	lock_verify(pthread_cond_destroy(cond), errno == 0)
+
+#endif // BFS_LOCK_H
diff --git a/src/main.c b/src/main.c
index c354553..95be48f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -31,6 +31,7 @@
  *     - dstring.[ch]  (a dynamic string library)
  *     - fsade.[ch]    (a facade over non-standard filesystem features)
  *     - list.h        (linked list macros)
+ *     - lock.h        (mutexes, condition variables, etc.)
  *     - mtab.[ch]     (parses the system's mount table)
  *     - pwcache.[ch]  (a cache for the user/group tables)
  *     - sanity.h      (sanitizer interfaces)
-- 
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