Hi Przemek,
Il 28/01/2009 3.52, Przemyslaw Czerpak ha scritto:
First of all thank you for your detailed explanation,
[snip]
HB_REINIT_STATIC
HB_KEEP_LOCAL_REFERENCES
good
HB_OVERLOAD_FUNCTIONS
interesting, but, as you pointed out, is dangerous in code like HTTP
server, so my vote is no
So what should you make now?
I suggest to ignore this problem until I'll not change structures used
to hold static variables. The chance for GPF is rather small. The side
effect of array preallocation added by Mindaugas is noticeable reduced
number of memory reallocation when new statics are added so the risk is
really small that the problem will be exploited. Of course it _MUST_ be
fixed but it should not be critical during uHTTPd developing.
Now concentrate on the above information. I hope it helps to understand
how .hrb modules works.
BTW all of the above is also valid with exactly the same conditions for
compiled .prg code loaded/unloaded from dynamic libraries (.dll, .so,
.sl, .dyn, ...).
Ok, I will go on. Thank you again.
Just 3 other questions:
1 - I would like to limit use of some functions that may be dangerous if
used from a user, like zap a database or FErase, but this are only two
samples and maybe not pertinent in real developing, or to other
functions, like dbUseArea(), that I want that not have to be used
because I would like to add an HTTP_dbUseArea() that can open databases
and control them. Is there a way to add a HRB_INHIBIT_FUNCTIONS that can
inhibit some function calls from hrb at HVM level ?
2 - In uhttpd.prg the piece of code that runs HRB modules is guarded
from a mutex:
--------------
.....
// Lock HRB to avoid MT race conditions
IF hb_mutexLock( s_hmtxHRB ) <<<<----
IF HRB_ACTIVATE_CACHE
// caching modules
IF !hb_HHasKey( s_hHRBModules, cFileName )
hb_HSet( s_hHRBModules, cFileName,
HRB_LoadFromFile( uOSFileName( cFileName ) ) )
ENDIF
cHRBBody := s_hHRBModules[ cFileName ]
ELSE
cHRBBody := HRB_LoadFromFile( uOSFileName(
cFileName ) )
ENDIF
IF !EMPTY( pHRB := HB_HRBLOAD( cHRBBody ) )
xResult := HRBMAIN()
HB_HRBUNLOAD( pHRB )
ELSE
uSetStatusCode( 404 )
t_cErrorMsg := "File does not exist: " + cFileName
ENDIF
hb_mutexUnlock( s_hmtxHRB ) <<<<----
ENDIF
.....
STATIC FUNCTION HRB_LoadFromFile( cFile )
RETURN hb_memoread( cFile )
--------------
Is it correct or is it unnecessary because this is already done from HVM ?
3 - In the same piece of code (not already uploaded) I have thought to a
memory cache of HRBBody code using an hash (actually HRB_ACTIVATE_CACHE
can has value .T. or .F.) but I'm not able to evaluate costs between
load from file everytime (where I suppose that OS helps caching file in
memory) or scanning an hash and retrieve the string (apart from a side
effect: loading an hrb module from file permits to update hrb code on
the fly, the other method load hrb only first time than I need to
"purge" list to have it loaded again).
TIA
Best regards,
Francesco
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