Programming

char *
get_gid(char *dest, const char *uid)
{
   FILE *sh=NULL;
   char cmd[40]={0x0};
   char result[80]={0x0};
   
   sprintf(cmd, "/usr/bin/id -G %s";, uid);
   sh=popen(cmd, "r");
   if(fgets(result, sizeof(result), sh)!=NULL)
       strcpy(dest, result);
   pclose(sh);
   return dest;
}

#include <grp.h>
#include <string.h>

gid_t *getGroups( const char *username, int *count )
{
    struct group *grp;
    gid_t *list = NULL;
    *count = 0;

    setgrent();

    for ( ;; )
    {
        int ii;

        grp = getgrent();
        if ( NULL == grp )
        {
            break;
        }

        if ( ( NULL == grp->gr_mem ) ||
             ( NULL == grp->gr_mem[ 0 ] ) )
        {
            continue;
        }

        ii = 0;
        for ( ii = 0;
              NULL != grp->gr_mem[ ii ];
              ii++ )
        {
            if ( 0 == strcmp( grp->gr_mem[ ii ], username ) )
            {
                list = ( gid_t * ) realloc( list,
                    ( *count + 1 ) * sizeof( gid_t ) );
                if ( NULL == list )
                {
                    endgrent();
                    return( NULL );
                }

                list[ *count ] = grp->gr_gid;
                ( *count )++;
                break;
            }
        }
    }
    endgrent();

    return( list );
}