bug#60896: dired-view-file vs. .7z

bug#60896: dired-view-file vs. .7z

[Dan Jacobson]

dired-view-file knows how to deal with .gz,
but not .7z.

$ apropos 7z
7z (1)               - A file archiver with high compression ratio format
7za (1)              - A file archiver with high compression ratio format
7zr (1)              - A file archiver with high compression ratio format
p7zip (1)            - Wrapper on 7-Zip file archiver with high compression ratio

bug#60896: dired-view-file vs. .7z

[Eli Zaretskii]

> From: Dan Jacobson <jidanni@jidanni.org>
> Date: Wed, 18 Jan 2023 08:52:06 +0800
> 
> dired-view-file knows how to deal with .gz,
> but not .7z.

It does here, at least with Emacs 27 and later.

bug#60896: dired-view-file vs. .7z

[Dan Jacobson]

rename 60896 make error if not in 7z format
thanks

I see.
OK.
Well, if the file is not in 7z format,
then I hope dired-view-file would make an error message,
like it does if a file is not in .gz format:
---
Error while executing "gzip -c -q -d < /tmp/x.gz"


gzip: stdin: not in gzip format
---

bug#60896: dired-view-file vs. .7z

[Eli Zaretskii]

> From: Dan Jacobson <jidanni@jidanni.org>
> Cc: 60896@debbugs.gnu.org,control@debbugs.gnu.org
> Date: Wed, 25 Jan 2023 10:51:43 +0800
> 
> Well, if the file is not in 7z format,
> then I hope dired-view-file would make an error message,
> like it does if a file is not in .gz format:
> ---
> Error while executing "gzip -c -q -d < /tmp/x.gz"
> 
> 
> gzip: stdin: not in gzip format

That gzip error message comes from the gzip program, not from Emacs.
What does 7z say in a similar case?  That's what dired-view-file
should show.

bug#60896: dired-view-file vs. .7z

[Ruijie Yu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

[-- Attachment #1: Type: text/plain, Size: 794 bytes --]


Eli Zaretskii <eliz@gnu.org> writes:

>> From: Dan Jacobson <jidanni@jidanni.org>
>> Cc: 60896@debbugs.gnu.org,control@debbugs.gnu.org
>> Date: Wed, 25 Jan 2023 10:51:43 +0800
>>
>> Well, if the file is not in 7z format,
>> then I hope dired-view-file would make an error message,
>> like it does if a file is not in .gz format:
>> ---
>> Error while executing "gzip -c -q -d < /tmp/x.gz"
>>
>>
>> gzip: stdin: not in gzip format
>
> That gzip error message comes from the gzip program, not from Emacs.
> What does 7z say in a similar case?  That's what dired-view-file
> should show.

See the attachments for example outputs.  #1 is a malformed 7z archive
(in my case just an empty file created by `touch`), and #2 contains an
actual 7z archive created by `7z a 2.7z memsize.c`.

Best,


RY


[-- Attachment #2: 1-out.txt --]
[-- Type: text/plain, Size: 286 bytes --]


7-Zip [64] 17.04 : Copyright (c) 1999-2021 Igor Pavlov : 2017-08-28
p7zip Version 17.04 (locale=en_US.UTF-8,Utf16=on,HugeFiles=on,64 bits,8 CPUs x64)

Scanning the drive for archives:
1 file, 0 bytes

Listing archive: 1.7z


ERROR: 1.7z : Can not open the file as archive



Errors: 1

[-- Attachment #3: 2-out.txt --]
[-- Type: text/plain, Size: 677 bytes --]


7-Zip [64] 17.04 : Copyright (c) 1999-2021 Igor Pavlov : 2017-08-28
p7zip Version 17.04 (locale=en_US.UTF-8,Utf16=on,HugeFiles=on,64 bits,8 CPUs x64)

Scanning the drive for archives:
1 file, 831 bytes (1 KiB)

Listing archive: 2.7z

--
Path = 2.7z
Type = 7z
Physical Size = 831
Headers Size = 122
Method = LZMA2:12
Solid = -
Blocks = 1

   Date      Time    Attr         Size   Compressed  Name
------------------- ----- ------------ ------------  ------------------------
2022-11-12 10:06:36 ....A         1495          709  memsize.c
------------------- ----- ------------ ------------  ------------------------
2022-11-12 10:06:36               1495          709  1 files

bug#60896: dired-view-file vs. .7z

[Eli Zaretskii]

> From: Ruijie Yu <ruijie@netyu.xyz>
> Cc: Dan Jacobson <jidanni@jidanni.org>, 60896@debbugs.gnu.org
> Date: Wed, 25 Jan 2023 21:13:15 +0800
> 
> >> gzip: stdin: not in gzip format
> >
> > That gzip error message comes from the gzip program, not from Emacs.
> > What does 7z say in a similar case?  That's what dired-view-file
> > should show.
> 
> See the attachments for example outputs.  #1 is a malformed 7z archive
> (in my case just an empty file created by `touch`), and #2 contains an
> actual 7z archive created by `7z a 2.7z memsize.c`.

Thanks, but I'm not sure I follow.  My point is that dired-view-file
should show what the archiver program says, no more, no less.  If
that's what happens, then we are good.

bug#60896: dired-view-file vs. .7z

[Dan Jacobson]

Also maybe some message should be printed if no .gz or .7z handler is
found. Same for the rest: .jpg etc.

Currently emacs just opens the file in fundamental mode.

Emacs should print a message that it looked for a handler but didn't
find one.

That way the user would know emacs already can deal with such files,
and all he needs to do is install a handler.

Else he thinks emacs is just acting like it is 1980 an has never heard
of such files.

bug#60896: dired-view-file vs. .7z

[Eli Zaretskii]

> From: Dan Jacobson <jidanni@jidanni.org>
> Cc: Eli Zaretskii <eliz@gnu.org>,  60896@debbugs.gnu.org
> Date: Thu, 26 Jan 2023 15:13:48 +0800
> 
> Also maybe some message should be printed if no .gz or .7z handler is
> found. Same for the rest: .jpg etc.
> 
> Currently emacs just opens the file in fundamental mode.
> 
> Emacs should print a message that it looked for a handler but didn't
> find one.

Sorry, no.  That way lies madness: most of the files Emacs users visit
have no handlers.  Announcing we didn't find a handler will be a
terrible annoyance.

bug#60896: make error if not in 7z format

[Stefan Kangas]

tags 60896
close 60896
thanks

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Dan Jacobson <jidanni@jidanni.org>
>> Cc: Eli Zaretskii <eliz@gnu.org>,  60896@debbugs.gnu.org
>> Date: Thu, 26 Jan 2023 15:13:48 +0800
>>
>> Also maybe some message should be printed if no .gz or .7z handler is
>> found. Same for the rest: .jpg etc.
>>
>> Currently emacs just opens the file in fundamental mode.
>>
>> Emacs should print a message that it looked for a handler but didn't
>> find one.
>
> Sorry, no.  That way lies madness: most of the files Emacs users visit
> have no handlers.  Announcing we didn't find a handler will be a
> terrible annoyance.

Having read this bug report, I see no bug in Emacs.  We print the
message from the external archiver, as we should, and suggestions for
other changes were rejected.

I'm therefore closing this bug report.