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