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         declaration_unref(&variant_declaration->untagged_variant->p);
  94         g_array_free(variant_declaration->tag_name, TRUE);
  95         g_free(variant_declaration);
  96 }
  97
  98 struct declaration_variant *
  99         variant_declaration_new(struct declaration_untagged_variant *untagged_variant, const char *tag)
 100 {
 101         struct declaration_variant *variant_declaration;
 102         struct declaration *declaration;
 103
 104         variant_declaration = g_new(struct declaration_variant, 1);
 105         declaration = &variant_declaration->p;
 106         variant_declaration->untagged_variant = untagged_variant;
 107         declaration_ref(&untagged_variant->p);
 108         variant_declaration->tag_name = g_array_new(FALSE, TRUE, sizeof(GQuark));
 109         append_scope_path(tag, variant_declaration->tag_name);
 110         declaration->id = CTF_TYPE_VARIANT;
 111         declaration->alignment = 1;
 112         declaration->declaration_free = _variant_declaration_free;
 113         declaration->definition_new = _variant_definition_new;
 114         declaration->definition_free = _variant_definition_free;
 115         declaration->ref = 1;
 116         return variant_declaration;
 117 }
 118
 119 /*
 120  * tag_instance is assumed to be an enumeration.
 121  * Returns 0 if OK, < 0 if error.
 122  */
 123 static
 124 int check_enum_tag(struct definition_variant *variant,
 125                    struct definition *enum_tag)
 126 {
 127         struct definition_enum *_enum =
 128                 container_of(enum_tag, struct definition_enum, p);
 129         struct declaration_enum *enum_declaration = _enum->declaration;
 130         int missing_field = 0;
 131         unsigned long i;
 132
 133         /*
 134          * Strictly speaking, each enumerator must map to a field of the
 135          * variant. However, we are even stricter here by requiring that each
 136          * variant choice map to an enumerator too. We then validate that the
 137          * number of enumerators equals the number of variant choices.
 138          */
 139         if (variant->declaration->untagged_variant->fields->len != enum_get_nr_enumerators(enum_declaration))
 140                 return -EPERM;
 141
 142         for (i = 0; i < variant->declaration->untagged_variant->fields->len; i++) {
 143                 struct declaration_field *field_declaration =
 144                         &g_array_index(variant->declaration->untagged_variant->fields,
 145                                        struct declaration_field, i);
 146                 if (!enum_quark_to_range_set(enum_declaration, field_declaration->name)) {
 147                         missing_field = 1;
 148                         break;
 149                 }
 150         }
 151         if (missing_field)
 152                 return -EPERM;
 153
 154         /*
 155          * Check the enumeration: it must map each value to one and only one
 156          * enumerator tag.
 157          * TODO: we should also check that each range map to one and only one
 158          * tag. For the moment, we will simply check this dynamically in
 159          * variant_declaration_get_current_field().
 160          */
 161         return 0;
 162 }
 163
 164
 165
 166 static
 167 struct definition *
 168         _variant_definition_new(struct declaration *declaration,
 169                                 struct definition_scope *parent_scope,
 170                                 GQuark field_name, int index,
 171                                 const char *root_name)
 172 {
 173         struct declaration_variant *variant_declaration =
 174                 container_of(declaration, struct declaration_variant, p);
 175         struct definition_variant *variant;
 176         unsigned long i;
 177         int ret;
 178
 179         variant = g_new(struct definition_variant, 1);
 180         declaration_ref(&variant_declaration->p);
 181         variant->p.declaration = declaration;
 182         variant->declaration = variant_declaration;
 183         variant->p.ref = 1;
 184         /*
 185          * Use INT_MAX order to ensure that all fields of the parent
 186          * scope are seen as being prior to this scope.
 187          */
 188         variant->p.index = root_name ? INT_MAX : index;
 189         variant->p.name = field_name;
 190         variant->p.path = new_definition_path(parent_scope, field_name, root_name);
 191         variant->p.scope = new_definition_scope(parent_scope, field_name, root_name);
 192
 193         ret = register_field_definition(field_name, &variant->p,
 194                                         parent_scope);
 195         assert(!ret);
 196
 197         variant->enum_tag = lookup_path_definition(variant->p.scope->scope_path,
 198                                                    variant_declaration->tag_name,
 199                                                    parent_scope);
 200
 201         if (!variant->enum_tag
 202             || check_enum_tag(variant, variant->enum_tag) < 0)
 203                 goto error;
 204         definition_ref(variant->enum_tag);
 205         variant->fields = g_ptr_array_sized_new(variant_declaration->untagged_variant->fields->len);
 206         g_ptr_array_set_size(variant->fields, variant_declaration->untagged_variant->fields->len);
 207         for (i = 0; i < variant_declaration->untagged_variant->fields->len; i++) {
 208                 struct declaration_field *declaration_field =
 209                         &g_array_index(variant_declaration->untagged_variant->fields,
 210                                        struct declaration_field, i);
 211                 struct definition **field =
 212                         (struct definition **) &g_ptr_array_index(variant->fields, i);
 213
 214                 /*
 215                  * All child definition are at index 0, because they are
 216                  * various choices of the same field.
 217                  */
 218                 *field = declaration_field->declaration->definition_new(declaration_field->declaration,
 219                                                   variant->p.scope,
 220                                                   declaration_field->name, 0, NULL);
 221                 if (!*field)
 222                         goto error;
 223         }
 224         variant->current_field = NULL;
 225         return &variant->p;
 226 error:
 227         free_definition_scope(variant->p.scope);
 228         declaration_unref(&variant_declaration->p);
 229         g_free(variant);
 230         return NULL;
 231 }
 232
 233 static
 234 void _variant_definition_free(struct definition *definition)
 235 {
 236         struct definition_variant *variant =
 237                 container_of(definition, struct definition_variant, p);
 238         unsigned long i;
 239
 240         assert(variant->fields->len == variant->declaration->untagged_variant->fields->len);
 241         for (i = 0; i < variant->fields->len; i++) {
 242                 struct definition *field = g_ptr_array_index(variant->fields, i);
 243                 definition_unref(field);
 244         }
 245         definition_unref(variant->enum_tag);
 246         free_definition_scope(variant->p.scope);
 247         declaration_unref(variant->p.declaration);
 248         g_ptr_array_free(variant->fields, TRUE);
 249         g_free(variant);
 250 }
 251
 252 void untagged_variant_declaration_add_field(struct declaration_untagged_variant *untagged_variant_declaration,
 253                             const char *field_name,
 254                             struct declaration *field_declaration)
 255 {
 256         struct declaration_field *field;
 257         unsigned long index;
 258
 259         g_array_set_size(untagged_variant_declaration->fields, untagged_variant_declaration->fields->len + 1);
 260         index = untagged_variant_declaration->fields->len - 1;  /* last field (new) */
 261         field = &g_array_index(untagged_variant_declaration->fields, struct declaration_field, index);
 262         field->name = g_quark_from_string(field_name);
 263         declaration_ref(field_declaration);
 264         field->declaration = field_declaration;
 265         /* Keep index in hash rather than pointer, because array can relocate */
 266         g_hash_table_insert(untagged_variant_declaration->fields_by_tag,
 267                             (gpointer) (unsigned long) field->name,
 268                             (gpointer) index);
 269         /*
 270          * Alignment of variant is based on the alignment of its currently
 271          * selected choice, so we leave variant alignment as-is (statically
 272          * speaking).
 273          */
 274 }
 275
 276 struct declaration_field *
 277 untagged_variant_declaration_get_field_from_tag(struct declaration_untagged_variant *untagged_variant_declaration, GQuark tag)
 278 {
 279         gpointer index;
 280         gboolean found;
 281
 282         found = g_hash_table_lookup_extended(
 283                                 untagged_variant_declaration->fields_by_tag,
 284                                 (gconstpointer) (unsigned long) tag, NULL, &index);
 285
 286         if (!found) {
 287                 return NULL;
 288         }
 289
 290         return &g_array_index(untagged_variant_declaration->fields, struct declaration_field, (unsigned long)index);
 291 }
 292
 293 /*
 294  * field returned only valid as long as the field structure is not appended to.
 295  */
 296 struct definition *variant_get_current_field(struct definition_variant *variant)
 297 {
 298         struct definition_enum *_enum =
 299                 container_of(variant->enum_tag, struct definition_enum, p);
 300         struct declaration_variant *variant_declaration = variant->declaration;
 301         unsigned long index;
 302         GArray *tag_array;
 303         GQuark tag;
 304
 305         tag_array = _enum->value;
 306         /*
 307          * The 1 to 1 mapping from enumeration to value should have been already
 308          * checked. (see TODO above)
 309          */
 310         assert(tag_array->len == 1);
 311         tag = g_array_index(tag_array, GQuark, 0);
 312         index = (unsigned long) g_hash_table_lookup(variant_declaration->untagged_variant->fields_by_tag,
 313                                                     (gconstpointer) (unsigned long) tag);
 314         variant->current_field = g_ptr_array_index(variant->fields, index);
 315         return variant->current_field;
 316 }