iovec-wrapper: rename iovw_append() to iovw_extend()

The naming is consistent with strv_extend().

This also
- introduces tiny iovw_extend_iov() wrapper,
- refuse when the source and target points to the same object,
- check the final count before extending in iovw_extend_iovw().

src/basic/iovec-wrapper.c

@@ -74,7 +74,7 @@ int iovw_consume(struct iovec_wrapper *iovw, void *data, size_t len) {
         return r;
 }
 
-int iovw_append(struct iovec_wrapper *iovw, const void *data, size_t len) {
+int iovw_extend(struct iovec_wrapper *iovw, const void *data, size_t len) {
         if (len == 0)
                 return 0;
 
@@ -85,6 +85,52 @@ int iovw_append(struct iovec_wrapper *iovw, const void *data, size_t len) {
         return iovw_consume(iovw, c, len);
 }
 
+int iovw_extend_iov(struct iovec_wrapper *iovw, const struct iovec *iov) {
+        assert(iovw);
+
+        if (!iovec_is_set(iov))
+                return 0;
+
+        return iovw_extend(iovw, iov->iov_base, iov->iov_len);
+}
+
+int iovw_extend_iovw(struct iovec_wrapper *iovw, const struct iovec_wrapper *source) {
+        int r;
+
+        assert(iovw);
+
+        /* This duplicates the source and merges it into the iovw. */
+
+        if (iovw_isempty(source))
+                return 0;
+
+        /* iovw->iovec will be reallocated in the loop below, hence source cannot point to the same object. */
+        if (iovw == source)
+                return -EINVAL;
+
+        if (iovw->count > SIZE_MAX - source->count)
+                return -E2BIG;
+        if (iovw->count + source->count > IOV_MAX)
+                return -E2BIG;
+
+        size_t original_count = iovw->count;
+
+        FOREACH_ARRAY(iovec, source->iovec, source->count) {
+                r = iovw_extend_iov(iovw, iovec);
+                if (r < 0)
+                        goto rollback;
+        }
+
+        return 0;
+
+rollback:
+        for (size_t i = original_count; i < iovw->count; i++)
+                iovec_done(iovw->iovec + i);
+
+        iovw->count = original_count;
+        return r;
+}
+
 int iovw_put_string_field_full(struct iovec_wrapper *iovw, bool replace, const char *field, const char *value) {
         _cleanup_free_ char *x = NULL;
         int r;
@@ -147,34 +193,6 @@ size_t iovw_size(const struct iovec_wrapper *iovw) {
         return iovec_total_size(iovw->iovec, iovw->count);
 }
 
-int iovw_append_iovw(struct iovec_wrapper *target, const struct iovec_wrapper *source) {
-        int r;
-
-        assert(target);
-
-        /* This duplicates the source and merges it into the target. */
-
-        if (iovw_isempty(source))
-                return 0;
-
-        size_t original_count = target->count;
-
-        FOREACH_ARRAY(iovec, source->iovec, source->count) {
-                r = iovw_append(target, iovec->iov_base, iovec->iov_len);
-                if (r < 0)
-                        goto rollback;
-        }
-
-        return 0;
-
-rollback:
-        for (size_t i = original_count; i < target->count; i++)
-                iovec_done(target->iovec + i);
-
-        target->count = original_count;
-        return r;
-}
-
 int iovw_concat(const struct iovec_wrapper *iovw, struct iovec *ret) {
         assert(iovw);
         assert(ret);

src/basic/iovec-wrapper.h

@@ -18,7 +18,9 @@ static inline bool iovw_equal(const struct iovec_wrapper *a, const struct iovec_
 
 int iovw_put(struct iovec_wrapper *iovw, void *data, size_t len);
 int iovw_consume(struct iovec_wrapper *iovw, void *data, size_t len);
-int iovw_append(struct iovec_wrapper *iovw, const void *data, size_t len);
+int iovw_extend(struct iovec_wrapper *iovw, const void *data, size_t len);
+int iovw_extend_iov(struct iovec_wrapper *iovw, const struct iovec *iov);
+int iovw_extend_iovw(struct iovec_wrapper *iovw, const struct iovec_wrapper *source);
 
 static inline bool iovw_isempty(const struct iovec_wrapper *iovw) {
         return !iovw || iovw->count == 0;
@@ -37,6 +39,5 @@ int iovw_put_string_fieldf_full(struct iovec_wrapper *iovw, bool replace, const
 int iovw_put_string_field_free(struct iovec_wrapper *iovw, const char *field, char *value);
 void iovw_rebase(struct iovec_wrapper *iovw, void *old, void *new);
 size_t iovw_size(const struct iovec_wrapper *iovw);
-int iovw_append_iovw(struct iovec_wrapper *target, const struct iovec_wrapper *source);
 int iovw_concat(const struct iovec_wrapper *iovw, struct iovec *ret);
 char* iovw_to_cstring(const struct iovec_wrapper *iovw);