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2278327eba
This change makes some miracle modifications to the System Five system call support, which lets us have safe, correct, and atomic handling of thread cancellations. It all turned out to be cheaper than anticipated because it wasn't necessary to modify the system call veneers. We were able to encode the cancellability of each system call into the magnums found in libc/sysv/syscalls.sh. Since cancellations are so waq, we are also supporting a lovely Musl Libc mask feature for raising ECANCELED.
220 lines
8.1 KiB
C
220 lines
8.1 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/calls.h"
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#include "libc/calls/internal.h"
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#include "libc/calls/sig.internal.h"
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#include "libc/calls/state.internal.h"
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#include "libc/calls/struct/sigaction.h"
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#include "libc/intrin/bits.h"
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#include "libc/intrin/strace.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/enum/filetype.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/ipc.h"
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#include "libc/nt/runtime.h"
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#include "libc/nt/struct/pollfd.h"
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#include "libc/nt/synchronization.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/sock/struct/pollfd.h"
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#include "libc/sock/struct/pollfd.internal.h"
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#include "libc/sysv/consts/o.h"
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#include "libc/sysv/consts/poll.h"
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#include "libc/sysv/consts/sig.h"
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#include "libc/sysv/errfuns.h"
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/*
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* Polls on the New Technology.
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*
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* This function is used to implement poll() and select(). You may poll
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* on both sockets and files at the same time. We also poll for signals
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* while poll is polling.
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*/
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textwindows int sys_poll_nt(struct pollfd *fds, uint64_t nfds, uint64_t *ms,
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const sigset_t *sigmask) {
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bool ok;
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uint32_t avail;
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sigset_t oldmask;
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struct sys_pollfd_nt pipefds[8];
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struct sys_pollfd_nt sockfds[64];
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int pipeindices[ARRAYLEN(pipefds)];
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int sockindices[ARRAYLEN(sockfds)];
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int i, rc, sn, pn, gotinvals, gotpipes, gotsocks, waitfor;
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// check for interrupts early before doing work
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if (sigmask) {
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__sig_mask(SIG_SETMASK, sigmask, &oldmask);
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}
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if ((rc = _check_interrupts(false, g_fds.p))) {
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goto ReturnPath;
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}
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// do the planning
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// we need to read static variables
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// we might need to spawn threads and open pipes
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__fds_lock();
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for (gotinvals = rc = sn = pn = i = 0; i < nfds; ++i) {
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if (fds[i].fd < 0) continue;
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if (__isfdopen(fds[i].fd)) {
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if (__isfdkind(fds[i].fd, kFdSocket)) {
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if (sn < ARRAYLEN(sockfds)) {
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// the magnums for POLLIN/OUT/PRI on NT include the other ones too
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// we need to clear ones like POLLNVAL or else WSAPoll shall whine
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sockindices[sn] = i;
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sockfds[sn].handle = g_fds.p[fds[i].fd].handle;
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sockfds[sn].events = fds[i].events & (POLLPRI | POLLIN | POLLOUT);
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sockfds[sn].revents = 0;
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++sn;
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} else {
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// too many socket fds
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rc = enomem();
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break;
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}
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} else if (pn < ARRAYLEN(pipefds)) {
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pipeindices[pn] = i;
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pipefds[pn].handle = g_fds.p[fds[i].fd].handle;
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pipefds[pn].events = 0;
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pipefds[pn].revents = 0;
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switch (g_fds.p[fds[i].fd].flags & O_ACCMODE) {
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case O_RDONLY:
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pipefds[pn].events = fds[i].events & POLLIN;
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break;
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case O_WRONLY:
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pipefds[pn].events = fds[i].events & POLLOUT;
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break;
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case O_RDWR:
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pipefds[pn].events = fds[i].events & (POLLIN | POLLOUT);
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break;
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default:
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unreachable;
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}
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++pn;
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} else {
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// too many non-socket fds
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rc = enomem();
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break;
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}
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} else {
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++gotinvals;
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}
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}
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__fds_unlock();
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if (rc) {
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// failed to create a polling solution
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goto ReturnPath;
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}
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// perform the i/o and sleeping and looping
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for (;;) {
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// see if input is available on non-sockets
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for (gotpipes = i = 0; i < pn; ++i) {
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if (pipefds[i].events & POLLOUT) {
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// we have no way of polling if a non-socket is writeable yet
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// therefore we assume that if it can happen, it shall happen
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pipefds[i].revents = POLLOUT;
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}
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if (pipefds[i].events & POLLIN) {
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if (GetFileType(pipefds[i].handle) == kNtFileTypePipe) {
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ok = PeekNamedPipe(pipefds[i].handle, 0, 0, 0, &avail, 0);
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POLLTRACE("PeekNamedPipe(%ld, 0, 0, 0, [%'u], 0) → %hhhd% m",
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pipefds[i].handle, avail, ok);
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if (ok) {
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if (avail) {
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pipefds[i].revents = POLLIN;
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}
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} else {
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pipefds[i].revents = POLLERR;
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}
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} else {
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// we have no way of polling if a non-socket is readable yet
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// therefore we assume that if it can happen it shall happen
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pipefds[i].revents = POLLIN;
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}
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}
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if (pipefds[i].revents) {
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++gotpipes;
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}
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}
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// if we haven't found any good results yet then here we
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// compute a small time slice we don't mind sleeping for
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waitfor = gotinvals || gotpipes ? 0 : MIN(__SIG_POLLING_INTERVAL_MS, *ms);
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if (sn) {
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// we need to poll the socket handles separately because
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// microsoft certainly loves to challenge us with coding
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// please note that winsock will fail if we pass zero fd
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#if _NTTRACE
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POLLTRACE("WSAPoll(%p, %u, %'d) out of %'lu", sockfds, sn, waitfor, *ms);
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#endif
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if ((gotsocks = WSAPoll(sockfds, sn, waitfor)) == -1) {
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rc = __winsockerr();
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goto ReturnPath;
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}
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*ms -= waitfor;
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} else {
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gotsocks = 0;
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if (!gotinvals && !gotpipes && waitfor) {
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// if we've only got pipes and none of them are ready
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// then we'll just explicitly sleep for the time left
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POLLTRACE("SleepEx(%'d, false) out of %'lu", waitfor, *ms);
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if (SleepEx(__SIG_POLLING_INTERVAL_MS, true) == kNtWaitIoCompletion) {
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POLLTRACE("IOCP EINTR");
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} else {
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*ms -= waitfor;
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}
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}
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}
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// we gave all the sockets and all the named pipes a shot
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// if we found anything at all then it's time to end work
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if (gotinvals || gotpipes || gotsocks || *ms <= 0) {
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break;
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}
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// otherwise loop limitlessly for timeout to elapse while
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// checking for signal delivery interrupts, along the way
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if ((rc = _check_interrupts(false, g_fds.p))) {
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goto ReturnPath;
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}
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}
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// the system call is going to succeed
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// it's now ok to start setting the output memory
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for (i = 0; i < nfds; ++i) {
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if (fds[i].fd < 0 || __isfdopen(fds[i].fd)) {
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fds[i].revents = 0;
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} else {
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fds[i].revents = POLLNVAL;
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}
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}
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for (i = 0; i < pn; ++i) {
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fds[pipeindices[i]].revents = pipefds[i].revents;
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}
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for (i = 0; i < sn; ++i) {
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fds[sockindices[i]].revents = sockfds[i].revents;
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}
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// and finally return
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rc = gotinvals + gotpipes + gotsocks;
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ReturnPath:
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if (sigmask) {
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__sig_mask(SIG_SETMASK, &oldmask, 0);
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}
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return rc;
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}
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