libihash: Make sure we do not remove a locp several times

Suggested by Brent W. Baccala.

* libihash/ihash.c: Include <assert-backtrace.h>.
(locp_remove): Assert that item->value is valid.
* libihash/Makefile (HURDLIBS): Add shouldbeinlibc.

2 files changed, 3 insertions, 0 deletions

diff --git a/libihash/Makefile b/libihash/Makefile
index 3377ef41..7ceaf1d7 100644
--- a/libihash/Makefile
+++ b/libihash/Makefile
@@ -23,6 +23,7 @@ libname := libihash
 SRCS = ihash.c murmur3.c
 installhdrs = ihash.h
 
+HURDLIBS = shouldbeinlibc
 OBJS = $(SRCS:.c=.o)
 
 include ../Makeconf
diff --git a/libihash/ihash.c b/libihash/ihash.c
index 2fc70930..1b255443 100644
--- a/libihash/ihash.c
+++ b/libihash/ihash.c
@@ -29,6 +29,7 @@
 #include <stdlib.h>
 #include <stdint.h>
 #include <assert.h>
+#include <assert-backtrace.h>
 
 #include "ihash.h"
 
@@ -110,6 +111,7 @@ static inline void
 locp_remove (hurd_ihash_t ht, hurd_ihash_locp_t locp)
 {
   struct _hurd_ihash_item *item = (struct _hurd_ihash_item *) locp;
+  assert_backtrace (hurd_ihash_value_valid (item->value));
   if (ht->cleanup)
     (*ht->cleanup) (item->value, ht->cleanup_data);
   item->value = _HURD_IHASH_DELETED;