text: // stb_leakcheck.h - v0.5 - quick & dirty malloc leak-checking - public domain
  // LICENSE
  //
  //   See end of file.
  
  #ifndef STB_LEAKCHECK_IMPLEMENTATION
  #ifndef JPR_NO_STDLIB
  #error need to avoid stdlib when leak-checking
  #endif
  #endif
  
  #ifdef STB_LEAKCHECK_IMPLEMENTATION
  #undef STB_LEAKCHECK_IMPLEMENTATION // don't implement more than once
  
  
  
  // if we've already included leakcheck before, undefine the macros
  #ifdef malloc
  #undef malloc
  #undef free
  #undef realloc
  #endif
  
  #include <assert.h>
  #include <string.h>
  #include <stdlib.h>
  #include <stdio.h>
  #include <stddef.h>
  typedef struct malloc_info stb_leakcheck_malloc_info;
  
  struct malloc_info
  {
     const char *file;
     int line;
     size_t size;
     stb_leakcheck_malloc_info *next,*prev;
  };
  
  static stb_leakcheck_malloc_info *mi_head;
  
  void *stb_leakcheck_malloc(size_t sz, const char *file, int line)
  {
     stb_leakcheck_malloc_info *mi = (stb_leakcheck_malloc_info *) malloc(sz + sizeof(*mi));
     if (mi == NULL) return mi;
     mi->file = file;
     mi->line = line;
     mi->next = mi_head;
     if (mi_head)
        mi->next->prev = mi;
     mi->prev = NULL;
     mi->size = (int) sz;
     mi_head = mi;
     return mi+1;
  }
  
  void stb_leakcheck_free(void *ptr)
  {
     if (ptr != NULL) {
        stb_leakcheck_malloc_info *mi = (stb_leakcheck_malloc_info *) ptr - 1;
        mi->size = ~mi->size;
        #ifndef STB_LEAKCHECK_SHOWALL
        if (mi->prev == NULL) {
           assert(mi_head == mi);
           mi_head = mi->next;
        } else
           mi->prev->next = mi->next;
        if (mi->next)
           mi->next->prev = mi->prev;
        free(mi);
        #endif
     }
  }
  
  void *stb_leakcheck_realloc(void *ptr, size_t sz, const char *file, int line)
  {
     if (ptr == NULL) {
        return stb_leakcheck_malloc(sz, file, line);
     } else if (sz == 0) {
        stb_leakcheck_free(ptr);
        return NULL;
     } else {
        stb_leakcheck_malloc_info *mi = (stb_leakcheck_malloc_info *) ptr - 1;
        if (sz <= mi->size)
           return ptr;
        else {
           #ifdef STB_LEAKCHECK_REALLOC_PRESERVE_MALLOC_FILELINE
           void *q = stb_leakcheck_malloc(sz, mi->file, mi->line);
           #else
           void *q = stb_leakcheck_malloc(sz, file, line);
           #endif
           if (q) {
              memcpy(q, ptr, mi->size);
              stb_leakcheck_free(ptr);
           }
           return q;
        }
     }
  }
  
  static void stblkck_internal_print(const char *reason, stb_leakcheck_malloc_info *mi)
  {
  #if defined(_MSC_VER) && _MSC_VER < 1900 // 1900=VS 2015
     // Compilers that use the old MS C runtime library don't have %zd
     // and the older ones don't even have %lld either... however, the old compilers
     // without "long long" don't support 64-bit targets either, so here's the
     // compromise:
     #if _MSC_VER < 1400 // before VS 2005
        printf("%s: %s (%4d): %8d bytes at %p\n", reason, mi->file, mi->line, (int)mi->size, (void*)(mi+1));
     #else
        printf("%s: %s (%4d): %16lld bytes at %p\n", reason, mi->file, mi->line, (long long)mi->size, (void*)(mi+1));
     #endif
  #else
     // Assume we have %zd on other targets.
     #ifdef __MINGW32__
        __mingw_printf("%s: %s (%4d): %zd bytes at %p\n", reason, mi->file, mi->line, mi->size, (void*)(mi+1));
     #else
        printf("%s: %s (%4d): %zd bytes at %p\n", reason, mi->file, mi->line, mi->size, (void*)(mi+1));
     #endif
  #endif
  }
  
  void stb_leakcheck_dumpmem(void)
  {
     stb_leakcheck_malloc_info *mi = mi_head;
     while (mi) {
        if ((ptrdiff_t) mi->size >= 0)
           stblkck_internal_print("LEAKED", mi);
        mi = mi->next;
     }
     #ifdef STB_LEAKCHECK_SHOWALL
     mi = mi_head;
     while (mi) {
        if ((ptrdiff_t) mi->size < 0)
           stblkck_internal_print("FREED ", mi);
        mi = mi->next;
     }
     #endif
  }
  #endif // STB_LEAKCHECK_IMPLEMENTATION
  
  #ifndef INCLUDE_STB_LEAKCHECK_H
  #define INCLUDE_STB_LEAKCHECK_H
  
  #include <stdlib.h> // we want to define the macros *after* stdlib to avoid a slew of errors
  
  #define malloc(sz)    stb_leakcheck_malloc(sz, __FILE__, __LINE__)
  #define free(p)       stb_leakcheck_free(p)
  #define realloc(p,sz) stb_leakcheck_realloc(p,sz, __FILE__, __LINE__)
  
  extern void * stb_leakcheck_malloc(size_t sz, const char *file, int line);
  extern void * stb_leakcheck_realloc(void *ptr, size_t sz, const char *file, int line);
  extern void   stb_leakcheck_free(void *ptr);
  extern void   stb_leakcheck_dumpmem(void);
  
  #endif // INCLUDE_STB_LEAKCHECK_H
  
  
  /*
  ------------------------------------------------------------------------------
  This software is available under 2 licenses -- choose whichever you prefer.
  ------------------------------------------------------------------------------
  ALTERNATIVE A - MIT License
  Copyright (c) 2017 Sean Barrett
  Permission is hereby granted, free of charge, to any person obtaining a copy of 
  this software and associated documentation files (the "Software"), to deal in 
  the Software without restriction, including without limitation the rights to 
  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies 
  of the Software, and to permit persons to whom the Software is furnished to do 
  so, subject to the following conditions:
  The above copyright notice and this permission notice shall be included in all 
  copies or substantial portions of the Software.
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 
  SOFTWARE.
  ------------------------------------------------------------------------------
  ALTERNATIVE B - Public Domain (www.unlicense.org)
  This is free and unencumbered software released into the public domain.
  Anyone is free to copy, modify, publish, use, compile, sell, or distribute this 
  software, either in source code form or as a compiled binary, for any purpose, 
  commercial or non-commercial, and by any means.
  In jurisdictions that recognize copyright laws, the author or authors of this 
  software dedicate any and all copyright interest in the software to the public 
  domain. We make this dedication for the benefit of the public at large and to 
  the detriment of our heirs and successors. We intend this dedication to be an 
  overt act of relinquishment in perpetuity of all present and future rights to 
  this software under copyright law.
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
  AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 
  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 
  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  ------------------------------------------------------------------------------
  */
  