1 files changed, 64 insertions, 5 deletions

diff --git a/inet/inet_ntoa.c b/inet/inet_ntoa.c
index 38794957c2..889435dd10 100644
--- a/inet/inet_ntoa.c
+++ b/inet/inet_ntoa.c
@@ -21,19 +21,78 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <arpa/inet.h>
+#include <bits/libc-lock.h>
 
 /* The interface of this function is completely stupid, it requires a
-   static buffer.  We relax this a bit in that we allow one buffer for
-   each thread.  */
-static __thread char buffer[18];
+   static buffer.  We relax this a bit in that we allow at least one
+   buffer for each thread.  */
+
+/* This is the key for the thread specific memory.  */
+static __libc_key_t key;
+
+/* If nonzero the key allocation failed and we should better use a
+   static buffer than fail.  */
+static char local_buf[18];
+static char *static_buf;
+
+/* Destructor for the thread-specific data.  */
+static void init (void);
+static void free_key_mem (void *mem);
 
 
 char *
 inet_ntoa (struct in_addr in)
 {
-  unsigned char *bytes = (unsigned char *) &in;
-  __snprintf (buffer, sizeof (buffer), "%d.%d.%d.%d",
+  __libc_once_define (static, once);
+  char *buffer;
+  unsigned char *bytes;
+
+  /* If we have not yet initialized the buffer do it now.  */
+  __libc_once (once, init);
+
+  if (static_buf != NULL)
+    buffer = static_buf;
+  else
+    {
+      /* We don't use the static buffer and so we have a key.  Use it
+	 to get the thread-specific buffer.  */
+      buffer = __libc_getspecific (key);
+      if (buffer == NULL)
+	{
+	  /* No buffer allocated so far.  */
+	  buffer = malloc (18);
+	  if (buffer == NULL)
+	    /* No more memory available.  We use the static buffer.  */
+	    buffer = local_buf;
+	  else
+	    __libc_setspecific (key, buffer);
+	}
+    }
+
+  bytes = (unsigned char *) &in;
+  __snprintf (buffer, 18, "%d.%d.%d.%d",
 	      bytes[0], bytes[1], bytes[2], bytes[3]);
 
   return buffer;
 }
+
+
+/* Initialize buffer.  */
+static void
+init (void)
+{
+  if (__libc_key_create (&key, free_key_mem))
+    /* Creating the key failed.  This means something really went
+       wrong.  In any case use a static buffer which is better than
+       nothing.  */
+    static_buf = local_buf;
+}
+
+
+/* Free the thread specific data, this is done if a thread terminates.  */
+static void
+free_key_mem (void *mem)
+{
+  free (mem);
+  __libc_setspecific (key, NULL);
+}