/* alloc - Convenience routines for safely allocating memory
 * Copyright (C) 2007-2009  Josh Coalson
 * Copyright (C) 2011-2022  Xiph.Org Foundation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of the Xiph.org Foundation nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef FLAC__SHARE__ALLOC_H
#define FLAC__SHARE__ALLOC_H

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

/* WATCHOUT: for c++ you may have to #define __STDC_LIMIT_MACROS 1 real early
 * before #including this file,  otherwise SIZE_MAX might not be defined
 */

#include <limits.h> /* for SIZE_MAX */
#ifdef HAVE_STDINT_H
#include <stdint.h> /* for SIZE_MAX in case limits.h didn't get it */
#endif
#include <stdlib.h> /* for size_t, malloc(), etc */
#include "share/compat.h"

#ifndef SIZE_MAX
#ifndef SIZE_T_MAX
#ifdef _MSC_VER
#ifdef _WIN64
#define SIZE_T_MAX FLAC__U64L(0xffffffffffffffff)
#else
#define SIZE_T_MAX 0xffffffff
#endif
#else
#error
#endif
#endif
#define SIZE_MAX SIZE_T_MAX
#endif

#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
extern int alloc_check_threshold, alloc_check_counter;

static inline int alloc_check() {
  if (alloc_check_threshold == INT32_MAX) {
    return 0;
  } else if (alloc_check_counter++ == alloc_check_threshold) {
    return 1;
  } else {
    return 0;
  }
}

#endif

/* avoid malloc()ing 0 bytes, see:
 * https://www.securecoding.cert.org/confluence/display/seccode/MEM04-A.+Do+not+make+assumptions+about+the+result+of+allocating+0+bytes?focusedCommentId=5407003
 */

static inline void* safe_malloc_(size_t size) {
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
  /* Fail if requested */
  if (alloc_check()) {
    return NULL;
  }
#endif
  /* malloc(0) is undefined; FLAC src convention is to always allocate */
  if (!size) {
    size++;
  }
  return malloc(size);
}

#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
static inline void* malloc_(size_t size) {
  /* Fail if requested */
  if (alloc_check()) {
    return NULL;
  }
  return malloc(size);
}
#else
#define malloc_ malloc
#endif

static inline void* safe_calloc_(size_t nmemb, size_t size) {
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
  /* Fail if requested */
  if (alloc_check()) {
    return NULL;
  }
#endif
  if (!nmemb || !size) {
    return malloc(1); /* malloc(0) is undefined; FLAC src convention is to
                         always allocate */
  }
  return calloc(nmemb, size);
}

/*@@@@ there's probably a better way to prevent overflows when allocating
 * untrusted sums but this works for now */

static inline void* safe_malloc_add_2op_(size_t size1, size_t size2) {
  size2 += size1;
  if (size2 < size1) {
    return 0;
  }
  return safe_malloc_(size2);
}

static inline void* safe_malloc_add_3op_(size_t size1,
                                         size_t size2,
                                         size_t size3) {
  size2 += size1;
  if (size2 < size1) {
    return 0;
  }
  size3 += size2;
  if (size3 < size2) {
    return 0;
  }
  return safe_malloc_(size3);
}

static inline void* safe_malloc_add_4op_(size_t size1,
                                         size_t size2,
                                         size_t size3,
                                         size_t size4) {
  size2 += size1;
  if (size2 < size1) {
    return 0;
  }
  size3 += size2;
  if (size3 < size2) {
    return 0;
  }
  size4 += size3;
  if (size4 < size3) {
    return 0;
  }
  return safe_malloc_(size4);
}

void* safe_malloc_mul_2op_(size_t size1, size_t size2);

static inline void* safe_malloc_mul_3op_(size_t size1,
                                         size_t size2,
                                         size_t size3) {
  if (!size1 || !size2 || !size3) {
    return malloc(1); /* malloc(0) is undefined; FLAC src convention is to
                         always allocate */
  }
  if (size1 > SIZE_MAX / size2) {
    return 0;
  }
  size1 *= size2;
  if (size1 > SIZE_MAX / size3) {
    return 0;
  }
  return malloc_(size1 * size3);
}

/* size1*size2 + size3 */
static inline void* safe_malloc_mul2add_(size_t size1,
                                         size_t size2,
                                         size_t size3) {
  if (!size1 || !size2) {
    return safe_malloc_(size3);
  }
  if (size1 > SIZE_MAX / size2) {
    return 0;
  }
  return safe_malloc_add_2op_(size1 * size2, size3);
}

/* size1 * (size2 + size3) */
static inline void* safe_malloc_muladd2_(size_t size1,
                                         size_t size2,
                                         size_t size3) {
  if (!size1 || (!size2 && !size3)) {
    return malloc(1); /* malloc(0) is undefined; FLAC src convention is to
                         always allocate */
  }
  size2 += size3;
  if (size2 < size3) {
    return 0;
  }
  if (size1 > SIZE_MAX / size2) {
    return 0;
  }
  return malloc_(size1 * size2);
}

static inline void* safe_realloc_(void* ptr, size_t size) {
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
  /* Fail if requested */
  if (alloc_check() && size > 0) {
    free(ptr);
    return NULL;
  }
#endif
  void* oldptr = ptr;
  void* newptr = realloc(ptr, size);
  if (size > 0 && newptr == 0) {
    free(oldptr);
  }
  return newptr;
}

#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
static inline void* realloc_(void* ptr, size_t size) {
  /* Fail if requested */
  if (alloc_check()) {
    return NULL;
  }
  return realloc(ptr, size);
}
#else
#define realloc_ realloc
#endif

static inline void* safe_realloc_nofree_add_2op_(void* ptr,
                                                 size_t size1,
                                                 size_t size2) {
  size2 += size1;
  if (size2 < size1) {
    return 0;
  }
  return realloc_(ptr, size2);
}

static inline void* safe_realloc_add_3op_(void* ptr,
                                          size_t size1,
                                          size_t size2,
                                          size_t size3) {
  size2 += size1;
  if (size2 < size1) {
    free(ptr);
    return 0;
  }
  size3 += size2;
  if (size3 < size2) {
    free(ptr);
    return 0;
  }
  return safe_realloc_(ptr, size3);
}

static inline void* safe_realloc_nofree_add_3op_(void* ptr,
                                                 size_t size1,
                                                 size_t size2,
                                                 size_t size3) {
  size2 += size1;
  if (size2 < size1) {
    return 0;
  }
  size3 += size2;
  if (size3 < size2) {
    return 0;
  }
  return realloc_(ptr, size3);
}

static inline void* safe_realloc_nofree_add_4op_(void* ptr,
                                                 size_t size1,
                                                 size_t size2,
                                                 size_t size3,
                                                 size_t size4) {
  size2 += size1;
  if (size2 < size1) {
    return 0;
  }
  size3 += size2;
  if (size3 < size2) {
    return 0;
  }
  size4 += size3;
  if (size4 < size3) {
    return 0;
  }
  return realloc_(ptr, size4);
}

static inline void* safe_realloc_mul_2op_(void* ptr,
                                          size_t size1,
                                          size_t size2) {
  if (!size1 || !size2) {
    return realloc(ptr, 0); /* preserve POSIX realloc(ptr, 0) semantics */
  }
  if (size1 > SIZE_MAX / size2) {
    free(ptr);
    return 0;
  }
  return safe_realloc_(ptr, size1 * size2);
}

static inline void* safe_realloc_nofree_mul_2op_(void* ptr,
                                                 size_t size1,
                                                 size_t size2) {
  if (!size1 || !size2) {
    return realloc(ptr, 0); /* preserve POSIX realloc(ptr, 0) semantics */
  }
  if (size1 > SIZE_MAX / size2) {
    return 0;
  }
  return realloc_(ptr, size1 * size2);
}

/* size1 * (size2 + size3) */
static inline void* safe_realloc_muladd2_(void* ptr,
                                          size_t size1,
                                          size_t size2,
                                          size_t size3) {
  if (!size1 || (!size2 && !size3)) {
    return realloc(ptr, 0); /* preserve POSIX realloc(ptr, 0) semantics */
  }
  size2 += size3;
  if (size2 < size3) {
    free(ptr);
    return 0;
  }
  return safe_realloc_mul_2op_(ptr, size1, size2);
}

/* size1 * (size2 + size3) */
static inline void* safe_realloc_nofree_muladd2_(void* ptr,
                                                 size_t size1,
                                                 size_t size2,
                                                 size_t size3) {
  if (!size1 || (!size2 && !size3)) {
    return realloc(ptr, 0); /* preserve POSIX realloc(ptr, 0) semantics */
  }
  size2 += size3;
  if (size2 < size3) {
    return 0;
  }
  return safe_realloc_nofree_mul_2op_(ptr, size1, size2);
}

#endif