Refactor libc stubs into libwrap

The --wrap feature of GNU ld supports a cleaner framework for linking in
alternative implementations of libc functions without cpp hacks.
Place wrappers in separate object files to reduce static code size.

1 files changed, 16 insertions, 0 deletions

diff --git a/bsp/libwrap/sys/sbrk.c b/bsp/libwrap/sys/sbrk.c
new file mode 100644
index 0000000..6e6b36a
--- /dev/null
+++ b/bsp/libwrap/sys/sbrk.c
@@ -0,0 +1,16 @@
+/* See LICENSE of license details. */
+
+#include <stddef.h>
+
+void *__wrap_sbrk(ptrdiff_t incr)
+{
+  extern char _end[];
+  extern char _heap_end[];
+  static char *curbrk = _end;
+
+  if ((curbrk + incr < _end) || (curbrk + incr > _heap_end))
+    return NULL - 1;
+
+  curbrk += incr;
+  return curbrk - incr;
+}