From f2e1a5be776de0a4d12c03820bcb5fb0d475d756 Mon Sep 17 00:00:00 2001
From: Yinan Zhang <zyn8950@gmail.com>
Date: Thu, 13 Aug 2020 13:26:44 -0700
Subject: [PATCH] Do not fail on partial ctl path for ctl_nametomib()

We do not fail on partial ctl path when the given `mib` array is
shorter than the given name, and we should keep the behavior the
same in the reverse case, which I feel is also the more natural way.
---
 src/ctl.c           |  8 ++------
 test/unit/mallctl.c | 15 +++++++++++++++
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/src/ctl.c b/src/ctl.c
index 7bb6c1dc..d139e6e0 100644
--- a/src/ctl.c
+++ b/src/ctl.c
@@ -1387,7 +1387,8 @@ ctl_lookup(tsdn_t *tsdn, const ctl_named_node_t *starting_node,
 			mibp[i] = (size_t)index;
 		}
 
-		if (node->ctl != NULL) {
+		/* Reached the end? */
+		if (node->ctl != NULL || *dot == '\0') {
 			/* Terminal node. */
 			if (*dot != '\0') {
 				/*
@@ -1403,11 +1404,6 @@ ctl_lookup(tsdn_t *tsdn, const ctl_named_node_t *starting_node,
 		}
 
 		/* Update elm. */
-		if (*dot == '\0') {
-			/* No more elements. */
-			ret = ENOENT;
-			goto label_return;
-		}
 		elm = &dot[1];
 		dot = ((tdot = strchr(elm, '.')) != NULL) ? tdot :
 		    strchr(elm, '\0');
diff --git a/test/unit/mallctl.c b/test/unit/mallctl.c
index 72dc0f3d..3cd0c4d2 100644
--- a/test/unit/mallctl.c
+++ b/test/unit/mallctl.c
@@ -117,6 +117,20 @@ TEST_BEGIN(test_mallctlnametomib_short_mib) {
 }
 TEST_END
 
+TEST_BEGIN(test_mallctlnametomib_short_name) {
+	size_t mib[4];
+	size_t miblen;
+
+	miblen = 4;
+	mib[3] = 42;
+	expect_d_eq(mallctlnametomib("arenas.bin.0", mib, &miblen), 0,
+	    "Unexpected mallctlnametomib() failure");
+	expect_zu_eq(miblen, 3, "Unexpected mib output length");
+	expect_zu_eq(mib[3], 42,
+	    "mallctlnametomib() wrote past the end of the input mib");
+}
+TEST_END
+
 TEST_BEGIN(test_mallctl_config) {
 #define TEST_MALLCTL_CONFIG(config, t) do {				\
 	t oldval;							\
@@ -1106,6 +1120,7 @@ main(void) {
 	    test_mallctlbymib_errors,
 	    test_mallctl_read_write,
 	    test_mallctlnametomib_short_mib,
+	    test_mallctlnametomib_short_name,
 	    test_mallctl_config,
 	    test_mallctl_opt,
 	    test_manpage_example,