Xen devel - Jan 2013 - [PATCH V2] libxc, libxenstore: make the headers C++-friendlier

Made the xenctrl.h and xenstore.h easier to use with C++:
added ''extern "C"'' statements, moved the definition
of
enum xc_error_code above it''s typedef, and renamed a
''new''
parameter (''new'' is a C++ keyword).

Signed-off-by: Razvan Cojocaru <rzvncj@gmail.com>

diff -r 5af4f2ab06f3 -r c273ee1fc8ba tools/libxc/xenctrl.h
--- a/tools/libxc/xenctrl.h	Tue Jan 22 09:33:10 2013 +0100
+++ b/tools/libxc/xenctrl.h	Wed Jan 23 11:18:49 2013 +0200
@@ -26,6 +26,10 @@
 #ifndef XENCTRL_H
 #define XENCTRL_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* Tell the Xen public headers we are a user-space tools build. */
 #ifndef __XEN_TOOLS__
 #define __XEN_TOOLS__ 1
@@ -114,6 +118,15 @@ typedef struct xc_interface_core xc_inte
 typedef struct xc_interface_core xc_evtchn;
 typedef struct xc_interface_core xc_gnttab;
 typedef struct xc_interface_core xc_gntshr;
+
+enum xc_error_code {
+  XC_ERROR_NONE = 0,
+  XC_INTERNAL_ERROR = 1,
+  XC_INVALID_KERNEL = 2,
+  XC_INVALID_PARAM = 3,
+  XC_OUT_OF_MEMORY = 4,
+  /* new codes need to be added to xc_error_level_to_desc too */
+};
 typedef enum xc_error_code xc_error_code;
 
 
@@ -1618,16 +1631,6 @@ int xc_hvm_inject_trap(
  *  LOGGING AND ERROR REPORTING
  */
 
-
-enum xc_error_code {
-  XC_ERROR_NONE = 0,
-  XC_INTERNAL_ERROR = 1,
-  XC_INVALID_KERNEL = 2,
-  XC_INVALID_PARAM = 3,
-  XC_OUT_OF_MEMORY = 4,
-  /* new codes need to be added to xc_error_level_to_desc too */
-};
-
 #define XC_MAX_ERROR_MSG_LEN 1024
 typedef struct xc_error {
   enum xc_error_code code;
@@ -2236,4 +2239,8 @@ int xc_compression_uncompress_page(xc_in
 				   unsigned long compbuf_size,
 				   unsigned long *compbuf_pos, char *dest);
 
+#ifdef __cplusplus
+}
+#endif 
+
 #endif /* XENCTRL_H */
diff -r 5af4f2ab06f3 -r c273ee1fc8ba tools/xenstore/xenstore.h
--- a/tools/xenstore/xenstore.h	Tue Jan 22 09:33:10 2013 +0100
+++ b/tools/xenstore/xenstore.h	Wed Jan 23 11:18:49 2013 +0200
@@ -20,6 +20,10 @@
 #ifndef XENSTORE_H
 #define XENSTORE_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #include <xenstore_lib.h>
 
 #define XBT_NULL 0
@@ -244,6 +248,11 @@ char *xs_debug_command(struct xs_handle 
 		       void *data, unsigned int len);
 
 int xs_suspend_evtchn_port(int domid);
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* XENSTORE_H */
 
 /*
diff -r 5af4f2ab06f3 -r c273ee1fc8ba xen/include/public/arch-x86/hvm/save.h
--- a/xen/include/public/arch-x86/hvm/save.h	Tue Jan 22 09:33:10 2013 +0100
+++ b/xen/include/public/arch-x86/hvm/save.h	Wed Jan 23 11:18:49 2013 +0200
@@ -269,15 +269,15 @@ struct hvm_hw_cpu_compat {
 };
 
 static inline int _hvm_hw_fix_cpu(void *h) {
-    struct hvm_hw_cpu *new=h;
-    struct hvm_hw_cpu_compat *old=h;
+    struct hvm_hw_cpu *newcpu = (struct hvm_hw_cpu *)h;
+    struct hvm_hw_cpu_compat *old = (struct hvm_hw_cpu_compat *)h;
 
     /* If we copy from the end backwards, we should
      * be able to do the modification in-place */
-    new->error_code=old->error_code;
-    new->pending_event=old->pending_event;
-    new->tsc=old->tsc;
-    new->msr_tsc_aux=0;
+    newcpu->error_code = old->error_code;
+    newcpu->pending_event = old->pending_event;
+    newcpu->tsc = old->tsc;
+    newcpu->msr_tsc_aux = 0;
 
     return 0;
 }

>>> On 23.01.13 at 10:19, Razvan Cojocaru <rzvncj@gmail.com>
wrote:
>  static inline int _hvm_hw_fix_cpu(void *h) {
> -    struct hvm_hw_cpu *new=h;
> -    struct hvm_hw_cpu_compat *old=h;
> +    struct hvm_hw_cpu *newcpu = (struct hvm_hw_cpu *)h;
> +    struct hvm_hw_cpu_compat *old = (struct hvm_hw_cpu_compat *)h;
>  
>      /* If we copy from the end backwards, we should
>       * be able to do the modification in-place */
> -    new->error_code=old->error_code;
> -    new->pending_event=old->pending_event;
> -    new->tsc=old->tsc;
> -    new->msr_tsc_aux=0;
> +    newcpu->error_code = old->error_code;
> +    newcpu->pending_event = old->pending_event;
> +    newcpu->tsc = old->tsc;
> +    newcpu->msr_tsc_aux = 0;
>  
>      return 0;
>  }
Actually I think this needs to be done differently anyway, as the
way it currently is it isn''t even correct. In particular, I
don''t
think there''s anything keeping the compiler from re-ordering
the reads and writes (gcc: without -fno-strict-aliasing), thus
invalidating the purposeful backward processing.

By means of using

union hvm_hw_cpu_union {
    struct hvm_hw_cpu nat;
    struct hvm_hw_cpu_compat cmp;
};

this can be avoided in a compatible manner (and the renaming
can be done basically as a side effect).

Sorry for not having noticed on the first run through.

Jan