i am trying to set a memory segment with a structure but its not
working , i am missing something :

typedef struct dataestrutura {
char * usr;
char * passwd;
char * osid;
} dataestrutura;


int main( int argc, char *argv[] )
{
key_t key;
int shmid;
int mode;
///struct em vez do char *///

dataestrutura *data_ptr;


cout <<"/* make the key: */"<<endl;
if ((key = ftok("/home/pedro/SHARED_MEMORY/teste.txt", 'LP')) ==
-1)
{
perror("ftok");
exit(1);
}


cout << "/* connect to (and possibly create) the segment: */" <<
endl;
if ((shmid = shmget(key,SHM_SIZE, 0644 | IPC_CREAT)) == -1)
{
perror("shmget");
exit(1);
}

cout << "/* attach to the segment to get a pointer to it: */"
<< endl;
data_ptr = (dataestrutura *)shmat(shmid,0, 0);
if (data_ptr == (dataestrutura *)(-1))
{
perror("shmat");
exit(1);
}

cout << "/* read or modify the segment, based on the command
line: */" << endl;


/*strcpy(data_ptr->usr, "bdsn");
strcpy(data_ptr->passwd, "bdsn");
strcpy(data_ptr->osid, "oesis");*/

data_ptr->usr="bdsn";
data_ptr->passwd="bdsn";
data_ptr->osid="osid";




cout <<"/* detach from the segment: */" << endl;
if (shmdt(data_ptr) == -1)
{
perror("shmdt");
exit(1);
}





cout << "/* Finish up */" << endl;

return 0;
}

On 6/26/2007 4:55 PM, pedro wrote:
> i am trying to set a memory segment with a structure but its not
> working , i am missing something :
>
> typedef struct dataestrutura {
> char * usr;
> char * passwd;
> char * osid;
> } dataestrutura;

I'd try this instead:

typedef struct dataestrutura {
char usr[MAX_USR_SIZE];
char passwd[MAX_PASSWD_SIZE];
char osid[MAX_OSID_SIZE];
} dataestrutura;

and #define the MAX_... values somewhere.

> int main( int argc, char *argv[] )
> {
> key_t key;
> int shmid;
> int mode;
> ///struct em vez do char *///
>
> dataestrutura *data_ptr;
>
>
> cout <<"/* make the key: */"<<endl;
> if ((key = ftok("/home/pedro/SHARED_MEMORY/teste.txt", 'LP')) ==
> -1)
> {
> perror("ftok");
> exit(1);
> }
>
>
> cout << "/* connect to (and possibly create) the segment: */" <<
> endl;
> if ((shmid = shmget(key,SHM_SIZE, 0644 | IPC_CREAT)) == -1)
> {
> perror("shmget");
> exit(1);
> }
>
> cout << "/* attach to the segment to get a pointer to it: */"
> << endl;
> data_ptr = (dataestrutura *)shmat(shmid,0, 0);
> if (data_ptr == (dataestrutura *)(-1))
> {
> perror("shmat");
> exit(1);
> }
>
> cout << "/* read or modify the segment, based on the command
> line: */" << endl;
>
>
> /*strcpy(data_ptr->usr, "bdsn");
> strcpy(data_ptr->passwd, "bdsn");
> strcpy(data_ptr->osid, "oesis");*/
>
> data_ptr->usr="bdsn";
> data_ptr->passwd="bdsn";
> data_ptr->osid="osid";
>
>
>
>
> cout <<"/* detach from the segment: */" << endl;
> if (shmdt(data_ptr) == -1)
> {
> perror("shmdt");
> exit(1);
> }
>
>
>
>
>
> cout << "/* Finish up */" << endl;
>
> return 0;
> }
>

Regards,
Stefan
--
Stefan Naewe stefan dot naewe at atlas-elektronik dot com
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