Add indirection for visitor arguments

In order to keep the argument vector const, add an indirection for
visitor arguments to a non-const area of memory, which is clearly
documented as modified by libside.

Add a "cached_arg" placeholder pointer to the visitor structures.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/include/side/abi/type-argument.h b/include/side/abi/type-argument.h
index fd1979c0157657cd0ef4b90a3acb8e8f051bd469..57ce5252fcde9bd854a5a0d103fbb1ce099f5670 100644 (file)
--- a/include/side/abi/type-argument.h
+++ b/include/side/abi/type-argument.h
@@ -61,6 +61,13 @@ enum side_arg_flag {
        SIDE_ARG_FLAG_INCOMPLETE = (1U << SIDE_ARG_FLAG_INCOMPLETE_BIT),
 };
 
+struct side_arg_vla_visitor {
+       side_ptr_t(void) app_ctx;
+       /* libside argument cache, initialize to NULL. */
+       side_ptr_t(struct side_arg) cached_arg;
+} SIDE_PACKED;
+side_check_size(struct side_arg_vla_visitor, 32);
+
 union side_arg_static {
        /* Stack-copy basic types */
        union side_bool_value bool_value;
@@ -74,7 +81,8 @@ union side_arg_static {
        side_ptr_t(const struct side_arg_variant) side_variant;
        side_ptr_t(const struct side_arg_vec) side_array;
        side_ptr_t(const struct side_arg_vec) side_vla;
-       void *side_vla_app_visitor_ctx;
+       /* Pointer to non-const structure. Content modified by libside. */
+       side_ptr_t(struct side_arg_vla_visitor) side_vla_visitor;
 
        /* Gather basic types */
        side_ptr_t(const void) side_bool_gather_ptr;
@@ -110,21 +118,25 @@ struct side_arg_dynamic_struct {
 } SIDE_PACKED;
 side_check_size(struct side_arg_dynamic_struct, 40);
 
-struct side_dynamic_struct_visitor {
+struct side_arg_dynamic_struct_visitor {
        side_func_ptr_t(side_dynamic_struct_visitor_func) visitor;
        side_ptr_t(void) app_ctx;
        side_ptr_t(const struct side_attr) attr;
+       /* libside argument cache, initialize to NULL. */
+       side_ptr_t(struct side_arg) cached_arg;
        uint32_t nr_attr;
 } SIDE_PACKED;
-side_check_size(struct side_dynamic_struct_visitor, 52);
+side_check_size(struct side_arg_dynamic_struct_visitor, 68);
 
-struct side_dynamic_vla_visitor {
+struct side_arg_dynamic_vla_visitor {
        side_func_ptr_t(side_visitor_func) visitor;
        side_ptr_t(void) app_ctx;
        side_ptr_t(const struct side_attr) attr;
+       /* libside argument cache, initialize to NULL. */
+       side_ptr_t(struct side_arg) cached_arg;
        uint32_t nr_attr;
 } SIDE_PACKED;
-side_check_size(struct side_dynamic_vla_visitor, 52);
+side_check_size(struct side_arg_dynamic_vla_visitor, 68);
 
 union side_arg_dynamic {
        /* Dynamic basic types */
@@ -154,8 +166,10 @@ union side_arg_dynamic {
        side_ptr_t(const struct side_arg_dynamic_struct) side_dynamic_struct;
        side_ptr_t(const struct side_arg_dynamic_vla) side_dynamic_vla;
 
-       struct side_dynamic_struct_visitor side_dynamic_struct_visitor;
-       struct side_dynamic_vla_visitor side_dynamic_vla_visitor;
+       /* Pointer to non-const structure. Content modified by libside. */
+       side_ptr_t(struct side_arg_dynamic_struct_visitor) side_dynamic_struct_visitor;
+       /* Pointer to non-const structure. Content modified by libside. */
+       side_ptr_t(struct side_arg_dynamic_vla_visitor) side_dynamic_vla_visitor;
 
        side_padding(58);
 } SIDE_PACKED;

diff --git a/include/side/instrumentation-c-api.h b/include/side/instrumentation-c-api.h
index 43ba3c02b0c4a79d502f1c4c8e0abe688729eb80..00cd20bd4f54b14f29e749cef84d0bdf407e6c4b 100644 (file)
--- a/include/side/instrumentation-c-api.h
+++ b/include/side/instrumentation-c-api.h
@@ -834,7 +834,22 @@
 
 #define side_arg_array(_side_type)     { .type = SIDE_ENUM_INIT(SIDE_TYPE_ARRAY), .flags = 0, .u = { .side_static = { .side_array = SIDE_PTR_INIT(_side_type) } } }
 #define side_arg_vla(_side_type)       { .type = SIDE_ENUM_INIT(SIDE_TYPE_VLA), .flags = 0, .u = { .side_static = { .side_vla = SIDE_PTR_INIT(_side_type) } } }
-#define side_arg_vla_visitor(_ctx)     { .type = SIDE_ENUM_INIT(SIDE_TYPE_VLA_VISITOR), .flags = 0, .u = { .side_static = { .side_vla_app_visitor_ctx = (_ctx) } } }
+#define side_arg_vla_visitor(_side_vla_visitor) \
+       { \
+               .type = SIDE_ENUM_INIT(SIDE_TYPE_VLA_VISITOR), \
+               .flags = 0, \
+               .u = { \
+                       .side_static = { \
+                               .side_vla_visitor = SIDE_PTR_INIT(_side_vla_visitor), \
+                        } \
+                } \
+       }
+
+#define side_arg_define_vla_visitor(_identifier, _ctx) \
+       struct side_arg_vla_visitor _identifier = { \
+               .app_ctx = SIDE_PTR_INIT(_ctx), \
+               .cached_arg = SIDE_PTR_INIT(NULL), \
+       }
 
 /* Gather field arguments */
 
@@ -1072,18 +1087,13 @@
                }, \
        }
 
-#define side_arg_dynamic_vla_visitor(_dynamic_vla_visitor, _ctx, _attr...) \
+#define side_arg_dynamic_vla_visitor(_dynamic_vla_visitor) \
        { \
                .type = SIDE_ENUM_INIT(SIDE_TYPE_DYNAMIC_VLA_VISITOR), \
                .flags = 0, \
                .u = { \
                        .side_dynamic = { \
-                               .side_dynamic_vla_visitor = { \
-                                       .app_ctx = SIDE_PTR_INIT(_ctx), \
-                                       .visitor = SIDE_PTR_INIT(_dynamic_vla_visitor), \
-                                       .attr = SIDE_PTR_INIT(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
-                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
-                               }, \
+                               .side_dynamic_vla_visitor = SIDE_PTR_INIT(_dynamic_vla_visitor), \
                        }, \
                }, \
        }
@@ -1099,18 +1109,13 @@
                }, \
        }
 
-#define side_arg_dynamic_struct_visitor(_dynamic_struct_visitor, _ctx, _attr...) \
+#define side_arg_dynamic_struct_visitor(_dynamic_struct_visitor) \
        { \
                .type = SIDE_ENUM_INIT(SIDE_TYPE_DYNAMIC_STRUCT_VISITOR), \
                .flags = 0, \
                .u = { \
                        .side_dynamic = { \
-                               .side_dynamic_struct_visitor = { \
-                                       .app_ctx = SIDE_PTR_INIT(_ctx), \
-                                       .visitor = SIDE_PTR_INIT(_dynamic_struct_visitor), \
-                                       .attr = SIDE_PTR_INIT(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
-                                       .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
-                               }, \
+                               .side_dynamic_struct_visitor = SIDE_PTR_INIT(_dynamic_struct_visitor), \
                        }, \
                }, \
        }
@@ -1133,6 +1138,24 @@
                .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
        }
 
+#define side_arg_dynamic_define_struct_visitor(_identifier, _dynamic_struct_visitor, _ctx, _attr...) \
+       struct side_arg_dynamic_struct_visitor _identifier = { \
+               .visitor = SIDE_PTR_INIT(_dynamic_struct_visitor), \
+               .app_ctx = SIDE_PTR_INIT(_ctx), \
+               .attr = SIDE_PTR_INIT(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
+               .cached_arg = SIDE_PTR_INIT(NULL), \
+               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
+       }
+
+#define side_arg_dynamic_define_vla_visitor(_identifier, _dynamic_vla_visitor, _ctx, _attr...) \
+       struct side_arg_dynamic_vla_visitor _identifier = { \
+               .visitor = SIDE_PTR_INIT(_dynamic_vla_visitor), \
+               .app_ctx = SIDE_PTR_INIT(_ctx), \
+               .attr = SIDE_PTR_INIT(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
+               .cached_arg = SIDE_PTR_INIT(NULL), \
+               .nr_attr = SIDE_ARRAY_SIZE(SIDE_PARAM_SELECT_ARG1(_, ##_attr, side_attr_list())), \
+       }
+
 #define side_arg_define_vec(_identifier, _sav) \
        const struct side_arg _identifier##_vec[] = { _sav }; \
        const struct side_arg_vec _identifier = { \

diff --git a/src/tracer.c b/src/tracer.c
index b4089a71efd03c33f7fa97ea6db43d0291ba2781..e4ccd86950ac0efbe36ffde2cf9768abb50a410e 100644 (file)
--- a/src/tracer.c
+++ b/src/tracer.c
@@ -36,7 +36,7 @@ void tracer_print_array(const struct side_type *type_desc, const struct side_arg
 static
 void tracer_print_vla(const struct side_type *type_desc, const struct side_arg_vec *side_arg_vec);
 static
-void tracer_print_vla_visitor(const struct side_type *type_desc, void *app_ctx);
+void tracer_print_vla_visitor(const struct side_type *type_desc, struct side_arg_vla_visitor *vla_visitor);
 static
 void tracer_print_dynamic(const struct side_arg *dynamic_item);
 static
@@ -1242,7 +1242,7 @@ void tracer_print_type(const struct side_type *type_desc, const struct side_arg
                tracer_print_vla(type_desc, side_ptr_get(item->u.side_static.side_vla));
                break;
        case SIDE_TYPE_VLA_VISITOR:
-               tracer_print_vla_visitor(type_desc, item->u.side_static.side_vla_app_visitor_ctx);
+               tracer_print_vla_visitor(type_desc, side_ptr_get(item->u.side_static.side_vla_visitor));
                break;
 
                /* Stack-copy enumeration types */
@@ -1792,8 +1792,9 @@ enum side_visitor_status tracer_write_elem_cb(const struct side_tracer_visitor_c
 }
 
 static
-void tracer_print_vla_visitor(const struct side_type *type_desc, void *app_ctx)
+void tracer_print_vla_visitor(const struct side_type *type_desc, struct side_arg_vla_visitor *vla_visitor)
 {
+       void *app_ctx;
        enum side_visitor_status status;
        struct tracer_visitor_priv tracer_priv = {
                .elem_type = side_ptr_get(type_desc->u.side_vla_visitor.elem_type),
@@ -1805,6 +1806,9 @@ void tracer_print_vla_visitor(const struct side_type *type_desc, void *app_ctx)
        };
        side_visitor_func func;
 
+       if (!vla_visitor)
+               abort();
+       app_ctx = side_ptr_get(vla_visitor->app_ctx);
        print_attributes("attr", ":", side_ptr_get(type_desc->u.side_vla_visitor.attr), type_desc->u.side_vla_visitor.nr_attr);
        printf("%s", type_desc->u.side_vla_visitor.nr_attr ? ", " : "");
        printf("elements: ");
@@ -1860,7 +1864,7 @@ enum side_visitor_status tracer_dynamic_struct_write_elem_cb(
 static
 void tracer_print_dynamic_struct_visitor(const struct side_arg *item)
 {
-       enum side_visitor_status status;
+       struct side_arg_dynamic_struct_visitor *dynamic_struct_visitor;
        struct tracer_dynamic_struct_visitor_priv tracer_priv = {
                .i = 0,
        };
@@ -1868,13 +1872,18 @@ void tracer_print_dynamic_struct_visitor(const struct side_arg *item)
                .write_field = tracer_dynamic_struct_write_elem_cb,
                .priv = &tracer_priv,
        };
-       void *app_ctx = side_ptr_get(item->u.side_dynamic.side_dynamic_struct_visitor.app_ctx);
+       enum side_visitor_status status;
+       void *app_ctx;
 
-       print_attributes("attr", "::", side_ptr_get(item->u.side_dynamic.side_dynamic_struct_visitor.attr), item->u.side_dynamic.side_dynamic_struct_visitor.nr_attr);
-       printf("%s", item->u.side_dynamic.side_dynamic_struct_visitor.nr_attr ? ", " : "");
+       dynamic_struct_visitor = side_ptr_get(item->u.side_dynamic.side_dynamic_struct_visitor);
+       if (!dynamic_struct_visitor)
+               abort();
+       app_ctx = side_ptr_get(dynamic_struct_visitor->app_ctx);
+       print_attributes("attr", "::", side_ptr_get(dynamic_struct_visitor->attr), dynamic_struct_visitor->nr_attr);
+       printf("%s", dynamic_struct_visitor->nr_attr ? ", " : "");
        printf("fields:: ");
        printf("[ ");
-       status = side_ptr_get(item->u.side_dynamic.side_dynamic_struct_visitor.visitor)(&tracer_ctx, app_ctx);
+       status = side_ptr_get(dynamic_struct_visitor->visitor)(&tracer_ctx, app_ctx);
        switch (status) {
        case SIDE_VISITOR_STATUS_OK:
                break;
@@ -1922,7 +1931,7 @@ enum side_visitor_status tracer_dynamic_vla_write_elem_cb(
 static
 void tracer_print_dynamic_vla_visitor(const struct side_arg *item)
 {
-       enum side_visitor_status status;
+       struct side_arg_dynamic_vla_visitor *dynamic_vla_visitor;
        struct tracer_dynamic_vla_visitor_priv tracer_priv = {
                .i = 0,
        };
@@ -1930,13 +1939,18 @@ void tracer_print_dynamic_vla_visitor(const struct side_arg *item)
                .write_elem = tracer_dynamic_vla_write_elem_cb,
                .priv = &tracer_priv,
        };
-       void *app_ctx = side_ptr_get(item->u.side_dynamic.side_dynamic_vla_visitor.app_ctx);
+       enum side_visitor_status status;
+       void *app_ctx;
 
-       print_attributes("attr", "::", side_ptr_get(item->u.side_dynamic.side_dynamic_vla_visitor.attr), item->u.side_dynamic.side_dynamic_vla_visitor.nr_attr);
-       printf("%s", item->u.side_dynamic.side_dynamic_vla_visitor.nr_attr ? ", " : "");
+       dynamic_vla_visitor = side_ptr_get(item->u.side_dynamic.side_dynamic_vla_visitor);
+       if (!dynamic_vla_visitor)
+               abort();
+       app_ctx = side_ptr_get(dynamic_vla_visitor->app_ctx);
+       print_attributes("attr", "::", side_ptr_get(dynamic_vla_visitor->attr), dynamic_vla_visitor->nr_attr);
+       printf("%s", dynamic_vla_visitor->nr_attr ? ", " : "");
        printf("elements:: ");
        printf("[ ");
-       status = side_ptr_get(item->u.side_dynamic.side_dynamic_vla_visitor.visitor)(&tracer_ctx, app_ctx);
+       status = side_ptr_get(dynamic_vla_visitor->visitor)(&tracer_ctx, app_ctx);
        switch (status) {
        case SIDE_VISITOR_STATUS_OK:
                break;

diff --git a/tests/unit/test.c b/tests/unit/test.c
index 7b142794244c85b26c5666bcf4d8b2a9d208631d..ef5e7c0e920e021b8aff2ecb599d7b9d72421834 100644 (file)
--- a/tests/unit/test.c
+++ b/tests/unit/test.c
@@ -186,7 +186,9 @@ void test_vla_visitor(void)
                        .ptr = testarray,
                        .length = SIDE_ARRAY_SIZE(testarray),
                };
-               side_event_call(my_provider_event_vla_visitor, side_arg_list(side_arg_vla_visitor(&ctx), side_arg_s64(42)));
+               side_arg_define_vla_visitor(side_visitor, &ctx);
+               side_event_call(my_provider_event_vla_visitor,
+                       side_arg_list(side_arg_vla_visitor(&side_visitor), side_arg_s64(42)));
        }
 }
 
@@ -228,7 +230,8 @@ enum side_visitor_status test_outer_visitor(const struct side_tracer_visitor_ctx
                        .ptr = ctx->ptr[i],
                        .length = 2,
                };
-               const struct side_arg elem = side_arg_vla_visitor(&inner_ctx);
+               side_arg_define_vla_visitor(side_inner_visitor, &inner_ctx);
+               const struct side_arg elem = side_arg_vla_visitor(&side_inner_visitor);
                if (tracer_ctx->write_elem(tracer_ctx, &elem) != SIDE_VISITOR_STATUS_OK)
                        return SIDE_VISITOR_STATUS_ERROR;
        }
@@ -262,7 +265,9 @@ void test_vla_visitor_2d(void)
                        .ptr = testarray2d,
                        .length = SIDE_ARRAY_SIZE(testarray2d),
                };
-               side_event_call(my_provider_event_vla_visitor2d, side_arg_list(side_arg_vla_visitor(&ctx), side_arg_s64(42)));
+               side_arg_define_vla_visitor(side_outer_visitor, &ctx);
+               side_event_call(my_provider_event_vla_visitor2d,
+                       side_arg_list(side_arg_vla_visitor(&side_outer_visitor), side_arg_s64(42)));
        }
 }
 
@@ -596,9 +601,10 @@ void test_dynamic_vla_with_visitor(void)
                        .ptr = testarray_dynamic_vla,
                        .length = SIDE_ARRAY_SIZE(testarray_dynamic_vla),
                };
+               side_arg_dynamic_define_vla_visitor(myvlavisitor, test_dynamic_vla_visitor, &ctx);
                side_event_call(my_provider_event_dynamic_vla_visitor,
                        side_arg_list(
-                               side_arg_dynamic_vla_visitor(test_dynamic_vla_visitor, &ctx)
+                               side_arg_dynamic_vla_visitor(&myvlavisitor)
                        )
                );
        }
@@ -652,9 +658,10 @@ void test_dynamic_struct_with_visitor(void)
                        .ptr = testarray_dynamic_struct,
                        .length = SIDE_ARRAY_SIZE(testarray_dynamic_struct),
                };
+               side_arg_dynamic_define_struct_visitor(mystructvisitor, test_dynamic_struct_visitor, &ctx);
                side_event_call(my_provider_event_dynamic_struct_visitor,
                        side_arg_list(
-                               side_arg_dynamic_struct_visitor(test_dynamic_struct_visitor, &ctx)
+                               side_arg_dynamic_struct_visitor(&mystructvisitor)
                        )
                );
        }