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package linux
import (
"errors"
"io"
"io/fs"
"os"
"os/exec"
"os/user"
"strconv"
"sync"
"git.ophivana.moe/security/fortify/internal"
"git.ophivana.moe/security/fortify/internal/fmsg"
)
// Std implements System using the standard library.
type Std struct {
paths Paths
pathsOnce sync.Once
sdBooted bool
sdBootedOnce sync.Once
uidOnce sync.Once
uidCopy map[int]struct {
uid int
err error
}
uidMu sync.RWMutex
}
func (s *Std) Geteuid() int { return os.Geteuid() }
func (s *Std) LookupEnv(key string) (string, bool) { return os.LookupEnv(key) }
func (s *Std) TempDir() string { return os.TempDir() }
func (s *Std) LookPath(file string) (string, error) { return exec.LookPath(file) }
func (s *Std) Executable() (string, error) { return os.Executable() }
func (s *Std) LookupGroup(name string) (*user.Group, error) { return user.LookupGroup(name) }
func (s *Std) ReadDir(name string) ([]os.DirEntry, error) { return os.ReadDir(name) }
func (s *Std) Stat(name string) (fs.FileInfo, error) { return os.Stat(name) }
func (s *Std) Open(name string) (fs.File, error) { return os.Open(name) }
func (s *Std) Exit(code int) { fmsg.Exit(code) }
func (s *Std) Stdout() io.Writer { return os.Stdout }
const xdgRuntimeDir = "XDG_RUNTIME_DIR"
func (s *Std) Paths() Paths {
s.pathsOnce.Do(func() { CopyPaths(s, &s.paths) })
return s.paths
}
func (s *Std) Uid(aid int) (int, error) {
s.uidOnce.Do(func() {
s.uidCopy = make(map[int]struct {
uid int
err error
})
})
s.uidMu.RLock()
if u, ok := s.uidCopy[aid]; ok {
s.uidMu.RUnlock()
return u.uid, u.err
}
s.uidMu.RUnlock()
s.uidMu.Lock()
defer s.uidMu.Unlock()
u := struct {
uid int
err error
}{}
defer func() { s.uidCopy[aid] = u }()
u.uid = -1
if fsu, ok := internal.Check(internal.Fsu); !ok {
fmsg.Fatal("invalid fsu path, this copy of fshim is not compiled correctly")
panic("unreachable")
} else {
cmd := exec.Command(fsu)
cmd.Path = fsu
cmd.Stderr = os.Stderr // pass through fatal messages
cmd.Env = []string{"FORTIFY_APP_ID=" + strconv.Itoa(aid)}
cmd.Dir = "/"
var p []byte
if p, u.err = cmd.Output(); u.err == nil {
u.uid, u.err = strconv.Atoi(string(p))
}
return u.uid, u.err
}
}
func (s *Std) SdBooted() bool {
s.sdBootedOnce.Do(func() { s.sdBooted = copySdBooted() })
return s.sdBooted
}
const systemdCheckPath = "/run/systemd/system"
func copySdBooted() bool {
if v, err := sdBooted(); err != nil {
fmsg.Println("cannot read systemd marker:", err)
return false
} else {
return v
}
}
func sdBooted() (bool, error) {
_, err := os.Stat(systemdCheckPath)
if err != nil {
if errors.Is(err, fs.ErrNotExist) {
err = nil
}
return false, err
}
return true, nil
}
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