In a future commit, we'll want the ability to efficiently swap the
contents of two strvec instances without needing to copy any data.
Since a strvec is simply a pointer and two sizes, swapping them is as
simply as copying the two pointers and sizes, so let's do that.

We use a temporary here simply because C doesn't provide a standard
swapping function, unlike C++ and Rust, but a good optimizing compiler
will recognize this syntax and handle it appropriately using an
optimization pass.

Signed-off-by: brian m. carlson <redacted>
---
 strvec.c | 7 +++++++
 strvec.h | 5 +++++
 2 files changed, 12 insertions(+)

diff --git a/strvec.c b/strvec.c
index 178f4f3748..93006f1e63 100644
--- a/strvec.c
+++ b/strvec.c

@@ -106,3 +106,10 @@ const char **strvec_detach(struct strvec *array)
 		return ret;
 	}
 }
+
+void strvec_swap(struct strvec *a, struct strvec *b)
+{
+	struct strvec t = *a;
+	*a = *b;
+	*b = t;
+}

diff --git a/strvec.h b/strvec.h
index 4715d3e51f..5b762532bb 100644
--- a/strvec.h
+++ b/strvec.h

@@ -88,4 +88,9 @@ void strvec_clear(struct strvec *);
  */
 const char **strvec_detach(struct strvec *);
 
+/**
+ * Swap the contents of two `strvec` structs without allocating.
+ */
+void strvec_swap(struct strvec *, struct strvec *);
+
 #endif /* STRVEC_H */