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package outcome
import (
"errors"
"fmt"
"log"
"os"
"os/exec"
"strconv"
"sync"
"hakurei.app/container/fhs"
"hakurei.app/hst"
"hakurei.app/message"
)
// Hsu caches responses from cmd/hsu.
type Hsu struct {
idOnce sync.Once
idErr error
id int
kOnce sync.Once
// msg is not populated
k syscallDispatcher
}
var ErrHsuAccess = errors.New("current user is not in the hsurc file")
// ensureDispatcher ensures Hsu.k is not nil.
func (h *Hsu) ensureDispatcher() {
h.kOnce.Do(func() {
if h.k == nil {
h.k = direct{}
}
})
}
// ID returns the current user hsurc identifier.
// [ErrHsuAccess] is returned if the current user is not in hsurc.
func (h *Hsu) ID() (int, error) {
h.ensureDispatcher()
h.idOnce.Do(func() {
h.id = -1
hsuPath := h.k.mustHsuPath().String()
cmd := exec.Command(hsuPath)
cmd.Path = hsuPath
cmd.Stderr = os.Stderr // pass through fatal messages
cmd.Env = make([]string, 0)
cmd.Dir = fhs.Root
var (
p []byte
exitError *exec.ExitError
)
const step = "obtain uid from hsu"
if p, h.idErr = h.k.cmdOutput(cmd); h.idErr == nil {
h.id, h.idErr = strconv.Atoi(string(p))
if h.idErr != nil {
h.idErr = &hst.AppError{Step: step, Err: h.idErr, Msg: "invalid uid string from hsu"}
}
} else if errors.As(h.idErr, &exitError) && exitError != nil && exitError.ExitCode() == 1 {
// hsu prints an error message in this case
h.idErr = &hst.AppError{Step: step, Err: ErrHsuAccess}
} else if errors.Is(h.idErr, os.ErrNotExist) {
h.idErr = &hst.AppError{Step: step, Err: h.idErr,
Msg: fmt.Sprintf("the setuid helper is missing: %s", hsuPath)}
}
})
return h.id, h.idErr
}
// MustID calls [Hsu.ID] and terminates on error.
func (h *Hsu) MustID(msg message.Msg) int {
id, err := h.ID()
if err == nil {
return id
}
const fallback = "cannot retrieve user id from setuid wrapper:"
if errors.Is(err, ErrHsuAccess) {
if msg != nil {
msg.Verbose("*"+fallback, err)
}
os.Exit(1)
return -0xbad // not reached
} else if m, ok := message.GetMessage(err); ok {
log.Fatal(m)
return -0xbad // not reached
} else {
log.Fatalln(fallback, err)
return -0xbad // not reached
}
}
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