Anything *_is_empty(), *_is_default(), or *_gen_json() is going to be
examining the pointed to thing, not modifying it.  This potentially
results in higher-performance output.  This also allows spreading
constants further, allowing more checking and security.

Signed-off-by: Elliott Mitchell <ehem+xen@m5p.com>
---
 tools/include/libxl_json.h        | 22 ++++++++++++----------
 tools/libs/light/gentypes.py      |  8 ++++----
 tools/libs/light/libxl_cpuid.c    |  2 +-
 tools/libs/light/libxl_internal.c |  4 ++--
 tools/libs/light/libxl_internal.h | 18 +++++++++---------
 tools/libs/light/libxl_json.c     | 18 ++++++++++--------
 tools/libs/light/libxl_nocpuid.c  |  4 ++--
 7 files changed, 40 insertions(+), 36 deletions(-)

diff --git a/tools/include/libxl_json.h b/tools/include/libxl_json.h
index 260783bfde..63f0e58fe1 100644
--- a/tools/include/libxl_json.h
+++ b/tools/include/libxl_json.h
@@ -23,17 +23,19 @@
 #endif
 
 yajl_gen_status libxl__uint64_gen_json(yajl_gen hand, uint64_t val);
-yajl_gen_status libxl_defbool_gen_json(yajl_gen hand, libxl_defbool *p);
-yajl_gen_status libxl_uuid_gen_json(yajl_gen hand, libxl_uuid *p);
-yajl_gen_status libxl_mac_gen_json(yajl_gen hand, libxl_mac *p);
-yajl_gen_status libxl_bitmap_gen_json(yajl_gen hand, libxl_bitmap *p);
+yajl_gen_status libxl_defbool_gen_json(yajl_gen hand, const libxl_defbool *p);
+yajl_gen_status libxl_uuid_gen_json(yajl_gen hand, const libxl_uuid *p);
+yajl_gen_status libxl_mac_gen_json(yajl_gen hand, const libxl_mac *p);
+yajl_gen_status libxl_bitmap_gen_json(yajl_gen hand, const libxl_bitmap *p);
 yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,
-                                                 libxl_cpuid_policy_list *p);
-yajl_gen_status libxl_string_list_gen_json(yajl_gen hand, libxl_string_list *p);
+                                                 const libxl_cpuid_policy_list *p);
+yajl_gen_status libxl_string_list_gen_json(yajl_gen hand,
+                                           const libxl_string_list *p);
 yajl_gen_status libxl_key_value_list_gen_json(yajl_gen hand,
-                                              libxl_key_value_list *p);
-yajl_gen_status libxl_hwcap_gen_json(yajl_gen hand, libxl_hwcap *p);
-yajl_gen_status libxl_ms_vm_genid_gen_json(yajl_gen hand, libxl_ms_vm_genid *p);
+                                              const libxl_key_value_list *p);
+yajl_gen_status libxl_hwcap_gen_json(yajl_gen hand, const libxl_hwcap *p);
+yajl_gen_status libxl_ms_vm_genid_gen_json(yajl_gen hand,
+                                           const libxl_ms_vm_genid *p);
 
 #include <_libxl_types_json.h>
 
@@ -91,6 +93,6 @@ static inline yajl_gen libxl_yajl_gen_alloc(const yajl_alloc_funcs *allocFuncs)
 #endif /* !HAVE_YAJL_V2 */
 
 yajl_gen_status libxl_domain_config_gen_json(yajl_gen hand,
-                                             libxl_domain_config *p);
+                                             const libxl_domain_config *p);
 
 #endif /* LIBXL_JSON_H */
diff --git a/tools/libs/light/gentypes.py b/tools/libs/light/gentypes.py
index 9a45e45acc..7e02a5366f 100644
--- a/tools/libs/light/gentypes.py
+++ b/tools/libs/light/gentypes.py
@@ -632,7 +632,7 @@ if __name__ == '__main__':
                                                ty.make_arg("p"),
                                                ku.keyvar.type.make_arg(ku.keyvar.name)))
         if ty.json_gen_fn is not None:
-            f.write("%schar *%s_to_json(libxl_ctx *ctx, %s);\n" % (ty.hidden(), ty.typename, ty.make_arg("p")))
+            f.write("%schar *%s_to_json(libxl_ctx *ctx, const %s);\n" % (ty.hidden(), ty.typename, ty.make_arg("p")))
         if ty.json_parse_fn is not None:
             f.write("%sint %s_from_json(libxl_ctx *ctx, %s, const char *s);\n" % (ty.hidden(), ty.typename, ty.make_arg("p", passby=idl.PASS_BY_REFERENCE)))
         if isinstance(ty, idl.Enumeration):
@@ -662,7 +662,7 @@ if __name__ == '__main__':
 """ % (header_json_define, header_json_define, " ".join(sys.argv)))
 
     for ty in [ty for ty in types if ty.json_gen_fn is not None]:
-        f.write("%syajl_gen_status %s_gen_json(yajl_gen hand, %s);\n" % (ty.hidden(), ty.typename, ty.make_arg("p", passby=idl.PASS_BY_REFERENCE)))
+        f.write("%syajl_gen_status %s_gen_json(yajl_gen hand, const %s);\n" % (ty.hidden(), ty.typename, ty.make_arg("p", passby=idl.PASS_BY_REFERENCE)))
 
     f.write("\n")
     f.write("""#endif /* %s */\n""" % header_json_define)
@@ -766,13 +766,13 @@ if __name__ == '__main__':
         f.write("\n")
 
     for ty in [t for t in types if t.json_gen_fn is not None]:
-        f.write("yajl_gen_status %s_gen_json(yajl_gen hand, %s)\n" % (ty.typename, ty.make_arg("p", passby=idl.PASS_BY_REFERENCE)))
+        f.write("yajl_gen_status %s_gen_json(yajl_gen hand, const %s)\n" % (ty.typename, ty.make_arg("p", passby=idl.PASS_BY_REFERENCE)))
         f.write("{\n")
         f.write(libxl_C_type_gen_json(ty, "p"))
         f.write("}\n")
         f.write("\n")
 
-        f.write("char *%s_to_json(libxl_ctx *ctx, %s)\n" % (ty.typename, ty.make_arg("p")))
+        f.write("char *%s_to_json(libxl_ctx *ctx, const %s)\n" % (ty.typename, ty.make_arg("p")))
         f.write("{\n")
         f.write(libxl_C_type_to_json(ty, "p"))
         f.write("}\n")
diff --git a/tools/libs/light/libxl_cpuid.c b/tools/libs/light/libxl_cpuid.c
index e1acf6648d..b076d7f4a3 100644
--- a/tools/libs/light/libxl_cpuid.c
+++ b/tools/libs/light/libxl_cpuid.c
@@ -14,7 +14,7 @@
 
 #include "libxl_internal.h"
 
-int libxl__cpuid_policy_is_empty(libxl_cpuid_policy_list *pl)
+int libxl__cpuid_policy_is_empty(const libxl_cpuid_policy_list *pl)
 {
     return !libxl_cpuid_policy_list_length(pl);
 }
diff --git a/tools/libs/light/libxl_internal.c b/tools/libs/light/libxl_internal.c
index 86556b6113..da2dbd67ad 100644
--- a/tools/libs/light/libxl_internal.c
+++ b/tools/libs/light/libxl_internal.c
@@ -333,7 +333,7 @@ _hidden int libxl__parse_mac(const char *s, libxl_mac mac)
     return 0;
 }
 
-_hidden int libxl__compare_macs(libxl_mac *a, libxl_mac *b)
+_hidden int libxl__compare_macs(const libxl_mac *a, const libxl_mac *b)
 {
     int i;
 
@@ -345,7 +345,7 @@ _hidden int libxl__compare_macs(libxl_mac *a, libxl_mac *b)
     return 0;
 }
 
-_hidden int libxl__mac_is_default(libxl_mac *mac)
+_hidden int libxl__mac_is_default(const libxl_mac *mac)
 {
     return (!(*mac)[0] && !(*mac)[1] && !(*mac)[2] &&
             !(*mac)[3] && !(*mac)[4] && !(*mac)[5]);
diff --git a/tools/libs/light/libxl_internal.h b/tools/libs/light/libxl_internal.h
index 37d5c27756..117a98acab 100644
--- a/tools/libs/light/libxl_internal.h
+++ b/tools/libs/light/libxl_internal.h
@@ -2080,9 +2080,9 @@ struct libxl__xen_console_reader {
 /* parse the string @s as a sequence of 6 colon separated bytes in to @mac */
 _hidden int libxl__parse_mac(const char *s, libxl_mac mac);
 /* compare mac address @a and @b. 0 if the same, -ve if a<b and +ve if a>b */
-_hidden int libxl__compare_macs(libxl_mac *a, libxl_mac *b);
+_hidden int libxl__compare_macs(const libxl_mac *a, const libxl_mac *b);
 /* return true if mac address is all zero (the default value) */
-_hidden int libxl__mac_is_default(libxl_mac *mac);
+_hidden int libxl__mac_is_default(const libxl_mac *mac);
 /* init a recursive mutex */
 _hidden int libxl__init_recursive_mutex(libxl_ctx *ctx, pthread_mutex_t *lock);
 
@@ -4580,7 +4580,7 @@ _hidden int libxl__ms_vm_genid_set(libxl__gc *gc, uint32_t domid,
 #define LIBXL__DEFBOOL_STR_DEFAULT "<default>"
 #define LIBXL__DEFBOOL_STR_FALSE   "False"
 #define LIBXL__DEFBOOL_STR_TRUE    "True"
-static inline int libxl__defbool_is_default(libxl_defbool *db)
+static inline int libxl__defbool_is_default(const libxl_defbool *db)
 {
     return !db->val;
 }
@@ -4675,22 +4675,22 @@ int libxl__random_bytes(libxl__gc *gc, uint8_t *buf, size_t len);
 #include "_libxl_types_internal_private.h"
 
 /* This always return false, there's no "default value" for hw cap */
-static inline int libxl__hwcap_is_default(libxl_hwcap *hwcap)
+static inline int libxl__hwcap_is_default(const libxl_hwcap *hwcap)
 {
     return 0;
 }
 
-static inline int libxl__string_list_is_empty(libxl_string_list *psl)
+static inline int libxl__string_list_is_empty(const libxl_string_list *psl)
 {
     return !libxl_string_list_length(psl);
 }
 
-static inline int libxl__key_value_list_is_empty(libxl_key_value_list *pkvl)
+static inline int libxl__key_value_list_is_empty(const libxl_key_value_list *pkvl)
 {
     return !libxl_key_value_list_length(pkvl);
 }
 
-int libxl__cpuid_policy_is_empty(libxl_cpuid_policy_list *pl);
+int libxl__cpuid_policy_is_empty(const libxl_cpuid_policy_list *pl);
 
 /* Portability note: a proper flock(2) implementation is required */
 typedef struct {
@@ -4821,12 +4821,12 @@ void* libxl__device_list(libxl__gc *gc, const libxl__device_type *dt,
 void libxl__device_list_free(const libxl__device_type *dt,
                              void *list, int num);
 
-static inline bool libxl__timer_mode_is_default(libxl_timer_mode *tm)
+static inline bool libxl__timer_mode_is_default(const libxl_timer_mode *tm)
 {
     return *tm == LIBXL_TIMER_MODE_DEFAULT;
 }
 
-static inline bool libxl__string_is_default(char **s)
+static inline bool libxl__string_is_default(char *const *s)
 {
     return *s == NULL;
 }
diff --git a/tools/libs/light/libxl_json.c b/tools/libs/light/libxl_json.c
index 9b8ef2cab9..88e81f9905 100644
--- a/tools/libs/light/libxl_json.c
+++ b/tools/libs/light/libxl_json.c
@@ -95,7 +95,7 @@ yajl_gen_status libxl__yajl_gen_enum(yajl_gen hand, const char *str)
  * YAJL generators for builtin libxl types.
  */
 yajl_gen_status libxl_defbool_gen_json(yajl_gen hand,
-                                       libxl_defbool *db)
+                                       const libxl_defbool *db)
 {
     return libxl__yajl_gen_asciiz(hand, libxl_defbool_to_string(*db));
 }
@@ -137,7 +137,7 @@ int libxl__bool_parse_json(libxl__gc *gc, const libxl__json_object *o,
 }
 
 yajl_gen_status libxl_uuid_gen_json(yajl_gen hand,
-                                    libxl_uuid *uuid)
+                                    const libxl_uuid *uuid)
 {
     char buf[LIBXL_UUID_FMTLEN+1];
     snprintf(buf, sizeof(buf), LIBXL_UUID_FMT, LIBXL_UUID_BYTES((*uuid)));
@@ -154,7 +154,7 @@ int libxl__uuid_parse_json(libxl__gc *gc, const libxl__json_object *o,
 }
 
 yajl_gen_status libxl_bitmap_gen_json(yajl_gen hand,
-                                      libxl_bitmap *bitmap)
+                                      const libxl_bitmap *bitmap)
 {
     yajl_gen_status s;
     int i;
@@ -208,7 +208,7 @@ int libxl__bitmap_parse_json(libxl__gc *gc, const libxl__json_object *o,
 }
 
 yajl_gen_status libxl_key_value_list_gen_json(yajl_gen hand,
-                                              libxl_key_value_list *pkvl)
+                                              const libxl_key_value_list *pkvl)
 {
     libxl_key_value_list kvl = *pkvl;
     yajl_gen_status s;
@@ -269,7 +269,8 @@ int libxl__key_value_list_parse_json(libxl__gc *gc, const libxl__json_object *o,
     return 0;
 }
 
-yajl_gen_status libxl_string_list_gen_json(yajl_gen hand, libxl_string_list *pl)
+yajl_gen_status libxl_string_list_gen_json(yajl_gen hand,
+                                           const libxl_string_list *pl)
 {
     libxl_string_list l = *pl;
     yajl_gen_status s;
@@ -322,7 +323,7 @@ int libxl__string_list_parse_json(libxl__gc *gc, const libxl__json_object *o,
     return 0;
 }
 
-yajl_gen_status libxl_mac_gen_json(yajl_gen hand, libxl_mac *mac)
+yajl_gen_status libxl_mac_gen_json(yajl_gen hand, const libxl_mac *mac)
 {
     char buf[LIBXL_MAC_FMTLEN+1];
     snprintf(buf, sizeof(buf), LIBXL_MAC_FMT, LIBXL_MAC_BYTES((*mac)));
@@ -339,7 +340,7 @@ int libxl__mac_parse_json(libxl__gc *gc, const libxl__json_object *o,
 }
 
 yajl_gen_status libxl_hwcap_gen_json(yajl_gen hand,
-                                     libxl_hwcap *p)
+                                     const libxl_hwcap *p)
 {
     yajl_gen_status s;
     int i;
@@ -377,7 +378,8 @@ int libxl__hwcap_parse_json(libxl__gc *gc, const libxl__json_object *o,
     return 0;
 }
 
-yajl_gen_status libxl_ms_vm_genid_gen_json(yajl_gen hand, libxl_ms_vm_genid *p)
+yajl_gen_status libxl_ms_vm_genid_gen_json(yajl_gen hand,
+                                           const libxl_ms_vm_genid *p)
 {
     yajl_gen_status s;
     int i;
diff --git a/tools/libs/light/libxl_nocpuid.c b/tools/libs/light/libxl_nocpuid.c
index 0630959e76..f40a004e95 100644
--- a/tools/libs/light/libxl_nocpuid.c
+++ b/tools/libs/light/libxl_nocpuid.c
@@ -14,7 +14,7 @@
 
 #include "libxl_internal.h"
 
-int libxl__cpuid_policy_is_empty(libxl_cpuid_policy_list *pl)
+int libxl__cpuid_policy_is_empty(const libxl_cpuid_policy_list *pl)
 {
     return 1;
 }
@@ -41,7 +41,7 @@ int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool restore,
 }
 
 yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,
-                                libxl_cpuid_policy_list *pcpuid)
+                                const libxl_cpuid_policy_list *pcpuid)
 {
     return 0;
 }
-- 
2.30.2

> On 18 Dec 2020, at 21:37, Elliott Mitchell <ehem+xen@m5p.com> wrote:
> 
> Anything *_is_empty(), *_is_default(), or *_gen_json() is going to be
> examining the pointed to thing, not modifying it.  This potentially
> results in higher-performance output.  This also allows spreading
> constants further, allowing more checking and security.

Looks ok to me
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>

> 
> Signed-off-by: Elliott Mitchell <ehem+xen@m5p.com>
> ---
> tools/include/libxl_json.h        | 22 ++++++++++++----------
> tools/libs/light/gentypes.py      |  8 ++++----
> tools/libs/light/libxl_cpuid.c    |  2 +-
> tools/libs/light/libxl_internal.c |  4 ++--
> tools/libs/light/libxl_internal.h | 18 +++++++++---------
> tools/libs/light/libxl_json.c     | 18 ++++++++++--------
> tools/libs/light/libxl_nocpuid.c  |  4 ++--
> 7 files changed, 40 insertions(+), 36 deletions(-)
> 
> diff --git a/tools/include/libxl_json.h b/tools/include/libxl_json.h
> index 260783bfde..63f0e58fe1 100644
> --- a/tools/include/libxl_json.h
> +++ b/tools/include/libxl_json.h
> @@ -23,17 +23,19 @@
> #endif
> 
> yajl_gen_status libxl__uint64_gen_json(yajl_gen hand, uint64_t val);
> -yajl_gen_status libxl_defbool_gen_json(yajl_gen hand, libxl_defbool *p);
> -yajl_gen_status libxl_uuid_gen_json(yajl_gen hand, libxl_uuid *p);
> -yajl_gen_status libxl_mac_gen_json(yajl_gen hand, libxl_mac *p);
> -yajl_gen_status libxl_bitmap_gen_json(yajl_gen hand, libxl_bitmap *p);
> +yajl_gen_status libxl_defbool_gen_json(yajl_gen hand, const libxl_defbool *p);
> +yajl_gen_status libxl_uuid_gen_json(yajl_gen hand, const libxl_uuid *p);
> +yajl_gen_status libxl_mac_gen_json(yajl_gen hand, const libxl_mac *p);
> +yajl_gen_status libxl_bitmap_gen_json(yajl_gen hand, const libxl_bitmap *p);
> yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,
> -                                                 libxl_cpuid_policy_list *p);
> -yajl_gen_status libxl_string_list_gen_json(yajl_gen hand, libxl_string_list *p);
> +                                                 const libxl_cpuid_policy_list *p);
> +yajl_gen_status libxl_string_list_gen_json(yajl_gen hand,
> +                                           const libxl_string_list *p);
> yajl_gen_status libxl_key_value_list_gen_json(yajl_gen hand,
> -                                              libxl_key_value_list *p);
> -yajl_gen_status libxl_hwcap_gen_json(yajl_gen hand, libxl_hwcap *p);
> -yajl_gen_status libxl_ms_vm_genid_gen_json(yajl_gen hand, libxl_ms_vm_genid *p);
> +                                              const libxl_key_value_list *p);
> +yajl_gen_status libxl_hwcap_gen_json(yajl_gen hand, const libxl_hwcap *p);
> +yajl_gen_status libxl_ms_vm_genid_gen_json(yajl_gen hand,
> +                                           const libxl_ms_vm_genid *p);
> 
> #include <_libxl_types_json.h>
> 
> @@ -91,6 +93,6 @@ static inline yajl_gen libxl_yajl_gen_alloc(const yajl_alloc_funcs *allocFuncs)
> #endif /* !HAVE_YAJL_V2 */
> 
> yajl_gen_status libxl_domain_config_gen_json(yajl_gen hand,
> -                                             libxl_domain_config *p);
> +                                             const libxl_domain_config *p);
> 
> #endif /* LIBXL_JSON_H */
> diff --git a/tools/libs/light/gentypes.py b/tools/libs/light/gentypes.py
> index 9a45e45acc..7e02a5366f 100644
> --- a/tools/libs/light/gentypes.py
> +++ b/tools/libs/light/gentypes.py
> @@ -632,7 +632,7 @@ if __name__ == '__main__':
>                                                ty.make_arg("p"),
>                                                ku.keyvar.type.make_arg(ku.keyvar.name)))
>         if ty.json_gen_fn is not None:
> -            f.write("%schar *%s_to_json(libxl_ctx *ctx, %s);\n" % (ty.hidden(), ty.typename, ty.make_arg("p")))
> +            f.write("%schar *%s_to_json(libxl_ctx *ctx, const %s);\n" % (ty.hidden(), ty.typename, ty.make_arg("p")))
>         if ty.json_parse_fn is not None:
>             f.write("%sint %s_from_json(libxl_ctx *ctx, %s, const char *s);\n" % (ty.hidden(), ty.typename, ty.make_arg("p", passby=idl.PASS_BY_REFERENCE)))
>         if isinstance(ty, idl.Enumeration):
> @@ -662,7 +662,7 @@ if __name__ == '__main__':
> """ % (header_json_define, header_json_define, " ".join(sys.argv)))
> 
>     for ty in [ty for ty in types if ty.json_gen_fn is not None]:
> -        f.write("%syajl_gen_status %s_gen_json(yajl_gen hand, %s);\n" % (ty.hidden(), ty.typename, ty.make_arg("p", passby=idl.PASS_BY_REFERENCE)))
> +        f.write("%syajl_gen_status %s_gen_json(yajl_gen hand, const %s);\n" % (ty.hidden(), ty.typename, ty.make_arg("p", passby=idl.PASS_BY_REFERENCE)))
> 
>     f.write("\n")
>     f.write("""#endif /* %s */\n""" % header_json_define)
> @@ -766,13 +766,13 @@ if __name__ == '__main__':
>         f.write("\n")
> 
>     for ty in [t for t in types if t.json_gen_fn is not None]:
> -        f.write("yajl_gen_status %s_gen_json(yajl_gen hand, %s)\n" % (ty.typename, ty.make_arg("p", passby=idl.PASS_BY_REFERENCE)))
> +        f.write("yajl_gen_status %s_gen_json(yajl_gen hand, const %s)\n" % (ty.typename, ty.make_arg("p", passby=idl.PASS_BY_REFERENCE)))
>         f.write("{\n")
>         f.write(libxl_C_type_gen_json(ty, "p"))
>         f.write("}\n")
>         f.write("\n")
> 
> -        f.write("char *%s_to_json(libxl_ctx *ctx, %s)\n" % (ty.typename, ty.make_arg("p")))
> +        f.write("char *%s_to_json(libxl_ctx *ctx, const %s)\n" % (ty.typename, ty.make_arg("p")))
>         f.write("{\n")
>         f.write(libxl_C_type_to_json(ty, "p"))
>         f.write("}\n")
> diff --git a/tools/libs/light/libxl_cpuid.c b/tools/libs/light/libxl_cpuid.c
> index e1acf6648d..b076d7f4a3 100644
> --- a/tools/libs/light/libxl_cpuid.c
> +++ b/tools/libs/light/libxl_cpuid.c
> @@ -14,7 +14,7 @@
> 
> #include "libxl_internal.h"
> 
> -int libxl__cpuid_policy_is_empty(libxl_cpuid_policy_list *pl)
> +int libxl__cpuid_policy_is_empty(const libxl_cpuid_policy_list *pl)
> {
>     return !libxl_cpuid_policy_list_length(pl);
> }
> diff --git a/tools/libs/light/libxl_internal.c b/tools/libs/light/libxl_internal.c
> index 86556b6113..da2dbd67ad 100644
> --- a/tools/libs/light/libxl_internal.c
> +++ b/tools/libs/light/libxl_internal.c
> @@ -333,7 +333,7 @@ _hidden int libxl__parse_mac(const char *s, libxl_mac mac)
>     return 0;
> }
> 
> -_hidden int libxl__compare_macs(libxl_mac *a, libxl_mac *b)
> +_hidden int libxl__compare_macs(const libxl_mac *a, const libxl_mac *b)
> {
>     int i;
> 
> @@ -345,7 +345,7 @@ _hidden int libxl__compare_macs(libxl_mac *a, libxl_mac *b)
>     return 0;
> }
> 
> -_hidden int libxl__mac_is_default(libxl_mac *mac)
> +_hidden int libxl__mac_is_default(const libxl_mac *mac)
> {
>     return (!(*mac)[0] && !(*mac)[1] && !(*mac)[2] &&
>             !(*mac)[3] && !(*mac)[4] && !(*mac)[5]);
> diff --git a/tools/libs/light/libxl_internal.h b/tools/libs/light/libxl_internal.h
> index 37d5c27756..117a98acab 100644
> --- a/tools/libs/light/libxl_internal.h
> +++ b/tools/libs/light/libxl_internal.h
> @@ -2080,9 +2080,9 @@ struct libxl__xen_console_reader {
> /* parse the string @s as a sequence of 6 colon separated bytes in to @mac */
> _hidden int libxl__parse_mac(const char *s, libxl_mac mac);
> /* compare mac address @a and @b. 0 if the same, -ve if a<b and +ve if a>b */
> -_hidden int libxl__compare_macs(libxl_mac *a, libxl_mac *b);
> +_hidden int libxl__compare_macs(const libxl_mac *a, const libxl_mac *b);
> /* return true if mac address is all zero (the default value) */
> -_hidden int libxl__mac_is_default(libxl_mac *mac);
> +_hidden int libxl__mac_is_default(const libxl_mac *mac);
> /* init a recursive mutex */
> _hidden int libxl__init_recursive_mutex(libxl_ctx *ctx, pthread_mutex_t *lock);
> 
> @@ -4580,7 +4580,7 @@ _hidden int libxl__ms_vm_genid_set(libxl__gc *gc, uint32_t domid,
> #define LIBXL__DEFBOOL_STR_DEFAULT "<default>"
> #define LIBXL__DEFBOOL_STR_FALSE   "False"
> #define LIBXL__DEFBOOL_STR_TRUE    "True"
> -static inline int libxl__defbool_is_default(libxl_defbool *db)
> +static inline int libxl__defbool_is_default(const libxl_defbool *db)
> {
>     return !db->val;
> }
> @@ -4675,22 +4675,22 @@ int libxl__random_bytes(libxl__gc *gc, uint8_t *buf, size_t len);
> #include "_libxl_types_internal_private.h"
> 
> /* This always return false, there's no "default value" for hw cap */
> -static inline int libxl__hwcap_is_default(libxl_hwcap *hwcap)
> +static inline int libxl__hwcap_is_default(const libxl_hwcap *hwcap)
> {
>     return 0;
> }
> 
> -static inline int libxl__string_list_is_empty(libxl_string_list *psl)
> +static inline int libxl__string_list_is_empty(const libxl_string_list *psl)
> {
>     return !libxl_string_list_length(psl);
> }
> 
> -static inline int libxl__key_value_list_is_empty(libxl_key_value_list *pkvl)
> +static inline int libxl__key_value_list_is_empty(const libxl_key_value_list *pkvl)
> {
>     return !libxl_key_value_list_length(pkvl);
> }
> 
> -int libxl__cpuid_policy_is_empty(libxl_cpuid_policy_list *pl);
> +int libxl__cpuid_policy_is_empty(const libxl_cpuid_policy_list *pl);
> 
> /* Portability note: a proper flock(2) implementation is required */
> typedef struct {
> @@ -4821,12 +4821,12 @@ void* libxl__device_list(libxl__gc *gc, const libxl__device_type *dt,
> void libxl__device_list_free(const libxl__device_type *dt,
>                              void *list, int num);
> 
> -static inline bool libxl__timer_mode_is_default(libxl_timer_mode *tm)
> +static inline bool libxl__timer_mode_is_default(const libxl_timer_mode *tm)
> {
>     return *tm == LIBXL_TIMER_MODE_DEFAULT;
> }
> 
> -static inline bool libxl__string_is_default(char **s)
> +static inline bool libxl__string_is_default(char *const *s)
> {
>     return *s == NULL;
> }
> diff --git a/tools/libs/light/libxl_json.c b/tools/libs/light/libxl_json.c
> index 9b8ef2cab9..88e81f9905 100644
> --- a/tools/libs/light/libxl_json.c
> +++ b/tools/libs/light/libxl_json.c
> @@ -95,7 +95,7 @@ yajl_gen_status libxl__yajl_gen_enum(yajl_gen hand, const char *str)
>  * YAJL generators for builtin libxl types.
>  */
> yajl_gen_status libxl_defbool_gen_json(yajl_gen hand,
> -                                       libxl_defbool *db)
> +                                       const libxl_defbool *db)
> {
>     return libxl__yajl_gen_asciiz(hand, libxl_defbool_to_string(*db));
> }
> @@ -137,7 +137,7 @@ int libxl__bool_parse_json(libxl__gc *gc, const libxl__json_object *o,
> }
> 
> yajl_gen_status libxl_uuid_gen_json(yajl_gen hand,
> -                                    libxl_uuid *uuid)
> +                                    const libxl_uuid *uuid)
> {
>     char buf[LIBXL_UUID_FMTLEN+1];
>     snprintf(buf, sizeof(buf), LIBXL_UUID_FMT, LIBXL_UUID_BYTES((*uuid)));
> @@ -154,7 +154,7 @@ int libxl__uuid_parse_json(libxl__gc *gc, const libxl__json_object *o,
> }
> 
> yajl_gen_status libxl_bitmap_gen_json(yajl_gen hand,
> -                                      libxl_bitmap *bitmap)
> +                                      const libxl_bitmap *bitmap)
> {
>     yajl_gen_status s;
>     int i;
> @@ -208,7 +208,7 @@ int libxl__bitmap_parse_json(libxl__gc *gc, const libxl__json_object *o,
> }
> 
> yajl_gen_status libxl_key_value_list_gen_json(yajl_gen hand,
> -                                              libxl_key_value_list *pkvl)
> +                                              const libxl_key_value_list *pkvl)
> {
>     libxl_key_value_list kvl = *pkvl;
>     yajl_gen_status s;
> @@ -269,7 +269,8 @@ int libxl__key_value_list_parse_json(libxl__gc *gc, const libxl__json_object *o,
>     return 0;
> }
> 
> -yajl_gen_status libxl_string_list_gen_json(yajl_gen hand, libxl_string_list *pl)
> +yajl_gen_status libxl_string_list_gen_json(yajl_gen hand,
> +                                           const libxl_string_list *pl)
> {
>     libxl_string_list l = *pl;
>     yajl_gen_status s;
> @@ -322,7 +323,7 @@ int libxl__string_list_parse_json(libxl__gc *gc, const libxl__json_object *o,
>     return 0;
> }
> 
> -yajl_gen_status libxl_mac_gen_json(yajl_gen hand, libxl_mac *mac)
> +yajl_gen_status libxl_mac_gen_json(yajl_gen hand, const libxl_mac *mac)
> {
>     char buf[LIBXL_MAC_FMTLEN+1];
>     snprintf(buf, sizeof(buf), LIBXL_MAC_FMT, LIBXL_MAC_BYTES((*mac)));
> @@ -339,7 +340,7 @@ int libxl__mac_parse_json(libxl__gc *gc, const libxl__json_object *o,
> }
> 
> yajl_gen_status libxl_hwcap_gen_json(yajl_gen hand,
> -                                     libxl_hwcap *p)
> +                                     const libxl_hwcap *p)
> {
>     yajl_gen_status s;
>     int i;
> @@ -377,7 +378,8 @@ int libxl__hwcap_parse_json(libxl__gc *gc, const libxl__json_object *o,
>     return 0;
> }
> 
> -yajl_gen_status libxl_ms_vm_genid_gen_json(yajl_gen hand, libxl_ms_vm_genid *p)
> +yajl_gen_status libxl_ms_vm_genid_gen_json(yajl_gen hand,
> +                                           const libxl_ms_vm_genid *p)
> {
>     yajl_gen_status s;
>     int i;
> diff --git a/tools/libs/light/libxl_nocpuid.c b/tools/libs/light/libxl_nocpuid.c
> index 0630959e76..f40a004e95 100644
> --- a/tools/libs/light/libxl_nocpuid.c
> +++ b/tools/libs/light/libxl_nocpuid.c
> @@ -14,7 +14,7 @@
> 
> #include "libxl_internal.h"
> 
> -int libxl__cpuid_policy_is_empty(libxl_cpuid_policy_list *pl)
> +int libxl__cpuid_policy_is_empty(const libxl_cpuid_policy_list *pl)
> {
>     return 1;
> }
> @@ -41,7 +41,7 @@ int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool restore,
> }
> 
> yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,
> -                                libxl_cpuid_policy_list *pcpuid)
> +                                const libxl_cpuid_policy_list *pcpuid)
> {
>     return 0;
> }
> -- 
> 2.30.2
> 
> 

On Fri, Dec 18, 2020 at 01:37:44PM -0800, Elliott Mitchell wrote:
> Anything *_is_empty(), *_is_default(), or *_gen_json() is going to be
> examining the pointed to thing, not modifying it.  This potentially
> results in higher-performance output.  This also allows spreading
> constants further, allowing more checking and security.
> 
> Signed-off-by: Elliott Mitchell <ehem+xen@m5p.com>

This patch doesn't build.

    libxl_cpuid.c:510:17: error: conflicting types for ‘libxl_cpuid_policy_list_gen_json’
      510 | yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,
          |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    In file included from libxl_internal.h:89,
                     from libxl_cpuid.c:15:
    /home/sheep/work/xen/tools/libs/light/../../../tools/include/libxl_json.h:30:17: note: previous declaration of ‘libxl_cpuid_policy_list_gen_json’ was here
       30 | yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,
          |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Also we talked about this patch before, in
    https://lore.kernel.org/xen-devel/YImXfc4oaPgWzkeT@perard/

Cheers,

-- 
Anthony PERARD

> On 5 Jan 2022, at 10:09, Anthony PERARD <anthony.perard@citrix.com> wrote:
> 
> On Fri, Dec 18, 2020 at 01:37:44PM -0800, Elliott Mitchell wrote:
>> Anything *_is_empty(), *_is_default(), or *_gen_json() is going to be
>> examining the pointed to thing, not modifying it.  This potentially
>> results in higher-performance output.  This also allows spreading
>> constants further, allowing more checking and security.
>> 
>> Signed-off-by: Elliott Mitchell <ehem+xen@m5p.com>
> 
> This patch doesn't build.
> 
>    libxl_cpuid.c:510:17: error: conflicting types for ‘libxl_cpuid_policy_list_gen_json’
>      510 | yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,
>          |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    In file included from libxl_internal.h:89,
>                     from libxl_cpuid.c:15:
>    /home/sheep/work/xen/tools/libs/light/../../../tools/include/libxl_json.h:30:17: note: previous declaration of ‘libxl_cpuid_policy_list_gen_json’ was here
>       30 | yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,
>          |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Also we talked about this patch before, in
>    https://lore.kernel.org/xen-devel/YImXfc4oaPgWzkeT@perard/
> 
> Cheers,

Sorry about that, when I’ve put my R-by I thought it was building, I’ve checked again and it’s not building for x86_64, arm32 and arm64 looks fine so far.

Cheers,
Luca

> 
> -- 
> Anthony PERARD
>