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2494b91604
From a safety perspective this might not be strictly required, but it paves the way for us to remove utils.ProcThreadSelf. Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
45 lines
1.1 KiB
Go
45 lines
1.1 KiB
Go
package linux
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import (
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"os"
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"golang.org/x/sys/unix"
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)
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// Readlinkat wraps [unix.Readlinkat].
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func Readlinkat(dir *os.File, path string) (string, error) {
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size := 4096
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for {
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linkBuf := make([]byte, size)
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n, err := unix.Readlinkat(int(dir.Fd()), path, linkBuf)
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if err != nil {
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return "", &os.PathError{Op: "readlinkat", Path: dir.Name() + "/" + path, Err: err}
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}
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if n != size {
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return string(linkBuf[:n]), nil
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}
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// Possible truncation, resize the buffer.
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size *= 2
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}
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}
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// GetPtyPeer is a wrapper for ioctl(TIOCGPTPEER).
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func GetPtyPeer(ptyFd uintptr, unsafePeerPath string, flags int) (*os.File, error) {
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// Make sure O_NOCTTY is always set -- otherwise runc might accidentally
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// gain it as a controlling terminal. O_CLOEXEC also needs to be set to
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// make sure we don't leak the handle either.
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flags |= unix.O_NOCTTY | unix.O_CLOEXEC
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// There is no nice wrapper for this kind of ioctl in unix.
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peerFd, _, errno := unix.Syscall(
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unix.SYS_IOCTL,
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ptyFd,
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uintptr(unix.TIOCGPTPEER),
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uintptr(flags),
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)
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if errno != 0 {
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return nil, os.NewSyscallError("ioctl TIOCGPTPEER", errno)
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}
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return os.NewFile(peerFd, unsafePeerPath), nil
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}
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