Made some progress on the pid hash case, code is still a mess, have fixed many bugs but still not 100% working

Author: Svetlitski

libdrgn/iterators.c

@@ -256,7 +256,40 @@ struct drgn_error *pid_iter_init(struct drgn_program *prog,
 			goto out;
 	} else if (err->code == DRGN_ERROR_LOOKUP) {
 		ret->has_idr = false;
-		// TODO: pid_hash case
+		ret->index = -1;
+		ret->ns = ns;
+		drgn_object_init(&ret->hlist_node, prog);
+		ret->hlist_node.value.bufp = NULL;
+		drgn_object_init(&ret->pid_hash, prog);
+		drgn_object_init(&ret->entry, prog);
+		err = drgn_program_find_object(prog, "pid_hash", NULL, DRGN_FIND_OBJECT_VARIABLE, &ret->pid_hash);
+		if (err)
+			goto out;
+		err = drgn_program_find_type(prog, "struct pid", NULL,
+					     &ret->pid_type);
+		if (err)
+			goto out;
+		err = drgn_program_find_type(prog, "struct upid", NULL,
+					     &ret->upid_type);
+		if (err)
+			goto out;
+		struct drgn_object ns_level;
+		drgn_object_init(&ns_level, prog);
+		err = drgn_object_member_dereference(&ns_level, ns, "level");
+		if (err)
+			goto out;
+		err = drgn_object_read_unsigned(&ns_level, &ret->ns_level);
+		if (err)
+			goto out;
+		struct drgn_object pidhash_shift;
+		drgn_object_init(&pidhash_shift, prog);
+		err = drgn_program_find_object(prog, "pidhash_shift", NULL, DRGN_FIND_OBJECT_VARIABLE, &pidhash_shift);
+		if (err)
+			goto out;
+		err = drgn_object_read_unsigned(&pidhash_shift, &ret->hash_length);
+		if (err)
+			goto out;
+		ret->hash_length = 1 << ret->hash_length;
 	} else {
 		goto out;
 	}
@@ -268,9 +301,10 @@ struct drgn_error *pid_iter_init(struct drgn_program *prog,
 
 struct drgn_error *pid_iter_next(struct pid_iter *iter, pid_iter_entry_t **ret)
 {
+	struct drgn_error *err;
 	if (iter->has_idr) {
 		idr_iter_entry_t *entry;
-		struct drgn_error *err = idr_iter_next(&iter->iter, &entry);
+		err = idr_iter_next(&iter->iter, &entry);
 		if (err)
 			return err;
 		if (!entry) {
@@ -283,9 +317,45 @@ struct drgn_error *pid_iter_next(struct pid_iter *iter, pid_iter_entry_t **ret)
 			*ret = &entry->node;
 		return err;
 	} else {
-		//TODO
-		return NULL;
+		while (true) {
+		if (iter->index != -1 && iter->index >= iter->hash_length) {
+			*ret = NULL;
+			return NULL;
+		}
+		if (!iter->hlist_node.value.bufp) {
+			err = drgn_object_subscript(&iter->hlist_node, &iter->pid_hash, ++iter->index);
+			if (err)
+				return err;
+			err = drgn_object_member(&iter->hlist_node, &iter->hlist_node, "first");
+			if (err)
+				return err;
+		} else {
+			 err = drgn_object_member(&iter->hlist_node, &iter->hlist_node, "next");
+			 if (err)
+				 return err;
+		 }
+		 err = drgn_object_container_of(&iter->entry, &iter->hlist_node, iter->upid_type, "pid_chain");
+		 if (err)
+			 return err;
+		 struct drgn_object upid_ns;
+		 drgn_object_init(&upid_ns, drgn_object_program(&iter->entry));
+		 err = drgn_object_member_dereference(&upid_ns, &iter->entry, "ns");
+		 if (err)
+			 return err;
+		 // TODO: if upid.ns == ns
+		 if (upid_ns.value.bufp != iter->ns->value.bufp)
+			 continue;
+		 char* member;
+		 // TODO do this at init and save it to iter->member or something
+		 asprintf(&member, "numbers[%lu]", iter->ns_level);
+		 err = drgn_object_container_of(&iter->entry, &iter->entry, iter->pid_type, member);
+		 if (err)
+			 return err;
+		 *ret = &iter->entry;
+		 break;
+		}
 	}
+	return NULL;
 }
 
 struct drgn_error *task_iter_init(struct drgn_program *prog,

libdrgn/iterators.h

@@ -57,15 +57,20 @@ typedef struct drgn_object pid_iter_entry_t;
 
 struct pid_iter {
 	bool has_idr;
+	struct drgn_qualified_type pid_type;
 	union {
 		struct {
 			struct idr_iter iter;
-			struct drgn_qualified_type pid_type;
 		};
 		struct {
+			struct drgn_object* ns;
 			pid_iter_entry_t entry;
 			struct drgn_object pid_hash;
-			uint64_t pid_hash_shift;
+			struct drgn_object hlist_node;
+			struct drgn_qualified_type upid_type;
+			size_t hash_length;
+			int index;
+			uint64_t ns_level;
 		};
 	};
 };