Do not rely on HOME variable being set.HEADmaster

Additionally, respect the XDG Base Directory Specification and
handle an unset USER variable.

See https://lists.gnu.org/archive/html/gash-devel/2024-12/msg00000.html

* gash/gash.scm (get-history-file): New procedure.
(main): Use it, and only read and write history when the filename
can be determined.
(prompt): Handle unset HOME and USER variables.

1 files changed, 17 insertions, 6 deletions

diff --git a/gash/gash.scm b/gash/gash.scm
index 68838e1..edf1336 100644
--- a/gash/gash.scm
+++ b/gash/gash.scm
@@ -1,6 +1,6 @@
 ;;; Gash --- Guile As SHell
 ;;; Copyright © 2016,2017,2018 R.E.W. van Beusekom <[email protected]>
-;;; Copyright © 2018, 2019 Timothy Sample <[email protected]>
+;;; Copyright © 2018, 2019, 2024 Timothy Sample <[email protected]>
 ;;; Copyright © 2018 Jan (janneke) Nieuwenhuizen <[email protected]>
 ;;;
 ;;; The careful invocation of 'seclocale' was taken from the
@@ -42,6 +42,7 @@
   #:use-module (ice-9 receive)
   #:use-module (ice-9 regex)
   #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-2)
   #:use-module (srfi srfi-26)
   #:export (main))
 
@@ -85,6 +86,14 @@ This is free software: you are free to change and redistribute it.
 There is NO WARRANTY, to the extent permitted by law.
 ")))
 
+(define (get-history-file)
+  "Lookup the location of the history file from the system environment.
+If the location cannot be determined, return @code{#f}."
+  (and-let* ((config-home (or (getenv "XDG_CONFIG_HOME")
+                              (and-let* ((home (getenv "HOME")))
+                                (string-append home "/.config")))))
+    (string-append config-home "/gash-history")))
+
 (define (main args)
   (let ((thunk
          (lambda ()
@@ -120,7 +129,7 @@ There is NO WARRANTY, to the extent permitted by law.
                    (lambda (port)
                      (exit (run-repl port parse?))))))
               ((isatty? (current-input-port))
-               (let* ((HOME (string-append (getenv "HOME") "/.gash_history"))
+               (let* ((history-file (get-history-file))
                       (thunk (lambda ()
                                (let loop ((line (readline (prompt))))
                                  (when (not (eof-object? line))
@@ -137,9 +146,11 @@ There is NO WARRANTY, to the extent permitted by law.
                                              (if (eof-object? next) next
                                                  (string-append previous next))))))))))
                  (clear-history)
-                 (read-history HOME)
+                 (when history-file
+                   (read-history history-file))
                  (with-readline-completion-function completion thunk)
-                 (write-history HOME)
+                 (when history-file
+                   (write-history history-file))
                  (newline)))
               (else (exit (run-repl (current-input-port) parse?))))))))
     (thunk)))
@@ -148,12 +159,12 @@ There is NO WARRANTY, to the extent permitted by law.
   (let* ((l (string #\001))
          (r (string #\002))
          (e (string #\033))
-         (user (getenv "USER"))
+         (user (or (getenv "USER") ""))
          (host (gethostname))
          (home (getenv "HOME")))
     (lambda ()
       (let* ((cwd (getcwd))
-             (cwd (if (string-prefix? home cwd)
+             (cwd (if (and home (string-prefix? home cwd))
                       (string-replace cwd "~" 0 (string-length home))
                       cwd)))
         (string-append