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 2.1 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; work around type aliasing */                   \
 117     union { char *in; gpointer *out; } _pp;                                    \
 118     gpointer _p;                                                               \
 119     /* This assignment is needed to avoid a gcc warning */                     \
 120     GDestroyNotify _destroy = (GDestroyNotify) (destroy);                      \
 121                                                                                \
 122     _pp.in = (char *) (pp);                                                    \
 123     _p = *_pp.out;                                                             \
 124     if (_p)                                                                    \
 125       {                                                                        \
 126         *_pp.out = NULL;                                                       \
 127         _destroy (_p);                                                         \
 128       }                                                                        \
 129   } G_STMT_END
 130
 131 /**
 132  * g_steal_pointer:
 133  * @pp: (not nullable): a pointer to a pointer
 134  *
 135  * Sets @pp to %NULL, returning the value that was there before.
 136  *
 137  * Conceptually, this transfers the ownership of the pointer from the
 138  * referenced variable to the "caller" of the macro (ie: "steals" the
 139  * reference).
 140  *
 141  * The return value will be properly typed, according to the type of
 142  * @pp.
 143  *
 144  * This can be very useful when combined with g_autoptr() to prevent the
 145  * return value of a function from being automatically freed.  Consider
 146  * the following example (which only works on GCC and clang):
 147  *
 148  * |[
 149  * GObject *
 150  * create_object (void)
 151  * {
 152  *   g_autoptr(GObject) obj = g_object_new (G_TYPE_OBJECT, NULL);
 153  *
 154  *   if (early_error_case)
 155  *     return NULL;
 156  *
 157  *   return g_steal_pointer (&obj);
 158  * }
 159  * ]|
 160  *
 161  * It can also be used in similar ways for 'out' parameters and is
 162  * particularly useful for dealing with optional out parameters:
 163  *
 164  * |[
 165  * gboolean
 166  * get_object (GObject **obj_out)
 167  * {
 168  *   g_autoptr(GObject) obj = g_object_new (G_TYPE_OBJECT, NULL);
 169  *
 170  *   if (early_error_case)
 171  *     return FALSE;
 172  *
 173  *   if (obj_out)
 174  *     *obj_out = g_steal_pointer (&obj);
 175  *
 176  *   return TRUE;
 177  * }
 178  * ]|
 179  *
 180  * In the above example, the object will be automatically freed in the
 181  * early error case and also in the case that %NULL was given for
 182  * @obj_out.
 183  *
 184  * Since: 2.44
 185  */
 186 static inline gpointer
 187 g_steal_pointer (gpointer pp)
 188 {
 189   gpointer *ptr = (gpointer *) pp;
 190   gpointer ref;
 191
 192   ref = *ptr;
 193   *ptr = NULL;
 194
 195   return ref;
 196 }
 197
 198 /* type safety */
 199 #define g_steal_pointer(pp) \
 200   (0 ? (*(pp)) : (g_steal_pointer) (pp))
 201
 202 /* Optimise: avoid the call to the (slower) _n function if we can
 203  * determine at compile-time that no overflow happens.
 204  */
 205 #if defined (__GNUC__) && (__GNUC__ >= 2) && defined (__OPTIMIZE__)
 206 #  define _G_NEW(struct_type, n_structs, func) \
 207         (struct_type *) (G_GNUC_EXTENSION ({                    \
 208           gsize __n = (gsize) (n_structs);                      \
 209           gsize __s = sizeof (struct_type);                     \
 210           gpointer __p;                                         \
 211           if (__s == 1)                                         \
 212             __p = g_##func (__n);                               \
 213           else if (__builtin_constant_p (__n) &&                \
 214                    (__s == 0 || __n <= G_MAXSIZE / __s))        \
 215             __p = g_##func (__n * __s);                         \
 216           else                                                  \
 217             __p = g_##func##_n (__n, __s);                      \
 218           __p;                                                  \
 219         }))
 220 #  define _G_RENEW(struct_type, mem, n_structs, func) \
 221         (struct_type *) (G_GNUC_EXTENSION ({                    \
 222           gsize __n = (gsize) (n_structs);                      \
 223           gsize __s = sizeof (struct_type);                     \
 224           gpointer __p = (gpointer) (mem);                      \
 225           if (__s == 1)                                         \
 226             __p = g_##func (__p, __n);                          \
 227           else if (__builtin_constant_p (__n) &&                \
 228                    (__s == 0 || __n <= G_MAXSIZE / __s))        \
 229             __p = g_##func (__p, __n * __s);                    \
 230           else                                                  \
 231             __p = g_##func##_n (__p, __n, __s);                 \
 232           __p;                                                  \
 233         }))
 234
 235 #else
 236
 237 /* Unoptimised version: always call the _n() function. */
 238
 239 #define _G_NEW(struct_type, n_structs, func) \
 240         ((struct_type *) g_##func##_n ((n_structs), sizeof (struct_type)))
 241 #define _G_RENEW(struct_type, mem, n_structs, func) \
 242         ((struct_type *) g_##func##_n (mem, (n_structs), sizeof (struct_type)))
 243
 244 #endif
 245
 246 /**
 247  * g_new:
 248  * @struct_type: the type of the elements to allocate
 249  * @n_structs: the number of elements to allocate
 250  *
 251  * Allocates @n_structs elements of type @struct_type.
 252  * The returned pointer is cast to a pointer to the given type.
 253  * If @n_structs is 0 it returns %NULL.
 254  * Care is taken to avoid overflow when calculating the size of the allocated block.
 255  *
 256  * Since the returned pointer is already casted to the right type,
 257  * it is normally unnecessary to cast it explicitly, and doing
 258  * so might hide memory allocation errors.
 259  *
 260  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type
 261  */
 262 #define g_new(struct_type, n_structs)                   _G_NEW (struct_type, n_structs, malloc)
 263 /**
 264  * g_new0:
 265  * @struct_type: the type of the elements to allocate.
 266  * @n_structs: the number of elements to allocate.
 267  *
 268  * Allocates @n_structs elements of type @struct_type, initialized to 0's.
 269  * The returned pointer is cast to a pointer to the given type.
 270  * If @n_structs is 0 it returns %NULL.
 271  * Care is taken to avoid overflow when calculating the size of the allocated block.
 272  *
 273  * Since the returned pointer is already casted to the right type,
 274  * it is normally unnecessary to cast it explicitly, and doing
 275  * so might hide memory allocation errors.
 276  *
 277  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type.
 278  */
 279 #define g_new0(struct_type, n_structs)                  _G_NEW (struct_type, n_structs, malloc0)
 280 /**
 281  * g_renew:
 282  * @struct_type: the type of the elements to allocate
 283  * @mem: the currently allocated memory
 284  * @n_structs: the number of elements to allocate
 285  *
 286  * Reallocates the memory pointed to by @mem, so that it now has space for
 287  * @n_structs elements of type @struct_type. It returns the new address of
 288  * the memory, which may have been moved.
 289  * Care is taken to avoid overflow when calculating the size of the allocated block.
 290  *
 291  * Returns: a pointer to the new allocated memory, cast to a pointer to @struct_type
 292  */
 293 #define g_renew(struct_type, mem, n_structs)            _G_RENEW (struct_type, mem, n_structs, realloc)
 294 /**
 295  * g_try_new:
 296  * @struct_type: the type of the elements to allocate
 297  * @n_structs: the number of elements to allocate
 298  *
 299  * Attempts to allocate @n_structs elements of type @struct_type, and returns
 300  * %NULL on failure. Contrast with g_new(), which aborts the program on failure.
 301  * The returned pointer is cast to a pointer to the given type.
 302  * The function returns %NULL when @n_structs is 0 of if an overflow occurs.
 303  *
 304  * Since: 2.8
 305  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type
 306  */
 307 #define g_try_new(struct_type, n_structs)               _G_NEW (struct_type, n_structs, try_malloc)
 308 /**
 309  * g_try_new0:
 310  * @struct_type: the type of the elements to allocate
 311  * @n_structs: the number of elements to allocate
 312  *
 313  * Attempts to allocate @n_structs elements of type @struct_type, initialized
 314  * to 0's, and returns %NULL on failure. Contrast with g_new0(), which aborts
 315  * the program on failure.
 316  * The returned pointer is cast to a pointer to the given type.
 317  * The function returns %NULL when @n_structs is 0 or if an overflow occurs.
 318  *
 319  * Since: 2.8
 320  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type
 321  */
 322 #define g_try_new0(struct_type, n_structs)              _G_NEW (struct_type, n_structs, try_malloc0)
 323 /**
 324  * g_try_renew:
 325  * @struct_type: the type of the elements to allocate
 326  * @mem: the currently allocated memory
 327  * @n_structs: the number of elements to allocate
 328  *
 329  * Attempts to reallocate the memory pointed to by @mem, so that it now has
 330  * space for @n_structs elements of type @struct_type, and returns %NULL on
 331  * failure. Contrast with g_renew(), which aborts the program on failure.
 332  * It returns the new address of the memory, which may have been moved.
 333  * The function returns %NULL if an overflow occurs.
 334  *
 335  * Since: 2.8
 336  * Returns: a pointer to the new allocated memory, cast to a pointer to @struct_type
 337  */
 338 #define g_try_renew(struct_type, mem, n_structs)        _G_RENEW (struct_type, mem, n_structs, try_realloc)
 339
 340
 341 /* Memory allocation virtualization for debugging purposes
 342  * g_mem_set_vtable() has to be the very first GLib function called
 343  * if being used
 344  */
 345 struct _GMemVTable {
 346   gpointer (*malloc)      (gsize    n_bytes);
 347   gpointer (*realloc)     (gpointer mem,
 348                            gsize    n_bytes);
 349   void     (*free)        (gpointer mem);
 350   /* optional; set to NULL if not used ! */
 351   gpointer (*calloc)      (gsize    n_blocks,
 352                            gsize    n_block_bytes);
 353   gpointer (*try_malloc)  (gsize    n_bytes);
 354   gpointer (*try_realloc) (gpointer mem,
 355                            gsize    n_bytes);
 356 };
 357 GLIB_DEPRECATED_IN_2_46
 358 void     g_mem_set_vtable (GMemVTable   *vtable);
 359 GLIB_DEPRECATED_IN_2_46
 360 gboolean g_mem_is_system_malloc (void);
 361
 362 GLIB_VAR gboolean g_mem_gc_friendly;
 363
 364 /* Memory profiler and checker, has to be enabled via g_mem_set_vtable()
 365  */
 366 GLIB_VAR GMemVTable     *glib_mem_profiler_table;
 367 GLIB_DEPRECATED_IN_2_46
 368 void    g_mem_profile   (void);
 369
 370 G_END_DECLS
 371
 372 #endif /* __G_MEM_H__ */