20000317 sourceware import

libgloss/sparc/fixctors.c

@@ -0,0 +1,54 @@
+/* Code to byte-swap static constructor/destructor tables on
+   broken a.out little-endian targets. The startup code should call
+   __fix_ctors just before calling main.  It is safe to use on non-broken
+   or big-endian targets. */
+
+extern long __CTOR_LIST__[];
+extern long __DTOR_LIST__[];
+
+static void
+byte_swap (long *entry)
+{
+  unsigned char *p = (unsigned char *)entry;
+  unsigned char tmp;
+
+  tmp = p[0];
+  p[0] = p[3];
+  p[3] = tmp;
+  tmp = p[1];
+  p[1] = p[2];
+  p[2] = tmp;
+}
+
+static void
+fix_table (long *table)
+{
+  long len = table[0];
+
+  /* The heuristic for deciding if a table is broken is to examine
+     the word at the start of the table, which contains the number
+     of function pointers immediately following.  If the low word
+     is zero, and the high word is non-zero, it's very likely that
+     it is byte-swapped.  This test will fail if the program has
+     an exact multiple of 64K static constructors or destructors, a very
+     unlikely situation. */
+  if ((len & 0xffff) == 0 && (len & 0xffff0000) != 0)
+    {
+
+      /* The table looks broken.  Byte-swap all the words in the table, up
+         to a NULL entry, which marks the end of the table. */
+      do
+	{
+	  byte_swap (table);
+	  table++;
+	}
+      while (*table);
+    }
+}
+
+void
+__fix_ctors (void)
+{
+  fix_table (__CTOR_LIST__);
+  fix_table (__DTOR_LIST__);
+}