Using application_id

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Using application_id

Tobias Leupold
Hi list!

I recently learned about the PRAGMA application_id feature of SQLite, which is
really nice to be able to identify an application-specific SQLite database at
the file system level, even with versioning support via the user_version
header.

SQLite encourages to use an SQLite database as one's application file format,
which I do for one of my projects (like probably hundreds of other projects
do). In the docs, a magic file is linked ( https://www.sqlite.org/src/
artifact?ci=trunk&filename=magic.txt ) with "registered" formats.

With SQLite being so widely used, I can hardly believe that only 6 projects
decided to make use of the application_id header until now.

So here's my question: Is there another list with "taken" application ids?
Some kind of wiki perhaps? And/or how can one "register" an application id to
prevent collisions?

Thanks for the information in advance!

Cheers, Tobias


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Re: Using application_id

Clemens Ladisch
Tobias Leupold wrote:
> In the docs, a magic file is linked ( https://www.sqlite.org/src/
> artifact?ci=trunk&filename=magic.txt ) with "registered" formats.
>
> Is there another list with "taken" application ids?

No.

Apparently, authors or 'private' file formats do not bother to register
their IDs.

> And/or how can one "register" an application id to prevent collisions?

Submit a patch here.


Regards,
Clemens
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Re: Using application_id

Dominique Devienne
On Mon, Nov 18, 2019 at 2:41 PM Clemens Ladisch <[hidden email]> wrote:

> Tobias Leupold wrote:
> Apparently, authors or 'private' file formats do not bother to register
> their IDs.
>

Indeed, there's little point, as those are rarely "public".

I tend to chose a 4 letter prefix related to the kind of app/report the
SQLite DB is for,
and use the hexa for each letter to generate the app_id 32-bit integer.

If you stick to lower or upper case letters, could encode up to 6 chars in
the app_id. --DD
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Re: Using application_id

Tobias Leupold
In reply to this post by Clemens Ladisch
Hi Clemens!

Thanks for your fast reply!

>> And/or how can one "register" an application id to prevent collisions?
>
> Submit a patch here.

In my case, that would be:

    --- magic.txt.orig      2019-11-18 18:12:00.957789352 +0100
    +++ magic.txt   2019-11-18 18:13:13.055463773 +0100
    @@ -29,4 +29,7 @@
     >68  belong  =0x47503130  OGC GeoPackage version 1.0 file -
     >68  belong  =0x45737269  Esri Spatially-Enabled Database -
     >68  belong  =0x4d504258  MBTiles tileset -
    +>68  belong  =0x4d75636b  Muckturnier.org tournament database
    +>>60 belong  x            \b (Revision %d) -
    +!:mime application/x-muckturnier
     >0   string  =SQLite      SQLite3 database

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Re: Using application_id

Peter da Silva-2
In reply to this post by Dominique Devienne

> If you stick to lower or upper case letters, could encode up to 6 chars in
> the app_id. --DD

The return of RADIX-50.

https://en.wikipedia.org/wiki/DEC_Radix-50

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Re: Using application_id

Dominique Devienne
On Tue, Nov 19, 2019 at 2:00 AM Peter da Silva <[hidden email]> wrote:

>
> > If you stick to lower or upper case letters, could encode up to 6 chars
> in the app_id. --DD
>
> The return of RADIX-50.
>
> https://en.wikipedia.org/wiki/DEC_Radix-50


Thanks! I might go with this going forward. --DD

PS: I tend to prefer reusing "old tech" like this, which already has a
"known" name, and Wikipedia page,
rather that inventing my own similar but poorly-documented-by-comparison
scheme. When I'm aware of them that is :)
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Re: Using application_id

Christian Gauger-Cosgrove
On 19/11/2019, Dominique Devienne <[hidden email]> wrote:
> On Tue, Nov 19, 2019 at 2:00 AM Peter da Silva <[hidden email]> wrote:
>> The return of RADIX-50.
>>
>> https://en.wikipedia.org/wiki/DEC_Radix-50
>
> Thanks! I might go with this going forward. --DD
>
To make life easier for those desiring to experience the Wonders of
RADIX-50™, if anyone wants I've attached a copy of my implementation
of RAD50 in both the "traditional" 16-bit form, and a 32-bit form.

The "*enc" functions encode a string into RAD50, and the "*dec"
functions decode. "rad50*" works on a 16-bit value, "xrad50*" on a
32-bit.

I leave it as an exercise for the reader to implement a 64-bit function.

If anyone has ideas of how to improve the functions: Please feel free
to contribute.

Best regards,
Christian
--
Christian M. Gauger-Cosgrove
STCKON08DS0
Contact information available upon request.
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Re: Using application_id

Christian Gauger-Cosgrove
Pardon the "double post" as it were. I was handily informed the
mailing list strips attachments.

Therefore, for those interested, here's text versions of the header
file (rad50.h) and the actual C that does the RADIX-50 conversions
(rad50.c):

/* ========================================================================== */
#ifndef _RAD50_H
#define _RAD50_H
#include <stdint.h>

int rad50enc(const char *, uint16_t *);
int rad50dec(uint16_t, char *);
int xrad50enc(const char *, uint32_t *);
int xrad50dec(uint32_t, char *);

#endif /* _RAD50_H */
/* ========================================================================== */
/*
 * Copyright (c) 2019 C. Gauger-Cosgrove
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#include <ctype.h>
#include <string.h>
#include "rad50.h"

#define RAD50TAB " ABCDEFGHIJKLMNOPQRSTUVWXYZ$.*0123456789"

int
rad50enc(const char *text, uint16_t *value) {
        size_t i;
        uint16_t t;
        const int mult[3] = {1600, 40, 1};
        char *c;

        if (strlen(text) == 0) {
                *value = 0;
                return 0;
        } else if (strlen(text) > 3) {
                *value = 0xFFFF;
                return 1;
        }

        t = 0;
        for (i = 0; i < strlen(text); ++i) {
                c = (char *) strchr(RAD50TAB, toupper(text[i]));
                if (c == NULL) {
                        *value = 0xFFFF;
                        return 1;
                }
                t += (c - RAD50TAB) * mult[i];
        }
        *value = t;

        return 0;
}

int
rad50dec(uint16_t value, char *text) {
        size_t i;
        const int mult[3] = {1600, 40, 1};

        if (value >= 0xFA00) {
                text[0] = 0;
                return 1;
        }
       
        for (i = 0; i < 3; ++i)
                text[i] = RAD50TAB[(value / mult[i]) % 40];
        text[3] = 0;

        return 0;
}

int
xrad50enc(const char *text, uint32_t *value) {
        size_t i;
        uint32_t t;
        const int mult[6] = {102400000, 2560000, 64000, 1600, 40, 1};
        char *c;

        if (strlen(text) == 0) {
                *value = 0;
                return 0;
        } else if (strlen(text) > 6) {
                *value = 0xFFFFFFFF;
                return 1;
        }

        t = 0;
        for (i = 0; i < strlen(text); ++i) {
                c = (char *) strchr(RAD50TAB, toupper(text[i]));
                if (c == NULL) {
                        *value = 0xFFFFFFFF;
                        return 1;
                }
                t += (c - RAD50TAB) * mult[i];
        }
        *value = t;

        return 0;
}

int
xrad50dec(uint32_t value, char *text) {
        size_t i;
        const int mult[6] = {102400000, 2560000, 64000, 1600, 40, 1};

        if (value >= 0xF4240000) {
                text[0] = 0;
                return 1;
        }

        for (i = 0; i < 6; ++i)
                text[i] = RAD50TAB[(value / mult[i]) % 40];
        text[6] = 0;

        return 0;
}
/* ========================================================================== */

Best regards,
Christian Gauger-Cosgrove

On 19/11/2019, Christian Gauger-Cosgrove <[hidden email]> wrote:

> On 19/11/2019, Dominique Devienne <[hidden email]> wrote:
>> On Tue, Nov 19, 2019 at 2:00 AM Peter da Silva <[hidden email]> wrote:
>>> The return of RADIX-50.
>>>
>>> https://en.wikipedia.org/wiki/DEC_Radix-50
>>
>> Thanks! I might go with this going forward. --DD
>>
> To make life easier for those desiring to experience the Wonders of
> RADIX-50™, if anyone wants I've attached a copy of my implementation
> of RAD50 in both the "traditional" 16-bit form, and a 32-bit form.
>
> The "*enc" functions encode a string into RAD50, and the "*dec"
> functions decode. "rad50*" works on a 16-bit value, "xrad50*" on a
> 32-bit.
>
> I leave it as an exercise for the reader to implement a 64-bit function.
>
> If anyone has ideas of how to improve the functions: Please feel free
> to contribute.
>
> Best regards,
> Christian
> --
> Christian M. Gauger-Cosgrove
> STCKON08DS0
> Contact information available upon request.
>


--
Christian M. Gauger-Cosgrove
STCKON08DS0
Contact information available upon request.
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