From 6a7dce9165a4a707382e49877334353618fcad9a Mon Sep 17 00:00:00 2001
From: Mark Wooding <mdw@distorted.org.uk>
Date: Sun, 22 Jan 2012 12:57:45 +0000
Subject: [PATCH] key-data.[ch] (key_copydata): New function copies filtered
 key data.

---
 key-data.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 key-data.h | 16 ++++++++++++++++
 2 files changed, 71 insertions(+)

diff --git a/key-data.c b/key-data.c
index c77b6a4..43ad901 100644
--- a/key-data.c
+++ b/key-data.c
@@ -410,4 +410,59 @@ int key_do(key_data *k, const key_filter *kf, dstr *d,
   }
 }
 
+/* --- @key_copydata@ --- *
+ *
+ * Arguments:	@key_data *k@ = key data to copy
+ *		@const key_filter *kf@ = pointer to filter block
+ *
+ * Returns:	Pointer to a copy of the data, or null if the root subkey
+ *		didn't match the filter.
+ *
+ * Use:		Copies a chunk of key data.  Subkeys, whether they're
+ *		structured or leaves, which don't match the filter aren't
+ *		copied.  The copy may or may not have structure in common
+ *		with the original.
+ */
+
+static int structmatchp(key_data *k, const key_filter *kf)
+{
+  key_subkeyiter i;
+
+  if (!KEY_MATCH(k, kf)) return (0);
+  else if ((k->e & KF_ENCMASK) == KENC_STRUCT) return (1);
+  else {
+    for (key_mksubkeyiter(&i, k); key_nextsubkey(&i, 0, &k); )
+      if (!structmatchp(k, kf)) return (0);
+    return (1);
+  }
+}
+
+key_data *key_copydata(key_data *k, const key_filter *kf)
+{
+  key_subkeyiter i;
+  const char *tag;
+  key_data *kd, *kkd;
+
+  /* --- Trivial cases --- */
+
+  if (!KEY_MATCH(k, kf))
+    return (0);
+  else if (structmatchp(k, kf)) {
+    key_incref(k);
+    return (k);
+  }
+
+  /* --- Copy a structured key recursively --- */
+
+  kkd = key_newstruct();
+  for (key_mksubkeyiter(&i, k); key_nextsubkey(&i, &tag, &kd); ) {
+    if ((kd = key_copydata(kd, kf)) != 0)
+      key_structsteal(kkd, tag, kd);
+  }
+
+  /* --- Done --- */
+
+  return (kkd);
+}
+
 /*----- That's all, folks -------------------------------------------------*/
diff --git a/key-data.h b/key-data.h
index e216bc0..e37c381 100644
--- a/key-data.h
+++ b/key-data.h
@@ -414,6 +414,22 @@ extern int key_do(key_data */*k*/, const key_filter */*kf*/, dstr */*d*/,
 				  dstr */*d*/, void */*p*/),
 		  void */*p*/);
 
+/* --- @key_copydata@ --- *
+ *
+ * Arguments:	@key_data *k@ = key data to copy
+ *		@const key_filter *kf@ = pointer to filter block
+ *
+ * Returns:	Pointer to a copy of the data, or null if the root subkey
+ *		didn't match the filter.
+ *
+ * Use:		Copies a chunk of key data.  Subkeys, whether they're
+ *		structured or leaves, which don't match the filter aren't
+ *		copied.  The copy may or may not have structure in common
+ *		with the original.
+ */
+
+extern key_data *key_copydata(key_data */*k*/, const key_filter */*kf*/);
+
 /*----- Textual encoding --------------------------------------------------*/
 
 /* --- @key_read@ --- *
-- 
2.11.0