feature/android 84d27fe53b2 1/2: Save build timestamps in Android builds

[Po Lu]

branch: feature/android
commit 84d27fe53b2888b6668ba8510f377eb0eabeeb09
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Save build timestamps in Android builds
    
    * java/Makefile.in (install_temp/assets/build_info): New
    rule.:(emacs.apk-in): Depend on that file.
    * lisp/version.el (android-read-build-system)
    (android-read-build-time): New functions.
    (emacs-build-system, emacs-build-time): Use those functions on
    Android, as dumping is done after installation on Android.
    * src/fileio.c (Finsert_file_contents):
    * src/window.c (replace_buffer_in_windows): Don't call functions
    if they are not defined, which can happen during loadup.
---
 java/Makefile.in |  6 +++++-
 lisp/version.el  | 34 ++++++++++++++++++++++++++++++++--
 src/fileio.c     |  6 ++++--
 src/window.c     |  5 ++++-
 4 files changed, 45 insertions(+), 6 deletions(-)

diff --git a/java/Makefile.in b/java/Makefile.in
index c7fe6e07c77..1a7852487ef 100644
--- a/java/Makefile.in
+++ b/java/Makefile.in
@@ -222,8 +222,12 @@ install_temp/assets/version: install_temp
                        && (git rev-parse --abbrev-ref HEAD             \
                            || echo "Unknown") } 2> /dev/null > $@
 
+install_temp/assets/build_info: install_temp
+       $(AM_V_GEN) { hostname; date +%s; } > $@
+
 emacs.apk-in: install_temp install_temp/assets/directory-tree \
-  install_temp/assets/version AndroidManifest.xml
+  install_temp/assets/version install_temp/assets/build_info  \
+  AndroidManifest.xml
 # Package everything.  Specifying the assets on this command line is
 # necessary for AAssetManager_getNextFileName to work on old versions
 # of Android.  Make sure not to generate R.java, as it's already been
diff --git a/lisp/version.el b/lisp/version.el
index 38a9f9c2be5..ca61f8cfeee 100644
--- a/lisp/version.el
+++ b/lisp/version.el
@@ -26,6 +26,31 @@
 
 ;;; Code:
 
+
+
+(defun android-read-build-system ()
+  "Obtain the host name of the system on which Emacs was built.
+Use the data stored in the special file `/assets/build_info'.
+Value is the string ``Unknown'' upon failure, else the hostname
+of the build system."
+  (with-temp-buffer
+    (insert-file-contents "/assets/build_info")
+    (let ((string (buffer-substring 1 (line-end-position))))
+      (and (not (equal string "Unknown")) string))))
+
+(defun android-read-build-time ()
+  "Obtain the time at which Emacs was built.
+Use the data stored in the special file `/assets/build_info'.
+Value is nil upon failure, else the time in the same format as
+returned by `current-time'."
+  (with-temp-buffer
+    (insert-file-contents "/assets/build_info")
+    (end-of-line)
+    (let ((number (read (current-buffer))))
+      (time-convert number 'list))))
+
+
+
 (defconst emacs-major-version
   (progn (string-match "^[0-9]+" emacs-version)
          (string-to-number (match-string 0 emacs-version)))
@@ -36,10 +61,15 @@
          (string-to-number (match-string 1 emacs-version)))
   "Minor version number of this version of Emacs.")
 
-(defconst emacs-build-system (system-name)
+(defconst emacs-build-system (or (and (eq system-type 'android)
+                                      (android-read-build-system))
+                                 (system-name))
   "Name of the system on which Emacs was built, or nil if not available.")
 
-(defconst emacs-build-time (if emacs-build-system (current-time))
+(defconst emacs-build-time (if emacs-build-system
+                               (or (and (eq system-type 'android)
+                                        (android-read-build-time))
+                                   (current-time)))
   "Time at which Emacs was dumped out, or nil if not available.")
 
 (defconst emacs-build-number 1          ; loadup.el may increment this
diff --git a/src/fileio.c b/src/fileio.c
index ae244b8f85a..88582704d7e 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -4991,8 +4991,10 @@ by calling `format-decode', which see.  */)
        }
     }
 
-  /* Decode file format.  */
-  if (inserted > 0)
+  /* Decode file format.  Don't do this if Qformat_decode is not
+     bound, which can happen when called early during loadup.  */
+
+  if (inserted > 0 && !NILP (Fboundp (Qformat_decode)))
     {
       /* Don't run point motion or modification hooks when decoding.  */
       specpdl_ref count1 = SPECPDL_INDEX ();
diff --git a/src/window.c b/src/window.c
index f4e09f49eae..9a29ecb8807 100644
--- a/src/window.c
+++ b/src/window.c
@@ -3514,7 +3514,10 @@ window-start value is reasonable when this function is 
called.  */)
 void
 replace_buffer_in_windows (Lisp_Object buffer)
 {
-  call1 (Qreplace_buffer_in_windows, buffer);
+  /* When kill-buffer is called early during loadup, this function is
+     undefined.  */
+  if (!NILP (Fboundp (Qreplace_buffer_in_windows)))
+    call1 (Qreplace_buffer_in_windows, buffer);
 }
 
 /* If BUFFER is shown in a window, safely replace it with some other