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https://github.com/jart/cosmopolitan.git
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f7780de24b
Cosmopolitan now supports mremap(), which is only supported on Linux and NetBSD. First, it allows memory mappings to be relocated without copying them; this can dramatically speed up data structures like std::vector if the array size grows larger than 256kb. The mremap() system call is also 10x faster than munmap() when shrinking large memory mappings. There's now two functions, getpagesize() and getgransize() which help to write portable code that uses mmap(MAP_FIXED). Alternative sysconf() may be called with our new _SC_GRANSIZE. The madvise() system call now has a better wrapper with improved documentation.
69 lines
3.5 KiB
C
69 lines
3.5 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et 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/calls.h"
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#include "libc/calls/syscall-nt.internal.h"
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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/intrin/strace.internal.h"
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#include "libc/runtime/runtime.h"
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#include "libc/sysv/errfuns.h"
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static int __madvise(void *addr, size_t length, int advice) {
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// simulate linux behavior of validating alignment
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if ((uintptr_t)addr & (getpagesize() - 1))
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return einval();
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// simulate linux behavior of checking for negative length
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if ((ssize_t)length < 0)
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return einval();
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// madvise(0, 0, advice) may be used to validate advice
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if (!length && (IsFreebsd() || IsNetbsd()))
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addr = (void *)65536l;
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if (!IsWindows())
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return sys_madvise(addr, length, advice);
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return sys_madvise_nt(addr, length, advice);
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}
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/**
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* Declares intent to OS on how memory region will be used.
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*
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* `madvise(0, 0, advice)` is recommended for validating `advise` and it
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* will always be the case that a `length` of zero is a no-op otherwise.
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*
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* Having the interval overlap unmapped pages has undefined behavior. On
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* Linux, this can be counted upon to raise ENOMEM. Other OSes vary much
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* in behavior here; they'll might ignore unmapped regions or they might
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* raise EINVAL, EFAULT, or ENOMEM.
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*
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* @param advice can be MADV_WILLNEED, MADV_SEQUENTIAL, MADV_FREE, etc.
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* @return 0 on success, or -1 w/ errno
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* @raise EINVAL if `advice` isn't valid or supported by system
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* @raise EINVAL if `addr` isn't getpagesize() aligned
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* @raise EINVAL if `length` is negative
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* @see libc/sysv/consts.sh
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* @see fadvise()
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*/
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int madvise(void *addr, size_t length, int advice) {
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int rc = __madvise(addr, length, advice);
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STRACE("madvise(%p, %'zu, %d) → %d% m", addr, length, advice, rc);
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return rc;
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}
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