From: Andrei Tatar <andrei@unikraft.io>
Date: Wed, 25 Sep 2024 14:42:26 +0000 (+0200)
Subject: lib/posix-fd: Provide public ofile refcounting
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=59993608a4cc890e0ae0234d7c2ab41cc9458e96;p=unikraft%2Funikraft.git

lib/posix-fd: Provide public ofile refcounting

This change adds public helpers for refcounting open file descriptions.

Signed-off-by: Andrei Tatar <andrei@unikraft.io>
Approved-by: Sergiu Moga <sergiu@unikraft.io>
Reviewed-by: Sergiu Moga <sergiu@unikraft.io>
GitHub-Closes: #1592
---

diff --git a/lib/posix-fd/include/uk/posix-fd.h b/lib/posix-fd/include/uk/posix-fd.h
index cec9de378..6532f7852 100644
--- a/lib/posix-fd/include/uk/posix-fd.h
+++ b/lib/posix-fd/include/uk/posix-fd.h
@@ -44,6 +44,36 @@ void uk_ofile_init(struct uk_ofile *of,
 	of->pos = 0;
 }
 
+/**
+ * Acquire a reference on open file description `of`.
+ *
+ * @param of Open file description
+ */
+static inline
+void uk_ofile_acquire(struct uk_ofile *of)
+{
+	uk_refcount_acquire(&of->refcnt);
+}
+
+/**
+ * Release a reference held on open file description `of`.
+ *
+ * Do not call directly unless you are prepared to handle cleanup after the last
+ * reference is dropped. Instead use the release function provided by the lib
+ * where you got the open file reference from.
+ *
+ * @param of Open file description
+ *
+ * @return
+ *  == 0: There are remaining references held
+ *  != 0: The last reference has just been released
+ */
+static inline
+int uk_ofile_release(struct uk_ofile *of)
+{
+	return uk_refcount_release(&of->refcnt);
+}
+
 
 /* Mode bits from fcntl.h that open files are interested in */
 #define UKFD_MODE_MASK \
diff --git a/lib/posix-fdtab/fdtab.c b/lib/posix-fdtab/fdtab.c
index 607ea240d..1a34e8f31 100644
--- a/lib/posix-fdtab/fdtab.c
+++ b/lib/posix-fdtab/fdtab.c
@@ -145,11 +145,11 @@ static inline void ofile_del(struct uk_fdtab *tab, struct uk_ofile *of)
 
 static inline void ofile_acq(struct uk_ofile *of)
 {
-	uk_refcount_acquire(&of->refcnt);
+	uk_ofile_acquire(of);
 }
 static inline void ofile_rel(struct uk_fdtab *tab, struct uk_ofile *of)
 {
-	if (uk_refcount_release(&of->refcnt)) {
+	if (uk_ofile_release(of)) {
 		uk_file_release(of->file);
 		ofile_del(tab, of);
 	}