Details
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Type:
Bug
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Status: Closed
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Priority:
Major
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Resolution: Fixed
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Affects Version/s: 10.0.6
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Fix Version/s: 10.0.10
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Component/s: None
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Labels:None
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Environment:Windows 7 32-bit application using Visual Studio Express 2012
Description
Using the libmysql client you can unpack a dynamic column using mariadb_dyncol_unpack(), but the data returned in the column_keys and values needs to be freed after use. It is not documented how to do this (i.e. which free function to call) but neither free(), HeapFree() or mariadb_dyncol_free() works. Looking at the code, sf_malloc is used to allocate the data but I can's see a corresponding function that will free data using sf_free().
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Sure, that's what I could see in the libmysqld source also. The issue is that my_free() isn't exported from libmysqld, nor is this documented, so I figured it might change and if my_free() really is to be used, then make sure my_free() is exported, make sure my_free() is documented and make sure to document that my_free() should be used for this purpose.
my_free should be used, but I do not understand what should be fixed, documentation?
Two things: Documentation and, on Windows, make sure that my_free is exported from the .dll. The following samle program:
#include <stdio.h>
#include <my_global.h>
#include <mysql.h>
#include <ma_dyncol.h>
int main(int argc, char* argv[])
{
DYNAMIC_COLUMN dc;
DYNAMIC_COLUMN_VALUE dcv[1];
uint colno[] =
;
dcv[0].type = DYN_COL_INT;
dcv[0].x.long_value = 1;
mariadb_dyncol_create_many_num(&dc, 1, colno, dcv, TRUE);
my_free(dc.str);
return 0;
}
Compiles and runs nicely on Linux, but on Windows I get:
Error 2 error C3861: 'my_free': identifier not found c:\programming\src\consoleapplication1\consoleapplication1\consoleapplication1.cpp 14 1 ConsoleApplication1
Tested with MariaDB 10.0.7 on both Linux and WIndows
Shall we rather provide mariadb_dyncol_unpack_free() for this? That'd be more logical, than explaining to use my_free(). Any better name than mariadb_dyncol_unpack_free()?
mariadb_dyncol_unpack_free() looks quite logical for me...
Anders Karlsson do you think we should provide mariadb_dyncol_unpack_free() or something like that?
Yes, mariadb_dyncol_unpack_free() solves the problem and looks logical. Just make that this is exported from the DLL on Windows (my_free() is not exported on Windows, so on that platform the workaround to just call my_free() doesn't work there. This was true in 10.0.7 at least).
As far as I understand, you should use my_free() for this.