(battery-status-function) Fix errors in Termux

* lisp/battery.el (battery-status-function): In Termux, neither
/sys/ or /proc/ are readable on phones that are not rooted. This
patch makes Emacs verify if they are readable before it attemps
reading them (bug#53026).

Copyright-paperwork-exempt: yes

diff --git a/lisp/battery.el b/lisp/battery.el
index 45334163fa647aaaedaf221041a00bbb646e0d74..b7b81a11a1c918809d1f0bc22e0e40a4811e64d4 100644 (file)
--- a/lisp/battery.el
+++ b/lisp/battery.el
@@ -96,12 +96,14 @@ Value does not include \".\" or \"..\"."
   (cond ((member battery-upower-service (dbus-list-activatable-names))
          #'battery-upower)
         ((and (eq system-type 'gnu/linux)
+              (file-readable-p "/sys/")
               (battery--find-linux-sysfs-batteries))
          #'battery-linux-sysfs)
        ((and (eq system-type 'gnu/linux)
              (file-directory-p "/proc/acpi/battery"))
         #'battery-linux-proc-acpi)
        ((and (eq system-type 'gnu/linux)
+              (file-readable-p "/proc/")
               (file-readable-p "/proc/apm"))
          #'battery-linux-proc-apm)
        ((and (eq system-type 'berkeley-unix)