From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.bugs Subject: bug#28156: Emacs quietly munges symlink contents Date: Mon, 21 Aug 2017 10:34:27 -0700 Organization: UCLA Computer Science Department Message-ID: <1fafa4ea-424e-53c5-3c91-6dd18fe47f1e@cs.ucla.edu> References: <68b2e6ef-bf0b-ebcf-c577-d296952d593f@cs.ucla.edu> <83pobqcnlf.fsf@gnu.org> <83h8x2ckqn.fsf@gnu.org> <83bmnacaob.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------A10EEAAF641D4F6D5B6A3411" X-Trace: blaine.gmane.org 1503336925 5125 195.159.176.226 (21 Aug 2017 17:35:25 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 21 Aug 2017 17:35:25 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 Cc: p.stephani2@gmail.com, michael.albinus@gmx.de, 28156@debbugs.gnu.org To: Eli Zaretskii Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Mon Aug 21 19:35:18 2017 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1djqbX-0000eR-Cv for geb-bug-gnu-emacs@m.gmane.org; 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charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable >> Quoting does not work for these cases. If I try to rename a symlink to= the >> literal string '~eggert' on my machine, Emacs will misbehave as descri= bed and >> there is no way to quote the string naming the symlink to fix this. >=20 > That is but one use case of many. In other cases, quoting does work. My point is that there is a bug in some cases. I agree that in other case= s,=20 make-symbolic-link does work. > your proposed changes will disallow some of the > users' capabilities to do what you want. With the proposed changes a user can create a local symlink to an any str= ing=20 supported by the operating system. This change increases users' capabilit= ies,=20 compared to what they can do now. This change does not take away any capa= bilities. > they seem to > sacrifice a very common interactive use case on behalf of a much more > rare and obscure one. I'm talking about a user typing this: >=20 > M-x make-symbolic-link RET ~/foo/bar RET /toto/quux RET Good suggestion, also made by others. Revised patch attached. --------------A10EEAAF641D4F6D5B6A3411 Content-Type: text/x-patch; name="0001-Do-not-munge-contents-of-local-symbolic-links.patch" Content-Transfer-Encoding: quoted-printable Content-Disposition: attachment; filename="0001-Do-not-munge-contents-of-local-symbolic-links.patch" =46rom 868a212ba636a7cab27e1ee88495a7f7dcf71b0d Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Mon, 21 Aug 2017 09:46:34 -0700 Subject: [PATCH] Do not munge contents of local symbolic links This lets Emacs deal with arbitrary local symlinks without mishandling their contents. For example, (progn (shell-command "ln -fs '~' 'x'") (rename-file "x" "/tmp/x")) now consistently creates a symbolic link from '/tmp/x' to '~'. Formerly, it did that only if the working directory was on the same filesystem as /tmp; otherwise, it expanded the '~' to the user's home directory. * etc/NEWS: Document the change. * src/fileio.c (Fmake_symbolic_link): Do not expand leading "~" in the target unless interactive, and look for special constructs only in the new link name, not the target. (emacs_readlinkat): Do not preprend "/:" to the link target if it starts with "/" and contains ":" before NUL. * test/lisp/net/tramp-tests.el (tramp-test21-file-links): Adjust to new behavior. * test/src/fileio-tests.el (try-link): Rename from try-char, and accept a string instead of a char. All uses changed. (fileio-tests--symlink-failure): Also test leading ~, and "/:", to test the new behavior. --- doc/emacs/files.texi | 7 ++++--- doc/lispref/files.texi | 3 ++- etc/NEWS | 15 +++++++++++++++ src/fileio.c | 21 +++------------------ test/lisp/net/tramp-tests.el | 9 ++++++--- test/src/fileio-tests.el | 21 ++++++++++----------- 6 files changed, 40 insertions(+), 36 deletions(-) diff --git a/doc/emacs/files.texi b/doc/emacs/files.texi index 9195bc4..56e3d2f 100644 --- a/doc/emacs/files.texi +++ b/doc/emacs/files.texi @@ -1609,9 +1609,10 @@ Copying and Naming @var{new}, which points at @var{target}. The effect is that future attempts to open file @var{new} will refer to whatever file is named @var{target} at the time the opening is done, or will get an error if -the name @var{target} is nonexistent at that time. This command does -not expand the argument @var{target}, so that it allows you to specify -a relative name as the target of the link. On MS-Windows, this +the name @var{target} is nonexistent at that time. This command +expands the argument @var{target} only if it begins with @samp{~}, so +that it allows you to specify most relative names as the target of the +link. On MS-Windows, this command works only on MS Windows Vista and later. On remote systems, it works depending on the system type. =20 diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi index 5a52765..11e4b43 100644 --- a/doc/lispref/files.texi +++ b/doc/lispref/files.texi @@ -1725,7 +1725,8 @@ Changing Files This command makes a symbolic link to @var{filename}, named @var{newname}. This is like the shell command @samp{ln -s @var{filename} @var{newname}}. The @var{filename} argument -is treated only as a string; it need not name an existing file. +need not name an existing file, and is expanded only if it begins with @= samp{~} +and @var{ok-if-already-exists} is an integer, indicating interactive use= =2E If @var{filename} is a relative file name, the resulting symbolic link is interpreted relative to the directory containing the symbolic link. @xref{Relative File Names}. diff --git a/etc/NEWS b/etc/NEWS index 0939033..97462ec 100644 --- a/etc/NEWS +++ b/etc/NEWS @@ -1215,6 +1215,21 @@ instead of to utf-8. Before this change, Emacs wo= uld sometimes mishandle file names containing these control characters. =20 +++ +** 'file-attributes', 'file-symlink-p' and 'make-symbolic-link' no +longer quietly mutate the target of a local symbolic link, so that +Emacs can access and copy them reliably regardless of their contents. +Two changes are involved. First, 'file-attributes' and +'file-symlink-p' no longer prepend "/:" to symbolic links whose +targets begin with "/" and contain ":". For example, if a symbolic +link "x" has a target "/y:z", (file-symlink-p "x") now returns "/y:z" +rather than "/:/y:z". Second, 'make-symbolic-link' now expands a link +target with leading "~" only when the optional third arg is an +integer, as when invoked interactively. For example, with +(make-symbolic-link "~y" "x") the link target is now the string "~y"; +to get the old behavior, use (make-symbolic-link (expand-file-name +"~y") "x"). + ++++ ** Module functions are now implemented slightly differently; in particular, the function 'internal--module-call' has been removed. Code that depends on undocumented internals of the module system might diff --git a/src/fileio.c b/src/fileio.c index f954ac1..ad2aab8 100644 --- a/src/fileio.c +++ b/src/fileio.c @@ -2415,7 +2415,8 @@ DEFUN ("make-symbolic-link", Fmake_symbolic_link, S= make_symbolic_link, 2, 3, Both args must be strings. Signal a `file-already-exists' error if a file LINKNAME already exists unless optional third argument OK-IF-ALREADY-EXISTS is non-nil. -An integer third arg means request confirmation if LINKNAME already exis= ts. +An integer third arg means request confirmation if LINKNAME +already exists, and expand TARGET if it begins with "~". This happens for interactive use with M-x. */) (Lisp_Object target, Lisp_Object linkname, Lisp_Object ok_if_already_e= xists) { @@ -2423,21 +2424,10 @@ This happens for interactive use with M-x. */) Lisp_Object encoded_target, encoded_linkname; =20 CHECK_STRING (target); - /* If the link target has a ~, we must expand it to get - a truly valid file name. Otherwise, do not expand; - we want to permit links to relative file names. */ - if (SREF (target, 0) =3D=3D '~') + if (INTEGERP (ok_if_already_exists) && SREF (target, 0) =3D=3D '~') target =3D Fexpand_file_name (target, Qnil); - linkname =3D expand_cp_target (target, linkname); =20 - /* If the file name has special constructs in it, - call the corresponding file handler. */ - handler =3D Ffind_file_name_handler (target, Qmake_symbolic_link); - if (!NILP (handler)) - return call4 (handler, Qmake_symbolic_link, target, - linkname, ok_if_already_exists); - /* If the new link name has special constructs in it, call the corresponding file handler. */ handler =3D Ffind_file_name_handler (linkname, Qmake_symbolic_link); @@ -2635,11 +2625,6 @@ emacs_readlinkat (int fd, char const *filename) return Qnil; =20 val =3D build_unibyte_string (buf); - if (buf[0] =3D=3D '/' && strchr (buf, ':')) - { - AUTO_STRING (slash_colon, "/:"); - val =3D concat2 (slash_colon, val); - } if (buf !=3D readlink_buf) xfree (buf); val =3D DECODE_FILE (val); diff --git a/test/lisp/net/tramp-tests.el b/test/lisp/net/tramp-tests.el index 129bc1d..8c0c8c8 100644 --- a/test/lisp/net/tramp-tests.el +++ b/test/lisp/net/tramp-tests.el @@ -2538,13 +2538,16 @@ tramp--test-backtrace (should-error (make-symbolic-link tmp-name1 tmp-name2)) (make-symbolic-link tmp-name1 tmp-name2 'ok-if-already-exists) (should (file-symlink-p tmp-name2)) - ;; `tmp-name3' is a local file name. - (should-error (make-symbolic-link tmp-name1 tmp-name3))) + ;; `tmp-name3' is a local file name, so its target is not + ;; interpreted. + (make-symbolic-link tmp-name1 tmp-name3) + (should (equal tmp-name1 (file-symlink-p tmp-name3)))) =20 ;; Cleanup. (ignore-errors (delete-file tmp-name1) - (delete-file tmp-name2))) + (delete-file tmp-name2) + (delete-file tmp-name3))) =20 ;; Check `add-name-to-file'. (unwind-protect diff --git a/test/src/fileio-tests.el b/test/src/fileio-tests.el index 2ef1b55..5103d2f 100644 --- a/test/src/fileio-tests.el +++ b/test/src/fileio-tests.el @@ -19,14 +19,13 @@ =20 (require 'ert) =20 -(defun try-char (char link) - (let ((target (string char))) - (make-symbolic-link target link) - (let* ((read-link (file-symlink-p link)) - (failure (unless (string-equal target read-link) - (list 'string-equal target read-link)))) - (delete-file link) - failure))) +(defun try-link (target link) + (make-symbolic-link target link) + (let* ((read-link (file-symlink-p link)) + (failure (unless (string-equal target read-link) + (list 'string-equal target read-link)))) + (delete-file link) + failure)) =20 (defun fileio-tests--symlink-failure () (let* ((dir (make-temp-file "fileio" t)) @@ -36,9 +35,9 @@ fileio-tests--symlink-failure (char 0)) (while (and (not failure) (< char 127)) (setq char (1+ char)) - (unless (=3D char ?~) - (setq failure (try-char char link)))) - failure) + (setq failure (try-link (string char) link))) + (or failure + (try-link "/:" link))) (delete-directory dir t)))) =20 (ert-deftest fileio-tests--odd-symlink-chars () --=20 2.7.4 --------------A10EEAAF641D4F6D5B6A3411--