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/gtypes.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 typedef struct _GMemVTable GMemVTable;
  50
  51
  52 #if GLIB_SIZEOF_VOID_P > GLIB_SIZEOF_LONG
  53 /**
  54  * G_MEM_ALIGN:
  55  *
  56  * Indicates the number of bytes to which memory will be aligned on the
  57  * current platform.
  58  */
  59 #  define G_MEM_ALIGN   GLIB_SIZEOF_VOID_P
  60 #else   /* GLIB_SIZEOF_VOID_P <= GLIB_SIZEOF_LONG */
  61 #  define G_MEM_ALIGN   GLIB_SIZEOF_LONG
  62 #endif  /* GLIB_SIZEOF_VOID_P <= GLIB_SIZEOF_LONG */
  63
  64
  65 /* Memory allocation functions
  66  */
  67
  68 GLIB_AVAILABLE_IN_ALL
  69 void     g_free           (gpointer      mem);
  70
  71 GLIB_AVAILABLE_IN_2_34
  72 void     g_clear_pointer  (gpointer      *pp,
  73                            GDestroyNotify destroy);
  74
  75 GLIB_AVAILABLE_IN_ALL
  76 gpointer g_malloc         (gsize         n_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE(1);
  77 GLIB_AVAILABLE_IN_ALL
  78 gpointer g_malloc0        (gsize         n_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE(1);
  79 GLIB_AVAILABLE_IN_ALL
  80 gpointer g_realloc        (gpointer      mem,
  81                            gsize         n_bytes) G_GNUC_WARN_UNUSED_RESULT;
  82 GLIB_AVAILABLE_IN_ALL
  83 gpointer g_try_malloc     (gsize         n_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE(1);
  84 GLIB_AVAILABLE_IN_ALL
  85 gpointer g_try_malloc0    (gsize         n_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE(1);
  86 GLIB_AVAILABLE_IN_ALL
  87 gpointer g_try_realloc    (gpointer      mem,
  88                            gsize         n_bytes) G_GNUC_WARN_UNUSED_RESULT;
  89
  90 GLIB_AVAILABLE_IN_ALL
  91 gpointer g_malloc_n       (gsize         n_blocks,
  92                            gsize         n_block_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE2(1,2);
  93 GLIB_AVAILABLE_IN_ALL
  94 gpointer g_malloc0_n      (gsize         n_blocks,
  95                            gsize         n_block_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE2(1,2);
  96 GLIB_AVAILABLE_IN_ALL
  97 gpointer g_realloc_n      (gpointer      mem,
  98                            gsize         n_blocks,
  99                            gsize         n_block_bytes) G_GNUC_WARN_UNUSED_RESULT;
 100 GLIB_AVAILABLE_IN_ALL
 101 gpointer g_try_malloc_n   (gsize         n_blocks,
 102                            gsize         n_block_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE2(1,2);
 103 GLIB_AVAILABLE_IN_ALL
 104 gpointer g_try_malloc0_n  (gsize         n_blocks,
 105                            gsize         n_block_bytes) G_GNUC_MALLOC G_GNUC_ALLOC_SIZE2(1,2);
 106 GLIB_AVAILABLE_IN_ALL
 107 gpointer g_try_realloc_n  (gpointer      mem,
 108                            gsize         n_blocks,
 109                            gsize         n_block_bytes) G_GNUC_WARN_UNUSED_RESULT;
 110
 111 #define g_clear_pointer(pp, destroy) \
 112   G_STMT_START {                                                               \
 113     G_STATIC_ASSERT (sizeof *(pp) == sizeof (gpointer));                       \
 114     /* Only one access, please */                                              \
 115     gpointer *_pp = (gpointer *) (pp);                                         \
 116     gpointer _p;                                                               \
 117     /* This assignment is needed to avoid a gcc warning */                     \
 118     GDestroyNotify _destroy = (GDestroyNotify) (destroy);                      \
 119                                                                                \
 120     (void) (0 ? (gpointer) *(pp) : 0);                                         \
 121     do                                                                         \
 122       _p = g_atomic_pointer_get (_pp);                                         \
 123     while G_UNLIKELY (!g_atomic_pointer_compare_and_exchange (_pp, _p, NULL)); \
 124                                                                                \
 125     if (_p)                                                                    \
 126       _destroy (_p);                                                           \
 127   } G_STMT_END
 128
 129 /* Optimise: avoid the call to the (slower) _n function if we can
 130  * determine at compile-time that no overflow happens.
 131  */
 132 #if defined (__GNUC__) && (__GNUC__ >= 2) && defined (__OPTIMIZE__)
 133 #  define _G_NEW(struct_type, n_structs, func) \
 134         (struct_type *) (G_GNUC_EXTENSION ({                    \
 135           gsize __n = (gsize) (n_structs);                      \
 136           gsize __s = sizeof (struct_type);                     \
 137           gpointer __p;                                         \
 138           if (__s == 1)                                         \
 139             __p = g_##func (__n);                               \
 140           else if (__builtin_constant_p (__n) &&                \
 141                    (__s == 0 || __n <= G_MAXSIZE / __s))        \
 142             __p = g_##func (__n * __s);                         \
 143           else                                                  \
 144             __p = g_##func##_n (__n, __s);                      \
 145           __p;                                                  \
 146         }))
 147 #  define _G_RENEW(struct_type, mem, n_structs, func) \
 148         (struct_type *) (G_GNUC_EXTENSION ({                    \
 149           gsize __n = (gsize) (n_structs);                      \
 150           gsize __s = sizeof (struct_type);                     \
 151           gpointer __p = (gpointer) (mem);                      \
 152           if (__s == 1)                                         \
 153             __p = g_##func (__p, __n);                          \
 154           else if (__builtin_constant_p (__n) &&                \
 155                    (__s == 0 || __n <= G_MAXSIZE / __s))        \
 156             __p = g_##func (__p, __n * __s);                    \
 157           else                                                  \
 158             __p = g_##func##_n (__p, __n, __s);                 \
 159           __p;                                                  \
 160         }))
 161
 162 #else
 163
 164 /* Unoptimised version: always call the _n() function. */
 165
 166 #define _G_NEW(struct_type, n_structs, func) \
 167         ((struct_type *) g_##func##_n ((n_structs), sizeof (struct_type)))
 168 #define _G_RENEW(struct_type, mem, n_structs, func) \
 169         ((struct_type *) g_##func##_n (mem, (n_structs), sizeof (struct_type)))
 170
 171 #endif
 172
 173 /**
 174  * g_new:
 175  * @struct_type: the type of the elements to allocate
 176  * @n_structs: the number of elements to allocate
 177  *
 178  * Allocates @n_structs elements of type @struct_type.
 179  * The returned pointer is cast to a pointer to the given type.
 180  * If @n_structs is 0 it returns %NULL.
 181  * Care is taken to avoid overflow when calculating the size of the allocated block.
 182  *
 183  * Since the returned pointer is already casted to the right type,
 184  * it is normally unnecessary to cast it explicitly, and doing
 185  * so might hide memory allocation errors.
 186  *
 187  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type
 188  */
 189 #define g_new(struct_type, n_structs)                   _G_NEW (struct_type, n_structs, malloc)
 190 /**
 191  * g_new0:
 192  * @struct_type: the type of the elements to allocate.
 193  * @n_structs: the number of elements to allocate.
 194  *
 195  * Allocates @n_structs elements of type @struct_type, initialized to 0's.
 196  * The returned pointer is cast to a pointer to the given type.
 197  * If @n_structs is 0 it returns %NULL.
 198  * Care is taken to avoid overflow when calculating the size of the allocated block.
 199  *
 200  * Since the returned pointer is already casted to the right type,
 201  * it is normally unnecessary to cast it explicitly, and doing
 202  * so might hide memory allocation errors.
 203  *
 204  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type.
 205  */
 206 #define g_new0(struct_type, n_structs)                  _G_NEW (struct_type, n_structs, malloc0)
 207 /**
 208  * g_renew:
 209  * @struct_type: the type of the elements to allocate
 210  * @mem: the currently allocated memory
 211  * @n_structs: the number of elements to allocate
 212  *
 213  * Reallocates the memory pointed to by @mem, so that it now has space for
 214  * @n_structs elements of type @struct_type. It returns the new address of
 215  * the memory, which may have been moved.
 216  * Care is taken to avoid overflow when calculating the size of the allocated block.
 217  *
 218  * Returns: a pointer to the new allocated memory, cast to a pointer to @struct_type
 219  */
 220 #define g_renew(struct_type, mem, n_structs)            _G_RENEW (struct_type, mem, n_structs, realloc)
 221 /**
 222  * g_try_new:
 223  * @struct_type: the type of the elements to allocate
 224  * @n_structs: the number of elements to allocate
 225  *
 226  * Attempts to allocate @n_structs elements of type @struct_type, and returns
 227  * %NULL on failure. Contrast with g_new(), which aborts the program on failure.
 228  * The returned pointer is cast to a pointer to the given type.
 229  * The function returns %NULL when @n_structs is 0 of if an overflow occurs.
 230  *
 231  * Since: 2.8
 232  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type
 233  */
 234 #define g_try_new(struct_type, n_structs)               _G_NEW (struct_type, n_structs, try_malloc)
 235 /**
 236  * g_try_new0:
 237  * @struct_type: the type of the elements to allocate
 238  * @n_structs: the number of elements to allocate
 239  *
 240  * Attempts to allocate @n_structs elements of type @struct_type, initialized
 241  * to 0's, and returns %NULL on failure. Contrast with g_new0(), which aborts
 242  * the program on failure.
 243  * The returned pointer is cast to a pointer to the given type.
 244  * The function returns %NULL when @n_structs is 0 of if an overflow occurs.
 245  *
 246  * Since: 2.8
 247  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type
 248  */
 249 #define g_try_new0(struct_type, n_structs)              _G_NEW (struct_type, n_structs, try_malloc0)
 250 /**
 251  * g_try_renew:
 252  * @struct_type: the type of the elements to allocate
 253  * @mem: the currently allocated memory
 254  * @n_structs: the number of elements to allocate
 255  *
 256  * Attempts to reallocate the memory pointed to by @mem, so that it now has
 257  * space for @n_structs elements of type @struct_type, and returns %NULL on
 258  * failure. Contrast with g_renew(), which aborts the program on failure.
 259  * It returns the new address of the memory, which may have been moved.
 260  * The function returns %NULL if an overflow occurs.
 261  *
 262  * Since: 2.8
 263  * Returns: a pointer to the new allocated memory, cast to a pointer to @struct_type
 264  */
 265 #define g_try_renew(struct_type, mem, n_structs)        _G_RENEW (struct_type, mem, n_structs, try_realloc)
 266
 267
 268 /* Memory allocation virtualization for debugging purposes
 269  * g_mem_set_vtable() has to be the very first GLib function called
 270  * if being used
 271  */
 272 struct _GMemVTable {
 273   gpointer (*malloc)      (gsize    n_bytes);
 274   gpointer (*realloc)     (gpointer mem,
 275                            gsize    n_bytes);
 276   void     (*free)        (gpointer mem);
 277   /* optional; set to NULL if not used ! */
 278   gpointer (*calloc)      (gsize    n_blocks,
 279                            gsize    n_block_bytes);
 280   gpointer (*try_malloc)  (gsize    n_bytes);
 281   gpointer (*try_realloc) (gpointer mem,
 282                            gsize    n_bytes);
 283 };
 284 GLIB_AVAILABLE_IN_ALL
 285 void     g_mem_set_vtable (GMemVTable   *vtable);
 286 GLIB_AVAILABLE_IN_ALL
 287 gboolean g_mem_is_system_malloc (void);
 288
 289 GLIB_VAR gboolean g_mem_gc_friendly;
 290
 291 /* Memory profiler and checker, has to be enabled via g_mem_set_vtable()
 292  */
 293 GLIB_VAR GMemVTable     *glib_mem_profiler_table;
 294 GLIB_AVAILABLE_IN_ALL
 295 void    g_mem_profile   (void);
 296
 297 G_END_DECLS
 298
 299 #endif /* __G_MEM_H__ */