ITEM: P8365L

Question about the unique_id structure and lvm_querylv

Question:

ENV:    AIX 3.2.5

DESC:   Customer is using the ODM subroutines odm_get_first and
        odm_get_next and gets an ascii representation of
        the volume group id in return.
  
        He wants to know if there is a function that will 
        translate the ascii value into the unique_id structure.

Response:

ACTION: The unique_id struct is in /usr/include/sys/types.h:

        struct unique_id {
               unsigned long word1;
               unsigned long word2;
               unsigned long word3;
               unsigned long word4;
        };

        There is no supplied function (as of today) for
        converting the ascii string to unique_id values.
        The get_uniq_id does exist but it is for INTERNAL
        USE ONLY and is not shipped with AIX.

        You can use sscanf as a workaround.  The following is
        an example.  Note: it provides no error checking and
        should be use only as a guide.

        sscanf(CuAt.value, "%8x", &id.word1);
        sscanf(CuAt.value+8, "%8x", &id.word2);

ACTION: Customer called back in.  He is getting a 133 error, 
        which is a programming error. He will need to look at 
        his code to determine the problem.

        Customer agrees, and thinks his problem is actually with the
        lvm_querylv function.  He has not been able to find sufficient
        documentation about what to pass to this structure. He would
        like some additional information.

Response:

Action: Here is a short sample C program that demonstrates the use
        of the lvm_querylv subroutine.  The executable expects two
        arguments, the lvid and the pvname to read the information
        from.  Please note that this code is provided as a sample
        only and IBM does not provide support for this program and
        it is provided as-is.

\#include\
\#include\
\#include\
main(int argc, char **argv)
{struct querylv *query;
struct lv_id lv_id;
char sstring[40];
int rc=0, i;

sscanf(argv[1], "%8x", &lv_id.vg_id.word1);
sscanf(argv[1]+8, "%8x", &lv_id.vg_id.word2);
sscanf(argv[1]+17, "%d", &lv_id.minor_num);
rc = lvm_querylv(&lv_id, &query, argv[2]);
if (rc != 0)
{  printf("errno = %d\\n", errno);
  perror ("myquerylv: lvm_querylv ");
}printf("lv_id = %08x%8x.%-3d\\n", lv_id.vg_id.word1, lv_id.vg_id.word2,
  lv_id.minor_num);
printf("pvname = %s\\n", argv[2]);
printf("lvname = %s\\n", query->lvname);
}
Compile with the following: cc -g -o myquerylv myquerylv.c -llvm

Sample run and output: 

\# myquerylv 00001595346a2edb.5 hdisk0
lv_id = 00001595346a2edb.5  
pvname = hdisk0
lvname = hd4



Support Line: Question about the unique_id structure and lvm_querylv ITEM: P8365L

Dated: December 1994 Category: N/A

This HTML file was generated 99/06/24~13:30:38

Comments or suggestions?
Contact us