src/: adns__internal_submit can modify ctx->tinfo.

[adns.git] / src / internal.h

diff --git a/src/internal.h b/src/internal.h
index 9df4da5f839ea89bc299a2400c86c6dbf33e3aad..38168814e8d32029beaecab2979874dffe337869 100644 (file)
--- a/src/internal.h
+++ b/src/internal.h
@@ -72,6 +72,27 @@ typedef unsigned char byte;
 
 #define MAX_POLLFDS  ADNS_POLLFDS_RECOMMENDED
 
+/* Some preprocessor hackery */
+
+#define GLUE(x, y) GLUE_(x, y)
+#define GLUE_(x, y) x##y
+
+/* C99 macro `...' must match at least one argument, so the naive definition
+ * `#define CAR(car, ...) car' won't work.  But it's easy to arrange for the
+ * tail to be nonempty if we're just going to discard it anyway. */
+#define CAR(...) CAR_(__VA_ARGS__, _)
+#define CAR_(car, ...) car
+
+/* Extracting the tail of an argument list is rather more difficult.  The
+ * following trick is based on one by Laurent Deniau to count the number of
+ * arguments to a macro, simplified in two ways: (a) it only handles up to
+ * eight arguments, and (b) it only needs to distinguish the one-argument
+ * case from many arguments. */
+#define CDR(...) CDR_(__VA_ARGS__, m, m, m, m, m, m, m, 1, _)(__VA_ARGS__)
+#define CDR_(_1, _2, _3, _4, _5, _6, _7, _8, n, ...) CDR_##n
+#define CDR_1(_)
+#define CDR_m(_, ...) __VA_ARGS__
+
 typedef enum {
   cc_user,
   cc_entex,
@@ -103,6 +124,20 @@ typedef struct {
   struct timeval now;
 } parseinfo;
 
+typedef struct {
+  void *ext;
+  void (*callback)(adns_query parent, adns_query child);
+
+  union {
+    adns_rr_addr ptr_addr;
+  } tinfo; /* type-specific state for the query itself: zero-init if you
+           * don't know better. */
+
+  union {
+    adns_rr_hostaddr *hostaddr;
+  } pinfo; /* state for use by parent's callback function */
+} qcontext;
+
 typedef struct typeinfo {
   adns_rrtype typekey;
   const char *rrtname;
@@ -178,15 +213,6 @@ union maxalign {
   union maxalign *up;
 } data;
 
-typedef struct {
-  void *ext;
-  void (*callback)(adns_query parent, adns_query child);
-  union {
-    adns_rr_addr ptr_parent_addr;
-    adns_rr_hostaddr *hostaddr;
-  } info;
-} qcontext;
-
 struct adns__query {
   adns_state ads;
   enum { query_tosend, query_tcpw, query_childw, query_done } state;
@@ -429,7 +455,7 @@ adns_status adns__internal_submit(adns_state ads, adns_query *query_r,
                                  const typeinfo *typei, vbuf *qumsg_vb,
                                  int id,
                                  adns_queryflags flags, struct timeval now,
-                                 const qcontext *ctx);
+                                 qcontext *ctx);
 /* Submits a query (for internal use, called during external submits).
  *
  * The new query is returned in *query_r, or we return adns_s_nomemory.
@@ -438,7 +464,8 @@ adns_status adns__internal_submit(adns_state ads, adns_query *query_r,
  * the memory for it is _taken over_ by this routine whether it
  * succeeds or fails (if it succeeds, the vbuf is reused for qu->vb).
  *
- * *ctx is copied byte-for-byte into the query.
+ * *ctx is copied byte-for-byte into the query.  Before doing this, its tinfo
+ * field may be modified by type hooks.
  *
  * When the child query is done, ctx->callback will be called.  The
  * child will already have been taken off both the global list of