How to copy/access a string from inside the driver

Question

is there any equivalent to strncpy() to use inside
the driver for copying user sent data to local buffer .
i used I_STRioctl and assigned struct to strioctl.ic_dp
as shown below..
char * buf;
struct user-data
int minor;
char* data;
struct user_data u_data;
buf="hello world"
u_data.minor=0;
u_data.data=buf;
strioctl.ic_dp=&u_data;
strioctl.ic_len=sizeof(struct user_data);
ioctl(fd,I_STR,&strioctl);
when i tried to copy/access the string sent by the user application from inside the driver, machine gets into
booting ...
here what i did was
in wput routine
struct user_data *u_data;    
u_data =(struct user_data*)mp->b_cont->b_rptr;      
cmn_err(CE_NOTE,"minor= %d",u_data->minor);
till here working well..
where as..
cmn_err(CE_NOTE,"data= %s",u_data->data);
causing panic to the system...booting happens.
please help me out ..
thank u all
ss vasu

Answer 1

looks like the data pointed to by 'data' is not copied from user space to kernel space.
u_data.data=buf, just makes pointer assignment, does not copy data pointed to by buf.
two solutions:
1. Declare data as a array(char data[10] or something
2. Copy buf after the structure and point data to it. strioctl.ic_len should be set to sizeof(struct) +
data size.
-Vijay
is there any equivalent to strncpy() to use inside
the driver for copying user sent data to local buffer
i used I_STRioctl and assigned struct to
strioctl.ic_dp
as shown below..
char * buf;
struct user-data
int minor;
char* data;
struct user_data u_data;
buf="hello world"
u_data.minor=0;
u_data.data=buf;
strioctl.ic_dp=&u_data;
strioctl.ic_len=sizeof(struct user_data);
ioctl(fd,I_STR,&strioctl);
when i tried to copy/access the string sent by the
user application from inside the driver, machine gets
into
booting ...
here what i did was
in wput routine
struct user_data *u_data;
u_data =(struct user_data*)mp->b_cont->b_rptr;
r;
cmn_err(CE_NOTE,"minor= %d",u_data->minor);
till here working well..
where as..
cmn_err(CE_NOTE,"data= %s",u_data->data);
causing panic to the system...booting happens.
please help me out ..
thank u all
ss vasu