Re: How to read file in kernel module?

["Pankaj G" <godepankaj@xxxxxxxxxxxxxx>]

hi all,

After reading all those mails on how to read file in kernel module, i think i should share my way of reading a file in a module.
I don't know whether it is right or wrong, but i have tried and it works.

Please give me views about this way of reading a file.
The code below is there to read a configuration file having count of number of systemcalls.


int ERR_RD_FILE;
static int errno;

int read_config_file(const char *fn)
{
     long l;
     int i,j,no_of_syscalls=0;     

     set_fs(KERNEL_DS);
     fd = open(fn, O_RDONLY, 0);
         set_fs(USER_DS);
     
     if (fd == -1)
     {
          printk("\nUnable to load config file '%s' %d.", fn, errno);
          ERR_RD_FILE=0;
          return NULL;
     }
         
     set_fs(KERNEL_DS);
     l = lseek(fd, 0L, 2);
         set_fs(USER_DS);
     
     if (l <= 0 || l > 131072)
     {
          printk("\nTOO big a file '%s' %d.", fn, errno);
          sys_close(fd);
          ERR_RD_FILE=0;
          return NULL;
     }
         
     set_fs(KERNEL_DS);
     lseek(fd, 0L, 0);
         set_fs(USER_DS);
          
     set_fs(KERNEL_DS);
     no_of_syscalls=(int*)vmalloc(sizeof(int));
     if( (read(fd,no_of_syscalls,sizeof(int) ))!=sizeof(int) )
     {
          set_fs(USER_DS);
          printk("\nFailed to read '%s' %d.", fn, errno);
          vfree(no_of_syscalls);
          sys_close(fd);
             set_fs(USER_DS);
          ERR_RD_FILE=0;
          return NULL;
     }


     sys_close(fd);     
     ERR_RD_FILE=1;
     return no_of_syscalls;
}