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