* include/cygwin/config.h (__getreent): Define inline version.

1 files changed, 21 insertions, 0 deletions

diff --git a/winsup/cygwin/include/cygwin/config.h b/winsup/cygwin/include/cygwin/config.h
index e3e09f051..0c2f157f8 100644
--- a/winsup/cygwin/include/cygwin/config.h
+++ b/winsup/cygwin/include/cygwin/config.h
@@ -20,6 +20,27 @@ extern "C" {
 #define _CYGWIN_CONFIG_H
 
 #define __DYNAMIC_REENT__
+
+/* The following provides an inline version of __getreent() for newlib,
+   which will be used throughout the library whereever there is a _r
+   version of a function that takes _REENT.  This saves the overhead
+   of a function call for what amounts to a simple computation.
+   
+   The definition below is essentially equivalent to the one in cygtls.h
+   (&_my_tls.local_clib) however it uses a fixed precomputed
+   offset rather than dereferencing a field of a structure.
+   
+   Including tlsoffets.h here in order to get this constant offset
+   tls_local_clib is a bit of a hack, but the alternative would require
+   dragging the entire definition of struct _cygtls (a large and complex
+   Cygwin internal data structure) into newlib.  The machinery to
+   compute these offsets already exists for the sake of gendef so
+   we might as well just use it here.  */
+
+#include "../tlsoffsets.h"
+extern char *_tlsbase __asm__ ("%fs:4");
+#define __getreent() (struct _reent *)(_tlsbase + tls_local_clib)
+
 #define __FILENAME_MAX__ (260 - 1 /* NUL */)
 #define _READ_WRITE_RETURN_TYPE _ssize_t
 #define __LARGE64_FILES 1