import the extend_alloca() macro from glibc

diff --git a/include/libc-internal.h b/include/libc-internal.h
index 2e37226..6cd4feb 100644 (file)
--- a/include/libc-internal.h
+++ b/include/libc-internal.h
@@ -322,6 +322,36 @@ extern int __sprintf (char *__restrict __s,
 #define fopen64 __fopen64
 #endif
 
+/* #include <alloca.h> */
+#include <bits/stackinfo.h>
+#if _STACK_GROWS_DOWN
+# define extend_alloca(buf, len, newlen) \
+  (__typeof (buf)) ({ size_t __newlen = (newlen);                            \
+                     char *__newbuf = alloca (__newlen);                     \
+                     if (__newbuf + __newlen == (char *) buf)                \
+                       len += __newlen;                                      \
+                     else                                                    \
+                       len = __newlen;                                       \
+                     __newbuf; })
+#elif _STACK_GROWS_UP
+# define extend_alloca(buf, len, newlen) \
+  (__typeof (buf)) ({ size_t __newlen = (newlen);                            \
+                     char *__newbuf = alloca (__newlen);                     \
+                     char *__buf = (buf);                                    \
+                     if (__buf + __newlen == __newbuf)                       \
+                       {                                                     \
+                         len += __newlen;                                    \
+                         __newbuf = __buf;                                   \
+                       }                                                     \
+                     else                                                    \
+                       len = __newlen;                                       \
+                     __newbuf; })
+#else
+# warning unknown stack
+# define extend_alloca(buf, len, newlen) \
+  alloca (((len) = (newlen)))
+#endif
+
 /* #include <stdlib.h> */
 extern char *__getenv (__const char *__name) attribute_hidden;
 extern void __exit (int __status) __THROW __attribute__ ((__noreturn__)) attribute_hidden;