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https://github.com/jart/cosmopolitan.git
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3b4fcd8575
We need to make sure no existing mappings exist between the MAP_GROWSDOWN page and the guard page, since otherwise it's not going to be able to grow down thus causing difficult to troubleshoot failures.
55 lines
3 KiB
C
55 lines
3 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 2020 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/calls/syscall-sysv.internal.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/describeflags.internal.h"
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#include "libc/intrin/likely.h"
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#include "libc/intrin/strace.internal.h"
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#include "libc/runtime/internal.h"
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#include "libc/sysv/consts/prot.h"
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/**
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* Modifies restrictions on virtual memory address range.
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*
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* @param addr needs to be 4kb aligned
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* @param prot can have PROT_{NONE,READ,WRITE,EXEC,GROWSDOWN,GROWSUP}
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* @return 0 on success, or -1 w/ errno
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* @see mmap()
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*/
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int mprotect(void *addr, size_t size, int prot) {
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int64_t rc;
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if (SupportsWindows() && (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC |
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PROT_GROWSDOWN | PROT_GROWSUP))) {
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errno = EINVAL; // unix checks prot before checking size
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rc = -1;
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} else if (!size) {
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return 0; // make new technology consistent with unix
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} else if (UNLIKELY((intptr_t)addr & 4095)) {
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errno = EINVAL; // unix checks prot before checking size
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rc = -1;
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} else if (!IsWindows()) {
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rc = sys_mprotect(addr, size, prot);
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} else {
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rc = sys_mprotect_nt(addr, size, prot);
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}
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STRACE("mprotect(%p, %'zu, %s) → %d% m", addr, size, DescribeProtFlags(prot),
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rc);
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return rc;
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}
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