Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Won't Fix
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3.0.2
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archlinux kernel 5.2.13
gcc (GCC) 9.1.0
mariadb 10.7.3 downloaded and compiled on host
same behavior on upgraded version 10.4.8
Description
i'm using mariadb c-connector with prepare, bind and execute. it works usualy. but one case end up in "corrupted unsorted chunks" and core dumping when freeing bind buffer. i suggest the whole malloc organisation is messed up after calling mysql_stmt_execute(). my test's MysqlDynamic.c show:
- the problem only is connected to x509cert variable bound by bnd[9]
- freeing memory only fails if bnd[9].is_null = 0, if is_null execute end normally
- freeing memory (using FreeStmt()) after bind and before execute end normally
- print of bnd[9].buffer before execute show (void*) is connected to the correct string buffer
- same behavior for setting bnd[9].buffer_length to STMT_INDICATOR_NTS or strlen()
- other similar bindings (picture, bnd[10]) do not lead to corrupted memory and core dump.
for more detailed explanation please see link stackoverflow.
i'm opening this issue after i did not get any useful answers.
please verify code MysqlDynamic.c and compile it. i especialy wrote for debugging purposes after running randomly into troubles. please let me know if <MysqlDynamic -i> run without problems.
thank you
Attachments
Activity
Hi SwissGeorge, I am changing the priority until we got a reproducible test case.
why are you doing
bnd[2].buffer_length = STMT_INDICATOR_NTS;
|
? Can you point to the documentation where you took it from?
hi sergei goulubchik
thank you for the hint. i changed my code to strlen(). now the program runs stable.
20 years ago i was using oracles, sybase and informix functionalities what they called Dynamic SQL. hence i tried to understand the way i have to use your functionalties. intention is to bind my buffer to database structure and use it by just move the pointer through the array of buffers. i went through any of your documents including Connector/C Types where i found <STMT_INDICATOR_NTS>.
after reading all of the documention around bind/execute i really do not feel to have understood all the features good enough in order to write stable applications. i tried to ask for more documentations alike c-type db-type relation. this because of i do not understand why i have to declare my c buffer as <MYSQL_TYPE_VARCHAR>. c only knows char and arrays of it. the database datatype is available after mysql_stmt_prepare, i do bind them together thereafter.
i was understanding there are two functions for mysql_stmt_bind; parameter for writing to the db and result for reading. to me it is obvious to use different bindings for input and output. but MYSQL_BIND in confused me as not all attributes are clear in effect to me. furthermore i discoverd implicit conversion c-string to DATE/TIME db structure.
i so changed to <try and error> i try to avoid.
why did i use <<STMT_INDICATOR_NTS> and wrote this issue as <need feedback>?
- mysql_stmt_bind did not fail
- most cases using <STMT_INDICATOR_NTS> works well, as ingle call of bind/exec works always without messing up memory.
- work always was done .. db touples were correct
- in a few cases the memory was messed up
BTW: <STMT_INDICATOR_NTS> would reduce mysql_stmt_bind calls substantialy.
please let me know for which cases <STMT_INDICATOR_NTS> is supported. if also supported for row-wise binding, i continue to provide a short testversion asked by Georg Richter. It looks like all single calls work well - recurring calls to bind/execute cause the problem.
it would be great if somebody could verify and some information to the description MYSQL_BIND in . please verify <is_null Pointer which indicates if column is NULL (not used for parameters)>. my test's show a <string with length and is_null = 1> will be stored as NULL - which is great. in what cases is <length_value Used if length pointer is NULL> used (input / output / both)?
hi Georg Richter
i was working on your request to extract a test case reproducing the issue.
then i got the question from sergei goulubchik why i'm using <bnd[2].buffer_length = STMT_INDICATOR_NTS;>.
now i'm hanging in the ropes not knowing if i was missunderstanding Connector/C Types and Definitions. if so, there is no motivation to continue debugging. otherwise i'll be glad to give something back to the community.
thank you for short answer.
Please provide a short reproducible test case, but not 645 lines of code (where most of the code is unrelated to your problem).
For an example check the tests in unittest/libmariadb, e.g. test_conc67