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 #if defined(g_has_typeof) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_58
 114 #define g_clear_pointer(pp, destroy)                                           \
 115   G_STMT_START {                                                               \
 116     G_STATIC_ASSERT (sizeof *(pp) == sizeof (gpointer));                       \
 117     __typeof__(*(pp)) _ptr = *(pp);                                            \
 118     *(pp) = NULL;                                                              \
 119     if (_ptr)                                                                  \
 120       (destroy) (_ptr);                                                        \
 121   } G_STMT_END
 122 #else /* __GNUC__ */
 123 #define g_clear_pointer(pp, destroy) \
 124   G_STMT_START {                                                               \
 125     G_STATIC_ASSERT (sizeof *(pp) == sizeof (gpointer));                       \
 126     /* Only one access, please; work around type aliasing */                   \
 127     union { char *in; gpointer *out; } _pp;                                    \
 128     gpointer _p;                                                               \
 129     /* This assignment is needed to avoid a gcc warning */                     \
 130     GDestroyNotify _destroy = (GDestroyNotify) (destroy);                      \
 131                                                                                \
 132     _pp.in = (char *) (pp);                                                    \
 133     _p = *_pp.out;                                                             \
 134     if (_p)                                                                    \
 135       {                                                                        \
 136         *_pp.out = NULL;                                                       \
 137         _destroy (_p);                                                         \
 138       }                                                                        \
 139   } G_STMT_END
 140 #endif /* __GNUC__ */
 141
 142 /**
 143  * g_steal_pointer:
 144  * @pp: (not nullable): a pointer to a pointer
 145  *
 146  * Sets @pp to %NULL, returning the value that was there before.
 147  *
 148  * Conceptually, this transfers the ownership of the pointer from the
 149  * referenced variable to the "caller" of the macro (ie: "steals" the
 150  * reference).
 151  *
 152  * The return value will be properly typed, according to the type of
 153  * @pp.
 154  *
 155  * This can be very useful when combined with g_autoptr() to prevent the
 156  * return value of a function from being automatically freed.  Consider
 157  * the following example (which only works on GCC and clang):
 158  *
 159  * |[
 160  * GObject *
 161  * create_object (void)
 162  * {
 163  *   g_autoptr(GObject) obj = g_object_new (G_TYPE_OBJECT, NULL);
 164  *
 165  *   if (early_error_case)
 166  *     return NULL;
 167  *
 168  *   return g_steal_pointer (&obj);
 169  * }
 170  * ]|
 171  *
 172  * It can also be used in similar ways for 'out' parameters and is
 173  * particularly useful for dealing with optional out parameters:
 174  *
 175  * |[
 176  * gboolean
 177  * get_object (GObject **obj_out)
 178  * {
 179  *   g_autoptr(GObject) obj = g_object_new (G_TYPE_OBJECT, NULL);
 180  *
 181  *   if (early_error_case)
 182  *     return FALSE;
 183  *
 184  *   if (obj_out)
 185  *     *obj_out = g_steal_pointer (&obj);
 186  *
 187  *   return TRUE;
 188  * }
 189  * ]|
 190  *
 191  * In the above example, the object will be automatically freed in the
 192  * early error case and also in the case that %NULL was given for
 193  * @obj_out.
 194  *
 195  * Since: 2.44
 196  */
 197 static inline gpointer
 198 g_steal_pointer (gpointer pp)
 199 {
 200   gpointer *ptr = (gpointer *) pp;
 201   gpointer ref;
 202
 203   ref = *ptr;
 204   *ptr = NULL;
 205
 206   return ref;
 207 }
 208
 209 /* type safety */
 210 #if defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)) && !defined(__cplusplus) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_58
 211 #define g_steal_pointer(pp) ((__typeof__(*pp)) (g_steal_pointer) (pp))
 212 #else  /* __GNUC__ */
 213 /* This version does not depend on gcc extensions, but gcc does not warn
 214  * about incompatible-pointer-types: */
 215 #define g_steal_pointer(pp) \
 216   (0 ? (*(pp)) : (g_steal_pointer) (pp))
 217 #endif /* __GNUC__ */
 218
 219 /* Optimise: avoid the call to the (slower) _n function if we can
 220  * determine at compile-time that no overflow happens.
 221  */
 222 #if defined (__GNUC__) && (__GNUC__ >= 2) && defined (__OPTIMIZE__)
 223 #  define _G_NEW(struct_type, n_structs, func) \
 224         (struct_type *) (G_GNUC_EXTENSION ({                    \
 225           gsize __n = (gsize) (n_structs);                      \
 226           gsize __s = sizeof (struct_type);                     \
 227           gpointer __p;                                         \
 228           if (__s == 1)                                         \
 229             __p = g_##func (__n);                               \
 230           else if (__builtin_constant_p (__n) &&                \
 231                    (__s == 0 || __n <= G_MAXSIZE / __s))        \
 232             __p = g_##func (__n * __s);                         \
 233           else                                                  \
 234             __p = g_##func##_n (__n, __s);                      \
 235           __p;                                                  \
 236         }))
 237 #  define _G_RENEW(struct_type, mem, n_structs, func) \
 238         (struct_type *) (G_GNUC_EXTENSION ({                    \
 239           gsize __n = (gsize) (n_structs);                      \
 240           gsize __s = sizeof (struct_type);                     \
 241           gpointer __p = (gpointer) (mem);                      \
 242           if (__s == 1)                                         \
 243             __p = g_##func (__p, __n);                          \
 244           else if (__builtin_constant_p (__n) &&                \
 245                    (__s == 0 || __n <= G_MAXSIZE / __s))        \
 246             __p = g_##func (__p, __n * __s);                    \
 247           else                                                  \
 248             __p = g_##func##_n (__p, __n, __s);                 \
 249           __p;                                                  \
 250         }))
 251
 252 #else
 253
 254 /* Unoptimised version: always call the _n() function. */
 255
 256 #define _G_NEW(struct_type, n_structs, func) \
 257         ((struct_type *) g_##func##_n ((n_structs), sizeof (struct_type)))
 258 #define _G_RENEW(struct_type, mem, n_structs, func) \
 259         ((struct_type *) g_##func##_n (mem, (n_structs), sizeof (struct_type)))
 260
 261 #endif
 262
 263 /**
 264  * g_new:
 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.
 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_new(struct_type, n_structs)                   _G_NEW (struct_type, n_structs, malloc)
 280 /**
 281  * g_new0:
 282  * @struct_type: the type of the elements to allocate.
 283  * @n_structs: the number of elements to allocate.
 284  *
 285  * Allocates @n_structs elements of type @struct_type, initialized to 0's.
 286  * The returned pointer is cast to a pointer to the given type.
 287  * If @n_structs is 0 it returns %NULL.
 288  * Care is taken to avoid overflow when calculating the size of the allocated block.
 289  *
 290  * Since the returned pointer is already casted to the right type,
 291  * it is normally unnecessary to cast it explicitly, and doing
 292  * so might hide memory allocation errors.
 293  *
 294  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type.
 295  */
 296 #define g_new0(struct_type, n_structs)                  _G_NEW (struct_type, n_structs, malloc0)
 297 /**
 298  * g_renew:
 299  * @struct_type: the type of the elements to allocate
 300  * @mem: the currently allocated memory
 301  * @n_structs: the number of elements to allocate
 302  *
 303  * Reallocates the memory pointed to by @mem, so that it now has space for
 304  * @n_structs elements of type @struct_type. It returns the new address of
 305  * the memory, which may have been moved.
 306  * Care is taken to avoid overflow when calculating the size of the allocated block.
 307  *
 308  * Returns: a pointer to the new allocated memory, cast to a pointer to @struct_type
 309  */
 310 #define g_renew(struct_type, mem, n_structs)            _G_RENEW (struct_type, mem, n_structs, realloc)
 311 /**
 312  * g_try_new:
 313  * @struct_type: the type of the elements to allocate
 314  * @n_structs: the number of elements to allocate
 315  *
 316  * Attempts to allocate @n_structs elements of type @struct_type, and returns
 317  * %NULL on failure. Contrast with g_new(), which aborts the program on failure.
 318  * The returned pointer is cast to a pointer to the given type.
 319  * The function returns %NULL when @n_structs is 0 of if an overflow occurs.
 320  *
 321  * Since: 2.8
 322  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type
 323  */
 324 #define g_try_new(struct_type, n_structs)               _G_NEW (struct_type, n_structs, try_malloc)
 325 /**
 326  * g_try_new0:
 327  * @struct_type: the type of the elements to allocate
 328  * @n_structs: the number of elements to allocate
 329  *
 330  * Attempts to allocate @n_structs elements of type @struct_type, initialized
 331  * to 0's, and returns %NULL on failure. Contrast with g_new0(), which aborts
 332  * the program on failure.
 333  * The returned pointer is cast to a pointer to the given type.
 334  * The function returns %NULL when @n_structs is 0 or if an overflow occurs.
 335  *
 336  * Since: 2.8
 337  * Returns: a pointer to the allocated memory, cast to a pointer to @struct_type
 338  */
 339 #define g_try_new0(struct_type, n_structs)              _G_NEW (struct_type, n_structs, try_malloc0)
 340 /**
 341  * g_try_renew:
 342  * @struct_type: the type of the elements to allocate
 343  * @mem: the currently allocated memory
 344  * @n_structs: the number of elements to allocate
 345  *
 346  * Attempts to reallocate the memory pointed to by @mem, so that it now has
 347  * space for @n_structs elements of type @struct_type, and returns %NULL on
 348  * failure. Contrast with g_renew(), which aborts the program on failure.
 349  * It returns the new address of the memory, which may have been moved.
 350  * The function returns %NULL if an overflow occurs.
 351  *
 352  * Since: 2.8
 353  * Returns: a pointer to the new allocated memory, cast to a pointer to @struct_type
 354  */
 355 #define g_try_renew(struct_type, mem, n_structs)        _G_RENEW (struct_type, mem, n_structs, try_realloc)
 356
 357
 358 /* Memory allocation virtualization for debugging purposes
 359  * g_mem_set_vtable() has to be the very first GLib function called
 360  * if being used
 361  */
 362 struct _GMemVTable {
 363   gpointer (*malloc)      (gsize    n_bytes);
 364   gpointer (*realloc)     (gpointer mem,
 365                            gsize    n_bytes);
 366   void     (*free)        (gpointer mem);
 367   /* optional; set to NULL if not used ! */
 368   gpointer (*calloc)      (gsize    n_blocks,
 369                            gsize    n_block_bytes);
 370   gpointer (*try_malloc)  (gsize    n_bytes);
 371   gpointer (*try_realloc) (gpointer mem,
 372                            gsize    n_bytes);
 373 };
 374 GLIB_DEPRECATED_IN_2_46
 375 void     g_mem_set_vtable (GMemVTable   *vtable);
 376 GLIB_DEPRECATED_IN_2_46
 377 gboolean g_mem_is_system_malloc (void);
 378
 379 GLIB_VAR gboolean g_mem_gc_friendly;
 380
 381 /* Memory profiler and checker, has to be enabled via g_mem_set_vtable()
 382  */
 383 GLIB_VAR GMemVTable     *glib_mem_profiler_table;
 384 GLIB_DEPRECATED_IN_2_46
 385 void    g_mem_profile   (void);
 386
 387 G_END_DECLS
 388
 389 #endif /* __G_MEM_H__ */