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-rw-r--r--libc/misc/search/insremque.c20
1 files changed, 14 insertions, 6 deletions
diff --git a/libc/misc/search/insremque.c b/libc/misc/search/insremque.c
index c4a75ab89..99399427e 100644
--- a/libc/misc/search/insremque.c
+++ b/libc/misc/search/insremque.c
@@ -26,12 +26,20 @@
void
insque (void *elem, void *prev)
{
- struct qelem *next = ((struct qelem *) prev)->q_forw;
- ((struct qelem *) prev)->q_forw = (struct qelem *) elem;
- if (next != NULL)
- next->q_back = (struct qelem *) elem;
- ((struct qelem *) elem)->q_forw = next;
- ((struct qelem *) elem)->q_back = (struct qelem *) prev;
+ if (prev == NULL)
+ {
+ ((struct qelem *) elem)->q_forw = NULL;
+ ((struct qelem *) elem)->q_back = NULL;
+ }
+ else
+ {
+ struct qelem *next = ((struct qelem *) prev)->q_forw;
+ ((struct qelem *) prev)->q_forw = (struct qelem *) elem;
+ if (next != NULL)
+ next->q_back = (struct qelem *) elem;
+ ((struct qelem *) elem)->q_forw = next;
+ ((struct qelem *) elem)->q_back = (struct qelem *) prev;
+ }
}
#endif