brk.c 1.6 KB

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  1. /* brk system call for Linux/i386.
  2. Copyright (C) 1995, 1996, 2000 Free Software Foundation, Inc.
  3. This file is part of the GNU C Library.
  4. The GNU C Library is free software; you can redistribute it and/or
  5. modify it under the terms of the GNU Lesser General Public
  6. License as published by the Free Software Foundation; either
  7. version 2.1 of the License, or (at your option) any later version.
  8. The GNU C Library is distributed in the hope that it will be useful,
  9. but WITHOUT ANY WARRANTY; without even the implied warranty of
  10. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11. Lesser General Public License for more details.
  12. You should have received a copy of the GNU Lesser General Public
  13. License along with the GNU C Library; if not, write to the Free
  14. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  15. 02111-1307 USA. */
  16. #include <errno.h>
  17. #include <unistd.h>
  18. #include <sys/syscall.h>
  19. #ifndef __ptrvalue
  20. #define __ptrvalue
  21. #endif
  22. /* This must be initialized data because commons can't have aliases. */
  23. void *___brk_addr = 0;
  24. int brk (void *addr)
  25. {
  26. void *newbrk, *scratch;
  27. asm ("movl %%ebx, %1\n" /* Save %ebx in scratch register. */
  28. "movl %3, %%ebx\n" /* Put ADDR in %ebx to be syscall arg. */
  29. "int $0x80 # %2\n" /* Perform the system call. */
  30. "movl %1, %%ebx\n" /* Restore %ebx from scratch register. */
  31. : "=a" (newbrk), "=r" (scratch)
  32. : "0" (__NR_brk), "g" (__ptrvalue (addr)));
  33. ___brk_addr = newbrk;
  34. if (newbrk < addr)
  35. {
  36. __set_errno (ENOMEM);
  37. return -1;
  38. }
  39. return 0;
  40. }