mirrors/cosmopolitan
1
0
Fork 0
mirror of https://github.com/jart/cosmopolitan.git synced 2025-06-27 14:58:30 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 1

Initial import

Browse source
This commit is contained in:
Justine Tunney 2020-06-15 07:18:57 -07:00
commit c91b3c5006
14915 changed files with 590219 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

53
libc/mem/malloc_usable_size.S Normal file
View file

@ -0,0 +1,53 @@
/*-*- mode:asm; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
│vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/macros.h"
#include "libc/notice.inc"
.yoink __FILE__
/ Returns the number of bytes you can actually use in
/ an allocated chunk, which may be more than you requested
/ (although often not) due to alignment and minimum size
/ constraints.
/
/ You can use this many bytes without worrying about overwriting
/ other allocated objects. This is not a particularly great
/ programming practice. malloc_usable_size can be more useful in
/ debugging and assertions, for example:
/
/ p = malloc(n)
/ assert(malloc_usable_size(p) >= 256)
/
/ @param rdi is address of allocation
/ @return rax is total number of bytes
/ @see dlmalloc_usable_size()
malloc_usable_size:
jmp *hook$malloc_usable_size(%rip)
.endfn malloc_usable_size,globl
.initbss 800,_init_malloc_usable_size
hook$malloc_usable_size:
.quad 0
.endobj hook$malloc_usable_size,globl,hidden
.previous
.init.start 800,_init_malloc_usable_size
ezlea dlmalloc_usable_size,ax
stosq
.init.end 800,_init_malloc_usable_size