1: /* Copyright (C) 1991,1995,1996,1997,2000,2002 Free Software Foundation, Inc.
    2:    This file is part of the GNU C Library.
    3: 
    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: 
    9:    The GNU C Library is distributed in the hope that it will be useful,
   10:    but WITHOUT ANY WARRANTY; without even the implied warranty of
   11:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   12:    Lesser General Public License for more details.
   13: 
   14:    You should have received a copy of the GNU Lesser General Public
   15:    License along with the GNU C Library; if not, write to the Free
   16:    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   17:    02111-1307 USA.  */
   18: 
   19: #include <unistd.h>
   20: #include <errno.h>
   21: 
   22: /* Defined in brk.c.  */
   23: extern void *__curbrk;
   24: extern int __brk (void *addr);
   25: 
   26: /* Defined in init-first.c.  */
   27: extern int __libc_multiple_libcs attribute_hidden;
   28: 
   29: /* Extend the process's data space by INCREMENT.
   30:    If INCREMENT is negative, shrink data space by - INCREMENT.
   31:    Return start of new space allocated, or -1 for errors.  */
   32: void *
   33: __sbrk (intptr_t increment)
   34: {
   35:   void *oldbrk;
   36: 
   37:   /* If this is not part of the dynamic library or the library is used
   38:      via dynamic loading in a statically linked program update
   39:      __curbrk from the kernel's brk value.  That way two separate
   40:      instances of __brk and __sbrk can share the heap, returning
   41:      interleaved pieces of it.  */
   42:   if (__curbrk == NULL || __libc_multiple_libcs)
   43:     if (__brk (0) < 0)          /* Initialize the break.  */
   44:       return (void *) -1;
   45: 
   46:   if (increment == 0)
   47:     return __curbrk;
   48: 
   49:   oldbrk = __curbrk;
   50:   if (__brk (oldbrk + increment) < 0)
   51:     return (void *) -1;
   52: 
   53:   return oldbrk;
   54: }
   55: libc_hidden_def (__sbrk)
   56: weak_alias (__sbrk, sbrk)