Hi Brett,
I believe SQLite doesn't use the standard memory allocation routines, but
instead has its own routines. These (might) use global variables. If each
module of your application statically links to the SQLite source rather than
having SQLite in a common DLL, then each module will have its own set of global
variables. As such, passing raw SQLite pointers across module boundaries can
result in undefined behaviour. I suspect other issues could also occur with
other global variables in SQLite.
Note that passing the raw pointer is not the real culprit, but rather having
different modules attempt to work on the pointer. For example:, the following
should work fine:
sqlite3* pDb = DLL1GetDb();
DLL1DoSomething(pDb);
But either of the following could fail:
sqlite3* pDb = DLL1GetDb();
DLL2DoSomething(pDb);
// or, if the calling module is not DLL1
sqlite3_exec(pDb,...);
Personally, to enforce this I do not expose (either in arguments or return
values) raw sqlite objects (dbs, statements, or anything else) in exported
functions.
If you already have SQLite in a common DLL, or you perform all sqlite3_* calls
from the same module, I apologise for wasting your time.
Also, SQLite is written in C so it uses error return codes rather than throwing
exceptions. The exception you are catching would have to be thrown by another
library that SQLite is calling. This would mean that the output of
sqlite3_errmsg is likely unrelated to the exception since SQLite would never
have intercepted it. Perhaps your debugging environment could tell you more
details of the real proximate cause of the error (unless the you mean that the
error message of the exception, by coincidence, was the same as a standard
SQLite error message)
Cheers,
- Barry
> On 8 Feb 2017, at 9:30 AM, Brett Goodman <bre...@eztools-software.com> wrote:
>
> Hello Sqlite users. I have a problem I can't solve. I have a C++ DLL
> project in which I compile the Sqlite amalgamation code. The purpose is to
> wrap the key Sqlite functions with exported functions I can call from another
> C++ COM DLL. I'm using VS2003 for this because its part of a legacy
> product. I've been using this project for years, updating the Sqlite source
> code from time to time with no problems. I can call functions like
> sqlite3_open_v2, sqlite3_prepare, sqlite3_step, etc. with no problems. Now
> I'm trying to integrate the Backup API. When I call sqlite3_backup_init it
> throws this error: _/"library /__/
> /__/routine called out of sequence"/_. I want to step into the Sqlite code
> to find out why but for some reason my debugger won't allow me to step into
> the C code from my C++ code. So I'm hoping someone can help me. Below is my
> C++ implementation which I modeled from the sample on this page:
> sqlite.org/backup.html. My calling code is from a VB6 project which simply
> creates/opens a memory DB and calls the below function (via my COM DLL). Any
> help is much appreciated.
>
> Thanks,
> BrettG
>
>
> SQLITE_DLL_API int backup( /*sqlite3*/ void* pdb, const WCHAR *pFilename,
> BOOL toFile )
> {
> int rc;
> sqlite3 *pFileDb;
> sqlite3_backup *pBackup;
> sqlite3 *pTo;
> sqlite3 *pFrom;
>
> CTextConverter c(CP_UTF8);
> //rc = sqlite3_open_v2( c.U2M(pFilename), &pFileDb, SQLITE_OPEN_READWRITE,
> NULL);
> rc = sqlite3_open( c.U2M(pFilename), &pFileDb);
>
> if( rc==SQLITE_OK )
> {
> try
> {
> sqlite3 *pMemoryDb = (sqlite3*) pdb;
> pFrom = (toFile ? pMemoryDb : pFileDb);
> pTo = (toFile ? pFileDb : pMemoryDb);
>
> // this line throws exception: "library routine called out of
> sequence"
> *pBackup = sqlite3_backup_init(pTo, "main", pFrom, "temp");*
> if( pBackup )
> {
> sqlite3_backup_step(pBackup, -1);
> sqlite3_backup_finish(pBackup);
> }
> rc = sqlite3_errcode(pTo);
> sqlite3_close(pFileDb);
> }
> catch(...)
> {
> sqlite3_close(pFileDb);
> const char* err = sqlite3_errmsg( (sqlite3*) pdb );
> throw err;
> }
> }
> return rc;
> }
>
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