From 9b3f4ef6eec6a5981dcaa62f45da49b8f4f95388 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Tue, 24 Jan 2017 16:52:00 +1030
Subject: [PATCH] tal: make tal_len/tal_count(NULL) return 0.

Previously it crashed, but if you're always dealing with tal arrays,
this is painful.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 ccan/tal/tal.c            |  3 +++
 ccan/tal/tal.h            | 10 +++++-----
 ccan/tal/test/run-count.c |  6 +++++-
 tools/depends.c           |  2 +-
 4 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/ccan/tal/tal.c b/ccan/tal/tal.c
index 2a2eca77..555dd133 100644
--- a/ccan/tal/tal.c
+++ b/ccan/tal/tal.c
@@ -654,6 +654,9 @@ size_t tal_len(const tal_t *ptr)
 {
 	struct length *l;
 
+	if (!ptr)
+		return 0;
+
 	l = find_property(debug_tal(to_tal_hdr(ptr)), LENGTH);
 	if (!l)
 		return 0;
diff --git a/ccan/tal/tal.h b/ccan/tal/tal.h
index 200c2b16..e525a01d 100644
--- a/ccan/tal/tal.h
+++ b/ccan/tal/tal.h
@@ -304,18 +304,18 @@ const char *tal_name(const tal_t *ptr);
 
 /**
  * tal_count - get the count of objects in a tal_arr.
- * @ptr: The tal allocated object array.
+ * @ptr: The tal allocated object array (or NULL)
  *
- * Returns 0 if @ptr has no length property, but be aware that that is
- * also a valid size!
+ * Returns 0 if @ptr has no length property or is NULL, but be aware
+ * that that is also a valid size!
  */
 #define tal_count(p) (tal_len(p) / sizeof(*p))
 
 /**
  * tal_len - get the count of bytes in a tal_arr.
- * @ptr: The tal allocated object array.
+ * @ptr: The tal allocated object array (or NULL)
  *
- * Returns 0 if @ptr has no length property, but be aware that that is
+ * Returns 0 if @ptr has no length property or NULL, but be aware that that is
  * also a valid size!
  */
 size_t tal_len(const tal_t *ptr);
diff --git a/ccan/tal/test/run-count.c b/ccan/tal/test/run-count.c
index 6a4eb4ab..33049b9f 100644
--- a/ccan/tal/test/run-count.c
+++ b/ccan/tal/test/run-count.c
@@ -43,7 +43,11 @@ int main(void)
 
 	tal_set_backend(my_alloc, my_realloc, my_free, NULL);
 
-	plan_tests(19 * 3);
+	plan_tests(2 + 19 * 3);
+
+	p1 = NULL;
+	ok1(tal_len(p1) == 0);
+	ok1(tal_count(p1) == 0);
 
 	for (i = 0; i < 3; i++) {
 		move = i;
diff --git a/tools/depends.c b/tools/depends.c
index 95bda1b5..e6a79d71 100644
--- a/tools/depends.c
+++ b/tools/depends.c
@@ -306,7 +306,7 @@ static char *get_one_ported(const void *ctx, const char *dir,
 	char **ported = get_one_prop(ctx, dir, "ported", get_info);
 
 	/* No news is good news. */
-	if (!ported || tal_count(ported) == 0)
+	if (tal_count(ported) == 0)
 		return NULL;
 
 	if (tal_count(ported) != 1)
-- 
2.39.2