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Message-ID: <8a05330d-6260-2375-9284-38ed7e500052@dunslane.net>
Date: Sat, 25 Feb 2023 10:54:52 -0500
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Subject: Re: using libjansson in postgres extension
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To: mahendrakar s <mahendrakarforpg@gmail.com>,
 pgsql-novice <pgsql-novice@lists.postgresql.org>
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 <CABkiuWpS0d24E4rZV9WhWuWM6BBgi3P3pti5seuAgKOkhVJ7TA@mail.gmail.com>
From: Andrew Dunstan <andrew@dunslane.net>
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On 2023-02-23 Th 20:59, mahendrakar s wrote:
>
> On Thu, 23 Feb 2023 at 19:08, mahendrakar s 
> <mahendrakarforpg@gmail.com> wrote:
>
>     Hello Hackers,
>
>     I'm developing an extension where in it indirectly references
>     (libjansson) and libjansson has a symbol json_object
>     <https://github.com/akheron/jansson/blob/master/src/load.c#:~:text=json_t%20*object%20%3D%20json_object()%3B>which
>     conflicts with postgres  symbol 'json_object
>     <https://github.com/postgres/postgres/blob/master/src/backend/utils/adt/json.c#:~:text=json_object(PG_FUNCTION_ARGS)>'.
>
>     I see below:
>     PostgreSQL: Documentation: 11: 38.10. C-Language Functions
>     <https://www.postgresql.org/docs/11/xfunc-c.html#id-1.8.3.13.8>
>     "Symbol names defined within object files must not conflict with
>     each other or with symbols defined in the PostgreSQL server
>     executable. You will have to rename your functions or variables if
>     you get error messages to this effect."
>
>     But this requires to maintain libjansson with customizations(have
>     a different symbol) to meet the needs.
>
>     Do you have any suggestions to use the libjansson 'as it is'
>     without using the different symbol.
>
>


No. AFAICT you will have to create a fork of the library as the 
documentation suggests.


cheers


andrew


--
Andrew Dunstan
EDB:https://www.enterprisedb.com

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    </p>
    <div class="moz-cite-prefix">On 2023-02-23 Th 20:59, mahendrakar s
      wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CABkiuWpS0d24E4rZV9WhWuWM6BBgi3P3pti5seuAgKOkhVJ7TA@mail.gmail.com">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
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        <div class="gmail_quote">
          <div dir="ltr" class="gmail_attr">On Thu, 23 Feb 2023 at
            19:08, mahendrakar s &lt;<a
              href="mailto:mahendrakarforpg@gmail.com"
              moz-do-not-send="true" class="moz-txt-link-freetext">mahendrakarforpg@gmail.com</a>&gt;
            wrote:<br>
          </div>
          <blockquote class="gmail_quote" style="margin:0px 0px 0px
            0.8ex;border-left:1px solid
            rgb(204,204,204);padding-left:1ex">
            <div dir="ltr">Hello Hackers,
              <div><br>
              </div>
              <div>I'm developing an extension where in it indirectly
                references (libjansson) and libjansson has a symbol <a
href="https://github.com/akheron/jansson/blob/master/src/load.c#:~:text=json_t%20*object%20%3D%20json_object()%3B"
                  target="_blank" moz-do-not-send="true">json_object </a>which
                conflicts with postgres  symbol '<a
href="https://github.com/postgres/postgres/blob/master/src/backend/utils/adt/json.c#:~:text=json_object(PG_FUNCTION_ARGS)"
                  target="_blank" moz-do-not-send="true">json_object</a>'.</div>
              <div><br>
              </div>
              <div>I see below:<br>
              </div>
              <div><a
                  href="https://www.postgresql.org/docs/11/xfunc-c.html#id-1.8.3.13.8"
                  target="_blank" moz-do-not-send="true">PostgreSQL:
                  Documentation: 11: 38.10. C-Language Functions</a><br>
                "Symbol names defined within object files must not
                conflict with each other or with symbols defined in the
                PostgreSQL server executable. You will have to rename
                your functions or variables if you get error messages to
                this effect."<br>
              </div>
              <div><br>
              </div>
              <div>But this requires to maintain libjansson with
                customizations(have a different symbol) to meet the
                needs.<br>
              </div>
              <div><br>
              </div>
              <div>Do you have any suggestions to use the libjansson 'as
                it is' without using the different symbol.</div>
              <div><br>
              </div>
              <br>
            </div>
          </blockquote>
        </div>
      </div>
    </blockquote>
    <p><br>
    </p>
    <p><br>
    </p>
    <p>No. AFAICT you will have to create a fork of the library as the
      documentation suggests.<br>
    </p>
    <p><br>
    </p>
    <p>cheers</p>
    <p><br>
    </p>
    <p>andrew<br>
    </p>
    <p><br>
    </p>
    <pre class="moz-signature" signature-switch-id="d0437855-2267-4610-80b3-83167ec45b0b" cols="72">--
Andrew Dunstan
EDB: <a class="moz-txt-link-freetext" href="https://www.enterprisedb.com">https://www.enterprisedb.com</a>
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