QlgFtok()--Generate IPC Key from File Name (using NLS-enabled path name)

 #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.

Parameters

path

(Input) The path name of the file used in combination with id to generate the key. For more information on the Qlg_Path_Name_T structure, see Path name format.

Related Information

ftok()--Generate IPC Key from File Name

Example

See Code disclaimer information for information pertaining to code examples.

The following example uses the QlgFtok() and semget() functions.

#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;
}