Add `make-nearby-temp-file' and `temporary-file-directory'

* doc/lispref/files.texi (Unique File Names):
Introduce `make-nearby-temp-file' and `temporary-file-directory'.
(Magic File Names): Mention `make-nearby-temp-file' and
`temporary-file-directory'.

* etc/NEWS (provided): Mention `make-nearby-temp-file' and
`temporary-file-directory'.

* lisp/files.el (mounted-file-systems): New defcustom.
(temporary-file-directory, make-nearby-temp-file): New defuns.
(normal-backup-enable-predicate): Fix docstring.

* lisp/net/tramp-adb.el (tramp-adb-file-name-handler-alist):
* lisp/net/tramp-gvfs.el (tramp-gvfs-file-name-handler-alist):
* lisp/net/tramp-sh.el (tramp-sh-file-name-handler-alist):
* lisp/net/tramp-smb.el (tramp-smb-file-name-handler-alist):
<make-nearby-temp-file, temporary-file-directory>: Add handler.

* lisp/net/tramp.el (tramp-file-name-for-operation):
Add `make-nearby-temp-file' and `temporary-file-directory'.
(tramp-get-remote-tmpdir): Remove compatibility code.
(tramp-handle-temporary-file-directory)
(tramp-handle-make-nearby-temp-file): New defuns.

* lisp/org/ob-core.el (org-babel-local-file-name):
* lisp/progmodes/gud.el (gud-common-init):
* lisp/vc/vc-hooks.el (vc-user-login-name): Use `file-remote-p'.

* lisp/vc/vc-git.el (vc-git-checkin): Handle remote log message.

* test/lisp/net/tramp-tests.el (tramp-test06-directory-file-name):
Check `tramp--test-enabled'.
(tramp-test18-file-attributes): Add tests for
`file-ownership-preserved-p'.
(tramp-test27-start-file-process, tramp-test28-shell-command):
Reduce timeouts in `accept-process-output'.
(tramp-test--shell-command-to-string-asynchronously): Add timeout.
(tramp-test29-environment-variables): Remove additional sleep calls.
(tramp-test32-make-nearby-temp-file): New test.
(tramp--test-special-characters, tramp--test-utf8): Adapt docstring.
(tramp-test33-special-characters)
(tramp-test33-special-characters-with-stat)
(tramp-test33-special-characters-with-perl)
(tramp-test33-special-characters-with-ls, tramp-test34-utf8)
(tramp-test34-utf8-with-stat, tramp-test34-utf8-with-perl)
(tramp-test34-utf8-with-ls)
(tramp-test35-asynchronous-requests)
(tramp-test36-recursive-load, tramp-test37-unload): Rename.
(tramp--test-ftp-p): Simplify check.
(tramp--test-sh-p): New defun.
(tramp-test20-file-modes, tramp-test22-file-times)
(tramp-test26-process-file, tramp-test27-start-file-process)
(tramp-test28-shell-command)
(tramp-test29-environment-variables)
(tramp-test30-vc-registered)
(tramp-test33-special-characters-with-stat)
(tramp-test33-special-characters-with-perl)
(tramp-test33-special-characters-with-ls)
(tramp-test34-utf8-with-stat, tramp-test34-utf8-with-perl)
(tramp-test34-utf8-with-ls)
(tramp-test35-asynchronous-requests): Use it.

1 files changed, 46 insertions, 0 deletions

diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
index ea9d53b0ea..0aea1dfd9a 100644
--- a/doc/lispref/files.texi
+++ b/doc/lispref/files.texi
@@ -2440,6 +2440,50 @@ condition, between the @code{make-temp-name} call and the creation of
 the file, which in some cases may cause a security hole.
 @end defun
 
+Sometimes, it is necessary to create a temporary file on a remote host
+or a mounted directory.  The following two functions support this.
+
+@defun make-nearby-temp-file prefix &optional dir-flag suffix
+This function is similar to @code{make-temp-file}, but it creates a
+temporary file as close as possible to @code{default-directory}.  If
+@var{prefix} is a relative file name, and @code{default-directory} is
+a remote file name or located on a mounted file systems, the temporary
+file is created in the directory returned by the function
+@code{temporary-file-directory}.  Otherwise, the function
+@code{make-temp-file} is used.  @var{prefix}, @var{dir-flag} and
+@var{suffix} have the same meaning as in @code{make-temp-file}.
+
+@example
+@group
+(let ((default-directory "/ssh:remotehost:"))
+  (make-nearby-temp-file "foo"))
+     @result{} "/ssh:remotehost:/tmp/foo232J6v"
+@end group
+@end example
+@end defun
+
+@defun temporary-file-directory
+The directory for writing temporary files via
+@code{make-nearby-temp-file}.  In case of a remote
+@code{default-directory}, this is a directory for temporary files on
+that remote host.  If such a directory does not exist, or
+@code{default-directory} ought to be located on a mounted file system
+(see @code{mounted-file-systems}), the function returns
+@code{default-directory}.  For a non-remote and non-mounted
+@code{default-directory}, the value of the variable
+@code{temporary-file-directory} is returned.
+@end defun
+
+In order to extract the local part of the path name from a temporary
+file, the following code could be used:
+
+@example
+@group
+(let ((tmpfile (make-nearby-temp-file "foo")))
+  (or (file-remote-p tmpfile 'localname) tmpfile))
+@end group
+@end example
+
 @node File Name Completion
 @subsection File Name Completion
 @cindex file name completion subroutines
@@ -2903,6 +2947,7 @@ first, before handlers for jobs such as remote file access.
 @code{make-auto-save-file-name},
 @code{make-directory},
 @code{make-directory-internal},
+@code{make-nearby-temp-file},
 @code{make-symbolic-link},@*
 @code{process-file},
 @code{rename-file}, @code{set-file-acl}, @code{set-file-modes},
@@ -2910,6 +2955,7 @@ first, before handlers for jobs such as remote file access.
 @code{set-visited-file-modtime}, @code{shell-command},
 @code{start-file-process},
 @code{substitute-in-file-name},@*
+@code{temporary-file-directory},
 @code{unhandled-file-name-directory},
 @code{vc-registered},
 @code{verify-visited-file-modtime},@*