On Thu, 9 Aug 2007, Matt Bailey wrote:
> I'm trying to use ddi_copyin to copy a string from a user application to a
> psuedo driver in kernel space.
>
> How do I copy data and print it out? Anyone know of any resources I can look
> at with an example?
>
> Here's the ioctl code:
>
> char *strPtr, *string;
> ...
> case STR_COPY:
> ddi_copyin((char *)arg, strPtr, sizeof (char*), mode);
> strcpy(string, strPtr); // EXPLODES HERE
Of course it explodes. You've been copying in a "char *", not an array of
characters terminated by a zero-valued byte.
> break;
> ...
>
> User code:
>
> ioctl(fd, STR_COPY, stringPtr);
Such things are a big problem, since your kernel driver doesn't know the
length of the data. It's not passed on.
The only solution I can see to your request is to do the copyin() byte by
byte, and return errors on failure to do so:
char *uaddr, *curaddr, lastbyte;
case STR_COPY:
uaddr = (char *)arg;
curaddr = strPtr;
memset(strPtr, -1, SIZE_DRIVER_BUFFER);
while (ddi_copyin(uaddr++, curaddr, 1, mode) == 0 &&
*(curaddr++) != '\0');
/*
* Check if we overflowed the source or target buffers
*/
if (*curaddr)
return (EFAULT);
else if (strlen(strPtr) + 1 == SIZE_DRIVER_BUFFER &&
ddi_copyin(uaddr++, &lastbyte, 1, mode) == 0)
return (EOVERFLOW);
strcpy(string, strPtr);
>
> New to driver programming, be gentle...
Does the above work ?
I don't understand the second strcpy, though - you could directly read
into your kernel driver buffer to start with. And unbounded strcpy - brrr
:(
>
> Thanks
You're welcome,
FrankH.
>
>
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