Re: Graphics and C with linux
Try this http://www.gtk.org. Hope this is what you are looking for Van Sy [EMAIL PROTECTED] On Mon, 21 Sep 1998, Richard Ivanowich wrote: Very simple question... I want to know how to draw lines, rectangles, circle, etc. in the console or in X windows. Can anyone give me some example code or point me in the right direction. Richard Ivanowich
Re: Graphics and C with linux
On Mon, 21 Sep 1998, Richard Ivanowich wrote: Very simple question... I want to know how to draw lines, rectangles, circle, etc. in the console or in X windows. Can anyone give me some example code or point me in the right direction. www.gtk.org A SI BIRI -- Italian Linux Meeting - http://www.pluto.linux.it/meeting/ -- Morelli 'ZioBudda' Davide Michel - Member of Pluto Linux User Group [EMAIL PROTECTED] - http://ziobudda.enter.it/ Linux Problem? Ask to [EMAIL PROTECTED] "/dev/ziobudda: access to /var/tmp/beer denied, use /var/adm/pineapple"
Re: FD_ISSET -- select -- bug?? need help.
On Fri, 18 Sep 1998, Bug Hunter wrote:
We are using a stock redhat 5.1 in an embedded system.
It is not on the internet, and has _very_ few services. (for
you hacker types).
If this is on the wrong list, please point me to a
better list. thanks!
we opened a pipe without error. we then did this:
FD_ZERO(InputFD); // initialize read
descriptors
FD_SET(s,InputFD); // Add
socket to descriptors to
FD_SET(FromDH,InputFD);// wait on Modem
data as well
FD_ZERO(wErrorFD);
FD_SET(s,wErrorFD);
FD_SET(FromDH, wErrorFD);
signal(SIGALRM,SignalHandler);
while(1){
wInputFD = InputFD;
// don't wait more than 500msec before
reporting
timeout.tv_sec = 0;
timeout.tv_usec = 50;
short result =
select(FD_SETSIZE,wInputFD,NULL,wErrorFD,timeout);
...
We get a 2 from select, then the pipe (FromDH) indicates
an error. errno is zero. There is no error that we can
see. any clues?
I am not sure, but I think the SIGALARM and select use the same timer.
If my suposition is true, should be normaly for select to have strange
behavior when got a interrupt.
Any oppinion ?
--
Best wishes,
Marcel - Titus MARGINEAN
[EMAIL PROTECTED], [EMAIL PROTECTED]
Re: How to use getopt() ?
On Tue, 22 Sep 1998, Antonis Kanavouras wrote: - my C books are too old- no reference to getopt(). - till today I wrote loops from scratch to manipulate comnd line options - ~# man 3 getopt makes me more confused Try the glibc info pages ( Ctrl -H, I from Emacs, then browse to glibc / Process Startup / Program Arguments / Parsing Options / ) - Any simple source files for example ? - There is a nice example too. U may find useful some simple option parsing program sources ( ping , traceroute). BTW any security FAQ proposes avoiding getopt() but this is hard to achieve... Regards, Marin "Knowledge is not a crime. Some of its applications are..." - Unknown hacker
Re: FD_ISSET -- select -- bug?? need help.
Henrik Nordstrom wrote: Glynn Clements wrote: I don't think that you should use select() on descriptors which are non-blocking. You would normally either use select() or non-blocking I/O, but not both. I have to disagree here. Using select is REQUIRED when doing non-blocking I/O. There is no other method for waiting until data is available (or check which filedescriptors that have data waiting if you are using a zero timeout). Using select() is required if you only want to read from a descriptor when there is data available (e.g. because the read() would otherwise block). If the descriptor is non-blocking (O_NONBLOCK), read() will return -1 and set errno to EAGAIN. You don't need to check whether data is available in order to prevent blocking. -- Glynn Clements [EMAIL PROTECTED]
Re: How to use getopt() ?
Antonis Kanavouras wrote: my C books are too old- no reference to getopt(). till today I wrote loops from scratch to manipulate comnd line options ~# man 3 getopt makes me more confused Any simple source files for example ? Look at the source for any of the GNU utilities. They nearly all use getopt() for parsing the command line. Also, the libc Info file has a couple of examples of using getopt(). -- Glynn Clements [EMAIL PROTECTED]
Re: Graphics and C with linux
Richard Ivanowich wrote: I want to know how to draw lines, rectangles, circle, etc. in the console or in X windows. Can anyone give me some example code or point me in the right direction. For the console, see the SVGAlib documentation, specifically the stuff about the VGAGL library. For X, you need to create a shell containing a suitable canvas widget. If you're using Motif, use an XmDrawingArea widget. I can send you the code for a non-Motif canvas widget. Then, add a callback for Expose events, which redraws the window using the appropriate Xlib calls. If you are unfamiliar with X programming, get a decent book. -- Glynn Clements [EMAIL PROTECTED]
Re: Need help writing a terminal emulator
Syslab Sales and Services Pvt Ltd. wrote: You just need to be able to receive and send data via a serial .. Whenever a key is pressed, you need to send the corresponding ASCII code via the serial connection. 1. How do I describe this terminal in termcap/terminfo? You only need a termcap/terminfo entry if you wish to use the terminal for `full-screen' applications, e.g. vi, Emacs. With only 2 lines, this isn't likely to be of much use. I have just read something about the curses library, however a book on the curses library is not available here in India. Where could I get more info/downloadable tutorial perhaps? I'm currently reading the man page. The manual pages should provide adequate documentation. Try looking at some existing entries (use `infocmp' to read terminfo files). 2. How do I make sure that Linux initialises this terminal on startup? 3. How do I make sure that the getty login processes are carried out on starting? If the terminal will be permanently connected, add a getty process to /etc/inittab, e.g. s1:12345:respawn:/sbin/agetty 19200 ttyS0 dumb `19200' is the line speed, `ttyS0' is the serial port, and `dumb' is the terminal type (used to initialise $TERM). -- Glynn Clements [EMAIL PROTECTED]
Re: daemons
James wrote:
how do i write a daemon? I know what they are (little programs that do something
useful in the background), but are they just normal programs that get pushed
into the background?
Basically, yes.
how do i make one (e.g foobar) and have it so that it runs in the background
if you type 'foobar -D' (or something).
I have a feeling it has something to do with fork() but how? For a fork() to
work you need a parent process and a child don't you?
No. fork() creates the child process.
To create a daemon, you would basically:
1. Call fork(). The parent process then exits, leaving the child
running in the background.
2. Call setsid() to establish a new session and process group.
3. Call `chdir("/")'.
4. Call umask(0), so that file modes aren't affected by any inherited
umask setting.
5. Close all open file descriptors.
Also, you should specify O_NOCTTY when opening anything which might be
a terminal device, so that the process doesn't inadvertantly acquire a
controlling TTY.
and how do i monitor a /dev/TTYS? device so that when my modem picks up
the line and connects to a remote computer my daemon does something, then
when the modem puts down the line the daemon does something else?
This is difficult to do in a portable manner. You could try using the
TIOCMGET ioctl() to monitor the status lines; that may be adequate.
Alternatively, you could try polling for a lock file.
--
Glynn Clements [EMAIL PROTECTED]
Re: daemons
On Tue, 22 Sep 1998, James wrote:
-how do i write a daemon? I know what they are (little programs that do something
-useful in the background), but are they just normal programs that get pushed
-into the background?
-
Take a look at the c-programming FAQ available under
ftp://rtfm.mit.edu/pub/usenet-by-hierarchy/comp/lang/c
-and how do i monitor a /dev/TTYS? device so that when my modem picks up
-the line and connects to a remote computer my daemon does something, then
-when the modem puts down the line the daemon does something else?
-
U need to watch for the DCD line. Glynn Clements proposed once using the
TIOCMGET ioctl call and I find this quite useful. Something like this:
#include unistd.h
#include stdio.h
#include fcntl.h
#include sys/types.h
#include sys/stat.h
#include sys/ioctl.h
#include syslog.h
#define SLEEP_INTERVAL 5
#define DCD_HIGH1
#define DCD_LOW 0
extern char* program_invocation_short_name;
int TestDCD(int nDevice)
{
int nStatus;
if (ioctl(nDevice,TIOCMGET,nStatus) == -1)
{
// oops something went wrong...
syslog(LOG_ERR,"ioctl error!\n");
exit(1);
}
else
return nStatus TIOCM_CD;
}
int main(int argc,char** argv)
{
int fd;
openlog(program_invocation_short_name,0,LOG_DAEMON);
if (-1 == (fd = open( /*PUT THE TTYS DEVICE HERE*/ ,O_RDWR)))
{
syslog(LOG_ERR,"Canot open device\n");
exit(1);
};
while ( DCD_LOW == TestDCD(fd) )
sleep(SLEEP_INTERVAL);
/* here u have the DCD high i.e. modem connected */
/* do some stuff*/
while ( DCD_HIGH == TestDCD(fd) )
sleep(SLEEP_INTERVAL);
/* here the modems are already disconnected */
/* do other stuff */
closelog();
return 0;
}
U may consider installing SIGALARM handler.
Regards,
Marin
"Knowledge is not a crime. Some of its applications are..."
- Unknown hacker
Re: FD_ISSET -- select -- bug?? need help.
hmmm. I'm not sure that is it. We have abandoned looking at select for
errors for the pipe.
It could be a sigalarm, as the timeout may have tripped. However we are also
using sigalarm, and that code was not executed. And, select did not return a -1,
and there were no errors indicated on the non-pipe handles.
bug
[EMAIL PROTECTED] wrote:
On Fri, 18 Sep 1998, Bug Hunter wrote:
We are using a stock redhat 5.1 in an embedded system.
It is not on the internet, and has _very_ few services. (for
you hacker types).
If this is on the wrong list, please point me to a
better list. thanks!
we opened a pipe without error. we then did this:
FD_ZERO(InputFD); // initialize read
descriptors
FD_SET(s,InputFD); // Add
socket to descriptors to
FD_SET(FromDH,InputFD);// wait on Modem
data as well
FD_ZERO(wErrorFD);
FD_SET(s,wErrorFD);
FD_SET(FromDH, wErrorFD);
signal(SIGALRM,SignalHandler);
while(1){
wInputFD = InputFD;
// don't wait more than 500msec before
reporting
timeout.tv_sec = 0;
timeout.tv_usec = 50;
short result =
select(FD_SETSIZE,wInputFD,NULL,wErrorFD,timeout);
...
We get a 2 from select, then the pipe (FromDH) indicates
an error. errno is zero. There is no error that we can
see. any clues?
I am not sure, but I think the SIGALARM and select use the same timer.
If my suposition is true, should be normaly for select to have strange
behavior when got a interrupt.
Any oppinion ?
--
Best wishes,
Marcel - Titus MARGINEAN
[EMAIL PROTECTED], [EMAIL PROTECTED]
