types/variant.c

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