mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-03-03 15:38:22 +00:00
a359de7893
This changes *NSYNC to allocate waiters on the stack so our locks don't need to depend on dynamic memory. This make our runtiem simpler, and it also fixes bugs with thread cancellation support.
404 lines
13 KiB
C
404 lines
13 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/calls.h"
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#include "libc/calls/internal.h"
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#include "libc/calls/struct/fd.internal.h"
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#include "libc/calls/struct/flock.h"
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#include "libc/calls/syscall-nt.internal.h"
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#include "libc/calls/syscall_support-nt.internal.h"
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#include "libc/calls/wincrash.internal.h"
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#include "libc/errno.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/intrin/leaky.internal.h"
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#include "libc/intrin/weaken.h"
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#include "libc/limits.h"
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#include "libc/log/backtrace.internal.h"
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#include "libc/macros.internal.h"
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#include "libc/mem/mem.h"
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#include "libc/nt/createfile.h"
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#include "libc/nt/enum/fileflagandattributes.h"
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#include "libc/nt/enum/filelockflags.h"
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#include "libc/nt/errors.h"
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#include "libc/nt/files.h"
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#include "libc/nt/runtime.h"
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#include "libc/nt/struct/byhandlefileinformation.h"
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#include "libc/nt/struct/overlapped.h"
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#include "libc/nt/winsock.h"
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#include "libc/sock/internal.h"
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#include "libc/stdckdint.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/f.h"
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#include "libc/sysv/consts/fd.h"
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#include "libc/sysv/consts/fio.h"
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#include "libc/sysv/consts/o.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/thread/thread.h"
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struct FileLock {
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struct FileLock *next;
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int64_t off;
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int64_t len;
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int fd;
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bool exc;
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};
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struct FileLocks {
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pthread_mutex_t mu;
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struct FileLock *list;
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struct FileLock *free;
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};
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static struct FileLocks g_locks;
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static textwindows struct FileLock *NewFileLock(void) {
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struct FileLock *fl;
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if (g_locks.free) {
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fl = g_locks.free;
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g_locks.free = fl->next;
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} else {
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unassert((fl = _weaken(malloc)(sizeof(*fl))));
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}
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bzero(fl, sizeof(*fl));
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fl->next = g_locks.list;
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g_locks.list = fl;
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return fl;
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}
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IGNORE_LEAKS(NewFileLock)
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static textwindows void FreeFileLock(struct FileLock *fl) {
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fl->next = g_locks.free;
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g_locks.free = fl;
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}
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static textwindows bool OverlapsFileLock(struct FileLock *fl, int64_t off,
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int64_t len) {
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uint64_t BegA, EndA, BegB, EndB;
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BegA = off;
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EndA = off + (len - 1);
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BegB = fl->off;
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EndB = fl->off + (fl->len - 1);
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return MAX(BegA, BegB) < MIN(EndA, EndB);
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}
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static textwindows bool EncompassesFileLock(struct FileLock *fl, int64_t off,
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int64_t len) {
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return off <= fl->off && fl->off + fl->len <= off + len;
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}
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static textwindows bool EqualsFileLock(struct FileLock *fl, int64_t off,
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int64_t len) {
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return fl->off == off && off + len == fl->off + fl->len;
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}
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textwindows void sys_fcntl_nt_lock_cleanup(int fd) {
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struct FileLock *fl, *ft, **flp;
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pthread_mutex_lock(&g_locks.mu);
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for (flp = &g_locks.list, fl = *flp; fl;) {
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if (fl->fd == fd) {
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*flp = fl->next;
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ft = fl->next;
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FreeFileLock(fl);
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fl = ft;
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} else {
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flp = &fl->next;
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fl = *flp;
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}
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}
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pthread_mutex_unlock(&g_locks.mu);
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}
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static textwindows int sys_fcntl_nt_lock(struct Fd *f, int fd, int cmd,
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uintptr_t arg) {
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uint32_t flags;
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struct flock *l;
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int64_t pos, off, len, end;
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struct FileLock *fl, *ft, **flp;
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if (!_weaken(malloc)) {
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return enomem();
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}
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l = (struct flock *)arg;
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len = l->l_len;
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off = l->l_start;
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switch (l->l_whence) {
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case SEEK_SET:
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break;
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case SEEK_CUR:
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pos = 0;
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if (SetFilePointerEx(f->handle, 0, &pos, SEEK_CUR)) {
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off = pos + off;
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} else {
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return __winerr();
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}
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break;
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case SEEK_END:
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off = INT64_MAX - off;
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break;
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default:
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return einval();
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}
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if (!len) {
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len = INT64_MAX - off;
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}
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if (off < 0 || len < 0 || ckd_add(&end, off, len)) {
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return einval();
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}
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bool32 ok;
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struct NtOverlapped ov = {.hEvent = f->handle,
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.Pointer = (void *)(uintptr_t)off};
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if (l->l_type == F_RDLCK || l->l_type == F_WRLCK) {
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if (cmd == F_SETLK || cmd == F_SETLKW) {
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// make it possible to transition read locks to write locks
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for (flp = &g_locks.list, fl = *flp; fl;) {
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if (fl->fd == fd) {
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if (EqualsFileLock(fl, off, len)) {
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if (fl->exc == (l->l_type == F_WRLCK)) {
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// we already have this lock
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return 0;
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} else {
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// unlock our read lock and acquire write lock below
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if (UnlockFileEx(f->handle, 0, len, len >> 32, &ov)) {
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*flp = fl->next;
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ft = fl->next;
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FreeFileLock(fl);
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fl = ft;
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continue;
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} else {
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return -1;
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}
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}
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break;
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} else if (OverlapsFileLock(fl, off, len)) {
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return enotsup();
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}
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}
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flp = &fl->next;
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fl = *flp;
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}
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}
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// return better information on conflicting locks if possible
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if (cmd == F_GETLK) {
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for (fl = g_locks.list; fl; fl = fl->next) {
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if (fl->fd == fd && //
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OverlapsFileLock(fl, off, len) &&
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(l->l_type == F_WRLCK || !fl->exc)) {
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l->l_whence = SEEK_SET;
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l->l_start = fl->off;
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l->l_len = fl->len;
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l->l_type = fl->exc ? F_WRLCK : F_RDLCK;
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l->l_pid = getpid();
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return 0;
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}
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}
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}
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flags = 0;
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if (cmd != F_SETLKW) {
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// TODO(jart): we should use expo backoff in wrapper function
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// should not matter since sqlite doesn't need it
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flags |= kNtLockfileFailImmediately;
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}
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if (l->l_type == F_WRLCK) {
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flags |= kNtLockfileExclusiveLock;
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}
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ok = LockFileEx(f->handle, flags, 0, len, len >> 32, &ov);
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if (cmd == F_GETLK) {
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if (ok) {
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l->l_type = F_UNLCK;
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if (!UnlockFileEx(f->handle, 0, len, len >> 32, &ov)) {
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return -1;
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}
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} else {
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l->l_pid = -1;
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ok = true;
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}
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} else if (ok) {
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fl = NewFileLock();
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fl->off = off;
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fl->len = len;
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fl->exc = l->l_type == F_WRLCK;
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fl->fd = fd;
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}
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return ok ? 0 : -1;
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}
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if (l->l_type == F_UNLCK) {
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if (cmd == F_GETLK) return einval();
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// allow a big range to unlock many small ranges
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for (flp = &g_locks.list, fl = *flp; fl;) {
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if (fl->fd == fd && EncompassesFileLock(fl, off, len)) {
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struct NtOverlapped ov = {.hEvent = f->handle,
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.Pointer = (void *)(uintptr_t)fl->off};
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if (UnlockFileEx(f->handle, 0, fl->len, fl->len >> 32, &ov)) {
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*flp = fl->next;
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ft = fl->next;
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FreeFileLock(fl);
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fl = ft;
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} else {
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return -1;
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}
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} else {
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flp = &fl->next;
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fl = *flp;
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}
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}
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// win32 won't let us carve up existing locks
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int overlap_count = 0;
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for (fl = g_locks.list; fl; fl = fl->next) {
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if (fl->fd == fd && //
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OverlapsFileLock(fl, off, len)) {
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++overlap_count;
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}
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}
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// try to handle the carving cases needed by sqlite
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if (overlap_count == 1) {
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for (fl = g_locks.list; fl; fl = fl->next) {
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if (fl->fd == fd && //
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off <= fl->off && //
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off + len >= fl->off && //
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off + len < fl->off + fl->len) {
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// cleave left side of lock
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struct NtOverlapped ov = {.hEvent = f->handle,
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.Pointer = (void *)(uintptr_t)fl->off};
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if (!UnlockFileEx(f->handle, 0, fl->len, fl->len >> 32, &ov)) {
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return -1;
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}
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fl->len = (fl->off + fl->len) - (off + len);
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fl->off = off + len;
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ov.Pointer = (void *)(uintptr_t)fl->off;
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if (!LockFileEx(f->handle, kNtLockfileExclusiveLock, 0, fl->len,
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fl->len >> 32, &ov)) {
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return -1;
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}
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return 0;
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}
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}
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}
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if (overlap_count) {
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return enotsup();
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}
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return 0;
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}
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return einval();
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}
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static textwindows int sys_fcntl_nt_dupfd(int fd, int cmd, int start) {
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if (start < 0) return einval();
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return sys_dup_nt(fd, -1, (cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0), start);
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}
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static textwindows int sys_fcntl_nt_setfl(int fd, unsigned *flags,
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unsigned mode, unsigned arg,
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intptr_t *handle) {
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// you may change the following:
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//
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// - O_NONBLOCK make read() raise EAGAIN
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// - O_APPEND for toggling append mode
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// - O_RANDOM alt. for posix_fadvise()
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// - O_SEQUENTIAL alt. for posix_fadvise()
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// - O_DIRECT works but haven't tested
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//
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// the other bits are ignored.
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unsigned allowed = O_APPEND | O_SEQUENTIAL | O_RANDOM | O_DIRECT | O_NONBLOCK;
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unsigned needreo = O_APPEND | O_SEQUENTIAL | O_RANDOM | O_DIRECT;
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unsigned newflag = (*flags & ~allowed) | (arg & allowed);
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if ((*flags & needreo) ^ (arg & needreo)) {
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unsigned perm, share, attr;
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if (GetNtOpenFlags(newflag, mode, &perm, &share, 0, &attr) == -1) {
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return -1;
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}
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// MSDN says only these are allowed, otherwise it returns EINVAL.
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attr &= kNtFileFlagBackupSemantics | kNtFileFlagDeleteOnClose |
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kNtFileFlagNoBuffering | kNtFileFlagOpenNoRecall |
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kNtFileFlagOpenReparsePoint | kNtFileFlagOverlapped |
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kNtFileFlagPosixSemantics | kNtFileFlagRandomAccess |
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kNtFileFlagSequentialScan | kNtFileFlagWriteThrough;
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intptr_t hand;
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if ((hand = ReOpenFile(*handle, perm, share, attr)) != -1) {
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if (hand != *handle) {
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CloseHandle(*handle);
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*handle = hand;
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}
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} else {
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return __winerr();
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}
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}
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// 1. ignore flags that aren't access mode flags
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// 2. return zero if nothing's changed
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*flags = newflag;
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return 0;
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}
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textwindows int sys_fcntl_nt(int fd, int cmd, uintptr_t arg) {
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int rc;
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if (__isfdkind(fd, kFdFile) || //
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__isfdkind(fd, kFdSocket) || //
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__isfdkind(fd, kFdConsole)) {
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if (cmd == F_GETFL) {
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rc = g_fds.p[fd].flags & (O_ACCMODE | O_APPEND | O_DIRECT | O_NONBLOCK |
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O_RANDOM | O_SEQUENTIAL);
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} else if (cmd == F_SETFL) {
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rc = sys_fcntl_nt_setfl(fd, &g_fds.p[fd].flags, g_fds.p[fd].mode, arg,
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&g_fds.p[fd].handle);
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} else if (cmd == F_GETFD) {
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if (g_fds.p[fd].flags & O_CLOEXEC) {
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rc = FD_CLOEXEC;
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} else {
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rc = 0;
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}
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} else if (cmd == F_SETFD) {
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if (arg & FD_CLOEXEC) {
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g_fds.p[fd].flags |= O_CLOEXEC;
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} else {
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g_fds.p[fd].flags &= ~O_CLOEXEC;
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}
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rc = 0;
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} else if (cmd == F_SETLK || cmd == F_SETLKW || cmd == F_GETLK) {
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pthread_mutex_lock(&g_locks.mu);
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rc = sys_fcntl_nt_lock(g_fds.p + fd, fd, cmd, arg);
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pthread_mutex_unlock(&g_locks.mu);
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} else if (cmd == F_DUPFD || cmd == F_DUPFD_CLOEXEC) {
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rc = sys_fcntl_nt_dupfd(fd, cmd, arg);
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} else {
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rc = einval();
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}
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} else {
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rc = ebadf();
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}
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return rc;
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}
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