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backend: Use IoctlSetPointerInt for tcsetpgrp

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This function casts its argument to int32 before passing it to the
system call, so that big-endian CPUs read the lower rather than the
upper 32 bits of the pid.

This also gets rid of the last import of "unsafe" in the Unix build.
I changed syscall to x/sys/unix while I was at it, to remove one more
import line. The constants and types there are aliases for their syscall
counterparts.
This commit is contained in:
greatroar 2023-05-25 17:31:51 +02:00
parent ddbc0c1b37
commit 51dc80be5b
1 changed files with 11 additions and 15 deletions
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26
internal/backend/foreground_unix.go
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@ -7,21 +7,17 @@ import (
"os"
"os/exec"
"os/signal"
"syscall"
"unsafe"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
"golang.org/x/sys/unix"
)
func tcsetpgrp(fd int, pid int) error {
_, _, errno := syscall.RawSyscall(syscall.SYS_IOCTL, uintptr(fd),
uintptr(syscall.TIOCSPGRP), uintptr(unsafe.Pointer(&pid)))
if errno == 0 {
return nil
}
return errno
// IoctlSetPointerInt silently casts to int32 internally,
// so this assumes pid fits in 31 bits.
return unix.IoctlSetPointerInt(fd, unix.TIOCSPGRP, pid)
}
func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
@ -35,11 +31,11 @@ func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
return bg, cmd.Start()
}
signal.Ignore(syscall.SIGTTIN)
signal.Ignore(syscall.SIGTTOU)
signal.Ignore(unix.SIGTTIN)
signal.Ignore(unix.SIGTTOU)
// run the command in its own process group
cmd.SysProcAttr = &syscall.SysProcAttr{
cmd.SysProcAttr = &unix.SysProcAttr{
Setpgid: true,
}
@ -51,7 +47,7 @@ func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
}
// move the command's process group into the foreground
prev := syscall.Getpgrp()
prev := unix.Getpgrp()
err = tcsetpgrp(int(tty.Fd()), cmd.Process.Pid)
if err != nil {
_ = tty.Close()
@ -59,8 +55,8 @@ func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
}
bg = func() error {
signal.Reset(syscall.SIGTTIN)
signal.Reset(syscall.SIGTTOU)
signal.Reset(unix.SIGTTIN)
signal.Reset(unix.SIGTTOU)
// reset the foreground process group
err = tcsetpgrp(int(tty.Fd()), prev)