Re: fractional file timestamps in tramp-adb

[Paul Eggert <eggert@cs.ucla.edu>]

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On 2/15/19 12:11 AM, Michael Albinus wrote:
> I'm afraid, I'm not an experienced Android developer (tramp-adb.el was
> written by somebody else). Any help appreciated!

Older versions of toybox touch mishandle nanoseconds, and perhaps you've 
run into one of those. How about the attached patch, to try fractional 
timestamps (with "Z" for UTC) if it works, and fall back on the existing 
code otherwise? Plus, we can fall back on touch -t for hosts that don't 
yet support POSIX-2008, though that may be overkill nowadays.


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From c4dad9e5d60153870cca647ece7e266b4eb4e19e Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Fri, 15 Feb 2019 14:36:30 -0800
Subject: [PATCH] Port tramp-adb to various 'touch' platforms

* lisp/net/tramp-adb.el (tramp-adb-handle-set-file-times):
Try nanoseconds first, then plain seconds, then touch -t.
---
 lisp/net/tramp-adb.el | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/lisp/net/tramp-adb.el b/lisp/net/tramp-adb.el
index 22f2c5f6bf..4fba4e14f3 100644
--- a/lisp/net/tramp-adb.el
+++ b/lisp/net/tramp-adb.el
@@ -677,11 +677,22 @@ tramp-adb-handle-set-file-times
 			(tramp-compat-time-equal-p time tramp-time-doesnt-exist)
 			(tramp-compat-time-equal-p time tramp-time-dont-know))
 		    (current-time)
-		  time)))
+		  time))
+	  (quoted-name (tramp-shell-quote-argument localname)))
+      ;; Older versions of toybox 'touch' mishandle nanoseconds and/or
+      ;; trailing "Z", so fall back on plain seconds if nanoseconds+Z
+      ;; fails.  Also, fall back on old POSIX 'touch -t' if 'touch -d'
+      ;; (introduced in POSIX.1-2008) fails.
       (tramp-adb-send-command-and-check
-       v (format "touch -d %s %s"
+       v (format (concat "touch -d %s %s 2>/dev/null || "
+			 "touch -d %s %s 2>/dev/null || "
+			 "touch -t %s %s")
+		 (format-time-string "%Y-%m-%dT%H:%M:%S.%NZ" time t)
+		 quoted-name
 		 (format-time-string "%Y-%m-%dT%H:%M:%S" time t)
-		 (tramp-shell-quote-argument localname))))))
+		 quoted-name
+		 (format-time-string "%Y%m%d%H%M.%S" time t)
+		 quoted-name)))))
 
 (defun tramp-adb-handle-copy-file
   (filename newname &optional ok-if-already-exists keep-date
-- 
2.20.1