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//go:build unix
package shell
import (
"fmt"
"os"
"path/filepath"
"syscall"
"src.elv.sh/pkg/env"
"src.elv.sh/pkg/fsutil"
)
func defaultConfigHome() (string, error) { return homePath(".config") }
func defaultDataHome() (string, error) { return homePath(".local/share") }
var defaultDataDirs = []string{
"/usr/local/share/elvish/lib",
"/usr/share/elvish/lib",
}
func defaultStateHome() (string, error) { return homePath(".local/state") }
func homePath(suffix string) (string, error) {
home, err := fsutil.GetHome("")
if err != nil {
return "", fmt.Errorf("resolve ~/%s: %w", suffix, err)
}
return filepath.Join(home, suffix), nil
}
// Returns a "run directory" for storing ephemeral files, which is guaranteed
// to be only accessible to the current user.
//
// The path of the run directory is either $XDG_RUNTIME_DIR/elvish or
// $tmpdir/elvish-$uid (where $tmpdir is the system temporary directory). The
// former is used if the XDG_RUNTIME_DIR environment variable exists and the
// latter directory does not exist.
func secureRunDir() (string, error) {
runDirs := runDirCandidates()
for _, runDir := range runDirs {
if checkExclusiveAccess(runDir) {
return runDir, nil
}
}
runDir := runDirs[0]
err := os.MkdirAll(runDir, 0700)
if err != nil {
return "", fmt.Errorf("mkdir: %v", err)
}
if !checkExclusiveAccess(runDir) {
return "", fmt.Errorf("cannot create %v as a secure run directory", runDir)
}
return runDir, nil
}
// Returns one or more candidates for the run directory, in descending order of
// preference.
func runDirCandidates() []string {
tmpDirPath := filepath.Join(os.TempDir(), fmt.Sprintf("elvish-%d", os.Getuid()))
if os.Getenv(env.XDG_RUNTIME_DIR) != "" {
xdgDirPath := filepath.Join(os.Getenv(env.XDG_RUNTIME_DIR), "elvish")
return []string{xdgDirPath, tmpDirPath}
}
return []string{tmpDirPath}
}
func checkExclusiveAccess(runDir string) bool {
info, err := os.Stat(runDir)
if err != nil {
return false
}
stat := info.Sys().(*syscall.Stat_t)
return info.IsDir() && int(stat.Uid) == os.Getuid() && stat.Mode&077 == 0
}
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