[Bluez-devel] Wrong errno

[Bluez-devel] Wrong errno

[Xavier Garreau]

Hi,

I'm currently developping an application with bluez. I wrote a little cod=
e to=20
test the alarm behaviour with bluez sockets code.

The connect and read (or recv) get interrupted but errno is set to ESPIPE=
 (29)=20
instead of EINTR (4). Does any one of you guys know why i'm getting this=20
illegal seek operation errno ?

Regards,

my sample code is below :

#include <signal.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>
#include <bluetooth/hci_lib.h>
#include <bluetooth/l2cap.h>
#include <sys/ioctl.h>
#include <errno.h>

extern int errno;

void alarm_handler(int sig) {
=09printf ("IN alarm_handler\n");
}

int get_socket(char* watch_addr) {
=09int s;
=09struct sockaddr_l2 addr;
=09bdaddr_t bdaddr;


=09if ((s =3D socket(PF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_L2CAP)) < 0) {
=09=09perror("Can't create socket ");
=09=09return 0;
=09}

=09bacpy(&bdaddr, BDADDR_ANY);
=09memset(&addr, 0, sizeof(addr));
=09addr.l2_family =3D AF_BLUETOOTH;
=09addr.l2_bdaddr =3D bdaddr;
=09addr.l2_psm =3D htobs(0XCC33);

        if (bind(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
=09=09perror("Can't bind socket ");
=09=09return 0;
        }

=09baswap(&addr.l2_bdaddr, strtoba(watch_addr));
        if (connect(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
=09=09perror("Can't connect ");
=09=09printf ("errno : %d\n", errno);
=09=09return 0;
        }
=09return s;
}

char* attends_data(int s) {
=09int i;
=09int encore =3D 0;
=09char buff[256];

=09encore =3D read(s, buff, 256);
=09if (encore =3D=3D -1 || errno) {
=09=09perror("Echec lors de la lecture");
=09=09return NULL;
=09}
=09return NULL;
}


int main (void) {
=09int aSocket;

=09signal (SIGALRM, alarm_handler);
=09siginterrupt (SIGALRM, 1);

=09alarm(20);
=09printf ("Connexion ! \n");
=09aSocket =3D get_socket ("00:04:76:f1:6c:f9");

=09if (aSocket) {
=09=09printf ("Connect=E9 ! \n");
=09=09alarm(5);
=09=09printf ("Lecture ! \n");
=09=09if (!attends_data (aSocket)) {
=09=09=09printf ("errno : %d\n", errno);
=09=09} else {
=09=09=09printf ("OK !\n");
=09=09=09alarm(0);
=09=09}
=09=09shutdown (aSocket, 2);
=09}
=09close (aSocket);
}

--=20
Xavier Garreau
http://www.xgarreau.org



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Re: [Bluez-devel] Wrong errno

[Aurelien Minet]

Xavier Garreau wrote:

> Hi,
> 
> I'm currently developping an application with bluez. I wrote a little code to 
> test the alarm behaviour with bluez sockets code.
> 
> The connect and read (or recv) get interrupted but errno is set to ESPIPE (29) 
> instead of EINTR (4). Does any one of you guys know why i'm getting this 
> illegal seek operation errno ?
> 
> Regards,
> 
> my sample code is below :
> 
> #include <signal.h>
> #include <unistd.h>
> #include <stdio.h>
> #include <sys/socket.h>
> #include <netinet/in.h>
> #include <bluetooth/bluetooth.h>
> #include <bluetooth/hci.h>
> #include <bluetooth/hci_lib.h>
> #include <bluetooth/l2cap.h>
> #include <sys/ioctl.h>
> #include <errno.h>
> 
> extern int errno;
> 
> void alarm_handler(int sig) {
> 	printf ("IN alarm_handler\n");
> }
> 
> int get_socket(char* watch_addr) {
> 	int s;
> 	struct sockaddr_l2 addr;
> 	bdaddr_t bdaddr;
> 
> 
> 	if ((s = socket(PF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_L2CAP)) < 0) {
> 		perror("Can't create socket ");
> 		return 0;
> 	}
> 
> 	bacpy(&bdaddr, BDADDR_ANY);
> 	memset(&addr, 0, sizeof(addr));
> 	addr.l2_family = AF_BLUETOOTH;
> 	addr.l2_bdaddr = bdaddr;
> 	addr.l2_psm = htobs(0XCC33);
> 
>         if (bind(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
> 		perror("Can't bind socket ");
> 		return 0;
>         }
> 
> 	baswap(&addr.l2_bdaddr, strtoba(watch_addr));
>         if (connect(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
> 		perror("Can't connect ");
> 		printf ("errno : %d\n", errno);
> 		return 0;
>         }
> 	return s;
> }
> 
> char* attends_data(int s) {
> 	int i;
> 	int encore = 0;
> 	char buff[256];
> 
> 	encore = read(s, buff, 256);
> 	if (encore == -1 || errno) {
> 		perror("Echec lors de la lecture");
> 		return NULL;
> 	}
> 	return NULL;
> }
> 
> 
> int main (void) {
> 	int aSocket;
> 
> 	signal (SIGALRM, alarm_handler);
> 	siginterrupt (SIGALRM, 1);
> 
> 	alarm(20);
> 	printf ("Connexion ! \n");
> 	aSocket = get_socket ("00:04:76:f1:6c:f9");
> 
> 	if (aSocket) {
> 		printf ("Connecté ! \n");
> 		alarm(5);
> 		printf ("Lecture ! \n");
> 		if (!attends_data (aSocket)) {
> 			printf ("errno : %d\n", errno);
> 		} else {
> 			printf ("OK !\n");
> 			alarm(0);
> 		}
> 		shutdown (aSocket, 2);
> 	}
> 	close (aSocket);
> }
> 

Hi Xavier,

I don't know why ESPIPE error.
But after a connect I negociate the MTU and MRU and I haven'y noticed 
any error with a recv() :

(g_error()/g_message are GTK+ functions)

struct l2cap_options opts;
int  opt;
.......
opt = sizeof(opts);
if( getsockopt(montre->sk_bluez, SOL_L2CAP, L2CAP_OPTIONS, &opts, &opt) 
< 0 )
	g_error("Can't get L2CAP options. %s(%d)", strerror(errno), errno);
else
	g_message("Actual MTU is %d & MRU is %d ",opts.omtu,opts.imtu);

opts.imtu = MY_IMTU ;
opts.omtu = MY_OMTU ;

if (setsockopt(montre->sk_bluez, SOL_L2CAP, L2CAP_OPTIONS, &opts, opt) < 0)
	g_error("Can't set L2CAP options. %s(%d)", strerror(errno), errno);
else
	g_message("Setting MTU to %d & MRU to %d ",opts.omtu,opts.imtu);
.......
r=recv(s,&buff,sizeof(buff),0))


regards

	Aurelien







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Re: [Bluez-devel] Wrong errno

[Xavier Garreau]

Hi,

This code does not use alarm, sigaction, signal or siginterrrupt and thus
won't be interrupted by SIGALRM. My question is about bluez socket
implementation behaviour when a system call is interrupted.

> I don't know why ESPIPE error.
> But after a connect I negociate the MTU and MRU and I haven'y noticed
> any error with a recv() :
>
> (g_error()/g_message are GTK+ functions)
>
> struct l2cap_options opts;
> int  opt;
> .......

Regards,
-- 
Xavier Garreau <x.garreau@prim-time.fr>
Prim'Time Technology
http://www.prim-time.fr/



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Re: [Bluez-devel] Wrong errno

[Marcel Holtmann]

Hi Xavier,

> I'm currently developping an application with bluez. I wrote a little code to 
> test the alarm behaviour with bluez sockets code.
> 
> The connect and read (or recv) get interrupted but errno is set to ESPIPE (29) 
> instead of EINTR (4). Does any one of you guys know why i'm getting this 
> illegal seek operation errno ?

I don't see any usage of ESPIPE in L2CAP, so this can be a general
behaviour of the socket code. What errno do you get if you try this with
TCP socket code?

BTW what kernel and/or patches do you use?

Regards

Marcel




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