#include <sys/ipc.h> #include <qlg.h> key_t QlgFtok(const Qlg_Path_Name_T *path, int id);
The QlgFtok() function, like the ftok() function, generates an IPC key based on the combination of path and id. The difference is that the QlgFtok() function takes a pointer to a Qlg_Path_Name_T structure, while the ftok() function takes a pointer to a character string.
Limited information on the path parameter is provided here. For more information on the path parameter and for a discussion of other parameters, authorities required, returnvalues, and related information, see ftok()--Generate IPC Key from File Name.
ftok()--Generate IPC Key from File Name
The following example uses the QlgFtok() and semget() functions.
Note: By using the code examples, you agree to the terms of the Code license and disclaimer information.
#include <sys/ipc.h>
#include <sys/sem.h>
#include <errno.h>
#include <stdio.h>
#include <qlg.h>
int main(int argc, char *argv[])
{
key_t myKey;
int semid;
#define mypath "/myApplication/myFile"
const char US_const[3]= "US";
const char Language_const[4]="ENU";
const char Path_Name_Del_const[2]= "/";
typedef struct pnstruct
{
Qlg_Path_Name_T qlg_struct;
char[100] pn; /* This size must be >= the path */
/* name length or be a pointer */
/* to the path name. */
};
struct pnstruct path;
/***************************************************************/
/* Initialize Qlg_Path_Name_T parameters */
/***************************************************************/
memset((void*)path name, 0x00, sizeof(struct pnstruct));
path.qlg_struct.CCSID = 37;
memcpy(path.qlg_struct.Country_ID,US_const,2);
memcpy(path.qlg_struct.Language_ID,Language_const,3);
path.qlg_struct.Path_Type = QLG_CHAR_SINGLE;
path.qlg_struct.Path_Length = sizeof(mypath)-1;
memcpy(path.qlg_struct.Path_Name_Delimiter,Path_Name_Del_const,1);
memcpy(path.pn,mypath,sizeof(mypath));
/* Use QlgFtok to generate a key associated with a file. */
/* Every process will get the same key back if the caller */
/* calls with the same parameters. */
myKey = QlgFtok((Qlg_Path_Name_T *)path name, 42);
if(myKey == -1) {
printf("QlgFtok failed with errno = %d\n", errno);
return -1;
}
/* Call an xxxget() API, where xxx is sem, shm, or msg. */
/* This will create or reference an existing IPC object */
/* with the 'well known' key associated with the file */
/* name used above. */
semid = semget(myKey, 1, 0666 | IPC_CREAT);
if(semid == -1) {
printf("semget failed with errno = %d\n", errno);
return -1;
}
/* ... Use the semaphore as required ... */
return 0;
}