Fix battery detection for non-Linux systems

Some non-Linux systems do not have a `/sys/` directory. Therefore,
check it only if we are in a Linux system.

Fixes #19

eshell-info-banner.el

@@ -2,7 +2,7 @@
 
 ;; Author: Lucien Cartier-Tilet <lucien@phundrak.com>
 ;; Maintainer: Lucien Cartier-Tilet <lucien@phundrak.com>
-;; Version: 0.8.1
+;; Version: 0.8.3
 ;; Package-Requires: ((emacs "25.1") (f "0.20") (s "1"))
 ;; Homepage: https://github.com/Phundrak/eshell-info-banner.el
 
@@ -65,7 +65,11 @@
 
 (eval-when-compile
   (defconst eshell-info-banner--macos-versions
-    '(("10.4"  . "Mac OS X Tiger")
+    '(("10.0"  . "Mac OS X Cheetah")
+      ("10.1"  . "Mac OS X Puma")
+      ("10.2"  . "Mac OS X Jaguar")
+      ("10.3"  . "Mac OS X Panther")
+      ("10.4"  . "Mac OS X Tiger")
       ("10.5"  . "Mac OS X Leopard")
       ("10.6"  . "Mac OS X Snow Leopard")
       ("10.7"  . "Mac OS X Lion")
@@ -84,7 +88,10 @@
       ("11.3"  . "macOS Big Sur")
       ("11.4"  . "macOS Big Sur")
       ("11.5"  . "macOS Big Sur")
-      ("11.6"  . "macOS Big Sur"))
+      ("11.6"  . "macOS Big Sur")
+      ("12.0"  . "macOS Monterey")
+      ("12.1"  . "macOS Monterey")
+      ("12.2"  . "macOS Monterey"))
     "Versions of OSX and macOS and their name."))
 
 (defconst eshell-info-banner--posix-shells '("bash" "zsh" "sh")
@@ -460,21 +467,19 @@ For TEXT-PADDING and BAR-LENGTH, see the documentation of
                         "\n"
                         t)))
 
-(defun eshell-info-banner--get-memory-unix ()
+(defun eshell-info-banner--get-memory-unix-command-to-mem (command)
-  "Get memory usage for UNIX systems.
-Compatible with Darwin and FreeBSD at least."
-  (let* ((command-to-mem (lambda (command)
   (string-to-number
    (s-trim
     (car (last
           (split-string (eshell-info-banner--shell-command-to-string command)
                         " "
-                                                 t)))))))
+                        t))))))
-         (netbsdp        (and (equal system-type 'berkeley-unix)
+
-                              (string-match-p "NetBSD" (eshell-info-banner--shell-command-to-string "uname"))))
+(defun eshell-info-banner--get-memory-netbsd ()
-         (total          (apply command-to-mem `(,(if netbsdp "sysctl hw.physmem64" "sysctl hw.physmem"))))
+  "Get memory usage for NetBSD systems.
-         (used           (if netbsdp
+See `eshell-info-banner--get-memory'."
-                             (- total
+  (let* ((total (eshell-info-banner--get-memory-unix-command-to-mem `("sysctl hw.physmem64")))
+         (used  (- total
                    (* 1024 (string-to-number
                             (s-trim
                              (with-temp-buffer
@@ -489,10 +494,52 @@ Compatible with Darwin and FreeBSD at least."
                                                (buffer-string))
                                  (substring-no-properties (buffer-string)
                                                           (match-beginning 1)
-                                                                       (match-end 1))))))))
+                                                          (match-end 1))))))))))
-                           (apply command-to-mem '("sysctl hw.usermem")))))
     `(("RAM" ,total ,used))))
 
+(defun eshell-info-banner--get-memory-darwin ()
+  "Get memory usage for Darwin systems.
+See `eshell-info-banner--get-memory'."
+  (let* ((total  (eshell-info-banner--get-memory-unix-command-to-mem "sysctl -n hw.memsize"))
+         (vmstat (with-temp-buffer
+                   (call-process "vm_stat" nil t nil)
+                   (buffer-string)))
+         (wired  (save-match-data
+                   (string-match (rx " wired" (* (not digit)) (+ blank) (group (+ digit)) ".")
+                                 vmstat)
+                   (* 1024 4
+                      (string-to-number (substring-no-properties vmstat
+                                                                 (match-beginning 1)
+                                                                 (match-end 1))))))
+         (active (save-match-data
+                   (string-match (rx " active" (* (not digit)) (+ blank) (group (+ digit)) ".")
+                                 vmstat)
+                   (* 1024 4
+                      (string-to-number (substring-no-properties vmstat
+                                                                 (match-beginning 1)
+                                                                 (match-end 1))))))
+         (compressed (save-match-data
+                       (if (string-match (rx " occupied" (* (not digit)) (+ blank) (group (+ digit)) ".")
+                                         vmstat)
+                           (* 1024 4
+                              (string-to-number (substring-no-properties vmstat
+                                                                         (match-beginning 1)
+                                                                         (match-end 1))))
+                         0))))
+    `(("RAM" ,total ,(+ wired active compressed)))))
+
+(defun eshell-info-banner--get-memory-unix ()
+  "Get memory usage for UNIX systems."
+  (cond ((and (equal system-type 'berkeley-unix)
+              (string-match-p "NetBSD" (eshell-info-banner--shell-command-to-string "uname")))
+         (eshell-info-banner--get-memory-netbsd))
+        ((equal system-type 'darwin)
+         (eshell-info-banner--get-memory-darwin))
+        (t
+         (let* ((total (eshell-info-banner--get-memory-unix-command-to-mem "sysctl hw.physmem"))
+                (used  (eshell-info-banner--get-memory-unix-command-to-mem "sysctl hw.usermem")))
+           `(("RAM" ,total ,used))))))
+
 (defun eshell-info-banner--get-memory-windows ()
   "Get memory usage for Window."
   (warn "Memory usage not yet implemented for Windows and DOS")
@@ -608,7 +655,9 @@ The usage of `eshell-info-banner-warning-percentage' and
 thought of as the “percentage of discharge” of the computer.
 Thus, setting the warning at 75% will be translated as showing
 the warning face with a battery level of 25% or less."
-  (let ((battery-level (when (file-readable-p "/sys/") (battery))))
+  (let ((battery-level (unless (and (equal system-type 'gnu/linux)
+                                    (not (file-readable-p "/sys/")))
+                         (battery))))
     (if (or (null battery-level)
             (string= battery-level "Battery status not available")
             (string-match-p (regexp-quote "N/A") battery-level))