src/util/ralloc.c

   1 /*
   2  * Copyright © 2010 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 #include <assert.h>
  25 #include <stdlib.h>
  26 #include <stdarg.h>
  27 #include <stdio.h>
  28 #include <string.h>
  29 #include <stdint.h>
  30
  31 /* Some versions of MinGW are missing _vscprintf's declaration, although they
  32  * still provide the symbol in the import library. */
  33 #ifdef __MINGW32__
  34 _CRTIMP int _vscprintf(const char *format, va_list argptr);
  35 #endif
  36
  37 #include "ralloc.h"
  38
  39 #ifndef va_copy
  40 #ifdef __va_copy
  41 #define va_copy(dest, src) __va_copy((dest), (src))
  42 #else
  43 #define va_copy(dest, src) (dest) = (src)
  44 #endif
  45 #endif
  46
  47 #define CANARY 0x5A1106
  48
  49 /* Align the header's size so that ralloc() allocations will return with the
  50  * same alignment as a libc malloc would have (8 on 32-bit GLIBC, 16 on
  51  * 64-bit), avoiding performance penalities on x86 and alignment faults on
  52  * ARM.
  53  */
  54 struct
  55 #ifdef _MSC_VER
  56  __declspec(align(8))
  57 #elif defined(__LP64__)
  58  __attribute__((aligned(16)))
  59 #else
  60  __attribute__((aligned(8)))
  61 #endif
  62    ralloc_header
  63 {
  64 #ifndef NDEBUG
  65    /* A canary value used to determine whether a pointer is ralloc'd. */
  66    unsigned canary;
  67 #endif
  68
  69    struct ralloc_header *parent;
  70
  71    /* The first child (head of a linked list) */
  72    struct ralloc_header *child;
  73
  74    /* Linked list of siblings */
  75    struct ralloc_header *prev;
  76    struct ralloc_header *next;
  77
  78    void (*destructor)(void *);
  79 };
  80
  81 typedef struct ralloc_header ralloc_header;
  82
  83 static void unlink_block(ralloc_header *info);
  84 static void unsafe_free(ralloc_header *info);
  85
  86 static ralloc_header *
  87 get_header(const void *ptr)
  88 {
  89    ralloc_header *info = (ralloc_header *) (((char *) ptr) -
  90                                             sizeof(ralloc_header));
  91    assert(info->canary == CANARY);
  92    return info;
  93 }
  94
  95 #define PTR_FROM_HEADER(info) (((char *) info) + sizeof(ralloc_header))
  96
  97 static void
  98 add_child(ralloc_header *parent, ralloc_header *info)
  99 {
 100    if (parent != NULL) {
 101       info->parent = parent;
 102       info->next = parent->child;
 103       parent->child = info;
 104
 105       if (info->next != NULL)
 106          info->next->prev = info;
 107    }
 108 }
 109
 110 void *
 111 ralloc_context(const void *ctx)
 112 {
 113    return ralloc_size(ctx, 0);
 114 }
 115
 116 void *
 117 ralloc_size(const void *ctx, size_t size)
 118 {
 119    void *block = malloc(size + sizeof(ralloc_header));
 120    ralloc_header *info;
 121    ralloc_header *parent;
 122
 123    if (unlikely(block == NULL))
 124       return NULL;
 125
 126    info = (ralloc_header *) block;
 127    /* measurements have shown that calloc is slower (because of
 128     * the multiplication overflow checking?), so clear things
 129     * manually
 130     */
 131    info->parent = NULL;
 132    info->child = NULL;
 133    info->prev = NULL;
 134    info->next = NULL;
 135    info->destructor = NULL;
 136
 137    parent = ctx != NULL ? get_header(ctx) : NULL;
 138
 139    add_child(parent, info);
 140
 141 #ifndef NDEBUG
 142    info->canary = CANARY;
 143 #endif
 144
 145    return PTR_FROM_HEADER(info);
 146 }
 147
 148 void *
 149 rzalloc_size(const void *ctx, size_t size)
 150 {
 151    void *ptr = ralloc_size(ctx, size);
 152
 153    if (likely(ptr))
 154       memset(ptr, 0, size);
 155
 156    return ptr;
 157 }
 158
 159 /* helper function - assumes ptr != NULL */
 160 static void *
 161 resize(void *ptr, size_t size)
 162 {
 163    ralloc_header *child, *old, *info;
 164
 165    old = get_header(ptr);
 166    info = realloc(old, size + sizeof(ralloc_header));
 167
 168    if (info == NULL)
 169       return NULL;
 170
 171    /* Update parent and sibling's links to the reallocated node. */
 172    if (info != old && info->parent != NULL) {
 173       if (info->parent->child == old)
 174          info->parent->child = info;
 175
 176       if (info->prev != NULL)
 177          info->prev->next = info;
 178
 179       if (info->next != NULL)
 180          info->next->prev = info;
 181    }
 182
 183    /* Update child->parent links for all children */
 184    for (child = info->child; child != NULL; child = child->next)
 185       child->parent = info;
 186
 187    return PTR_FROM_HEADER(info);
 188 }
 189
 190 void *
 191 reralloc_size(const void *ctx, void *ptr, size_t size)
 192 {
 193    if (unlikely(ptr == NULL))
 194       return ralloc_size(ctx, size);
 195
 196    assert(ralloc_parent(ptr) == ctx);
 197    return resize(ptr, size);
 198 }
 199
 200 void *
 201 rerzalloc_size(const void *ctx, void *ptr, size_t old_size, size_t new_size)
 202 {
 203    if (unlikely(ptr == NULL))
 204       return rzalloc_size(ctx, new_size);
 205
 206    assert(ralloc_parent(ptr) == ctx);
 207    ptr = resize(ptr, new_size);
 208
 209    if (new_size > old_size)
 210       memset((char *)ptr + old_size, 0, new_size - old_size);
 211
 212    return ptr;
 213 }
 214
 215 void *
 216 ralloc_array_size(const void *ctx, size_t size, unsigned count)
 217 {
 218    if (count > SIZE_MAX/size)
 219       return NULL;
 220
 221    return ralloc_size(ctx, size * count);
 222 }
 223
 224 void *
 225 rzalloc_array_size(const void *ctx, size_t size, unsigned count)
 226 {
 227    if (count > SIZE_MAX/size)
 228       return NULL;
 229
 230    return rzalloc_size(ctx, size * count);
 231 }
 232
 233 void *
 234 reralloc_array_size(const void *ctx, void *ptr, size_t size, unsigned count)
 235 {
 236    if (count > SIZE_MAX/size)
 237       return NULL;
 238
 239    return reralloc_size(ctx, ptr, size * count);
 240 }
 241
 242 void *
 243 rerzalloc_array_size(const void *ctx, void *ptr, size_t size,
 244                      unsigned old_count, unsigned new_count)
 245 {
 246    if (new_count > SIZE_MAX/size)
 247       return NULL;
 248
 249    return rerzalloc_size(ctx, ptr, size * old_count, size * new_count);
 250 }
 251
 252 void
 253 ralloc_free(void *ptr)
 254 {
 255    ralloc_header *info;
 256
 257    if (ptr == NULL)
 258       return;
 259
 260    info = get_header(ptr);
 261    unlink_block(info);
 262    unsafe_free(info);
 263 }
 264
 265 static void
 266 unlink_block(ralloc_header *info)
 267 {
 268    /* Unlink from parent & siblings */
 269    if (info->parent != NULL) {
 270       if (info->parent->child == info)
 271          info->parent->child = info->next;
 272
 273       if (info->prev != NULL)
 274          info->prev->next = info->next;
 275
 276       if (info->next != NULL)
 277          info->next->prev = info->prev;
 278    }
 279    info->parent = NULL;
 280    info->prev = NULL;
 281    info->next = NULL;
 282 }
 283
 284 static void
 285 unsafe_free(ralloc_header *info)
 286 {
 287    /* Recursively free any children...don't waste time unlinking them. */
 288    ralloc_header *temp;
 289    while (info->child != NULL) {
 290       temp = info->child;
 291       info->child = temp->next;
 292       unsafe_free(temp);
 293    }
 294
 295    /* Free the block itself.  Call the destructor first, if any. */
 296    if (info->destructor != NULL)
 297       info->destructor(PTR_FROM_HEADER(info));
 298
 299    free(info);
 300 }
 301
 302 void
 303 ralloc_steal(const void *new_ctx, void *ptr)
 304 {
 305    ralloc_header *info, *parent;
 306
 307    if (unlikely(ptr == NULL))
 308       return;
 309
 310    info = get_header(ptr);
 311    parent = new_ctx ? get_header(new_ctx) : NULL;
 312
 313    unlink_block(info);
 314
 315    add_child(parent, info);
 316 }
 317
 318 void
 319 ralloc_adopt(const void *new_ctx, void *old_ctx)
 320 {
 321    ralloc_header *new_info, *old_info, *child;
 322
 323    if (unlikely(old_ctx == NULL))
 324       return;
 325
 326    old_info = get_header(old_ctx);
 327    new_info = get_header(new_ctx);
 328
 329    /* If there are no children, bail. */
 330    if (unlikely(old_info->child == NULL))
 331       return;
 332
 333    /* Set all the children's parent to new_ctx; get a pointer to the last child. */
 334    for (child = old_info->child; child->next != NULL; child = child->next) {
 335       child->parent = new_info;
 336    }
 337    child->parent = new_info;
 338
 339    /* Connect the two lists together; parent them to new_ctx; make old_ctx empty. */
 340    child->next = new_info->child;
 341    if (child->next)
 342       child->next->prev = child;
 343    new_info->child = old_info->child;
 344    old_info->child = NULL;
 345 }
 346
 347 void *
 348 ralloc_parent(const void *ptr)
 349 {
 350    ralloc_header *info;
 351
 352    if (unlikely(ptr == NULL))
 353       return NULL;
 354
 355    info = get_header(ptr);
 356    return info->parent ? PTR_FROM_HEADER(info->parent) : NULL;
 357 }
 358
 359 void
 360 ralloc_set_destructor(const void *ptr, void(*destructor)(void *))
 361 {
 362    ralloc_header *info = get_header(ptr);
 363    info->destructor = destructor;
 364 }
 365
 366 char *
 367 ralloc_strdup(const void *ctx, const char *str)
 368 {
 369    size_t n;
 370    char *ptr;
 371
 372    if (unlikely(str == NULL))
 373       return NULL;
 374
 375    n = strlen(str);
 376    ptr = ralloc_array(ctx, char, n + 1);
 377    memcpy(ptr, str, n);
 378    ptr[n] = '\0';
 379    return ptr;
 380 }
 381
 382 char *
 383 ralloc_strndup(const void *ctx, const char *str, size_t max)
 384 {
 385    size_t n;
 386    char *ptr;
 387
 388    if (unlikely(str == NULL))
 389       return NULL;
 390
 391    n = strnlen(str, max);
 392    ptr = ralloc_array(ctx, char, n + 1);
 393    memcpy(ptr, str, n);
 394    ptr[n] = '\0';
 395    return ptr;
 396 }
 397
 398 /* helper routine for strcat/strncat - n is the exact amount to copy */
 399 static bool
 400 cat(char **dest, const char *str, size_t n)
 401 {
 402    char *both;
 403    size_t existing_length;
 404    assert(dest != NULL && *dest != NULL);
 405
 406    existing_length = strlen(*dest);
 407    both = resize(*dest, existing_length + n + 1);
 408    if (unlikely(both == NULL))
 409       return false;
 410
 411    memcpy(both + existing_length, str, n);
 412    both[existing_length + n] = '\0';
 413
 414    *dest = both;
 415    return true;
 416 }
 417
 418
 419 bool
 420 ralloc_strcat(char **dest, const char *str)
 421 {
 422    return cat(dest, str, strlen(str));
 423 }
 424
 425 bool
 426 ralloc_strncat(char **dest, const char *str, size_t n)
 427 {
 428    return cat(dest, str, strnlen(str, n));
 429 }
 430
 431 bool
 432 ralloc_str_append(char **dest, const char *str,
 433                   size_t existing_length, size_t str_size)
 434 {
 435    char *both;
 436    assert(dest != NULL && *dest != NULL);
 437
 438    both = resize(*dest, existing_length + str_size + 1);
 439    if (unlikely(both == NULL))
 440       return false;
 441
 442    memcpy(both + existing_length, str, str_size);
 443    both[existing_length + str_size] = '\0';
 444
 445    *dest = both;
 446
 447    return true;
 448 }
 449
 450 char *
 451 ralloc_asprintf(const void *ctx, const char *fmt, ...)
 452 {
 453    char *ptr;
 454    va_list args;
 455    va_start(args, fmt);
 456    ptr = ralloc_vasprintf(ctx, fmt, args);
 457    va_end(args);
 458    return ptr;
 459 }
 460
 461 /* Return the length of the string that would be generated by a printf-style
 462  * format and argument list, not including the \0 byte.
 463  */
 464 static size_t
 465 printf_length(const char *fmt, va_list untouched_args)
 466 {
 467    int size;
 468    char junk;
 469
 470    /* Make a copy of the va_list so the original caller can still use it */
 471    va_list args;
 472    va_copy(args, untouched_args);
 473
 474 #ifdef _WIN32
 475    /* We need to use _vcsprintf to calculate the size as vsnprintf returns -1
 476     * if the number of characters to write is greater than count.
 477     */
 478    size = _vscprintf(fmt, args);
 479    (void)junk;
 480 #else
 481    size = vsnprintf(&junk, 1, fmt, args);
 482 #endif
 483    assert(size >= 0);
 484
 485    va_end(args);
 486
 487    return size;
 488 }
 489
 490 char *
 491 ralloc_vasprintf(const void *ctx, const char *fmt, va_list args)
 492 {
 493    size_t size = printf_length(fmt, args) + 1;
 494
 495    char *ptr = ralloc_size(ctx, size);
 496    if (ptr != NULL)
 497       vsnprintf(ptr, size, fmt, args);
 498
 499    return ptr;
 500 }
 501
 502 bool
 503 ralloc_asprintf_append(char **str, const char *fmt, ...)
 504 {
 505    bool success;
 506    va_list args;
 507    va_start(args, fmt);
 508    success = ralloc_vasprintf_append(str, fmt, args);
 509    va_end(args);
 510    return success;
 511 }
 512
 513 bool
 514 ralloc_vasprintf_append(char **str, const char *fmt, va_list args)
 515 {
 516    size_t existing_length;
 517    assert(str != NULL);
 518    existing_length = *str ? strlen(*str) : 0;
 519    return ralloc_vasprintf_rewrite_tail(str, &existing_length, fmt, args);
 520 }
 521
 522 bool
 523 ralloc_asprintf_rewrite_tail(char **str, size_t *start, const char *fmt, ...)
 524 {
 525    bool success;
 526    va_list args;
 527    va_start(args, fmt);
 528    success = ralloc_vasprintf_rewrite_tail(str, start, fmt, args);
 529    va_end(args);
 530    return success;
 531 }
 532
 533 bool
 534 ralloc_vasprintf_rewrite_tail(char **str, size_t *start, const char *fmt,
 535                               va_list args)
 536 {
 537    size_t new_length;
 538    char *ptr;
 539
 540    assert(str != NULL);
 541
 542    if (unlikely(*str == NULL)) {
 543       // Assuming a NULL context is probably bad, but it's expected behavior.
 544       *str = ralloc_vasprintf(NULL, fmt, args);
 545       *start = strlen(*str);
 546       return true;
 547    }
 548
 549    new_length = printf_length(fmt, args);
 550
 551    ptr = resize(*str, *start + new_length + 1);
 552    if (unlikely(ptr == NULL))
 553       return false;
 554
 555    vsnprintf(ptr + *start, new_length + 1, fmt, args);
 556    *str = ptr;
 557    *start += new_length;
 558    return true;
 559 }
 560
 561 /***************************************************************************
 562  * Linear allocator for short-lived allocations.
 563  ***************************************************************************
 564  *
 565  * The allocator consists of a parent node (2K buffer), which requires
 566  * a ralloc parent, and child nodes (allocations). Child nodes can't be freed
 567  * directly, because the parent doesn't track them. You have to release
 568  * the parent node in order to release all its children.
 569  *
 570  * The allocator uses a fixed-sized buffer with a monotonically increasing
 571  * offset after each allocation. If the buffer is all used, another buffer
 572  * is allocated, sharing the same ralloc parent, so all buffers are at
 573  * the same level in the ralloc hierarchy.
 574  *
 575  * The linear parent node is always the first buffer and keeps track of all
 576  * other buffers.
 577  */
 578
 579 #define MIN_LINEAR_BUFSIZE 2048
 580 #define SUBALLOC_ALIGNMENT 8
 581 #define LMAGIC 0x87b9c7d3
 582
 583 struct
 584 #ifdef _MSC_VER
 585  __declspec(align(8))
 586 #elif defined(__LP64__)
 587  __attribute__((aligned(16)))
 588 #else
 589  __attribute__((aligned(8)))
 590 #endif
 591    linear_header {
 592 #ifndef NDEBUG
 593    unsigned magic;   /* for debugging */
 594 #endif
 595    unsigned offset;  /* points to the first unused byte in the buffer */
 596    unsigned size;    /* size of the buffer */
 597    void *ralloc_parent;          /* new buffers will use this */
 598    struct linear_header *next;   /* next buffer if we have more */
 599    struct linear_header *latest; /* the only buffer that has free space */
 600
 601    /* After this structure, the buffer begins.
 602     * Each suballocation consists of linear_size_chunk as its header followed
 603     * by the suballocation, so it goes:
 604     *
 605     * - linear_size_chunk
 606     * - allocated space
 607     * - linear_size_chunk
 608     * - allocated space
 609     * etc.
 610     *
 611     * linear_size_chunk is only needed by linear_realloc.
 612     */
 613 };
 614
 615 struct linear_size_chunk {
 616    unsigned size; /* for realloc */
 617    unsigned _padding;
 618 };
 619
 620 typedef struct linear_header linear_header;
 621 typedef struct linear_size_chunk linear_size_chunk;
 622
 623 #define LINEAR_PARENT_TO_HEADER(parent) \
 624    (linear_header*) \
 625    ((char*)(parent) - sizeof(linear_size_chunk) - sizeof(linear_header))
 626
 627 /* Allocate the linear buffer with its header. */
 628 static linear_header *
 629 create_linear_node(void *ralloc_ctx, unsigned min_size)
 630 {
 631    linear_header *node;
 632
 633    min_size += sizeof(linear_size_chunk);
 634
 635    if (likely(min_size < MIN_LINEAR_BUFSIZE))
 636       min_size = MIN_LINEAR_BUFSIZE;
 637
 638    node = ralloc_size(ralloc_ctx, sizeof(linear_header) + min_size);
 639    if (unlikely(!node))
 640       return NULL;
 641
 642 #ifndef NDEBUG
 643    node->magic = LMAGIC;
 644 #endif
 645    node->offset = 0;
 646    node->size = min_size;
 647    node->ralloc_parent = ralloc_ctx;
 648    node->next = NULL;
 649    node->latest = node;
 650    return node;
 651 }
 652
 653 void *
 654 linear_alloc_child(void *parent, unsigned size)
 655 {
 656    linear_header *first = LINEAR_PARENT_TO_HEADER(parent);
 657    linear_header *latest = first->latest;
 658    linear_header *new_node;
 659    linear_size_chunk *ptr;
 660    unsigned full_size;
 661
 662    assert(first->magic == LMAGIC);
 663    assert(!latest->next);
 664
 665    size = ALIGN_POT(size, SUBALLOC_ALIGNMENT);
 666    full_size = sizeof(linear_size_chunk) + size;
 667
 668    if (unlikely(latest->offset + full_size > latest->size)) {
 669       /* allocate a new node */
 670       new_node = create_linear_node(latest->ralloc_parent, size);
 671       if (unlikely(!new_node))
 672          return NULL;
 673
 674       first->latest = new_node;
 675       latest->latest = new_node;
 676       latest->next = new_node;
 677       latest = new_node;
 678    }
 679
 680    ptr = (linear_size_chunk *)((char*)&latest[1] + latest->offset);
 681    ptr->size = size;
 682    latest->offset += full_size;
 683
 684    assert((uintptr_t)&ptr[1] % SUBALLOC_ALIGNMENT == 0);
 685    return &ptr[1];
 686 }
 687
 688 void *
 689 linear_alloc_parent(void *ralloc_ctx, unsigned size)
 690 {
 691    linear_header *node;
 692
 693    if (unlikely(!ralloc_ctx))
 694       return NULL;
 695
 696    size = ALIGN_POT(size, SUBALLOC_ALIGNMENT);
 697
 698    node = create_linear_node(ralloc_ctx, size);
 699    if (unlikely(!node))
 700       return NULL;
 701
 702    return linear_alloc_child((char*)node +
 703                              sizeof(linear_header) +
 704                              sizeof(linear_size_chunk), size);
 705 }
 706
 707 void *
 708 linear_zalloc_child(void *parent, unsigned size)
 709 {
 710    void *ptr = linear_alloc_child(parent, size);
 711
 712    if (likely(ptr))
 713       memset(ptr, 0, size);
 714    return ptr;
 715 }
 716
 717 void *
 718 linear_zalloc_parent(void *parent, unsigned size)
 719 {
 720    void *ptr = linear_alloc_parent(parent, size);
 721
 722    if (likely(ptr))
 723       memset(ptr, 0, size);
 724    return ptr;
 725 }
 726
 727 void
 728 linear_free_parent(void *ptr)
 729 {
 730    linear_header *node;
 731
 732    if (unlikely(!ptr))
 733       return;
 734
 735    node = LINEAR_PARENT_TO_HEADER(ptr);
 736    assert(node->magic == LMAGIC);
 737
 738    while (node) {
 739       void *ptr = node;
 740
 741       node = node->next;
 742       ralloc_free(ptr);
 743    }
 744 }
 745
 746 void
 747 ralloc_steal_linear_parent(void *new_ralloc_ctx, void *ptr)
 748 {
 749    linear_header *node;
 750
 751    if (unlikely(!ptr))
 752       return;
 753
 754    node = LINEAR_PARENT_TO_HEADER(ptr);
 755    assert(node->magic == LMAGIC);
 756
 757    while (node) {
 758       ralloc_steal(new_ralloc_ctx, node);
 759       node->ralloc_parent = new_ralloc_ctx;
 760       node = node->next;
 761    }
 762 }
 763
 764 void *
 765 ralloc_parent_of_linear_parent(void *ptr)
 766 {
 767    linear_header *node = LINEAR_PARENT_TO_HEADER(ptr);
 768    assert(node->magic == LMAGIC);
 769    return node->ralloc_parent;
 770 }
 771
 772 void *
 773 linear_realloc(void *parent, void *old, unsigned new_size)
 774 {
 775    unsigned old_size = 0;
 776    ralloc_header *new_ptr;
 777
 778    new_ptr = linear_alloc_child(parent, new_size);
 779
 780    if (unlikely(!old))
 781       return new_ptr;
 782
 783    old_size = ((linear_size_chunk*)old)[-1].size;
 784
 785    if (likely(new_ptr && old_size))
 786       memcpy(new_ptr, old, MIN2(old_size, new_size));
 787
 788    return new_ptr;
 789 }
 790
 791 /* All code below is pretty much copied from ralloc and only the alloc
 792  * calls are different.
 793  */
 794
 795 char *
 796 linear_strdup(void *parent, const char *str)
 797 {
 798    unsigned n;
 799    char *ptr;
 800
 801    if (unlikely(!str))
 802       return NULL;
 803
 804    n = strlen(str);
 805    ptr = linear_alloc_child(parent, n + 1);
 806    if (unlikely(!ptr))
 807       return NULL;
 808
 809    memcpy(ptr, str, n);
 810    ptr[n] = '\0';
 811    return ptr;
 812 }
 813
 814 char *
 815 linear_asprintf(void *parent, const char *fmt, ...)
 816 {
 817    char *ptr;
 818    va_list args;
 819    va_start(args, fmt);
 820    ptr = linear_vasprintf(parent, fmt, args);
 821    va_end(args);
 822    return ptr;
 823 }
 824
 825 char *
 826 linear_vasprintf(void *parent, const char *fmt, va_list args)
 827 {
 828    unsigned size = printf_length(fmt, args) + 1;
 829
 830    char *ptr = linear_alloc_child(parent, size);
 831    if (ptr != NULL)
 832       vsnprintf(ptr, size, fmt, args);
 833
 834    return ptr;
 835 }
 836
 837 bool
 838 linear_asprintf_append(void *parent, char **str, const char *fmt, ...)
 839 {
 840    bool success;
 841    va_list args;
 842    va_start(args, fmt);
 843    success = linear_vasprintf_append(parent, str, fmt, args);
 844    va_end(args);
 845    return success;
 846 }
 847
 848 bool
 849 linear_vasprintf_append(void *parent, char **str, const char *fmt, va_list args)
 850 {
 851    size_t existing_length;
 852    assert(str != NULL);
 853    existing_length = *str ? strlen(*str) : 0;
 854    return linear_vasprintf_rewrite_tail(parent, str, &existing_length, fmt, args);
 855 }
 856
 857 bool
 858 linear_asprintf_rewrite_tail(void *parent, char **str, size_t *start,
 859                              const char *fmt, ...)
 860 {
 861    bool success;
 862    va_list args;
 863    va_start(args, fmt);
 864    success = linear_vasprintf_rewrite_tail(parent, str, start, fmt, args);
 865    va_end(args);
 866    return success;
 867 }
 868
 869 bool
 870 linear_vasprintf_rewrite_tail(void *parent, char **str, size_t *start,
 871                               const char *fmt, va_list args)
 872 {
 873    size_t new_length;
 874    char *ptr;
 875
 876    assert(str != NULL);
 877
 878    if (unlikely(*str == NULL)) {
 879       *str = linear_vasprintf(parent, fmt, args);
 880       *start = strlen(*str);
 881       return true;
 882    }
 883
 884    new_length = printf_length(fmt, args);
 885
 886    ptr = linear_realloc(parent, *str, *start + new_length + 1);
 887    if (unlikely(ptr == NULL))
 888       return false;
 889
 890    vsnprintf(ptr + *start, new_length + 1, fmt, args);
 891    *str = ptr;
 892    *start += new_length;
 893    return true;
 894 }
 895
 896 /* helper routine for strcat/strncat - n is the exact amount to copy */
 897 static bool
 898 linear_cat(void *parent, char **dest, const char *str, unsigned n)
 899 {
 900    char *both;
 901    unsigned existing_length;
 902    assert(dest != NULL && *dest != NULL);
 903
 904    existing_length = strlen(*dest);
 905    both = linear_realloc(parent, *dest, existing_length + n + 1);
 906    if (unlikely(both == NULL))
 907       return false;
 908
 909    memcpy(both + existing_length, str, n);
 910    both[existing_length + n] = '\0';
 911
 912    *dest = both;
 913    return true;
 914 }
 915
 916 bool
 917 linear_strcat(void *parent, char **dest, const char *str)
 918 {
 919    return linear_cat(parent, dest, str, strlen(str));
 920 }