107 lines
2.4 KiB
Go
107 lines
2.4 KiB
Go
package helper
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import (
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"flag"
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"fmt"
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"io"
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"os"
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"strconv"
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"syscall"
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)
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// InternalHelperStub is an internal function but exported because it is cross-package;
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// it is part of the implementation of the helper stub.
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func InternalHelperStub() {
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// this test mocks the helper process
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var ap, sp string
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if v, ok := os.LookupEnv(FortifyHelper); !ok {
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return
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} else {
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ap = v
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}
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if v, ok := os.LookupEnv(FortifyStatus); !ok {
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panic(FortifyStatus)
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} else {
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sp = v
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}
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genericStub(flagRestoreFiles(3, ap, sp))
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os.Exit(0)
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}
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func newFile(fd int, name, p string) *os.File {
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present := false
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switch p {
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case "0":
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case "1":
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present = true
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default:
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panic(fmt.Sprintf("%s fd has unexpected presence value %q", name, p))
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}
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f := os.NewFile(uintptr(fd), name)
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if !present && f != nil {
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panic(fmt.Sprintf("%s fd set but not present", name))
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}
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if present && f == nil {
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panic(fmt.Sprintf("%s fd preset but unset", name))
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}
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return f
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}
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func flagRestoreFiles(offset int, ap, sp string) (argsFile, statFile *os.File) {
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argsFd := flag.Int("args", -1, "")
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statFd := flag.Int("fd", -1, "")
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_ = flag.CommandLine.Parse(os.Args[offset:])
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argsFile = newFile(*argsFd, "args", ap)
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statFile = newFile(*statFd, "stat", sp)
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return
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}
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func genericStub(argsFile, statFile *os.File) {
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if argsFile != nil {
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// this output is checked by parent
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if _, err := io.Copy(os.Stdout, argsFile); err != nil {
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panic("cannot read args: " + err.Error())
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}
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}
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// simulate status pipe behaviour
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if statFile != nil {
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if _, err := statFile.Write([]byte{'x'}); err != nil {
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panic("cannot write to status pipe: " + err.Error())
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}
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done := make(chan struct{})
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go func() {
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// wait for status pipe close
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var epoll int
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if fd, err := syscall.EpollCreate1(0); err != nil {
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panic("cannot open epoll fd: " + err.Error())
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} else {
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defer func() {
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if err = syscall.Close(fd); err != nil {
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panic("cannot close epoll fd: " + err.Error())
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}
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}()
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epoll = fd
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}
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if err := syscall.EpollCtl(epoll, syscall.EPOLL_CTL_ADD, int(statFile.Fd()), &syscall.EpollEvent{}); err != nil {
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panic("cannot add status pipe to epoll: " + err.Error())
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}
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events := make([]syscall.EpollEvent, 1)
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if _, err := syscall.EpollWait(epoll, events, -1); err != nil {
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panic("cannot poll status pipe: " + err.Error())
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}
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if events[0].Events != syscall.EPOLLERR {
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panic(strconv.Itoa(int(events[0].Events)))
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}
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close(done)
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}()
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<-done
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}
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}
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