mirror of
https://github.com/jart/cosmopolitan.git
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78 lines
3.6 KiB
C
78 lines
3.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2021 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/assert.h"
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#include "libc/calls/calls.h"
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#include "libc/macros.internal.h"
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#include "libc/runtime/runtime.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/prot.h"
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#include "libc/sysv/errfuns.h"
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uintptr_t __break;
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/**
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* Sets end of data section.
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*
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* This can be used to allocate and deallocate memory. It won't
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* conflict with malloc() and mmap(NULL, ...) allocations since
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* APE binaries load the image at 0x440000 and does allocations
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* starting at 0x100080040000. You should consult _end, or call
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* sbrk(NULL), to figure out where the existing break is first.
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*
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* @return 0 on success or -1 w/ errno
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* @see mmap(), sbrk(), _end
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*/
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int brk(void *end) {
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int rc;
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uintptr_t x;
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if (!__break) __break = (uintptr_t)_end;
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x = (uintptr_t)end;
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if (x < (uintptr_t)_end) x = (uintptr_t)_end;
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x = ROUNDUP(x, FRAMESIZE);
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if (x == __break) return 0;
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/* allocate one frame at a time due to nt pickiness */
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for (; x > __break; __break += FRAMESIZE) {
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if (mmap((void *)__break, FRAMESIZE, PROT_READ | PROT_WRITE,
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MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0) == MAP_FAILED) {
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return -1;
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}
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}
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for (rc = 0; x < __break; __break -= FRAMESIZE) {
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rc |= munmap((void *)(__break - FRAMESIZE), FRAMESIZE);
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}
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return 0;
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}
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/**
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* Adjusts end of data section.
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*
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* This shrinks or increases the program break by delta bytes. On
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* success, the previous program break is returned. It's possible
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* to pass zero to this function to get the current program break
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*
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* @return old break on success or -1 w/ errno
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* @see mmap(), brk(), _end
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*/
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void *sbrk(intptr_t delta) {
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uintptr_t oldbreak;
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if (!__break) __break = (uintptr_t)_end;
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oldbreak = __break;
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return (void *)(brk((void *)(__break + delta)) != -1 ? oldbreak : -1);
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}
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