On Fri, Jun 13, 2008 at 4:31 AM, Alexey Pechnikov <[EMAIL PROTECTED]> wrote:
>> The extension-functions file doesn't actually implement any of the
>> math functinos, it simply acts as a glue layer between SQLite and the
>> system math library. In this case, it looks like the run-time linker
>> that loads the extension can't resolve the call for log() from the
>> extension into the math library, resulting in an unresolved link.
>>
>> On many systems the math library is part of the standard set of libs
>> that are imported by the linker for all applications. There are a
>> few systems, however, where the math library is not part of the
>> standard lib set. On those systems, you need to explicitly tell the
>> linker you want the math library made avaliable. You can do that
>> by compiling the lib with -lm to import the math library. The math
>> lib won't be pulled into the .so, but it will be noted that if the
>> run-time linker pulls in the extension, it will also need to pull in
>> the math library before it attepts to resolve all the symbols.
>>
>> At least, in theory.
>
> Thanks for coherent explanation. I am compiling library with switch -lm and
> now it's work.
>
> $ gcc -fPIC -lm -shared extension-functions.c -o libsqlitefunctions.so
> $ sqlite3 :memory:
> sqlite> SELECT load_extension('./libsqlitefunctions.so');
>
> sqlite> select sqrt(16);
> 4.0
> sqlite>
>
>>
>> What OS are you trying this on?
>
> Linux Debian Etch (sqlite pakage backported from Debian Lenny).
>
Interesting; I tried it on Debian sid (unstable) and it worked as
well. I guess the statement in
http://www.sqlite.org/cvstrac/wiki?p=LoadableExtensions that the
extensions loading mechanism being turned off by default doesn't apply
to Debian. I've revised the instructions to include -lm for Linux and
to indicate the possibility that the program as compiled by some
distributions will work. Does anyone know if -lm is need on Mac OS X
as well?
Liam
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