malloc/dynarray-skeleton.c

   1 /* Type-safe arrays which grow dynamically.
   2    Copyright (C) 2017-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 /* Pre-processor macros which act as parameters:
  20
  21    DYNARRAY_STRUCT
  22       The struct tag of dynamic array to be defined.
  23    DYNARRAY_ELEMENT
  24       The type name of the element type.  Elements are copied
  25       as if by memcpy, and can change address as the dynamic
  26       array grows.
  27    DYNARRAY_PREFIX
  28       The prefix of the functions which are defined.
  29
  30    The following parameters are optional:
  31
  32    DYNARRAY_ELEMENT_FREE
  33       DYNARRAY_ELEMENT_FREE (E) is evaluated to deallocate the
  34       contents of elements. E is of type  DYNARRAY_ELEMENT *.
  35    DYNARRAY_ELEMENT_INIT
  36       DYNARRAY_ELEMENT_INIT (E) is evaluated to initialize a new
  37       element.  E is of type  DYNARRAY_ELEMENT *.
  38       If DYNARRAY_ELEMENT_FREE but not DYNARRAY_ELEMENT_INIT is
  39       defined, new elements are automatically zero-initialized.
  40       Otherwise, new elements have undefined contents.
  41    DYNARRAY_INITIAL_SIZE
  42       The size of the statically allocated array (default:
  43       at least 2, more elements if they fit into 128 bytes).
  44       Must be a preprocessor constant.  If DYNARRAY_INITIAL_SIZE is 0,
  45       there is no statically allocated array at, and all non-empty
  46       arrays are heap-allocated.
  47    DYNARRAY_FINAL_TYPE
  48       The name of the type which holds the final array.  If not
  49       defined, is PREFIX##finalize not provided.  DYNARRAY_FINAL_TYPE
  50       must be a struct type, with members of type DYNARRAY_ELEMENT and
  51       size_t at the start (in this order).
  52
  53    These macros are undefined after this header file has been
  54    included.
  55
  56    The following types are provided (their members are private to the
  57    dynarray implementation):
  58
  59      struct DYNARRAY_STRUCT
  60
  61    The following functions are provided:
  62
  63      void DYNARRAY_PREFIX##init (struct DYNARRAY_STRUCT *);
  64      void DYNARRAY_PREFIX##free (struct DYNARRAY_STRUCT *);
  65      bool DYNARRAY_PREFIX##has_failed (const struct DYNARRAY_STRUCT *);
  66      void DYNARRAY_PREFIX##mark_failed (struct DYNARRAY_STRUCT *);
  67      size_t DYNARRAY_PREFIX##size (const struct DYNARRAY_STRUCT *);
  68      DYNARRAY_ELEMENT *DYNARRAY_PREFIX##begin (const struct DYNARRAY_STRUCT *);
  69      DYNARRAY_ELEMENT *DYNARRAY_PREFIX##end (const struct DYNARRAY_STRUCT *);
  70      DYNARRAY_ELEMENT *DYNARRAY_PREFIX##at (struct DYNARRAY_STRUCT *, size_t);
  71      void DYNARRAY_PREFIX##add (struct DYNARRAY_STRUCT *, DYNARRAY_ELEMENT);
  72      DYNARRAY_ELEMENT *DYNARRAY_PREFIX##emplace (struct DYNARRAY_STRUCT *);
  73      bool DYNARRAY_PREFIX##resize (struct DYNARRAY_STRUCT *, size_t);
  74      void DYNARRAY_PREFIX##remove_last (struct DYNARRAY_STRUCT *);
  75      void DYNARRAY_PREFIX##clear (struct DYNARRAY_STRUCT *);
  76
  77    The following functions are provided are provided if the
  78    prerequisites are met:
  79
  80      bool DYNARRAY_PREFIX##finalize (struct DYNARRAY_STRUCT *,
  81                                      DYNARRAY_FINAL_TYPE *);
  82        (if DYNARRAY_FINAL_TYPE is defined)
  83      DYNARRAY_ELEMENT *DYNARRAY_PREFIX##finalize (struct DYNARRAY_STRUCT *,
  84                                                   size_t *);
  85        (if DYNARRAY_FINAL_TYPE is not defined)
  86 */
  87
  88 #include <malloc/dynarray.h>
  89
  90 #include <errno.h>
  91 #include <stdlib.h>
  92 #include <string.h>
  93
  94 #ifndef DYNARRAY_STRUCT
  95 # error "DYNARRAY_STRUCT must be defined"
  96 #endif
  97
  98 #ifndef DYNARRAY_ELEMENT
  99 # error "DYNARRAY_ELEMENT must be defined"
 100 #endif
 101
 102 #ifndef DYNARRAY_PREFIX
 103 # error "DYNARRAY_PREFIX must be defined"
 104 #endif
 105
 106 #ifdef DYNARRAY_INITIAL_SIZE
 107 # if DYNARRAY_INITIAL_SIZE < 0
 108 #  error "DYNARRAY_INITIAL_SIZE must be non-negative"
 109 # endif
 110 # if DYNARRAY_INITIAL_SIZE > 0
 111 #  define DYNARRAY_HAVE_SCRATCH 1
 112 # else
 113 #  define DYNARRAY_HAVE_SCRATCH 0
 114 # endif
 115 #else
 116 /* Provide a reasonable default which limits the size of
 117    DYNARRAY_STRUCT.  */
 118 # define DYNARRAY_INITIAL_SIZE \
 119   (sizeof (DYNARRAY_ELEMENT) > 64 ? 2 : 128 / sizeof (DYNARRAY_ELEMENT))
 120 # define DYNARRAY_HAVE_SCRATCH 1
 121 #endif
 122
 123 /* Public type definitions.  */
 124
 125 /* All fields of this struct are private to the implementation.  */
 126 struct DYNARRAY_STRUCT
 127 {
 128   union
 129   {
 130     struct dynarray_header dynarray_abstract;
 131     struct
 132     {
 133       /* These fields must match struct dynarray_header.  */
 134       size_t used;
 135       size_t allocated;
 136       DYNARRAY_ELEMENT *array;
 137     } dynarray_header;
 138   } u;
 139
 140 #if DYNARRAY_HAVE_SCRATCH
 141   /* Initial inline allocation.  */
 142   DYNARRAY_ELEMENT scratch[DYNARRAY_INITIAL_SIZE];
 143 #endif
 144 };
 145
 146 /* Internal use only: Helper macros.  */
 147
 148 /* Ensure macro-expansion of DYNARRAY_PREFIX.  */
 149 #define DYNARRAY_CONCAT0(prefix, name) prefix##name
 150 #define DYNARRAY_CONCAT1(prefix, name) DYNARRAY_CONCAT0(prefix, name)
 151 #define DYNARRAY_NAME(name) DYNARRAY_CONCAT1(DYNARRAY_PREFIX, name)
 152
 153 /* Use DYNARRAY_FREE instead of DYNARRAY_NAME (free),
 154    so that Gnulib does not change 'free' to 'rpl_free'.  */
 155 #define DYNARRAY_FREE DYNARRAY_CONCAT1 (DYNARRAY_NAME (f), ree)
 156
 157 /* Address of the scratch buffer if any.  */
 158 #if DYNARRAY_HAVE_SCRATCH
 159 # define DYNARRAY_SCRATCH(list) (list)->scratch
 160 #else
 161 # define DYNARRAY_SCRATCH(list) NULL
 162 #endif
 163
 164 /* Internal use only: Helper functions.  */
 165
 166 /* Internal function.  Call DYNARRAY_ELEMENT_FREE with the array
 167    elements.  Name mangling needed due to the DYNARRAY_ELEMENT_FREE
 168    macro expansion.  */
 169 static inline void
 170 DYNARRAY_NAME (free__elements__) (DYNARRAY_ELEMENT *__dynarray_array,
 171                                   size_t __dynarray_used)
 172 {
 173 #ifdef DYNARRAY_ELEMENT_FREE
 174   for (size_t __dynarray_i = 0; __dynarray_i < __dynarray_used; ++__dynarray_i)
 175     DYNARRAY_ELEMENT_FREE (&__dynarray_array[__dynarray_i]);
 176 #endif /* DYNARRAY_ELEMENT_FREE */
 177 }
 178
 179 /* Internal function.  Free the non-scratch array allocation.  */
 180 static inline void
 181 DYNARRAY_NAME (free__array__) (struct DYNARRAY_STRUCT *list)
 182 {
 183 #if DYNARRAY_HAVE_SCRATCH
 184   if (list->u.dynarray_header.array != list->scratch)
 185     free (list->u.dynarray_header.array);
 186 #else
 187   free (list->u.dynarray_header.array);
 188 #endif
 189 }
 190
 191 /* Public functions.  */
 192
 193 /* Initialize a dynamic array object.  This must be called before any
 194    use of the object.  */
 195 __nonnull ((1))
 196 static void
 197 DYNARRAY_NAME (init) (struct DYNARRAY_STRUCT *list)
 198 {
 199   list->u.dynarray_header.used = 0;
 200   list->u.dynarray_header.allocated = DYNARRAY_INITIAL_SIZE;
 201   list->u.dynarray_header.array = DYNARRAY_SCRATCH (list);
 202 }
 203
 204 /* Deallocate the dynamic array and its elements.  */
 205 __attribute_maybe_unused__ __nonnull ((1))
 206 static void
 207 DYNARRAY_FREE (struct DYNARRAY_STRUCT *list)
 208 {
 209   DYNARRAY_NAME (free__elements__)
 210     (list->u.dynarray_header.array, list->u.dynarray_header.used);
 211   DYNARRAY_NAME (free__array__) (list);
 212   DYNARRAY_NAME (init) (list);
 213 }
 214
 215 /* Return true if the dynamic array is in an error state.  */
 216 __nonnull ((1))
 217 static inline bool
 218 DYNARRAY_NAME (has_failed) (const struct DYNARRAY_STRUCT *list)
 219 {
 220   return list->u.dynarray_header.allocated == __dynarray_error_marker ();
 221 }
 222
 223 /* Mark the dynamic array as failed.  All elements are deallocated as
 224    a side effect.  */
 225 __nonnull ((1))
 226 static void
 227 DYNARRAY_NAME (mark_failed) (struct DYNARRAY_STRUCT *list)
 228 {
 229   DYNARRAY_NAME (free__elements__)
 230     (list->u.dynarray_header.array, list->u.dynarray_header.used);
 231   DYNARRAY_NAME (free__array__) (list);
 232   list->u.dynarray_header.array = DYNARRAY_SCRATCH (list);
 233   list->u.dynarray_header.used = 0;
 234   list->u.dynarray_header.allocated = __dynarray_error_marker ();
 235 }
 236
 237 /* Return the number of elements which have been added to the dynamic
 238    array.  */
 239 __nonnull ((1))
 240 static inline size_t
 241 DYNARRAY_NAME (size) (const struct DYNARRAY_STRUCT *list)
 242 {
 243   return list->u.dynarray_header.used;
 244 }
 245
 246 /* Return a pointer to the array element at INDEX.  Terminate the
 247    process if INDEX is out of bounds.  */
 248 __nonnull ((1))
 249 static inline DYNARRAY_ELEMENT *
 250 DYNARRAY_NAME (at) (struct DYNARRAY_STRUCT *list, size_t index)
 251 {
 252   if (__glibc_unlikely (index >= DYNARRAY_NAME (size) (list)))
 253     __libc_dynarray_at_failure (DYNARRAY_NAME (size) (list), index);
 254   return list->u.dynarray_header.array + index;
 255 }
 256
 257 /* Return a pointer to the first array element, if any.  For a
 258    zero-length array, the pointer can be NULL even though the dynamic
 259    array has not entered the failure state.  */
 260 __nonnull ((1))
 261 static inline DYNARRAY_ELEMENT *
 262 DYNARRAY_NAME (begin) (struct DYNARRAY_STRUCT *list)
 263 {
 264   return list->u.dynarray_header.array;
 265 }
 266
 267 /* Return a pointer one element past the last array element.  For a
 268    zero-length array, the pointer can be NULL even though the dynamic
 269    array has not entered the failure state.  */
 270 __nonnull ((1))
 271 static inline DYNARRAY_ELEMENT *
 272 DYNARRAY_NAME (end) (struct DYNARRAY_STRUCT *list)
 273 {
 274   return list->u.dynarray_header.array + list->u.dynarray_header.used;
 275 }
 276
 277 /* Internal function.  Slow path for the add function below.  */
 278 static void
 279 DYNARRAY_NAME (add__) (struct DYNARRAY_STRUCT *list, DYNARRAY_ELEMENT item)
 280 {
 281   if (__glibc_unlikely
 282       (!__libc_dynarray_emplace_enlarge (&list->u.dynarray_abstract,
 283                                          DYNARRAY_SCRATCH (list),
 284                                          sizeof (DYNARRAY_ELEMENT))))
 285     {
 286       DYNARRAY_NAME (mark_failed) (list);
 287       return;
 288     }
 289
 290   /* Copy the new element and increase the array length.  */
 291   list->u.dynarray_header.array[list->u.dynarray_header.used++] = item;
 292 }
 293
 294 /* Add ITEM at the end of the array, enlarging it by one element.
 295    Mark *LIST as failed if the dynamic array allocation size cannot be
 296    increased.  */
 297 __nonnull ((1))
 298 static inline void
 299 DYNARRAY_NAME (add) (struct DYNARRAY_STRUCT *list, DYNARRAY_ELEMENT item)
 300 {
 301   /* Do nothing in case of previous error.  */
 302   if (DYNARRAY_NAME (has_failed) (list))
 303     return;
 304
 305   /* Enlarge the array if necessary.  */
 306   if (__glibc_unlikely (list->u.dynarray_header.used
 307                         == list->u.dynarray_header.allocated))
 308     {
 309       DYNARRAY_NAME (add__) (list, item);
 310       return;
 311     }
 312
 313   /* Copy the new element and increase the array length.  */
 314   list->u.dynarray_header.array[list->u.dynarray_header.used++] = item;
 315 }
 316
 317 /* Internal function.  Building block for the emplace functions below.
 318    Assumes space for one more element in *LIST.  */
 319 static inline DYNARRAY_ELEMENT *
 320 DYNARRAY_NAME (emplace__tail__) (struct DYNARRAY_STRUCT *list)
 321 {
 322   DYNARRAY_ELEMENT *result
 323     = &list->u.dynarray_header.array[list->u.dynarray_header.used];
 324   ++list->u.dynarray_header.used;
 325 #if defined (DYNARRAY_ELEMENT_INIT)
 326   DYNARRAY_ELEMENT_INIT (result);
 327 #elif defined (DYNARRAY_ELEMENT_FREE)
 328   memset (result, 0, sizeof (*result));
 329 #endif
 330   return result;
 331 }
 332
 333 /* Internal function.  Slow path for the emplace function below.  */
 334 static DYNARRAY_ELEMENT *
 335 DYNARRAY_NAME (emplace__) (struct DYNARRAY_STRUCT *list)
 336 {
 337   if (__glibc_unlikely
 338       (!__libc_dynarray_emplace_enlarge (&list->u.dynarray_abstract,
 339                                          DYNARRAY_SCRATCH (list),
 340                                          sizeof (DYNARRAY_ELEMENT))))
 341     {
 342       DYNARRAY_NAME (mark_failed) (list);
 343       return NULL;
 344     }
 345   return DYNARRAY_NAME (emplace__tail__) (list);
 346 }
 347
 348 /* Allocate a place for a new element in *LIST and return a pointer to
 349    it.  The pointer can be NULL if the dynamic array cannot be
 350    enlarged due to a memory allocation failure.  */
 351 __attribute_maybe_unused__ __attribute_warn_unused_result__ __nonnull ((1))
 352 static
 353 /* Avoid inlining with the larger initialization code.  */
 354 #if !(defined (DYNARRAY_ELEMENT_INIT) || defined (DYNARRAY_ELEMENT_FREE))
 355 inline
 356 #endif
 357 DYNARRAY_ELEMENT *
 358 DYNARRAY_NAME (emplace) (struct DYNARRAY_STRUCT *list)
 359 {
 360   /* Do nothing in case of previous error.  */
 361   if (DYNARRAY_NAME (has_failed) (list))
 362     return NULL;
 363
 364   /* Enlarge the array if necessary.  */
 365   if (__glibc_unlikely (list->u.dynarray_header.used
 366                         == list->u.dynarray_header.allocated))
 367     return (DYNARRAY_NAME (emplace__) (list));
 368   return DYNARRAY_NAME (emplace__tail__) (list);
 369 }
 370
 371 /* Change the size of *LIST to SIZE.  If SIZE is larger than the
 372    existing size, new elements are added (which can be initialized).
 373    Otherwise, the list is truncated, and elements are freed.  Return
 374    false on memory allocation failure (and mark *LIST as failed).  */
 375 __attribute_maybe_unused__ __nonnull ((1))
 376 static bool
 377 DYNARRAY_NAME (resize) (struct DYNARRAY_STRUCT *list, size_t size)
 378 {
 379   if (size > list->u.dynarray_header.used)
 380     {
 381       bool ok;
 382 #if defined (DYNARRAY_ELEMENT_INIT)
 383       /* The new elements have to be initialized.  */
 384       size_t old_size = list->u.dynarray_header.used;
 385       ok = __libc_dynarray_resize (&list->u.dynarray_abstract,
 386                                    size, DYNARRAY_SCRATCH (list),
 387                                    sizeof (DYNARRAY_ELEMENT));
 388       if (ok)
 389         for (size_t i = old_size; i < size; ++i)
 390           {
 391             DYNARRAY_ELEMENT_INIT (&list->u.dynarray_header.array[i]);
 392           }
 393 #elif defined (DYNARRAY_ELEMENT_FREE)
 394       /* Zero initialization is needed so that the elements can be
 395          safely freed.  */
 396       ok = __libc_dynarray_resize_clear
 397         (&list->u.dynarray_abstract, size,
 398          DYNARRAY_SCRATCH (list), sizeof (DYNARRAY_ELEMENT));
 399 #else
 400       ok =  __libc_dynarray_resize (&list->u.dynarray_abstract,
 401                                     size, DYNARRAY_SCRATCH (list),
 402                                     sizeof (DYNARRAY_ELEMENT));
 403 #endif
 404       if (__glibc_unlikely (!ok))
 405         DYNARRAY_NAME (mark_failed) (list);
 406       return ok;
 407     }
 408   else
 409     {
 410       /* The list has shrunk in size.  Free the removed elements.  */
 411       DYNARRAY_NAME (free__elements__)
 412         (list->u.dynarray_header.array + size,
 413          list->u.dynarray_header.used - size);
 414       list->u.dynarray_header.used = size;
 415       return true;
 416     }
 417 }
 418
 419 /* Remove the last element of LIST if it is present.  */
 420 __attribute_maybe_unused__ __nonnull ((1))
 421 static void
 422 DYNARRAY_NAME (remove_last) (struct DYNARRAY_STRUCT *list)
 423 {
 424   /* used > 0 implies that the array is the non-failed state.  */
 425   if (list->u.dynarray_header.used > 0)
 426     {
 427       size_t new_length = list->u.dynarray_header.used - 1;
 428 #ifdef DYNARRAY_ELEMENT_FREE
 429       DYNARRAY_ELEMENT_FREE (&list->u.dynarray_header.array[new_length]);
 430 #endif
 431       list->u.dynarray_header.used = new_length;
 432     }
 433 }
 434
 435 /* Remove all elements from the list.  The elements are freed, but the
 436    list itself is not.  */
 437 __attribute_maybe_unused__ __nonnull ((1))
 438 static void
 439 DYNARRAY_NAME (clear) (struct DYNARRAY_STRUCT *list)
 440 {
 441   /* free__elements__ does nothing if the list is in the failed
 442      state.  */
 443   DYNARRAY_NAME (free__elements__)
 444     (list->u.dynarray_header.array, list->u.dynarray_header.used);
 445   list->u.dynarray_header.used = 0;
 446 }
 447
 448 #ifdef DYNARRAY_FINAL_TYPE
 449 /* Transfer the dynamic array to a permanent location at *RESULT.
 450    Returns true on success on false on allocation failure.  In either
 451    case, *LIST is re-initialized and can be reused.  A NULL pointer is
 452    stored in *RESULT if LIST refers to an empty list.  On success, the
 453    pointer in *RESULT is heap-allocated and must be deallocated using
 454    free.  */
 455 __attribute_maybe_unused__ __attribute_warn_unused_result__ __nonnull ((1, 2))
 456 static bool
 457 DYNARRAY_NAME (finalize) (struct DYNARRAY_STRUCT *list,
 458                           DYNARRAY_FINAL_TYPE *result)
 459 {
 460   struct dynarray_finalize_result res;
 461   if (__libc_dynarray_finalize (&list->u.dynarray_abstract,
 462                                 DYNARRAY_SCRATCH (list),
 463                                 sizeof (DYNARRAY_ELEMENT), &res))
 464     {
 465       /* On success, the result owns all the data.  */
 466       DYNARRAY_NAME (init) (list);
 467       *result = (DYNARRAY_FINAL_TYPE) { res.array, res.length };
 468       return true;
 469     }
 470   else
 471     {
 472       /* On error, we need to free all data.  */
 473       DYNARRAY_FREE (list);
 474       errno = ENOMEM;
 475       return false;
 476     }
 477 }
 478 #else /* !DYNARRAY_FINAL_TYPE */
 479 /* Transfer the dynamic array to a heap-allocated array and return a
 480    pointer to it.  The pointer is NULL if memory allocation fails, or
 481    if the array is empty, so this function should be used only for
 482    arrays which are known not be empty (usually because they always
 483    have a sentinel at the end).  If LENGTHP is not NULL, the array
 484    length is written to *LENGTHP.  *LIST is re-initialized and can be
 485    reused.  */
 486 __attribute_maybe_unused__ __attribute_warn_unused_result__ __nonnull ((1))
 487 static DYNARRAY_ELEMENT *
 488 DYNARRAY_NAME (finalize) (struct DYNARRAY_STRUCT *list, size_t *lengthp)
 489 {
 490   struct dynarray_finalize_result res;
 491   if (__libc_dynarray_finalize (&list->u.dynarray_abstract,
 492                                 DYNARRAY_SCRATCH (list),
 493                                 sizeof (DYNARRAY_ELEMENT), &res))
 494     {
 495       /* On success, the result owns all the data.  */
 496       DYNARRAY_NAME (init) (list);
 497       if (lengthp != NULL)
 498         *lengthp = res.length;
 499       return res.array;
 500     }
 501   else
 502     {
 503       /* On error, we need to free all data.  */
 504       DYNARRAY_FREE (list);
 505       errno = ENOMEM;
 506       return NULL;
 507     }
 508 }
 509 #endif /* !DYNARRAY_FINAL_TYPE */
 510
 511 /* Undo macro definitions.  */
 512
 513 #undef DYNARRAY_CONCAT0
 514 #undef DYNARRAY_CONCAT1
 515 #undef DYNARRAY_NAME
 516 #undef DYNARRAY_SCRATCH
 517 #undef DYNARRAY_HAVE_SCRATCH
 518
 519 #undef DYNARRAY_STRUCT
 520 #undef DYNARRAY_ELEMENT
 521 #undef DYNARRAY_PREFIX
 522 #undef DYNARRAY_ELEMENT_FREE
 523 #undef DYNARRAY_ELEMENT_INIT
 524 #undef DYNARRAY_INITIAL_SIZE
 525 #undef DYNARRAY_FINAL_TYPE