bug#43231: 27.1; hexl-insert-hex-char on an empty file "hexl-current-address: Point is not on a character in the file".

bug#43231: 27.1; hexl-insert-hex-char on an empty file "hexl-current-address: Point is not on a character in the file".

[Igor Saprykin]

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hexl-mode doesn't seem to allow me to create a binary file.

Steps:
1. Open Emacs
2. Create a new file using C-x C-f /tmp/boot-sect.bin
3. M-x hexl-mode
4. M-x hexl-insert-hex-char
5. e
6. Nothing is written into the buffer and the message buffer says "Point is
not on a character file".

I took a brief look at the source code and it appears
that (hexl-current-address) expected the cursor to not be in the top left
(0,0) location of the buffer.  Normally in hexl-mode those columns are
going to be occupied by addresses.  Yet, that's exactly where the cursor is
because that's an empty file.

I tried on my two Macs and on a Linux box too.
It works as expected if I do "echo 0 > /tmp/boot-sect.bin" first so that
the file isn't empty.

Cheers,
Igor
-----

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bug#43231: 27.1; hexl-insert-hex-char on an empty file "hexl-current-address: Point is not on a character in the file".

[Eli Zaretskii]

tags 43231 notabug
thanks

> From: Igor Saprykin <sheleztt@gmail.com>
> Date: Sat, 5 Sep 2020 12:22:42 -0700
> 
> hexl-mode doesn't seem to allow me to create a binary file.
> 
> Steps:
> 1. Open Emacs
> 2. Create a new file using C-x C-f /tmp/boot-sect.bin
> 3. M-x hexl-mode
> 4. M-x hexl-insert-hex-char
> 5. e
> 6. Nothing is written into the buffer and the message buffer says "Point is not on a character file".

hexl-mode doesn't support adding or deleting characters, it only
supports replacing them.  E.g., hexl-insert-hex-char _replaces_ the
character at point with what you type.  So what you see is what this
mode is supposed to do: it is based on the assumption that the size of
the file you are editing shouldn't be changed.

If you want to create a file from scratch, why do you need hexl-mode?
You can type bytes in hex or octal using C-q.

bug#43231: 27.1; hexl-insert-hex-char on an empty file "hexl-current-address: Point is not on a character in the file".

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> 4. M-x hexl-insert-hex-char
>> 5. e
>> 6. Nothing is written into the buffer and the message buffer says
>> "Point is not on a character file".
>
> hexl-mode doesn't support adding or deleting characters, it only
> supports replacing them.

The error message could be more helpful, though?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#43231: 27.1; hexl-insert-hex-char on an empty file "hexl-current-address: Point is not on a character in the file".

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: Igor Saprykin <sheleztt@gmail.com>,  43231@debbugs.gnu.org
> Date: Sun, 06 Sep 2020 16:40:22 +0200
> 
> > hexl-mode doesn't support adding or deleting characters, it only
> > supports replacing them.
> 
> The error message could be more helpful, though?

Feel free to suggest a better message.

bug#43231: 27.1; hexl-insert-hex-char on an empty file "hexl-current-address: Point is not on a character in the file".

[Unknown]

Eli Zaretskii <eliz@gnu.org> writes:
>
> Feel free to suggest a better message.

Is there any operation that hexl-mode provides that makes sense when the
buffer is empty? If not, then maybe we could refuse to enable hexl-mode
in an empty buffer, and print a descriptive message.

--
Daniel Martín

bug#43231: 27.1; hexl-insert-hex-char on an empty file "hexl-current-address: Point is not on a character in the file".

[Eli Zaretskii]

> From: Daniel Martín <mardani29@yahoo.es>
> Cc: Lars Ingebrigtsen <larsi@gnus.org>,  sheleztt@gmail.com,
>   43231@debbugs.gnu.org
> Date: Mon, 07 Sep 2020 00:10:54 +0200
> 
> Is there any operation that hexl-mode provides that makes sense when the
> buffer is empty? If not, then maybe we could refuse to enable hexl-mode
> in an empty buffer, and print a descriptive message.

hexl-mode-exit?

bug#43231: 27.1; hexl-insert-hex-char on an empty file "hexl-current-address: Point is not on a character in the file".

[Unknown]

Eli Zaretskii <eliz@gnu.org> writes:
>
> hexl-mode-exit?

Then what's the point in letting a user enable hexl-mode in a situation
where the only useful thing they can do is exiting the mode?

bug#43231: 27.1; hexl-insert-hex-char on an empty file "hexl-current-address: Point is not on a character in the file".

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> 6. Nothing is written into the buffer and the message buffer says
>> "Point is not on a character file".

[...]

>> The error message could be more helpful, though?
>
> Feel free to suggest a better message.

I see now that the error message isn't really "Point is not on a
character file" (which I found very confusing), but instead "Point is
not on a character in the file", which I think is OK.

So I agree that there's nothing here to fix, and I'm closing this bug
report.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#43231: 27.1; hexl-insert-hex-char on an empty file "hexl-current-address: Point is not on a character in the file".

[Igor Saprykin]

Thanks for taking a look.  I thought it might be the case that it's
for replacing them.

I do find it confusing, because
1) "insert" in the name of the function.
2) "C-h f" for that function talks about inserting.
3) "C-h f" for hexl-mode talks about inserting.

Admittedly nothing talks about "deleting" things.

Thanks for the C-q pointer.

Best,
Igor

On Sun, Sep 6, 2020 at 10:25 AM Lars Ingebrigtsen <larsi@gnus.org> wrote:
>
> Eli Zaretskii <eliz@gnu.org> writes:
>
> >> 6. Nothing is written into the buffer and the message buffer says
> >> "Point is not on a character file".
>
> [...]
>
> >> The error message could be more helpful, though?
> >
> > Feel free to suggest a better message.
>
> I see now that the error message isn't really "Point is not on a
> character file" (which I found very confusing), but instead "Point is
> not on a character in the file", which I think is OK.
>
> So I agree that there's nothing here to fix, and I'm closing this bug
> report.
>
> --
> (domestic pets only, the antidote for overdose, milk.)
>    bloggy blog: http://lars.ingebrigtsen.no