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glibc  2.9
brk.c
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00001 /*
00002    Copyright (C) 2000 Free Software Foundation, Inc.
00003    Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
00004    This file is part of the GNU C Library.
00005 
00006    The GNU C Library is free software; you can redistribute it and/or
00007    modify it under the terms of the GNU Lesser General Public
00008    License as published by the Free Software Foundation; either
00009    version 2.1 of the License, or (at your option) any later version.
00010 
00011    The GNU C Library is distributed in the hope that it will be useful,
00012    but WITHOUT ANY WARRANTY; without even the implied warranty of
00013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014    Lesser General Public License for more details.
00015 
00016    You should have received a copy of the GNU Lesser General Public
00017    License along with the GNU C Library; if not, write to the Free
00018    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00019    02111-1307 USA.  */
00020 
00021 #include <errno.h>
00022 #include <unistd.h>
00023 #include <sysdep.h>
00024 
00025 void *__curbrk = 0;
00026 
00027 /* Old braindamage in GCC's crtstuff.c requires this symbol in an attempt
00028    to work around different old braindamage in the old Linux/x86 ELF
00029    dynamic linker.  Sigh.  */
00030 weak_alias (__curbrk, ___brk_addr)
00031 
00032 int
00033 __brk (void *addr)
00034 {
00035   void *newbrk;
00036 
00037   {
00038     register void *__addr asm("2") = addr;
00039 
00040     asm ("svc  %b1\n\t"            /* call sys_brk */
00041         : "=d" (__addr)
00042         : "I" (SYS_ify(brk)), "r" (__addr)
00043         : "cc", "memory" );
00044     newbrk = __addr;
00045   }
00046   __curbrk = newbrk;
00047 
00048   if (newbrk < addr)
00049     {
00050       __set_errno (ENOMEM);
00051       return -1;
00052     }
00053 
00054   return 0;
00055 }
00056 weak_alias (__brk, brk)