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package internal
import (
"errors"
"io/fs"
"os"
"os/exec"
"os/user"
"path"
"strconv"
"sync"
"git.ophivana.moe/security/fortify/internal/fmsg"
)
// System provides safe access to operating system resources.
type System interface {
// Geteuid provides [os.Geteuid].
Geteuid() int
// LookupEnv provides [os.LookupEnv].
LookupEnv(key string) (string, bool)
// TempDir provides [os.TempDir].
TempDir() string
// LookPath provides [exec.LookPath].
LookPath(file string) (string, error)
// Executable provides [os.Executable].
Executable() (string, error)
// Lookup provides [user.Lookup].
Lookup(username string) (*user.User, error)
// ReadDir provides [os.ReadDir].
ReadDir(name string) ([]fs.DirEntry, error)
// Stat provides [os.Stat].
Stat(name string) (fs.FileInfo, error)
// Open provides [os.Open]
Open(name string) (fs.File, error)
// Exit provides [os.Exit].
Exit(code int)
// Paths returns a populated [Paths] struct.
Paths() Paths
// SdBooted implements https://www.freedesktop.org/software/systemd/man/sd_booted.html
SdBooted() bool
}
// Paths contains environment dependent paths used by fortify.
type Paths struct {
// path to shared directory e.g. /tmp/fortify.%d
SharePath string `json:"share_path"`
// XDG_RUNTIME_DIR value e.g. /run/user/%d
RuntimePath string `json:"runtime_path"`
// application runtime directory e.g. /run/user/%d/fortify
RunDirPath string `json:"run_dir_path"`
}
// CopyPaths is a generic implementation of [System.Paths].
func CopyPaths(os System, v *Paths) {
v.SharePath = path.Join(os.TempDir(), "fortify."+strconv.Itoa(os.Geteuid()))
fmsg.VPrintf("process share directory at %q", v.SharePath)
if r, ok := os.LookupEnv(xdgRuntimeDir); !ok || r == "" || !path.IsAbs(r) {
// fall back to path in share since fortify has no hard XDG dependency
v.RunDirPath = path.Join(v.SharePath, "run")
v.RuntimePath = path.Join(v.RunDirPath, "compat")
} else {
v.RuntimePath = r
v.RunDirPath = path.Join(v.RuntimePath, "fortify")
}
fmsg.VPrintf("runtime directory at %q", v.RunDirPath)
}
// Std implements System using the standard library.
type Std struct {
paths Paths
pathsOnce sync.Once
sdBooted bool
sdBootedOnce sync.Once
}
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) Lookup(username string) (*user.User, error) { return user.Lookup(username) }
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) }
const xdgRuntimeDir = "XDG_RUNTIME_DIR"
func (s *Std) Paths() Paths {
s.pathsOnce.Do(func() { CopyPaths(s, &s.paths) })
return s.paths
}
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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