From f21830d2a8097333fd7a85ad0ddbd925eb5f1877 Mon Sep 17 00:00:00 2001
From: Sam Edwards <CFSworks@gmail.com>
Date: Wed, 29 May 2019 17:27:16 -0600
Subject: [PATCH] dtoolutil: Fix UB when musl's dlinfo(RTLD_DI_LINKMAP) fails

---
 dtool/src/dtoolutil/executionEnvironment.cxx | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/dtool/src/dtoolutil/executionEnvironment.cxx b/dtool/src/dtoolutil/executionEnvironment.cxx
index 4152a8c356..9fce349268 100644
--- a/dtool/src/dtoolutil/executionEnvironment.cxx
+++ b/dtool/src/dtoolutil/executionEnvironment.cxx
@@ -610,16 +610,16 @@ read_args() {
 #else
     void *self = dlopen(NULL, RTLD_NOW | RTLD_NOLOAD);
 #endif
-    dlinfo(self, RTLD_DI_LINKMAP, &map);
-
-    while (map != nullptr) {
-      const char *tail = strrchr(map->l_name, '/');
-      const char *head = strchr(map->l_name, '/');
-      if (tail && head && (strcmp(tail, "/libp3dtool.so." PANDA_ABI_VERSION_STR) == 0
-                        || strcmp(tail, "/libp3dtool.so") == 0)) {
-        _dtool_name = head;
+    if (dlinfo(self, RTLD_DI_LINKMAP, &map)) {
+      while (map != nullptr) {
+        const char *tail = strrchr(map->l_name, '/');
+        const char *head = strchr(map->l_name, '/');
+        if (tail && head && (strcmp(tail, "/libp3dtool.so." PANDA_ABI_VERSION_STR) == 0
+                          || strcmp(tail, "/libp3dtool.so") == 0)) {
+          _dtool_name = head;
+        }
+        map = map->l_next;
       }
-      map = map->l_next;
     }
   }
 #endif