sbrk.c 1.4 KB

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  1. /* Copyright (C) 1991, 1995, 1996, 1997, 2000 Free Software Foundation, Inc.
  2. This file is part of the GNU C Library.
  3. The GNU C Library is free software; you can redistribute it and/or
  4. modify it under the terms of the GNU Lesser General Public
  5. License as published by the Free Software Foundation; either
  6. version 2.1 of the License, or (at your option) any later version.
  7. The GNU C Library is distributed in the hope that it will be useful,
  8. but WITHOUT ANY WARRANTY; without even the implied warranty of
  9. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  10. Lesser General Public License for more details.
  11. You should have received a copy of the GNU Lesser General Public
  12. License along with the GNU C Library; if not, write to the Free
  13. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  14. 02111-1307 USA. */
  15. #include <unistd.h>
  16. #include <errno.h>
  17. /* Defined in brk.c. */
  18. extern void *___brk_addr;
  19. extern int brk (void *addr);
  20. /* Extend the process's data space by INCREMENT.
  21. If INCREMENT is negative, shrink data space by - INCREMENT.
  22. Return start of new space allocated, or -1 for errors. */
  23. void * sbrk (intptr_t increment)
  24. {
  25. void *oldbrk;
  26. if (___brk_addr == NULL)
  27. if (brk (0) < 0) /* Initialize the break. */
  28. return (void *) -1;
  29. if (increment == 0)
  30. return ___brk_addr;
  31. oldbrk = ___brk_addr;
  32. if (brk (oldbrk + increment) < 0)
  33. return (void *) -1;
  34. return oldbrk;
  35. }