When I call
---->>> SetLog("WinMain", Msg("Loading %s ...", filename)); <<---


TCHAR *Msg(TCHAR *szFormat, ...)
{
TCHAR szBuffer[1024]=""; // Large buffer for long filenames or
URLs
const size_t NUMCHARS = sizeof(szBuffer) / sizeof(szBuffer[0]);
const int LASTCHAR = NUMCHARS - 1;

// Format the input string
va_list pArgs;
va_start(pArgs, szFormat);

// Use a bounded buffer size to prevent buffer overruns. Limit
count to
// character size minus one to allow for a NULL terminating
character.
_vsntprintf(szBuffer, NUMCHARS - 1, szFormat, pArgs);
va_end(pArgs);

// Ensure that the formatted string is NULL-terminated
szBuffer[LASTCHAR] = TEXT('\0');

// Display a message box with the formatted string
return szBuffer;
}

void SetLog(TCHAR *ID, TCHAR *szMsg)
{<-----------------------------------------------------szMsg =
szBuffer (of Msg(..))
TCHAR str[BUFSIZE]=""; <------------------------- szMsg reseted!
WHY!?!!!??
TCHAR gt1[BUFSIZE]="", gt2[BUFSIZE]="";
struct tm *newtime;
time_t aclock;
time( &aclock ); // Get time in seconds
newtime = localtime( &aclock ); // Convert time to struct tm form

_tcscpy(gt1, _tasctime(newtime));
_tcsncat(gt2, gt1, _tcslen(gt1)-1);

wsprintf(str, "[%s]%s : %s \n", gt2, ID, szMsg);

AppendText(ghSttEM, str);

FILE *stream = fopen("dc.log","a+");
_ftprintf(stream, str);
fclose(stream);
}




I go through SetLog, it first calls Msg(...) in order to display in
format.

As i debug step by step, I found out some weird problems...
I indicated the problem on the source, can someone tell me what's
going wrong with this code?

On Apr 4, 10:22pm, Simon K <monol...@gmail.com> wrote:
> When I call
> ---->>> SetLog("WinMain", Msg("Loading %s ...", filename)); <<---
>
> TCHAR *Msg(TCHAR *szFormat, ...)
> {
> TCHAR szBuffer[1024]=""; // Large buffer for long filenames or
> URLs
> const size_t NUMCHARS = sizeof(szBuffer) / sizeof(szBuffer[0]);
> const int LASTCHAR = NUMCHARS - 1;
>
> // Format the input string
> va_list pArgs;
> va_start(pArgs, szFormat);
>
> // Use a bounded buffer size to prevent buffer overruns. Limit
> count to
> // character size minus one to allow for a NULL terminating
> character.
> _vsntprintf(szBuffer, NUMCHARS - 1, szFormat, pArgs);
> va_end(pArgs);
>
> // Ensure that the formatted string is NULL-terminated
> szBuffer[LASTCHAR] = TEXT('\0');
>
> // Display a message box with the formatted string
> return szBuffer;
>
> }
>
> void SetLog(TCHAR *ID, TCHAR *szMsg)
> {<-----------------------------------------------------szMsg =
> szBuffer (of Msg(..))
> TCHAR str[BUFSIZE]=""; <------------------------- szMsg reseted!
> WHY!?!!!??
> TCHAR gt1[BUFSIZE]="", gt2[BUFSIZE]="";
> struct tm *newtime;
> time_t aclock;
> time( &aclock ); // Get time in seconds
> newtime = localtime( &aclock ); // Convert time to struct tm form
>
> _tcscpy(gt1, _tasctime(newtime));
> _tcsncat(gt2, gt1, _tcslen(gt1)-1);
>
> wsprintf(str, "[%s]%s : %s \n", gt2, ID, szMsg); ------>> szMsg = str!!! WHY!?!?!?
>
> AppendText(ghSttEM, str);
>
> FILE *stream = fopen("dc.log","a+");
> _ftprintf(stream, str);
> fclose(stream);
>
> }
>
> I go through SetLog, it first calls Msg(...) in order to display in
> format.
>
> As i debug step by step, I found out some weird problems...
> I indicated the problem on the source, can someone tell me what's
> going wrong with this code?

One thing more, I indicated one more problem up here.

On Fri, 04 Apr 2008 06:22:11 -0700, Simon K wrote:

> When I call
> ---->>> SetLog("WinMain", Msg("Loading %s ...", filename)); <<---
>
>
> TCHAR *Msg(TCHAR *szFormat, ...)
> {
> TCHAR szBuffer[1024]=""; // Large buffer for long filenames or
> URLs

Local object.


[snip>
>
> // Display a message box with the formatted string return szBuffer;

I assume there is an actual return statement here, or?
It returns a local object which dies when the function exits.

> }
>
> void SetLog(TCHAR *ID, TCHAR *szMsg)
> {<-----------------------------------------------------szMsg = szBuffer
> (of Msg(..))
> TCHAR str[BUFSIZE]=""; <------------------------- szMsg reseted!
> WHY!?!!!??

Why? Since SetLog() is called directly after Msg() it most likely
overwrites the stack part that Msg() used with its own local object.

[snip]
>
>
>
>
> I go through SetLog, it first calls Msg(...) in order to display in
> format.
>
> As i debug step by step, I found out some weird problems... I indicated
> the problem on the source, can someone tell me what's going wrong with
> this code?

It's written terribly wrong. Compare to this example:

#include <iostream>

int * get_address_to_local_object() {
int local[1024] = {1};
return &local[0];
}

void use_invalid_pointer(int * ptr) {
int local[1024] = {0};
std::cout<<ptr[0]<<std::endl;
}


int main() {
use_invalid_pointer(get_address_to_local_object()) ;
return 0;
}

If you're lucky it will print 0 to illustrate the problem:

:~$ g++ test.cpp
test.cpp: In function ‘int* get_address_to_local_object()’:
test.cpp:4: warning: address of local variable ‘local’ returned
:~$ ./a.out
0
:~$
--
OU

On Apr 4, 11:44 pm, Obnoxious User <O...@127.0.0.1> wrote:
> On Fri, 04 Apr 2008 06:22:11 -0700, Simon K wrote:
> > When I call
> > ---->>> SetLog("WinMain", Msg("Loading %s ...", filename)); <<---
>
> > TCHAR *Msg(TCHAR *szFormat, ...)
> > {
> > TCHAR szBuffer[1024]=""; // Large buffer for long filenames or
> > URLs
>
> Local object.
>
> [snip>
>
>
>
> > // Display a message box with the formatted string return szBuffer;
>
> I assume there is an actual return statement here, or?
> It returns a local object which dies when the function exits.
>
> > }
>
> > void SetLog(TCHAR *ID, TCHAR *szMsg)
> > {<-----------------------------------------------------szMsg = szBuffer
> > (of Msg(..))
> > TCHAR str[BUFSIZE]=""; <------------------------- szMsg reseted!
> > WHY!?!!!??
>
> Why? Since SetLog() is called directly after Msg() it most likely
> overwrites the stack part that Msg() used with its own local object.
>
> [snip]
>
>
>
> > I go through SetLog, it first calls Msg(...) in order to display in
> > format.
>
> > As i debug step by step, I found out some weird problems... I indicated
> > the problem on the source, can someone tell me what's going wrong with
> > this code?
>
> It's written terribly wrong. Compare to this example:
>
> #include <iostream>
>
> int * get_address_to_local_object() {
> int local[1024] = {1};
> return &local[0];
>
> }
>
> void use_invalid_pointer(int * ptr) {
> int local[1024] = {0};
> std::cout<<ptr[0]<<std::endl;
>
> }
>
> int main() {
> use_invalid_pointer(get_address_to_local_object()) ;
> return 0;
>
> }
>
> If you're lucky it will print 0 to illustrate the problem:
>
> :~$ g++ test.cpp
> test.cpp: In function 'int* get_address_to_local_object()':
> test.cpp:4: warning: address of local variable 'local' returned
> :~$ ./a.out
> 0
> :~$
> --
> OU

I just looked up to find out what was wrong, exactly what u said.
Thou, I can't figure out how to solve this problem.

It looks really stupid to answer my own question but I just found out
one solution

In Msg,

TCHAR *Msg(TCHAR *szFormat, ...)
{
TCHAR szBuffer[1024]=""; // Large buffer for long filenames or
URLs


I changed

TCHAR szBuffer[1024]=""; ==> static TCHAR szBuffer[1024]="";

and added one more line,
ZeroMemory(szBuffer, sizeof(szBuffer));

in order to reset szBuffer everytime I get thru Msg.


Well, I don't think this is a firm solution, any better idea?

[Please quote some context.]

On Fri, 04 Apr 2008 09:15:02 -0700, Simon K wrote:
> It looks really stupid to answer my own question but I just found out
> one solution
>
> In Msg,
>
> TCHAR *Msg(TCHAR *szFormat, ...)
> {
> TCHAR szBuffer[1024]=""; // Large buffer for long filenames or
> URLs
>
>
> I changed
>
> TCHAR szBuffer[1024]=""; ==> static TCHAR szBuffer[1024]="";
>
> and added one more line,
> ZeroMemory(szBuffer, sizeof(szBuffer));

Unnecessary.

>
> in order to reset szBuffer everytime I get thru Msg.

int written = _vsntprintf(szBuffer, NUMCHARS - 1, szFormat, pArgs);
if(written == -1) throw "error";
szBuffer[written] = 0;

>
>
> Well, I don't think this is a firm solution, any better idea?

boost::shared_ptr<>, std::string, std::vector, so many options

And what about this situation:

TCHAR * m1 = Msg("Loading %s ...", filename);
TCHAR * m2 = Msg("Loading %s ...", filename);

SetLog("WinMain", m1);
SetLog("WinMain", m2);

--
OU