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