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