Re: why I can not write to the file after initialize the MFC in a service program

What problem? Remember, all you gave was the vague "cannot work" description, so there is
actually no way for anyone reading this thread to get the foggiest idea what you mean by
"cannot work". Have you tried single-stepping the code to see what is executing? Looked
at the values with the debugger? We need more to go on than "cannot work". We don't even
know if the code is being executed!
joe

On Thu, 8 Feb 2007 11:14:48 +0800, "zhang" <makefriend8@xxxxxxx> wrote:

Problem still exist





"Joseph M. Newcomer" <newcomer@xxxxxxxxxxxx>
??????:cnqjs2lma6ce9ud757u3n6sq7tnn6sl7s6@xxxxxxxxxx
I have no idea what "cannot work" means. Do you get an error? This is a
SERVICE!!!! This
means that

(a) you don't use strcpy, strcat, or other unsafe mechanisms
(b) you don't use char, an obsolete data type
(c) you check EVERY return from a call that can fail, and any file system
call can fail,
and when logging errors you report EVERY fact you can. [Take a look at my
ErrorString
function described in my article on FormatMessage]

When debugging, and reporting a bug, never use meaningless terms like
"cannot work". Use
descriptions like

"It failed to write, and the GetLastError code was xxxxxxxxxx after the
<call that failed>
in the line indicated below <show which line failed>"

As far as I can tell,

Why do you need an intermedate buffer to write literal strings anyway?

WriteToError(_T("Place 1 OK"));

works fine and doesn't need some strange and pointless intermediate
buffer, particularly
not one of fixed size! Assume that fixed-size arrays are evil anyway.
You could have
done
LPCTSTR buffer = _T("Place 1 OK");
WriteToError(buffer);

which is only slightly silly, but the use of strcpy to a fixed buffer
screams "I want to
fail horrendously! PLEASE LET MY CODE FAIL! PLEASE!"

For example, if AfxWinInit fails, you copy a 45-character string into a
30-character
buffer. Your wish has been granted. Your code failed, because you used
what are now
thought of as irresponsible programming techniques. Had you written
WriteToError(_T("Fatal Error: MFC initialization failed"));
it would have worked, but no, you had to do a gratuitous copy to a buffer.
Why? There is
no need for the variable 'buf2' to exist; it certainly does not need to be
an array of
fixed size, and there is certainly no need to copy to it to log a literal
string.
joe


On Wed, 7 Feb 2007 16:54:06 +0800, "zhang" <makefriend8@xxxxxxx> wrote:

service can run.
void ServiceMain(int argc, char** argv)
{
......
while (ServiceStatus.dwCurrentState ==
SERVICE_RUNNING)
{
****
ServiceMain should not have a loop in it like this.
****
char buf2[30]="place 1 is ok";
*****
There are so many things wrong with the above line it is mind-boggling
that it could have
ever been written
(a) the variable does not need to exist
(b) it it does exist, why is there a fixed bound
const char buf2[] = "place 1 is ok";
but that is about as silly as having the variable
(c) why is it not const?
(d) why is it so much bigger than the string?
*****
WriteToError(buf2);//It's a function write to a file. and here
is ok!!!!!!
///////////////////////////////////////////////////////////////////////////////
if (!AfxWinInit(::GetModuleHandle(NULL), NULL,
::GetCommandLine(), 0))
****
So you are going to try to initialize MFC EACH TIME THROUGH THE LOOP?
WHY?
****
{
strcpy(buffer,"Fatal Error: MFC initialization failed");
WriteToError(buffer);//they do not work
nRetCode = 1;
}
else
{
// TODO: code your application's behavior here.
InitDatabase();
****
AND, you are going to initialize your databases each time through the
loop, too! WHY?
****
strcpy(buffer,"Init OK");
WriteToError(buffer);//they do not work either
****
WriteToError(_T("Init OK"));
what good does an intermediate buffer do here, other than introduce the
possibility of
total disaster?
****
......////
}
.........
strcpy(buffer,"why can not write to file??");
WriteToError(buffer);//can not work
****
Why a strcpy? Silly.
****

Service can start ,can stop.


int WriteToError(char* str)
****
Since the string is not modified, the correct declaration should be
BOOL WriteToError(LPCTSTR str)
see below about the BOOL. The parameter should be const. Never use a
non-const parameter
when a const parameter would work. At the very least, assuming you want a
silly int value
returned, and insist on using obsolete concepts like char, you should have
written
int WriteToError(const char * str)
****
{
log = fopen("C:\\MyServices\\error.txt", "a+");
****
Why do you presume your service is in this directory? Hardwiring values
like this into a
service can be disastrous. A service should not assume that the directory
exists in such
a case; if it has a specific place to write to, it should try to create
the directory.
Presuming that the C: drive is the only drive also makes no sense. In a
multiboot system
it should probably be written to a directory in the drive where the system
booted. Look
at GetFolderPath to see about useful and interesting places to find
things.
****
if (log == NULL)
return -1;
fprintf(log, "%s\n", str);
fclose(log);
return 0;
}
****
Given you return only two values, success and failure, why isn't this a
BOOL? return
FALSE or TRUE! Why use weird values like -1 (a true value) to indicate
failure and 0 (a
false value) to indicate success?

Look at strsafe.h if you are working in earlier versions of VS (< VS2005),
or use the _s
versions of the functions in VS2005. These are the only string functions
you should be
using.

But the whole notion that ServiceMain is in a loop is deeply flawed.
Once-only
initialization should be done outside ANY loop, and it is very rare in a
service to put a
loop in ServiceMain; the more typical action is to spin off some number of
threads that
implement the service, and have ServiceMain block waiting for a
notification that the
service is being shut down.
joe

****


Joseph M. Newcomer [MVP]
email: newcomer@xxxxxxxxxxxx
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm

Joseph M. Newcomer [MVP]
email: newcomer@xxxxxxxxxxxx
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm
.

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