1 /* GDB/Scheme smobs (gsmob is pronounced "jee smob") 2 3 Copyright (C) 2014-2023 Free Software Foundation, Inc. 4 5 This file is part of GDB. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3 of the License, or 10 (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 19 20 /* See README file in this directory for implementation notes, coding 21 conventions, et.al. */ 22 23 /* Smobs are Guile's "small object". 24 They are used to export C structs to Scheme. 25 26 Note: There's only room in the encoding space for 256, and while we won't 27 come close to that, mixed with other libraries maybe someday we could. 28 We don't worry about it now, except to be aware of the issue. 29 We could allocate just a few smobs and use the unused smob flags field to 30 specify the gdb smob kind, that is left for another day if it ever is 31 needed. 32 33 Some GDB smobs are "chained gsmobs". They are used to assist with life-time 34 tracking of GDB objects vs Scheme objects. Gsmobs can "subclass" 35 chained_gdb_smob, which contains a doubly-linked list to assist with 36 life-time tracking. 37 38 Some other GDB smobs are "eqable gsmobs". Gsmob implementations can 39 "subclass" eqable_gdb_smob to make gsmobs eq?-able. This is done by 40 recording all gsmobs in a hash table and before creating a gsmob first 41 seeing if it's already in the table. Eqable gsmobs can also be used where 42 lifetime-tracking is required. */ 43 44 #include "defs.h" 45 #include "hashtab.h" 46 #include "objfiles.h" 47 #include "guile-internal.h" 48 49 /* We need to call this. Undo our hack to prevent others from calling it. */ 50 #undef scm_make_smob_type 51 52 static htab_t registered_gsmobs; 53 54 /* Hash function for registered_gsmobs hash table. */ 55 56 static hashval_t 57 hash_scm_t_bits (const void *item) 58 { 59 uintptr_t v = (uintptr_t) item; 60 61 return v; 62 } 63 64 /* Equality function for registered_gsmobs hash table. */ 65 66 static int 67 eq_scm_t_bits (const void *item_lhs, const void *item_rhs) 68 { 69 return item_lhs == item_rhs; 70 } 71 72 /* Record GSMOB_CODE as being a gdb smob. 73 GSMOB_CODE is the result of scm_make_smob_type. */ 74 75 static void 76 register_gsmob (scm_t_bits gsmob_code) 77 { 78 void **slot; 79 80 slot = htab_find_slot (registered_gsmobs, (void *) gsmob_code, INSERT); 81 gdb_assert (*slot == NULL); 82 *slot = (void *) gsmob_code; 83 } 84 85 /* Return non-zero if SCM is any registered gdb smob object. */ 86 87 static int 88 gdbscm_is_gsmob (SCM scm) 89 { 90 void **slot; 91 92 if (SCM_IMP (scm)) 93 return 0; 94 slot = htab_find_slot (registered_gsmobs, (void *) SCM_TYP16 (scm), 95 NO_INSERT); 96 return slot != NULL; 97 } 98 99 /* Call this to register a smob, instead of scm_make_smob_type. 100 Exports the created smob type from the current module. */ 101 102 scm_t_bits 103 gdbscm_make_smob_type (const char *name, size_t size) 104 { 105 scm_t_bits result = scm_make_smob_type (name, size); 106 107 register_gsmob (result); 108 109 #if SCM_MAJOR_VERSION == 2 && SCM_MINOR_VERSION == 0 110 /* Prior to Guile 2.1.0, smob classes were only exposed via exports 111 from the (oop goops) module. */ 112 SCM bound_name = scm_string_append (scm_list_3 (scm_from_latin1_string ("<"), 113 scm_from_latin1_string (name), 114 scm_from_latin1_string (">"))); 115 bound_name = scm_string_to_symbol (bound_name); 116 SCM smob_type = scm_public_ref (scm_list_2 (scm_from_latin1_symbol ("oop"), 117 scm_from_latin1_symbol ("goops")), 118 bound_name); 119 #elif SCM_MAJOR_VERSION == 2 && SCM_MINOR_VERSION == 1 && SCM_MICRO_VERSION == 0 120 /* Guile 2.1.0 doesn't provide any API for looking up smob classes. 121 We could try allocating a fake instance and using scm_class_of, 122 but it's probably not worth the trouble for the sake of a single 123 development release. */ 124 # error "Unsupported Guile version" 125 #else 126 /* Guile 2.1.1 and above provides scm_smob_type_class. */ 127 SCM smob_type = scm_smob_type_class (result); 128 #endif 129 130 SCM smob_type_name = scm_class_name (smob_type); 131 scm_define (smob_type_name, smob_type); 132 scm_module_export (scm_current_module (), scm_list_1 (smob_type_name)); 133 134 return result; 135 } 136 137 /* Initialize a gsmob. */ 138 139 void 140 gdbscm_init_gsmob (gdb_smob *base) 141 { 142 base->empty_base_class = 0; 143 } 144 145 /* Initialize a chained_gdb_smob. 146 This is the same as gdbscm_init_gsmob except that it also sets prev,next 147 to NULL. */ 148 149 void 150 gdbscm_init_chained_gsmob (chained_gdb_smob *base) 151 { 152 gdbscm_init_gsmob ((gdb_smob *) base); 153 base->prev = NULL; 154 base->next = NULL; 155 } 156 157 /* Initialize an eqable_gdb_smob. 158 This is the same as gdbscm_init_gsmob except that it also sets 159 BASE->containing_scm to CONTAINING_SCM. */ 160 161 void 162 gdbscm_init_eqable_gsmob (eqable_gdb_smob *base, SCM containing_scm) 163 { 164 gdbscm_init_gsmob ((gdb_smob *) base); 165 base->containing_scm = containing_scm; 166 } 167 168 169 /* gsmob accessors */ 170 171 /* Return the gsmob in SELF. 172 Throws an exception if SELF is not a gsmob. */ 173 174 static SCM 175 gsscm_get_gsmob_arg_unsafe (SCM self, int arg_pos, const char *func_name) 176 { 177 SCM_ASSERT_TYPE (gdbscm_is_gsmob (self), self, arg_pos, func_name, 178 _("any gdb smob")); 179 180 return self; 181 } 182 183 /* (gdb-object-kind gsmob) -> symbol 184 185 Note: While one might want to name this gdb-object-class-name, it is named 186 "-kind" because smobs aren't real GOOPS classes. */ 187 188 static SCM 189 gdbscm_gsmob_kind (SCM self) 190 { 191 SCM smob, result; 192 scm_t_bits smobnum; 193 const char *name; 194 195 smob = gsscm_get_gsmob_arg_unsafe (self, SCM_ARG1, FUNC_NAME); 196 197 smobnum = SCM_SMOBNUM (smob); 198 name = SCM_SMOBNAME (smobnum); 199 gdb::unique_xmalloc_ptr<char> kind = xstrprintf ("<%s>", name); 200 result = scm_from_latin1_symbol (kind.get ()); 201 return result; 202 } 203 204 205 /* When underlying gdb data structures are deleted, we need to update any 206 smobs with references to them. There are several smobs that reference 207 objfile-based data, so we provide helpers to manage this. */ 208 209 /* Create a hash table for mapping a pointer to a gdb data structure to the 210 gsmob that wraps it. */ 211 212 htab_t 213 gdbscm_create_eqable_gsmob_ptr_map (htab_hash hash_fn, htab_eq eq_fn) 214 { 215 htab_t htab = htab_create_alloc (7, hash_fn, eq_fn, 216 NULL, xcalloc, xfree); 217 218 return htab; 219 } 220 221 /* Return a pointer to the htab entry for the eq?-able gsmob BASE. 222 If the entry is found, *SLOT is non-NULL. 223 Otherwise *slot is NULL. */ 224 225 eqable_gdb_smob ** 226 gdbscm_find_eqable_gsmob_ptr_slot (htab_t htab, eqable_gdb_smob *base) 227 { 228 void **slot = htab_find_slot (htab, base, INSERT); 229 230 return (eqable_gdb_smob **) slot; 231 } 232 233 /* Record BASE in SLOT. SLOT must be the result of calling 234 gdbscm_find_eqable_gsmob_ptr_slot on BASE (or equivalent for lookup). */ 235 236 void 237 gdbscm_fill_eqable_gsmob_ptr_slot (eqable_gdb_smob **slot, 238 eqable_gdb_smob *base) 239 { 240 *slot = base; 241 } 242 243 /* Remove BASE from HTAB. 244 BASE is a pointer to a gsmob that wraps a pointer to a GDB datum. 245 This is used, for example, when an object is freed. 246 247 It is an error to call this if PTR is not in HTAB (only because it allows 248 for some consistency checking). */ 249 250 void 251 gdbscm_clear_eqable_gsmob_ptr_slot (htab_t htab, eqable_gdb_smob *base) 252 { 253 void **slot = htab_find_slot (htab, base, NO_INSERT); 254 255 gdb_assert (slot != NULL); 256 htab_clear_slot (htab, slot); 257 } 258 259 /* Initialize the Scheme gsmobs code. */ 260 261 static const scheme_function gsmob_functions[] = 262 { 263 /* N.B. There is a general rule of not naming symbols in gdb-guile with a 264 "gdb" prefix. This symbol does not violate this rule because it is to 265 be read as "gdb-object-foo", not "gdb-foo". */ 266 { "gdb-object-kind", 1, 0, 0, as_a_scm_t_subr (gdbscm_gsmob_kind), 267 "\ 268 Return the kind of the GDB object, e.g., <gdb:breakpoint>, as a symbol." }, 269 270 END_FUNCTIONS 271 }; 272 273 void 274 gdbscm_initialize_smobs (void) 275 { 276 registered_gsmobs = htab_create_alloc (10, 277 hash_scm_t_bits, eq_scm_t_bits, 278 NULL, xcalloc, xfree); 279 280 gdbscm_define_functions (gsmob_functions, 1); 281 } 282