krb5 commit: Log failure details for mutex errors

https://github.com/krb5/krb5/commit/70321d39b3043952f8567d95a36a22dfc74da1a8
commit 70321d39b3043952f8567d95a36a22dfc74da1a8
Author: Robbie Harwood <[email protected]>
Date:   Tue Aug 8 18:24:32 2017 -0400

    Log failure details for mutex errors
    
    Log only when assertions themselves are enabled in order to keep code
    small.

 src/include/k5-thread.h |   16 ++++++++++++++++
 1 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/src/include/k5-thread.h b/src/include/k5-thread.h
index 3e3901d..a310123 100644
--- a/src/include/k5-thread.h
+++ b/src/include/k5-thread.h
@@ -134,6 +134,10 @@
      More to be added, perhaps.  */
 
 #include <assert.h>
+#ifndef NDEBUG
+#include <stdio.h>
+#include <string.h>
+#endif
 
 /* The mutex structure we use, k5_mutex_t, is defined to some
    OS-specific bits.  The use of multiple layers of typedefs are an
@@ -363,12 +367,24 @@ static inline int k5_mutex_finish_init(k5_mutex_t *m)
 static inline void k5_mutex_lock(k5_mutex_t *m)
 {
     int r = k5_os_mutex_lock(m);
+#ifndef NDEBUG
+    if (r != 0) {
+        fprintf(stderr, "k5_mutex_lock: Received error %d (%s)\n",
+                r, strerror(r));
+    }
+#endif
     assert(r == 0);
 }
 
 static inline void k5_mutex_unlock(k5_mutex_t *m)
 {
     int r = k5_os_mutex_unlock(m);
+#ifndef NDEBUG
+    if (r != 0) {
+        fprintf(stderr, "k5_mutex_unlock: Received error %d (%s)\n",
+                r, strerror(r));
+    }
+#endif
     assert(r == 0);
 }