glib/gmem.h

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /*
  19  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  20  * file for a list of people on the GLib Team.  See the ChangeLog
  21  * files for a list of changes.  These files are distributed with
  22  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  23  */
  24
  25 #ifndef __G_MEM_H__
  26 #define __G_MEM_H__
  27
  28 #if !defined (__GLIB_H_INSIDE__) && !defined (GLIB_COMPILATION)
  29 #error "Only <glib.h> can be included directly."
  30 #endif
  31
  32 #include <glib/gutils.h>
  33
  34 G_BEGIN_DECLS
  35
  36 /**
  37  * GMemVTable:
  38  * @malloc: function to use for allocating memory.
  39  * @realloc: function to use for reallocating memory.
  40  * @free: function to use to free memory.
  41  * @calloc: function to use for allocating zero-filled memory.
  42  * @try_malloc: function to use for allocating memory without a default error handler.
  43  * @try_realloc: function to use for reallocating memory without a default error handler.
  44  *
  45  * A set of functions used to perform memory allocation. The same #GMemVTable must
  46  * be used for all allocations in the same program; a call to g_mem_set_vtable(),
  47  * if it exists, should be prior to any use of GLib.
  48  *
  49  * This functions related to this has been deprecated in 2.46, and no longer work.
  50  */
  51 typedef struct _GMemVTable GMemVTable;
  52
  53
  54 #if GLIB_SIZEOF_VOID_P > GLIB_SIZEOF_LONG
  55 /**
  56  * G_MEM_ALIGN:
  57  *
  58  * Indicates the number of bytes to which memory will be aligned on the
  59  * current platform.
  60  */
  61 #  define G_MEM_ALIGN   GLIB_SIZEOF_VOID_P
  62 #else   /* GLIB_SIZEOF_VOID_P <= GLIB_SIZEOF_LONG */
  63 #  define G_MEM_ALIGN   GLIB_SIZEOF_LONG
  64 #endif  /* GLIB_SIZEOF_VOID_P <= GLIB_SIZEOF_LONG */
  65
  66
  67 /* Memory allocation functions
  68  */
  69
  70 GLIB_AVAILABLE_IN_ALL
  71 void     g_free           (gpointer      mem);
  72
  73 GLIB_AVAILABLE_IN_2_34
  74 void     g_clear_pointer  (gpointer      *pp,
  75                            GDestroyNotify destroy);
  76
  77 GLIB_AVAILABLE_IN_ALL
  78 gpointer g_malloc         (gsize         n_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE(1);
  79 GLIB_AVAILABLE_IN_ALL
  80 gpointer g_malloc0        (gsize         n_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE(1);
  81 GLIB_AVAILABLE_IN_ALL
  82 gpointer g_realloc        (gpointer      mem,
  83                            gsize         n_bytes) G_GNUC_WARN_UNUSED_RESULT;
  84 GLIB_AVAILABLE_IN_ALL
  85 gpointer g_try_malloc     (gsize         n_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE(1);
  86 GLIB_AVAILABLE_IN_ALL
  87 gpointer g_try_malloc0    (gsize         n_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE(1);
  88 GLIB_AVAILABLE_IN_ALL
  89 gpointer g_try_realloc    (gpointer      mem,
  90                            gsize         n_bytes) G_GNUC_WARN_UNUSED_RESULT;
  91
  92 GLIB_AVAILABLE_IN_ALL
  93 gpointer g_malloc_n       (gsize         n_blocks,
  94                            gsize         n_block_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE2(1,2);
  95 GLIB_AVAILABLE_IN_ALL
  96 gpointer g_malloc0_n      (gsize         n_blocks,
  97                            gsize         n_block_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE2(1,2);
  98 GLIB_AVAILABLE_IN_ALL
  99 gpointer g_realloc_n      (gpointer      mem,
 100                            gsize         n_blocks,
 101                            gsize         n_block_bytes) G_GNUC_WARN_UNUSED_RESULT;
 102 GLIB_AVAILABLE_IN_ALL
 103 gpointer g_try_malloc_n   (gsize         n_blocks,
 104                            gsize         n_block_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE2(1,2);
 105 GLIB_AVAILABLE_IN_ALL
 106 gpointer g_try_malloc0_n  (gsize         n_blocks,
 107                            gsize         n_block_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE2(1,2);
 108 GLIB_AVAILABLE_IN_ALL
 109 gpointer g_try_realloc_n  (gpointer      mem,
 110                            gsize         n_blocks,
 111                            gsize         n_block_bytes) G_GNUC_WARN_UNUSED_RESULT;
 112
 113 #define g_clear_pointer(pp, destroy) \
 114   G_STMT_START {                                                               \
 115     G_STATIC_ASSERT (sizeof *(pp) == sizeof (gpointer));                       \
 116     /* Only one access, please */                                              \
 117     gpointer *_pp = (gpointer *) (pp);                                         \
 118     gpointer _p;                                                               \
 119     /* This assignment is needed to avoid a gcc warning */                     \
 120     GDestroyNotify _destroy = (GDestroyNotify) (destroy);                      \
 121                                                                                \
 122     _p = *_pp;                                                                 \
 123     if (_p)                                                                    \
 124       {                                                                        \
 125         *_pp = NULL;                                                           \
 126         _destroy (_p);                                                         \
 127       }                                                                        \
 128   } G_STMT_END
 129
 130 /**
 131  * g_steal_pointer:
 132  * @pp: (not nullable): a pointer to a pointer
 133  *
 134  * Sets @pp to %NULL, returning the value that was there before.
 135  *
 136  * Conceptually, this transfers the ownership of the pointer from the
 137  * referenced variable to the "caller" of the macro (ie: "steals" the
 138  * reference).
 139  *
 140  * The return value will be properly typed, according to the type of
 141  * @pp.
 142  *
 143  * This can be very useful when combined with g_autoptr() to prevent the
 144  * return value of a function from being automatically freed.  Consider
 145  * the following example (which only works on GCC and clang):
 146  *
 147  * |[
 148  * GObject *
 149  * create_object (void)
 150  * {
 151  *   g_autoptr(GObject) obj = g_object_new (G_TYPE_OBJECT, NULL);
 152  *
 153  *   if (early_error_case)
 154  *     return NULL;
 155  *
 156  *   return g_steal_pointer (&obj);
 157  * }
 158  * ]|
 159  *
 160  * It can also be used in similar ways for 'out' parameters and is
 161  * particularly useful for dealing with optional out parameters:
 162  *
 163  * |[
 164  * gboolean
 165  * get_object (GObject **obj_out)
 166  * {
 167  *   g_autoptr(GObject) obj = g_object_new (G_TYPE_OBJECT, NULL);
 168  *
 169  *   if (early_error_case)
 170  *     return FALSE;
 171  *
 172  *   if (obj_out)
 173  *     *obj_out = g_steal_pointer (&obj);
 174  *
 175  *   return TRUE;
 176  * }
 177  * ]|
 178  *
 179  * In the above example, the object will be automatically freed in the
 180  * early error case and also in the case that %NULL was given for
 181  * @obj_out.
 182  *
 183  * Since: 2.44
 184  */
 185 static inline gpointer
 186 g_steal_pointer (gpointer pp)
 187 {
 188   gpointer *ptr = (gpointer *) pp;
 189   gpointer ref;
 190
 191   ref = *ptr;
 192   *ptr = NULL;
 193
 194   return ref;
 195 }
 196
 197 /* type safety */
 198 #define g_steal_pointer(pp) \
 199   (0 ? (*(pp)) : (g_steal_pointer) (pp))
 200
 201 /* Optimise: avoid the call to the (slower) _n function if we can
 202  * determine at compile-time that no overflow happens.
 203  */
 204 #if defined (__GNUC__) && (__GNUC__ >= 2) && defined (__OPTIMIZE__)
 205 #  define _G_NEW(struct_type, n_structs, func) \
 206         (struct_type *) (G_GNUC_EXTENSION ({                    \
 207           gsize __n = (gsize) (n_structs);                      \
 208           gsize __s = sizeof (struct_type);                     \
 209           gpointer __p;                                         \
 210           if (__s == 1)                                         \
 211             __p = g_##func (__n);                               \
 212           else if (__builtin_constant_p (__n) &&                \
 213                    (__s == 0 || __n <= G_MAXSIZE / __s))        \
 214             __p = g_##func (__n * __s);                         \
 215           else                                                  \
 216             __p = g_##func##_n (__n, __s);                      \
 217           __p;                                                  \
 218         }))
 219 #  define _G_RENEW(struct_type, mem, n_structs, func) \
 220         (struct_type *) (G_GNUC_EXTENSION ({                    \
 221           gsize __n = (gsize) (n_structs);                      \
 222           gsize __s = sizeof (struct_type);                     \
 223           gpointer __p = (gpointer) (mem);                      \
 224           if (__s == 1)                                         \
 225             __p = g_##func (__p, __n);                          \
 226           else if (__builtin_constant_p (__n) &&                \
 227                    (__s == 0 || __n <= G_MAXSIZE / __s))        \
 228             __p = g_##func (__p, __n * __s);                    \
 229           else                                                  \
 230             __p = g_##func##_n (__p, __n, __s);                 \
 231           __p;                                                  \
 232         }))
 233
 234 #else
 235
 236 /* Unoptimised version: always call the _n() function. */
 237
 238 #define _G_NEW(struct_type, n_structs, func) \
 239         ((struct_type *) g_##func##_n ((n_structs), sizeof (struct_type)))
 240 #define _G_RENEW(struct_type, mem, n_structs, func) \
 241         ((struct_type *) g_##func##_n (mem, (n_structs), sizeof (struct_type)))
 242
 243 #endif
 244
 245 /**
 246  * g_new:
 247  * @struct_type: the type of the elements to allocate
 248  * @n_structs: the number of elements to allocate
 249  *
 250  * Allocates @n_structs elements of type @struct_type.
 251  * The returned pointer is cast to a pointer to the given type.
 252  * If @n_structs is 0 it returns %NULL.
 253  * Care is taken to avoid overflow when calculating the size of the allocated block.
 254  *
 255  * Since the returned pointer is already casted to the right type,
 256  * it is normally unnecessary to cast it explicitly, and doing
 257  * so might hide memory allocation errors.
 258  *
 259  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type
 260  */
 261 #define g_new(struct_type, n_structs)                   _G_NEW (struct_type, n_structs, malloc)
 262 /**
 263  * g_new0:
 264  * @struct_type: the type of the elements to allocate.
 265  * @n_structs: the number of elements to allocate.
 266  *
 267  * Allocates @n_structs elements of type @struct_type, initialized to 0's.
 268  * The returned pointer is cast to a pointer to the given type.
 269  * If @n_structs is 0 it returns %NULL.
 270  * Care is taken to avoid overflow when calculating the size of the allocated block.
 271  *
 272  * Since the returned pointer is already casted to the right type,
 273  * it is normally unnecessary to cast it explicitly, and doing
 274  * so might hide memory allocation errors.
 275  *
 276  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type.
 277  */
 278 #define g_new0(struct_type, n_structs)                  _G_NEW (struct_type, n_structs, malloc0)
 279 /**
 280  * g_renew:
 281  * @struct_type: the type of the elements to allocate
 282  * @mem: the currently allocated memory
 283  * @n_structs: the number of elements to allocate
 284  *
 285  * Reallocates the memory pointed to by @mem, so that it now has space for
 286  * @n_structs elements of type @struct_type. It returns the new address of
 287  * the memory, which may have been moved.
 288  * Care is taken to avoid overflow when calculating the size of the allocated block.
 289  *
 290  * Returns: a pointer to the new allocated memory, cast to a pointer to @struct_type
 291  */
 292 #define g_renew(struct_type, mem, n_structs)            _G_RENEW (struct_type, mem, n_structs, realloc)
 293 /**
 294  * g_try_new:
 295  * @struct_type: the type of the elements to allocate
 296  * @n_structs: the number of elements to allocate
 297  *
 298  * Attempts to allocate @n_structs elements of type @struct_type, and returns
 299  * %NULL on failure. Contrast with g_new(), which aborts the program on failure.
 300  * The returned pointer is cast to a pointer to the given type.
 301  * The function returns %NULL when @n_structs is 0 of if an overflow occurs.
 302  *
 303  * Since: 2.8
 304  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type
 305  */
 306 #define g_try_new(struct_type, n_structs)               _G_NEW (struct_type, n_structs, try_malloc)
 307 /**
 308  * g_try_new0:
 309  * @struct_type: the type of the elements to allocate
 310  * @n_structs: the number of elements to allocate
 311  *
 312  * Attempts to allocate @n_structs elements of type @struct_type, initialized
 313  * to 0's, and returns %NULL on failure. Contrast with g_new0(), which aborts
 314  * the program on failure.
 315  * The returned pointer is cast to a pointer to the given type.
 316  * The function returns %NULL when @n_structs is 0 or if an overflow occurs.
 317  *
 318  * Since: 2.8
 319  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type
 320  */
 321 #define g_try_new0(struct_type, n_structs)              _G_NEW (struct_type, n_structs, try_malloc0)
 322 /**
 323  * g_try_renew:
 324  * @struct_type: the type of the elements to allocate
 325  * @mem: the currently allocated memory
 326  * @n_structs: the number of elements to allocate
 327  *
 328  * Attempts to reallocate the memory pointed to by @mem, so that it now has
 329  * space for @n_structs elements of type @struct_type, and returns %NULL on
 330  * failure. Contrast with g_renew(), which aborts the program on failure.
 331  * It returns the new address of the memory, which may have been moved.
 332  * The function returns %NULL if an overflow occurs.
 333  *
 334  * Since: 2.8
 335  * Returns: a pointer to the new allocated memory, cast to a pointer to @struct_type
 336  */
 337 #define g_try_renew(struct_type, mem, n_structs)        _G_RENEW (struct_type, mem, n_structs, try_realloc)
 338
 339
 340 /* Memory allocation virtualization for debugging purposes
 341  * g_mem_set_vtable() has to be the very first GLib function called
 342  * if being used
 343  */
 344 struct _GMemVTable {
 345   gpointer (*malloc)      (gsize    n_bytes);
 346   gpointer (*realloc)     (gpointer mem,
 347                            gsize    n_bytes);
 348   void     (*free)        (gpointer mem);
 349   /* optional; set to NULL if not used ! */
 350   gpointer (*calloc)      (gsize    n_blocks,
 351                            gsize    n_block_bytes);
 352   gpointer (*try_malloc)  (gsize    n_bytes);
 353   gpointer (*try_realloc) (gpointer mem,
 354                            gsize    n_bytes);
 355 };
 356 GLIB_DEPRECATED_IN_2_46
 357 void     g_mem_set_vtable (GMemVTable   *vtable);
 358 GLIB_DEPRECATED_IN_2_46
 359 gboolean g_mem_is_system_malloc (void);
 360
 361 GLIB_VAR gboolean g_mem_gc_friendly;
 362
 363 /* Memory profiler and checker, has to be enabled via g_mem_set_vtable()
 364  */
 365 GLIB_VAR GMemVTable     *glib_mem_profiler_table;
 366 GLIB_DEPRECATED_IN_2_46
 367 void    g_mem_profile   (void);
 368
 369 G_END_DECLS
 370
 371 #endif /* __G_MEM_H__ */