> I use GBAK.EXE to perform backup and restore operation of Firebird
> database in my GUI application design. The reason I use GBAK instead
> of firebird service manager is I can perform remote backup and restore
> operation via TCP/IP network without transferring the backup file to
> firebird server first.
>
> However, as GBAK is a console utility, It display the output to STDOUT
> or STDERR. There is no easy way to capture the output while the
> console process is running. We need to invoke windows API to perform
> the task. We may use CreatePipe and CreateProcess to redirect the
> STDxxx handles and use ReadFile to capture the output in our GUI
> application.
>
> There is a drawback using windows native API aproach. As stated in
> microsoft knowledge base (http://support.microsoft.com/kb/190351):
>
> Child processes that use such C run-time functions as printf() and
> fprintf() can behave poorly when redirected. The C run-time functions
> maintain separate IO buffers. When redirected, these buffers might not
> be flushed immediately after each IO call. As a result, the output to
> the redirection pipe of a printf() call or the input from a getch()
> call is not flushed immediately and delays, sometimes-infinite delays
> occur. This problem is avoided if the child process flushes the IO
> buffers after each call to a C run-time IO function. Only the child
> process can flush its C run-time IO buffers. A process can flush its C
> run-time IO buffers by calling the fflush() function.
>
> I face this problem if I use GBAK to perform a lengthy backup and
> restore operation via this approach. The GUI application always stop
> half way in unforeseen point although it will finish the operation at
> last. There isn't any response from the ReadFile when it hang some
> where. I suspect it was due the GBAK utility written didn't perform
> flush as described.

What is your question? :-)


Can't you use a threaded approach to avoid the GUI application
to appear hanging?

Martijn Tonies
Database Workbench - tool for InterBase, Firebird, MySQL, NexusDB, Oracle &
MS SQL Server
Upscene Productions
http://www.upscene.com
My thoughts:
http://blog.upscene.com/martijn/
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