Add a pointer vector abstraction.

There are lots of places where we want a growable
vector of pointers.  Add one.

Signed-off-by: Dan Cross <patchdev@fat-dragon.org>

src/bbs.h

@@ -260,6 +260,21 @@ struct blog_entry_t {
 	time_t date;
 };
 
+struct ptr_vector {
+        size_t len;
+        size_t capacity;
+        void **ptrs;
+};
+
+extern void init_ptr_vector(struct ptr_vector *vec);
+extern void ptr_vector_clear(struct ptr_vector *vec);
+extern void *ptr_vector_get(struct ptr_vector *vec, size_t i);
+extern int ptr_vector_put(struct ptr_vector *vec, void *p, size_t i);
+extern void *ptr_vector_del(struct ptr_vector *vec, size_t i);
+extern int ptr_vector_append(struct ptr_vector *vec, void *p);
+extern size_t ptr_vector_len(struct ptr_vector *vec);
+extern void destroy_ptr_vector(struct ptr_vector *vec);
+
 extern char *str_replace(const char *orig, const char *rep, const char *with);
 extern int copy_file(char *src, char *dest);
 extern int recursive_delete(const char *dir);

src/util.c

@@ -1,6 +1,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 
+#include <assert.h>
 #include <fcntl.h>
 #include <stdlib.h>
 #include <string.h>
@@ -86,3 +87,76 @@ char *str3dup(const char *a, const char *b, const char *c) {
 char *str2dup(const char *a, const char *b) {
 	return str5dup(a, b, "", "", "");
 }
+
+void init_ptr_vector(struct ptr_vector *vec) {
+	assert(vec != NULL);
+	memset(vec, 0, sizeof(*vec));
+}
+
+void ptr_vector_clear(struct ptr_vector *vec) {
+	assert(vec != NULL);
+	vec->len = 0;
+	memset(vec->ptrs, 0, sizeof(void *) * vec->capacity);
+}
+
+void *ptr_vector_get(struct ptr_vector *vec, size_t i) {
+	assert(vec != NULL);
+	if (i >= vec->len)
+		return NULL;
+	assert(vec->ptrs != NULL);
+	return vec->ptrs[i];
+}
+
+int ptr_vector_put(struct ptr_vector *vec, void *p, size_t i) {
+	assert(vec != NULL);
+	if (i >= vec->len)
+		return 0;
+	assert(vec->ptrs != NULL);
+	vec->ptrs[i] = p;
+	return 1;
+}
+
+void *ptr_vector_del(struct ptr_vector *vec, size_t i) {
+	void *p;
+	assert(vec != NULL);
+	if (i >= vec->len)
+		return NULL;
+	assert(vec->ptrs != NULL);
+	p = vec->ptrs[i];
+	memmove(vec->ptrs + i, vec->ptrs + i + 1,
+	        (vec->len - (i + 1)) * sizeof(void *));
+	--vec->len;
+	return p;
+}
+
+int ptr_vector_append(struct ptr_vector *vec, void *p) {
+	assert(vec != NULL);
+	if (vec->len == vec->capacity) {
+		void **ps;
+		size_t oldcap = vec->capacity;
+                if (vec->capacity == 0)
+                        vec->capacity = 1;
+                else
+			vec->capacity *= 2;
+                ps = realloc(vec->ptrs, vec->capacity * sizeof(void *));
+                assert(ps != NULL);
+		memset(vec->ptrs + oldcap, 0, (vec->capacity - oldcap) * sizeof(void *));
+                vec->ptrs = ps;
+        }
+        vec->ptrs[vec->len] = p;
+        ++vec->len;
+	return 1;
+}
+
+size_t ptr_vector_len(struct ptr_vector *vec) {
+	assert(vec != NULL);
+	return vec->len;
+}
+
+void destroy_ptr_vector(struct ptr_vector *vec) {
+	assert(vec != NULL);
+	free(vec->ptrs);
+	vec->ptrs = NULL;
+	vec->capacity = 0;
+	vec->len = 0;
+}