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  1. /*
  2.  * Copyright (C) 2006 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. #include <libc.h>
  30. #include <unistd.h>
  31.  
  32. /** Mremap syscall */
  33. void *mremap(void *address, size_t size, unsigned long flags)
  34. {
  35.     return (void *) __SYSCALL3(SYS_MREMAP, (sysarg_t ) address, (sysarg_t) size, (sysarg_t) flags);
  36. }
  37.  
  38.  
  39. static size_t heapsize = 0;
  40. /* Start of heap linker symbol */
  41. extern char _heap;
  42.  
  43. /** Sbrk emulation
  44.  *
  45.  * @param size New area that should be allocated or negative,
  46.                if it should be shrinked
  47.  * @return Pointer to newly allocated area
  48.  */
  49. void *sbrk(ssize_t incr)
  50. {
  51.     void *res;
  52.     /* Check for invalid values */
  53.     if (incr < 0 && -incr > heapsize)
  54.         return NULL;
  55.     /* Check for too large value */
  56.     if (incr > 0 && incr+heapsize < heapsize)
  57.         return NULL;
  58.     /* Check for too small values */
  59.     if (incr < 0 && incr+heapsize > heapsize)
  60.         return NULL;
  61.  
  62.     res = mremap(&_heap, heapsize + incr,0);
  63.     if (!res)
  64.         return NULL;
  65.    
  66.     /* Compute start of new area */
  67.     res = (void *)&_heap + heapsize;
  68.  
  69.     heapsize += incr;
  70.  
  71.     return res;
  72. }
  73.