lib: allow static/pre-initialized vectors

Use alloced=0 to indicate that the array used in a vector is not in fact
dynamically allocated memory (yet).

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>

1 files changed, 19 insertions, 2 deletions

diff --git a/lib/vector.h b/lib/vector.h
index 534def4f3..ae05d4d3e 100644
--- a/lib/vector.h
+++ b/lib/vector.h
@@ -15,9 +15,26 @@ extern "C" {
 
 /* struct for vector */
 struct _vector {
-	unsigned int active;  /* number of active slots */
-	unsigned int alloced; /* number of allocated slot */
+	/* active: index of last non-NULL item (+1)
+	 * count:  number of non-NULL items (+1)
+	 *
+	 * the two will be different if a slot is set to NULL (without pulling
+	 * up later items in the array).  Whether this happens depends on
+	 * which vector functions are used.  If no empty slots are used, the
+	 * two fields will be identical.
+	 *
+	 * alloced: size of array pointed to by index.  If this is 0, index
+	 * points at a global variable rather than a malloc'd bit of memory.
+	 * The vector code will convert to malloc'd memory if necessary to
+	 * perform updates.
+	 */
+	unsigned int active;
+	unsigned int alloced;
 	unsigned int count;
+
+	/* whether struct _vector itself is dynamically allocated */
+	bool dynamic;
+
 	void **index;	 /* index to data */
 };
 typedef struct _vector *vector;