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https://github.com/jart/cosmopolitan.git
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3265324e00
This change fixes #496 where ASAN spotted a race condition that could happen in multithreaded programs, with more than OPEN_MAX descriptors when using ZipOS or Windows NT, which require tracking open file info and this change fixes that table so it never relocates, thus allowing us to continue to enjoy the benefits of avoiding locks while reading.
99 lines
4.5 KiB
C
99 lines
4.5 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set 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/assert.h"
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#include "libc/calls/internal.h"
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#include "libc/calls/state.internal.h"
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#include "libc/nt/enum/filemapflags.h"
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#include "libc/nt/enum/pageflags.h"
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#include "libc/nt/memory.h"
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#include "libc/nt/runtime.h"
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#include "libc/nt/struct/processmemorycounters.h"
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#include "libc/nt/struct/securityattributes.h"
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#include "libc/runtime/directmap.internal.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/o.h"
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textwindows struct DirectMap sys_mmap_nt(void *addr, size_t size, int prot,
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int flags, int fd, int64_t off) {
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size_t i;
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bool iscow;
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int64_t handle;
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uint32_t oldprot;
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struct DirectMap dm;
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struct ProtectNt fl;
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const struct NtSecurityAttributes *sec;
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struct NtProcessMemoryCountersEx memcount;
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if (fd != -1) {
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handle = g_fds.p[fd].handle;
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} else {
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handle = kNtInvalidHandleValue;
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}
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if ((flags & MAP_TYPE) != MAP_SHARED) {
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sec = 0; // MAP_PRIVATE isn't inherited across fork()
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} else {
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sec = &kNtIsInheritable; // MAP_SHARED gives us zero-copy fork()
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}
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// nt will whine under many circumstances if we change the execute bit
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// later using mprotect(). the workaround is to always request execute
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// and then virtualprotect() it away until we actually need it. please
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// note that open-nt.c always requests an kNtGenericExecute accessmask
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iscow = false;
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if (handle != -1) {
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if ((flags & MAP_TYPE) != MAP_SHARED) {
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// windows has cow pages but they can't propagate across fork()
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// that means we only get copy-on-write for the root process :(
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fl = (struct ProtectNt){kNtPageExecuteWritecopy,
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kNtFileMapCopy | kNtFileMapExecute};
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iscow = true;
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} else {
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if ((g_fds.p[fd].flags & O_ACCMODE) == O_RDONLY) {
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fl = (struct ProtectNt){kNtPageExecuteRead,
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kNtFileMapRead | kNtFileMapExecute};
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} else {
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fl = (struct ProtectNt){kNtPageExecuteReadwrite,
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kNtFileMapWrite | kNtFileMapExecute};
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}
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}
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} else {
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assert(flags & MAP_ANONYMOUS);
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fl = (struct ProtectNt){kNtPageExecuteReadwrite,
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kNtFileMapWrite | kNtFileMapExecute};
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}
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if ((dm.maphandle = CreateFileMapping(handle, sec, fl.flags1,
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(size + off) >> 32, (size + off), 0))) {
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if ((dm.addr = MapViewOfFileEx(dm.maphandle, fl.flags2, off >> 32, off,
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size, addr))) {
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if (VirtualProtect(addr, size, __prot2nt(prot, iscow), &oldprot)) {
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return dm;
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} else {
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return dm;
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UnmapViewOfFile(dm.addr);
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}
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}
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CloseHandle(dm.maphandle);
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}
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dm.maphandle = kNtInvalidHandleValue;
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dm.addr = (void *)(intptr_t)-1;
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return dm;
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}
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