From: Tassilo Horn <tsdh@gnu.org>
To: emacs-devel@gnu.org
Subject: [Patch/Question] Likely bugs in mailcap docs and mailcap-view-file
Date: Fri, 14 Jan 2022 22:24:43 +0100 [thread overview]
Message-ID: <875yqmvvx1.fsf@gnu.org> (raw)
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Hi all,
I wanted to use `mailcap-view-file' in some package (mu4e) in order to
view some attachment using some appropriate viewer. I've tested with
some pdf attachment which triggered an error because I use pdf-tools
which adds an entry to `mailcap-mime-data' where the viewer is the
symbol `pdf-view-mode' (a major-mode) whereas `mailcap-view-file'
currently only handles the "viewer is a string naming some executable"
case.
The default value of `mailcap-mime-data' has tons of viewers being
major-mode symbols, so that can't be wrong. It's docstring also says:
Where VIEWERINFO specifies how the content-type is viewed. Can be a
string, in which case it is run through a shell, with appropriate
parameters, or a symbol, in which case the symbol is ‘funcall’ed if
and only if it exists as a function, with the buffer as an argument.
Well, that's strange. All symbol-valued VIEWERINFOs are functions of
zero args, mostly major-modes. They can't get the buffer (which
buffer?!) as an argument.
So I propose the attached patch which teaches `mailcap-view-file' the
symbol/function-valued viewer case and adjust the docs to match what's
already there.
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diff --git a/lisp/net/mailcap.el b/lisp/net/mailcap.el
index bf3c8edd1e..151c6e0509 100644
--- a/lisp/net/mailcap.el
+++ b/lisp/net/mailcap.el
@@ -319,8 +319,9 @@ mailcap-mime-data
Where VIEWERINFO specifies how the content-type is viewed. Can be
a string, in which case it is run through a shell, with appropriate
-parameters, or a symbol, in which case the symbol is `funcall'ed if
-and only if it exists as a function, with the buffer as an argument.
+parameters, or a symbol, in which case the symbol must name a function
+of zero arguments which is called in a buffer holding the MIME part's
+content.
TESTINFO is a test for the viewer's applicability, or nil. If nil, it
means the viewer is always valid. If it is a Lisp function, it is
@@ -1174,34 +1175,45 @@ mailcap-view-file
(mailcap-parse-mailcaps)
(let ((command (mailcap-mime-info
(mailcap-extension-to-mime (file-name-extension file)))))
- (unless command
- (error "No viewer for %s" (file-name-extension file)))
- ;; Remove quotes around the file name - we'll use shell-quote-argument.
- (while (string-match "['\"]%s['\"]" command)
- (setq command (replace-match "%s" t t command)))
- (setq command (replace-regexp-in-string
- "%s"
- (shell-quote-argument (convert-standard-filename file))
- command
- nil t))
- ;; Handlers such as "gio open" and kde-open5 start viewer in background
- ;; and exit immediately. Avoid `start-process' since it assumes
- ;; :connection-type `pty' and kills children processes with SIGHUP
- ;; when temporary terminal session is finished (Bug#44824).
- ;; An alternative is `process-connection-type' let-bound to nil for
- ;; `start-process-shell-command' call (with no chance to report failure).
- (make-process
- :name "mailcap-view-file"
- :connection-type 'pipe
- :buffer nil ; "*Messages*" may be suitable for debugging
- :sentinel (lambda (proc event)
- (when (and (memq (process-status proc) '(exit signal))
- (/= (process-exit-status proc) 0))
- (message
- "Command %s: %s."
- (mapconcat #'identity (process-command proc) " ")
- (substring event 0 -1))))
- :command (list shell-file-name shell-command-switch command))))
+ (if (functionp command)
+ ;; command is a viewer function (a mode) expecting the file
+ ;; contents to be in the current buffer.
+ (let ((buf (generate-new-buffer (file-name-nondirectory file))))
+ (set-buffer buf)
+ (insert-file-contents file)
+ (setq buffer-file-name file)
+ (funcall command)
+ (set-buffer-modified-p nil)
+ (pop-to-buffer buf))
+ ;; command is a program to run with file as an argument.
+ (unless command
+ (error "No viewer for %s" (file-name-extension file)))
+ ;; Remove quotes around the file name - we'll use shell-quote-argument.
+ (while (string-match "['\"]%s['\"]" command)
+ (setq command (replace-match "%s" t t command)))
+ (setq command (replace-regexp-in-string
+ "%s"
+ (shell-quote-argument (convert-standard-filename file))
+ command
+ nil t))
+ ;; Handlers such as "gio open" and kde-open5 start viewer in background
+ ;; and exit immediately. Avoid `start-process' since it assumes
+ ;; :connection-type `pty' and kills children processes with SIGHUP
+ ;; when temporary terminal session is finished (Bug#44824).
+ ;; An alternative is `process-connection-type' let-bound to nil for
+ ;; `start-process-shell-command' call (with no chance to report failure).
+ (make-process
+ :name "mailcap-view-file"
+ :connection-type 'pipe
+ :buffer nil ; "*Messages*" may be suitable for debugging
+ :sentinel (lambda (proc event)
+ (when (and (memq (process-status proc) '(exit signal))
+ (/= (process-exit-status proc) 0))
+ (message
+ "Command %s: %s."
+ (mapconcat #'identity (process-command proc) " ")
+ (substring event 0 -1))))
+ :command (list shell-file-name shell-command-switch command)))))
(provide 'mailcap)
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Does anyone see a problem with that? I'm not very familiar with that
code.
Bye,
Tassilo
next reply other threads:[~2022-01-14 21:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-14 21:24 Tassilo Horn [this message]
2022-01-14 22:32 ` [Patch/Question] Likely bugs in mailcap docs and mailcap-view-file Stefan Monnier
2022-01-15 10:27 ` Tassilo Horn
2022-01-15 14:52 ` Stefan Monnier
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