1 /* GDB/Scheme smobs (gsmob is pronounced "jee smob")
3 Copyright (C) 2014-2017 Free Software Foundation, Inc.
5 This file is part of GDB.
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.
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.
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/>. */
20 /* See README file in this directory for implementation notes, coding
21 conventions, et.al. */
23 /* Smobs are Guile's "small object".
24 They are used to export C structs to Scheme.
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
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
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. */
47 #include "guile-internal.h"
49 /* We need to call this. Undo our hack to prevent others from calling it. */
50 #undef scm_make_smob_type
52 static htab_t registered_gsmobs;
54 /* Hash function for registered_gsmobs hash table. */
57 hash_scm_t_bits (const void *item)
59 uintptr_t v = (uintptr_t) item;
64 /* Equality function for registered_gsmobs hash table. */
67 eq_scm_t_bits (const void *item_lhs, const void *item_rhs)
69 return item_lhs == item_rhs;
72 /* Record GSMOB_CODE as being a gdb smob.
73 GSMOB_CODE is the result of scm_make_smob_type. */
76 register_gsmob (scm_t_bits gsmob_code)
80 slot = htab_find_slot (registered_gsmobs, (void *) gsmob_code, INSERT);
81 gdb_assert (*slot == NULL);
82 *slot = (void *) gsmob_code;
85 /* Return non-zero if SCM is any registered gdb smob object. */
88 gdbscm_is_gsmob (SCM scm)
94 slot = htab_find_slot (registered_gsmobs, (void *) SCM_TYP16 (scm),
99 /* Call this to register a smob, instead of scm_make_smob_type. */
102 gdbscm_make_smob_type (const char *name, size_t size)
104 scm_t_bits result = scm_make_smob_type (name, size);
106 register_gsmob (result);
110 /* Initialize a gsmob. */
113 gdbscm_init_gsmob (gdb_smob *base)
115 base->empty_base_class = 0;
118 /* Initialize a chained_gdb_smob.
119 This is the same as gdbscm_init_gsmob except that it also sets prev,next
123 gdbscm_init_chained_gsmob (chained_gdb_smob *base)
125 gdbscm_init_gsmob ((gdb_smob *) base);
130 /* Initialize an eqable_gdb_smob.
131 This is the same as gdbscm_init_gsmob except that it also sets
132 BASE->containing_scm to CONTAINING_SCM. */
135 gdbscm_init_eqable_gsmob (eqable_gdb_smob *base, SCM containing_scm)
137 gdbscm_init_gsmob ((gdb_smob *) base);
138 base->containing_scm = containing_scm;
142 /* gsmob accessors */
144 /* Return the gsmob in SELF.
145 Throws an exception if SELF is not a gsmob. */
148 gsscm_get_gsmob_arg_unsafe (SCM self, int arg_pos, const char *func_name)
150 SCM_ASSERT_TYPE (gdbscm_is_gsmob (self), self, arg_pos, func_name,
156 /* (gdb-object-kind gsmob) -> symbol
158 Note: While one might want to name this gdb-object-class-name, it is named
159 "-kind" because smobs aren't real GOOPS classes. */
162 gdbscm_gsmob_kind (SCM self)
169 smob = gsscm_get_gsmob_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
171 smobnum = SCM_SMOBNUM (smob);
172 name = SCM_SMOBNAME (smobnum);
173 kind = xstrprintf ("<%s>", name);
174 result = scm_from_latin1_symbol (kind);
181 /* When underlying gdb data structures are deleted, we need to update any
182 smobs with references to them. There are several smobs that reference
183 objfile-based data, so we provide helpers to manage this. */
185 /* Add G_SMOB to the reference chain for OBJFILE specified by DATA_KEY.
186 OBJFILE may be NULL, in which case just set prev,next to NULL. */
189 gdbscm_add_objfile_ref (struct objfile *objfile,
190 const struct objfile_data *data_key,
191 chained_gdb_smob *g_smob)
196 g_smob->next = (chained_gdb_smob *) objfile_data (objfile, data_key);
198 g_smob->next->prev = g_smob;
199 set_objfile_data (objfile, data_key, g_smob);
205 /* Remove G_SMOB from the reference chain for OBJFILE specified
206 by DATA_KEY. OBJFILE may be NULL. */
209 gdbscm_remove_objfile_ref (struct objfile *objfile,
210 const struct objfile_data *data_key,
211 chained_gdb_smob *g_smob)
214 g_smob->prev->next = g_smob->next;
215 else if (objfile != NULL)
216 set_objfile_data (objfile, data_key, g_smob->next);
218 g_smob->next->prev = g_smob->prev;
221 /* Create a hash table for mapping a pointer to a gdb data structure to the
222 gsmob that wraps it. */
225 gdbscm_create_eqable_gsmob_ptr_map (htab_hash hash_fn, htab_eq eq_fn)
227 htab_t htab = htab_create_alloc (7, hash_fn, eq_fn,
228 NULL, xcalloc, xfree);
233 /* Return a pointer to the htab entry for the eq?-able gsmob BASE.
234 If the entry is found, *SLOT is non-NULL.
235 Otherwise *slot is NULL. */
238 gdbscm_find_eqable_gsmob_ptr_slot (htab_t htab, eqable_gdb_smob *base)
240 void **slot = htab_find_slot (htab, base, INSERT);
242 return (eqable_gdb_smob **) slot;
245 /* Record BASE in SLOT. SLOT must be the result of calling
246 gdbscm_find_eqable_gsmob_ptr_slot on BASE (or equivalent for lookup). */
249 gdbscm_fill_eqable_gsmob_ptr_slot (eqable_gdb_smob **slot,
250 eqable_gdb_smob *base)
255 /* Remove BASE from HTAB.
256 BASE is a pointer to a gsmob that wraps a pointer to a GDB datum.
257 This is used, for example, when an object is freed.
259 It is an error to call this if PTR is not in HTAB (only because it allows
260 for some consistency checking). */
263 gdbscm_clear_eqable_gsmob_ptr_slot (htab_t htab, eqable_gdb_smob *base)
265 void **slot = htab_find_slot (htab, base, NO_INSERT);
267 gdb_assert (slot != NULL);
268 htab_clear_slot (htab, slot);
271 /* Initialize the Scheme gsmobs code. */
273 static const scheme_function gsmob_functions[] =
275 /* N.B. There is a general rule of not naming symbols in gdb-guile with a
276 "gdb" prefix. This symbol does not violate this rule because it is to
277 be read as "gdb-object-foo", not "gdb-foo". */
278 { "gdb-object-kind", 1, 0, 0, as_a_scm_t_subr (gdbscm_gsmob_kind),
280 Return the kind of the GDB object, e.g., <gdb:breakpoint>, as a symbol." },
286 gdbscm_initialize_smobs (void)
288 registered_gsmobs = htab_create_alloc (10,
289 hash_scm_t_bits, eq_scm_t_bits,
290 NULL, xcalloc, xfree);
292 gdbscm_define_functions (gsmob_functions, 1);