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Diffstat (limited to '')
-rw-r--r-- | dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/epoll_zos.go | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/epoll_zos.go b/dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/epoll_zos.go new file mode 100644 index 0000000..cedaf7e --- /dev/null +++ b/dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/epoll_zos.go @@ -0,0 +1,221 @@ +// Copyright 2020 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +//go:build zos && s390x +// +build zos,s390x + +package unix + +import ( + "sync" +) + +// This file simulates epoll on z/OS using poll. + +// Analogous to epoll_event on Linux. +// TODO(neeilan): Pad is because the Linux kernel expects a 96-bit struct. We never pass this to the kernel; remove? +type EpollEvent struct { + Events uint32 + Fd int32 + Pad int32 +} + +const ( + EPOLLERR = 0x8 + EPOLLHUP = 0x10 + EPOLLIN = 0x1 + EPOLLMSG = 0x400 + EPOLLOUT = 0x4 + EPOLLPRI = 0x2 + EPOLLRDBAND = 0x80 + EPOLLRDNORM = 0x40 + EPOLLWRBAND = 0x200 + EPOLLWRNORM = 0x100 + EPOLL_CTL_ADD = 0x1 + EPOLL_CTL_DEL = 0x2 + EPOLL_CTL_MOD = 0x3 + // The following constants are part of the epoll API, but represent + // currently unsupported functionality on z/OS. + // EPOLL_CLOEXEC = 0x80000 + // EPOLLET = 0x80000000 + // EPOLLONESHOT = 0x40000000 + // EPOLLRDHUP = 0x2000 // Typically used with edge-triggered notis + // EPOLLEXCLUSIVE = 0x10000000 // Exclusive wake-up mode + // EPOLLWAKEUP = 0x20000000 // Relies on Linux's BLOCK_SUSPEND capability +) + +// TODO(neeilan): We can eliminate these epToPoll / pToEpoll calls by using identical mask values for POLL/EPOLL +// constants where possible The lower 16 bits of epoll events (uint32) can fit any system poll event (int16). + +// epToPollEvt converts epoll event field to poll equivalent. +// In epoll, Events is a 32-bit field, while poll uses 16 bits. +func epToPollEvt(events uint32) int16 { + var ep2p = map[uint32]int16{ + EPOLLIN: POLLIN, + EPOLLOUT: POLLOUT, + EPOLLHUP: POLLHUP, + EPOLLPRI: POLLPRI, + EPOLLERR: POLLERR, + } + + var pollEvts int16 = 0 + for epEvt, pEvt := range ep2p { + if (events & epEvt) != 0 { + pollEvts |= pEvt + } + } + + return pollEvts +} + +// pToEpollEvt converts 16 bit poll event bitfields to 32-bit epoll event fields. +func pToEpollEvt(revents int16) uint32 { + var p2ep = map[int16]uint32{ + POLLIN: EPOLLIN, + POLLOUT: EPOLLOUT, + POLLHUP: EPOLLHUP, + POLLPRI: EPOLLPRI, + POLLERR: EPOLLERR, + } + + var epollEvts uint32 = 0 + for pEvt, epEvt := range p2ep { + if (revents & pEvt) != 0 { + epollEvts |= epEvt + } + } + + return epollEvts +} + +// Per-process epoll implementation. +type epollImpl struct { + mu sync.Mutex + epfd2ep map[int]*eventPoll + nextEpfd int +} + +// eventPoll holds a set of file descriptors being watched by the process. A process can have multiple epoll instances. +// On Linux, this is an in-kernel data structure accessed through a fd. +type eventPoll struct { + mu sync.Mutex + fds map[int]*EpollEvent +} + +// epoll impl for this process. +var impl epollImpl = epollImpl{ + epfd2ep: make(map[int]*eventPoll), + nextEpfd: 0, +} + +func (e *epollImpl) epollcreate(size int) (epfd int, err error) { + e.mu.Lock() + defer e.mu.Unlock() + epfd = e.nextEpfd + e.nextEpfd++ + + e.epfd2ep[epfd] = &eventPoll{ + fds: make(map[int]*EpollEvent), + } + return epfd, nil +} + +func (e *epollImpl) epollcreate1(flag int) (fd int, err error) { + return e.epollcreate(4) +} + +func (e *epollImpl) epollctl(epfd int, op int, fd int, event *EpollEvent) (err error) { + e.mu.Lock() + defer e.mu.Unlock() + + ep, ok := e.epfd2ep[epfd] + if !ok { + + return EBADF + } + + switch op { + case EPOLL_CTL_ADD: + // TODO(neeilan): When we make epfds and fds disjoint, detect epoll + // loops here (instances watching each other) and return ELOOP. + if _, ok := ep.fds[fd]; ok { + return EEXIST + } + ep.fds[fd] = event + case EPOLL_CTL_MOD: + if _, ok := ep.fds[fd]; !ok { + return ENOENT + } + ep.fds[fd] = event + case EPOLL_CTL_DEL: + if _, ok := ep.fds[fd]; !ok { + return ENOENT + } + delete(ep.fds, fd) + + } + return nil +} + +// Must be called while holding ep.mu +func (ep *eventPoll) getFds() []int { + fds := make([]int, len(ep.fds)) + for fd := range ep.fds { + fds = append(fds, fd) + } + return fds +} + +func (e *epollImpl) epollwait(epfd int, events []EpollEvent, msec int) (n int, err error) { + e.mu.Lock() // in [rare] case of concurrent epollcreate + epollwait + ep, ok := e.epfd2ep[epfd] + + if !ok { + e.mu.Unlock() + return 0, EBADF + } + + pollfds := make([]PollFd, 4) + for fd, epollevt := range ep.fds { + pollfds = append(pollfds, PollFd{Fd: int32(fd), Events: epToPollEvt(epollevt.Events)}) + } + e.mu.Unlock() + + n, err = Poll(pollfds, msec) + if err != nil { + return n, err + } + + i := 0 + for _, pFd := range pollfds { + if pFd.Revents != 0 { + events[i] = EpollEvent{Fd: pFd.Fd, Events: pToEpollEvt(pFd.Revents)} + i++ + } + + if i == n { + break + } + } + + return n, nil +} + +func EpollCreate(size int) (fd int, err error) { + return impl.epollcreate(size) +} + +func EpollCreate1(flag int) (fd int, err error) { + return impl.epollcreate1(flag) +} + +func EpollCtl(epfd int, op int, fd int, event *EpollEvent) (err error) { + return impl.epollctl(epfd, op, fd, event) +} + +// Because EpollWait mutates events, the caller is expected to coordinate +// concurrent access if calling with the same epfd from multiple goroutines. +func EpollWait(epfd int, events []EpollEvent, msec int) (n int, err error) { + return impl.epollwait(epfd, events, msec) +} |