types/variant.c

   1 /*
   2  * variant.c
   3  *
   4  * BabelTrace - Variant Type Converter
   5  *
   6  * Copyright 2010-2011 EfficiOS Inc. and Linux Foundation
   7  *
   8  * Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   9  *
  10  * Permission is hereby granted, free of charge, to any person obtaining a copy
  11  * of this software and associated documentation files (the "Software"), to deal
  12  * in the Software without restriction, including without limitation the rights
  13  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14  * copies of the Software, and to permit persons to whom the Software is
  15  * furnished to do so, subject to the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be included in
  18  * all copies or substantial portions of the Software.
  19  */
  20
  21 #include <babeltrace/compiler.h>
  22 #include <babeltrace/format.h>
  23 #include <babeltrace/types.h>
  24 #include <errno.h>
  25
  26 static
  27 struct definition *_variant_definition_new(struct declaration *declaration,
  28                                 struct definition_scope *parent_scope,
  29                                 GQuark field_name, int index,
  30                                 const char *root_name);
  31 static
  32 void _variant_definition_free(struct definition *definition);
  33
  34 int variant_rw(struct stream_pos *ppos, struct definition *definition)
  35 {
  36         struct definition_variant *variant_definition =
  37                 container_of(definition, struct definition_variant, p);
  38         struct definition *field;
  39
  40         field = variant_get_current_field(variant_definition);
  41         return generic_rw(ppos, field);
  42 }
  43
  44 static
  45 void _untagged_variant_declaration_free(struct declaration *declaration)
  46 {
  47         struct declaration_untagged_variant *untagged_variant_declaration =
  48                 container_of(declaration, struct declaration_untagged_variant, p);
  49         unsigned long i;
  50
  51         free_declaration_scope(untagged_variant_declaration->scope);
  52         g_hash_table_destroy(untagged_variant_declaration->fields_by_tag);
  53
  54         for (i = 0; i < untagged_variant_declaration->fields->len; i++) {
  55                 struct declaration_field *declaration_field =
  56                         &g_array_index(untagged_variant_declaration->fields,
  57                                        struct declaration_field, i);
  58                 declaration_unref(declaration_field->declaration);
  59         }
  60         g_array_free(untagged_variant_declaration->fields, true);
  61         g_free(untagged_variant_declaration);
  62 }
  63
  64 struct declaration_untagged_variant *untagged_variant_declaration_new(
  65                                       struct declaration_scope *parent_scope)
  66 {
  67         struct declaration_untagged_variant *untagged_variant_declaration;
  68         struct declaration *declaration;
  69
  70         untagged_variant_declaration = g_new(struct declaration_untagged_variant, 1);
  71         declaration = &untagged_variant_declaration->p;
  72         untagged_variant_declaration->fields_by_tag = g_hash_table_new(g_direct_hash,
  73                                                        g_direct_equal);
  74         untagged_variant_declaration->fields = g_array_sized_new(FALSE, TRUE,
  75                                                  sizeof(struct declaration_field),
  76                                                  DEFAULT_NR_STRUCT_FIELDS);
  77         untagged_variant_declaration->scope = new_declaration_scope(parent_scope);
  78         declaration->id = CTF_TYPE_UNTAGGED_VARIANT;
  79         declaration->alignment = 1;
  80         declaration->declaration_free = _untagged_variant_declaration_free;
  81         declaration->definition_new = NULL;
  82         declaration->definition_free = NULL;
  83         declaration->ref = 1;
  84         return untagged_variant_declaration;
  85 }
  86
  87 static
  88 void _variant_declaration_free(struct declaration *declaration)
  89 {
  90         struct declaration_variant *variant_declaration =
  91                 container_of(declaration, struct declaration_variant, p);
  92
  93         _untagged_variant_declaration_free(&variant_declaration->untagged_variant->p);
  94         g_array_free(variant_declaration->tag_name, TRUE);
  95 }
  96
  97 struct declaration_variant *
  98         variant_declaration_new(struct declaration_untagged_variant *untagged_variant, const char *tag)
  99 {
 100         struct declaration_variant *variant_declaration;
 101         struct declaration *declaration;
 102
 103         variant_declaration = g_new(struct declaration_variant, 1);
 104         declaration = &variant_declaration->p;
 105         variant_declaration->untagged_variant = untagged_variant;
 106         declaration_ref(&untagged_variant->p);
 107         variant_declaration->tag_name = g_array_new(FALSE, TRUE, sizeof(GQuark));
 108         append_scope_path(tag, variant_declaration->tag_name);
 109         declaration->id = CTF_TYPE_VARIANT;
 110         declaration->alignment = 1;
 111         declaration->declaration_free = _variant_declaration_free;
 112         declaration->definition_new = _variant_definition_new;
 113         declaration->definition_free = _variant_definition_free;
 114         declaration->ref = 1;
 115         return variant_declaration;
 116 }
 117
 118 /*
 119  * tag_instance is assumed to be an enumeration.
 120  * Returns 0 if OK, < 0 if error.
 121  */
 122 static
 123 int check_enum_tag(struct definition_variant *variant,
 124                    struct definition *enum_tag)
 125 {
 126         struct definition_enum *_enum =
 127                 container_of(enum_tag, struct definition_enum, p);
 128         struct declaration_enum *enum_declaration = _enum->declaration;
 129         int missing_field = 0;
 130         unsigned long i;
 131
 132         /*
 133          * Strictly speaking, each enumerator must map to a field of the
 134          * variant. However, we are even stricter here by requiring that each
 135          * variant choice map to an enumerator too. We then validate that the
 136          * number of enumerators equals the number of variant choices.
 137          */
 138         if (variant->declaration->untagged_variant->fields->len != enum_get_nr_enumerators(enum_declaration))
 139                 return -EPERM;
 140
 141         for (i = 0; i < variant->declaration->untagged_variant->fields->len; i++) {
 142                 struct declaration_field *field_declaration =
 143                         &g_array_index(variant->declaration->untagged_variant->fields,
 144                                        struct declaration_field, i);
 145                 if (!enum_quark_to_range_set(enum_declaration, field_declaration->name)) {
 146                         missing_field = 1;
 147                         break;
 148                 }
 149         }
 150         if (missing_field)
 151                 return -EPERM;
 152
 153         /*
 154          * Check the enumeration: it must map each value to one and only one
 155          * enumerator tag.
 156          * TODO: we should also check that each range map to one and only one
 157          * tag. For the moment, we will simply check this dynamically in
 158          * variant_declaration_get_current_field().
 159          */
 160         return 0;
 161 }
 162
 163
 164
 165 static
 166 struct definition *
 167         _variant_definition_new(struct declaration *declaration,
 168                                 struct definition_scope *parent_scope,
 169                                 GQuark field_name, int index,
 170                                 const char *root_name)
 171 {
 172         struct declaration_variant *variant_declaration =
 173                 container_of(declaration, struct declaration_variant, p);
 174         struct definition_variant *variant;
 175         unsigned long i;
 176         int ret;
 177
 178         variant = g_new(struct definition_variant, 1);
 179         declaration_ref(&variant_declaration->p);
 180         variant->p.declaration = declaration;
 181         variant->declaration = variant_declaration;
 182         variant->p.ref = 1;
 183         /*
 184          * Use INT_MAX order to ensure that all fields of the parent
 185          * scope are seen as being prior to this scope.
 186          */
 187         variant->p.index = root_name ? INT_MAX : index;
 188         variant->p.name = field_name;
 189         variant->p.path = new_definition_path(parent_scope, field_name, root_name);
 190         variant->p.scope = new_definition_scope(parent_scope, field_name, root_name);
 191
 192         ret = register_field_definition(field_name, &variant->p,
 193                                         parent_scope);
 194         assert(!ret);
 195
 196         variant->enum_tag = lookup_path_definition(variant->p.scope->scope_path,
 197                                                    variant_declaration->tag_name,
 198                                                    parent_scope);
 199
 200         if (!variant->enum_tag
 201             || check_enum_tag(variant, variant->enum_tag) < 0)
 202                 goto error;
 203         definition_ref(variant->enum_tag);
 204         variant->fields = g_ptr_array_sized_new(variant_declaration->untagged_variant->fields->len);
 205         g_ptr_array_set_size(variant->fields, variant_declaration->untagged_variant->fields->len);
 206         for (i = 0; i < variant_declaration->untagged_variant->fields->len; i++) {
 207                 struct declaration_field *declaration_field =
 208                         &g_array_index(variant_declaration->untagged_variant->fields,
 209                                        struct declaration_field, i);
 210                 struct definition **field =
 211                         (struct definition **) &g_ptr_array_index(variant->fields, i);
 212
 213                 /*
 214                  * All child definition are at index 0, because they are
 215                  * various choices of the same field.
 216                  */
 217                 *field = declaration_field->declaration->definition_new(declaration_field->declaration,
 218                                                   variant->p.scope,
 219                                                   declaration_field->name, 0, NULL);
 220                 if (!*field)
 221                         goto error;
 222         }
 223         variant->current_field = NULL;
 224         return &variant->p;
 225 error:
 226         free_definition_scope(variant->p.scope);
 227         declaration_unref(&variant_declaration->p);
 228         g_free(variant);
 229         return NULL;
 230 }
 231
 232 static
 233 void _variant_definition_free(struct definition *definition)
 234 {
 235         struct definition_variant *variant =
 236                 container_of(definition, struct definition_variant, p);
 237         unsigned long i;
 238
 239         assert(variant->fields->len == variant->declaration->untagged_variant->fields->len);
 240         for (i = 0; i < variant->fields->len; i++) {
 241                 struct definition *field = g_ptr_array_index(variant->fields, i);
 242                 definition_unref(field);
 243         }
 244         definition_unref(variant->enum_tag);
 245         free_definition_scope(variant->p.scope);
 246         declaration_unref(variant->p.declaration);
 247         g_free(variant);
 248 }
 249
 250 void untagged_variant_declaration_add_field(struct declaration_untagged_variant *untagged_variant_declaration,
 251                             const char *field_name,
 252                             struct declaration *field_declaration)
 253 {
 254         struct declaration_field *field;
 255         unsigned long index;
 256
 257         g_array_set_size(untagged_variant_declaration->fields, untagged_variant_declaration->fields->len + 1);
 258         index = untagged_variant_declaration->fields->len - 1;  /* last field (new) */
 259         field = &g_array_index(untagged_variant_declaration->fields, struct declaration_field, index);
 260         field->name = g_quark_from_string(field_name);
 261         declaration_ref(field_declaration);
 262         field->declaration = field_declaration;
 263         /* Keep index in hash rather than pointer, because array can relocate */
 264         g_hash_table_insert(untagged_variant_declaration->fields_by_tag,
 265                             (gpointer) (unsigned long) field->name,
 266                             (gpointer) index);
 267         /*
 268          * Alignment of variant is based on the alignment of its currently
 269          * selected choice, so we leave variant alignment as-is (statically
 270          * speaking).
 271          */
 272 }
 273
 274 struct declaration_field *
 275 untagged_variant_declaration_get_field_from_tag(struct declaration_untagged_variant *untagged_variant_declaration, GQuark tag)
 276 {
 277         gpointer index;
 278         gboolean found;
 279
 280         found = g_hash_table_lookup_extended(
 281                                 untagged_variant_declaration->fields_by_tag,
 282                                 (gconstpointer) (unsigned long) tag, NULL, &index);
 283
 284         if (!found) {
 285                 return NULL;
 286         }
 287
 288         return &g_array_index(untagged_variant_declaration->fields, struct declaration_field, (unsigned long)index);
 289 }
 290
 291 /*
 292  * field returned only valid as long as the field structure is not appended to.
 293  */
 294 struct definition *variant_get_current_field(struct definition_variant *variant)
 295 {
 296         struct definition_enum *_enum =
 297                 container_of(variant->enum_tag, struct definition_enum, p);
 298         struct declaration_variant *variant_declaration = variant->declaration;
 299         unsigned long index;
 300         GArray *tag_array;
 301         GQuark tag;
 302
 303         tag_array = _enum->value;
 304         /*
 305          * The 1 to 1 mapping from enumeration to value should have been already
 306          * checked. (see TODO above)
 307          */
 308         assert(tag_array->len == 1);
 309         tag = g_array_index(tag_array, GQuark, 0);
 310         index = (unsigned long) g_hash_table_lookup(variant_declaration->untagged_variant->fields_by_tag,
 311                                                     (gconstpointer) (unsigned long) tag);
 312         variant->current_field = g_ptr_array_index(variant->fields, index);
 313         return variant->current_field;
 314 }