C / C++ / MFC Discussion Boards

Arif Liminto1-Apr-07 5:00

1-Apr-07 5:00

hi iam making a program to implement pwd command under unix environment.. but the result is always segmentation fault, i think my code is alright, can you give me a solution? thanks

#include<stdio.h>
#include<sys stat.h="">
#include<sys types.h="">
#include<pwd.h>
#include<dirent.h>
#include<grp.h>
#include<stdlib.h>
#include<string.h>
int main()
{
struct dirent *ds = 0;
DIR *dirp = 0;
struct stat sbuf;
char pathname[1024];
char *dirname;
struct passwd *pw;
struct group *gr;

dirname = ".";
dirp = opendir(dirname);

if(dirp)
{
strcpy(pathname,dirname);
strcat(pathname,"/");
strcat(pathname,ds->d_name);
lstat(pathname,&sbuf);

pw = getpwuid(sbuf.st_uid);
gr = getpwuid(sbuf.st_gid);

printf("%-8s \n",pw->pw_dir);
}

return(0);
}

Re: pwd command

CPallini1-Apr-07 6:09

CPallini

1-Apr-07 6:09

You missed the forum (this is not Linux related).
Anyway I'll try to help you.

You forgot to allocate memory for ds variable. This may cause troubles to strcat(pathname,ds->d_name);.

Hope that helps
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: pwd command

Eytukan1-Apr-07 6:14

Eytukan

1-Apr-07 6:14

btw, what's a pwd command? Unsure | :~

Press: 1500 to 2,200 messages in just 6 days? How's that possible sir?
Dr.Brad :Well,I just replied to everything Graus did and then argued with Negus for a bit.

Re: pwd command

CPallini1-Apr-07 7:33

CPallini

1-Apr-07 7:33

From Linux man:

Pwd
Print the full filename of the current working directory.

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: pwd command

Eytukan1-Apr-07 19:56

Eytukan

1-Apr-07 19:56

Okie okie

Press: 1500 to 2,200 messages in just 6 days? How's that possible sir?
Dr.Brad :Well,I just replied to everything Graus did and then argued with Negus for a bit.

How to notice socket disconnection? [modified]

Hamed Musavi1-Apr-07 4:29

Hamed Musavi

1-Apr-07 4:29

In a project I use CAsyncSocket to connect 2 computers. If after the connection established, I disconnect the wire between the 2 computers, applications does not show any sign of a disconnection Confused | :confused:

I tried sending and receiving messages after disconnection several times, but non of applications notice any change until I reconnect the wire, at this point Send returned an error code. Sigh | :sigh:

Is it my fault or it's a usual behavior? How to recognize network failures if there is not an event available(On Disconnect doe's not work)? Is it good to continually check connection in a thread?

-- modified at 10:34 Sunday 1st April, 2007

//This is not a signature
while (I'm_alive) {
cout<<"I Love Programming";
}

Re: How to notice socket disconnection?

Eytukan1-Apr-07 4:54

Eytukan

1-Apr-07 4:54

Hamed Mosavi wrote:
Is it my fault or it's a usual behavior?

No it's not your fault!. TCP protocol has been designed in such a way. Sometimes it really looks stupid. You can never know if the client is not alive at the other end when there's a n/w distruption occurs. It's done because, there may be flucuations in the n/w then and there if all these are reported as disconnect events, this would degrade TCP. So it abstracts the disconnections to the user. Still not completely sure why they dont do it!.Implement a "ping" like solution to your problem. The server sends "Are you there" periodically to the clients and the clients "must" reply to the question. If it doesn't then it's not there. In short you are making your own *protocol* to overcome this handicap in TCP.

Press: 1500 to 2,200 messages in just 6 days? How's that possible sir?
Dr.Brad :Well,I just replied to everything Graus did and then argued with Negus for a bit.

Re: How to notice socket disconnection?

Hamed Musavi1-Apr-07 5:19

Hamed Musavi

1-Apr-07 5:19

Thanks

VuNic wrote:
n short you are making your own *protocol* to overcome this handicap in TCP.

I just thought about that when said: "Is it good to continually(periodically is much better word here as you suggested) check connection in a thread?"

This will solve my problem, but this increase workload significantly if I wanted to connect a server to a large group of clients and also may increase expenses extensively. Doesn't it?

//This is not a signature
while (I'm_alive) {
cout<<"I Love Programming";
}

Re: How to notice socket disconnection?

Eytukan1-Apr-07 5:48

Eytukan

1-Apr-07 5:48

Hamed Mosavi wrote:
check connection in a thread?"

Exactly. But you can still do it with timers but for console applications, threads would be prefered. Otherwise you need to implement callbacks& message loops.

Hamed Mosavi wrote:
but this increase workload significantly

Yeah it certainly is an overhead. But I haven't seen any visible degradation in the system. We can do like this. You can maintain a data structure that keeps track of "last" response recieved from the clients. Rather than sending ping to all clients, you traverse thru the container(data structure that you maintain to keep track of client event times) and send ping request only to clients that has not sent any messages for so long. This way you can reduce the overhead.

Press: 1500 to 2,200 messages in just 6 days? How's that possible sir?
Dr.Brad :Well,I just replied to everything Graus did and then argued with Negus for a bit.

Re: How to notice socket disconnection?

Hamed Musavi1-Apr-07 5:53

Hamed Musavi

1-Apr-07 5:53

Thank you very much. It was informative. Rose | [Rose]

//This is not a signature
while (I'm_alive) {
cout<<"I Love Programming";
}

Re: How to notice socket disconnection?

Eytukan1-Apr-07 5:57

Eytukan

1-Apr-07 5:57

You are welcome Hamed Smile | :)

Press: 1500 to 2,200 messages in just 6 days? How's that possible sir?
Dr.Brad :Well,I just replied to everything Graus did and then argued with Negus for a bit.

Re: How to notice socket disconnection?

ThatsAlok1-Apr-07 22:29

ThatsAlok

1-Apr-07 22:29

Hamed Mosavi wrote:
s it my fault or it's a usual behavior? How to recognize network failures if there is not an event available(On Disconnect doe's not work)? Is it good to continually check connection in a thread?

IsNetworkAlive

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Re: How to notice socket disconnection?

Hamed Musavi2-Apr-07 1:56

Hamed Musavi

2-Apr-07 1:56

Great, But what if the computer is connected to multiple LANs simultaneously?

//This is not a signature
while (I'm_alive) {
cout<<"I Love Programming";
}

Re: How to notice socket disconnection?

Sachin R Sangoi2-Apr-07 1:17

Sachin R Sangoi

2-Apr-07 1:17

Hi,
You u can have ur application specific protocol, say keep alive protocol which will send heart beat or a dummy message after every pre - determined interval of time. If the send fails u can get the reason in GetLastError and determine if the client is still alive (connected to network )or down.

Get the facts or facts will get you and when you get them, get them right or they will get you wrong.

Happy Coding Smile | :)

Re: How to notice socket disconnection?

Hamed Musavi2-Apr-07 1:50

Hamed Musavi

2-Apr-07 1:50

Thanks to Mr. Vunic, this solution discussed already and solved.

Anyway, thank you again.

//This is not a signature
while (I'm_alive) {
cout<<"I Love Programming";
}

retrieve registry key path from HKEY

bahaa1236541-Apr-07 2:53

bahaa123654

1-Apr-07 2:53

How can I retrieve a registry key path from HKEY (Key Handle) ?

Re: retrieve registry key path from HKEY

Eytukan1-Apr-07 6:13

Eytukan

1-Apr-07 6:13

RegQueryValueEx.

Press: 1500 to 2,200 messages in just 6 days? How's that possible sir?
Dr.Brad :Well,I just replied to everything Graus did and then argued with Negus for a bit.

Re: retrieve registry key path from HKEY

bahaa1236541-Apr-07 6:53

bahaa123654

1-Apr-07 6:53

Thanks, but according to MSDN RegQueryValueEx: Retrieves the type and data for the specified value name associated with an open registry key.

and I need to retrieve the path of the key handle.

Re: retrieve registry key path from HKEY

Hamed Musavi1-Apr-07 8:54

Hamed Musavi

1-Apr-07 8:54

I think he has a handle and is going to find out which key, the handle, refers to, i.e. He wants to find the key that he opened already and has a handle to it.

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while (I'm_alive) {
cout<<"I Love Programming";
}

Re: retrieve registry key path from HKEY

Hamid_RT1-Apr-07 18:17

Hamid_RT

1-Apr-07 18:17

See an example A Registry Class [^]

WhiteSky

Re: retrieve registry key path from HKEY

ThatsAlok1-Apr-07 22:27

ThatsAlok

1-Apr-07 22:27

bahaa123654 wrote:
How can I retrieve a registry key path from HKEY (Key Handle) ?

CRegKey!

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
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Global Interface Table: An Easy Way to Marshal an Interface Pointer[new]
VC Forum Q&A :- I/ IV
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Serial Programming

Guddappa T H1-Apr-07 2:50

Guddappa T H

1-Apr-07 2:50

Hai,
This is a program for serial data reception. Can anybody tell me how this code is working. It is programmed to receive 18 bytes (a configured data packet of 18 bytes) of data.......

Code is:

CTimerDlg::OnOnComm()
{
if(m_comm.GetCommevent() == 2) // m_comm is serial member variable
{
UCHAR *parray; // local array
COleVariant var;

var = m_comm.GetInput();
long comL;
HRESULT hr = SafeAraayGetUBound(var.parray , 1 , &comL);

if(hr == S_OK)
{

hr = SafeArrayAccessData(var.parray , (void**)&parray);
if(hr == S_OK)
{
Rxdata[RxBuffcount++]=parray[0]; //local array
}

SafeArrayUnaccessData(var.parray);

if(RxBuffcount == 18) // if 18 bytes received proceed
{

Processdata(); // data processing
RxBuffcount = 0;
}
}

}
}

My questions are:
1. How is this code working.
2. Is this code receiving data bytewise or not .
3. If so how and where to check for the first (header) byte (say 0xaa).

Plz help me.

Regards,
Guddappa T H Frown | :(

Re: Serial Programming

Eytukan1-Apr-07 6:19

Eytukan

1-Apr-07 6:19

where is Rxdata declared?

Press: 1500 to 2,200 messages in just 6 days? How's that possible sir?
Dr.Brad :Well,I just replied to everything Graus did and then argued with Negus for a bit.

Re: Serial Programming

ThatsAlok1-Apr-07 22:26

ThatsAlok

1-Apr-07 22:26

Guddappa T H wrote:
3. If so how and where to check for the first (header) byte (say 0xaa).

it is necessary to use this class or code

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
Global Interface Table: An Easy Way to Marshal an Interface Pointer[new]
VC Forum Q&A :- I/ IV
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Windows Explorer-Style MFC Application - urgent

deeps_cute1-Apr-07 1:55

deeps_cute

1-Apr-07 1:55

i need some advice on creating an application that looks'n feel like windows
explorer:
-one CTreeCtrl
-Below the CTreeCtrl an info region
-Below the info region, a status bar.
-Data displayed in CTreeCtrl are files and directories

pls help me i need it now

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