Messages in this thread | | | Date | Thu, 30 May 2002 17:25:44 +0200 | From | Ingo Oeser <> | Subject | Re: large copy_to_user fills only one page? |
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Hi Emmanuel,
On Thu, May 30, 2002 at 04:36:22PM +0200, Emmanuel Michon wrote: > I'm working with linux-2.4.18, and writing some > trivial code to get from kernel a grabbed image working this way: > What I get actually is only 4K filled in userland, but copy_to_user > returns IMSIZE!
copy_to_user() returns the number of bytes NOT copied. same for copy_from_user().
This is a common mistake and your code using this functions should look like this:
if (copy_from_user(to,uptr,size)) { return -EFAULT; }
/* Do some processing */
if (copy_to_user(uptr,from,size)) { return -EFAULT; }
PS: CC'ed linux-kernel, that you will not get 1000 answers ;-)
Regards
Ingo Oeser -- Science is what we can tell a computer. Art is everything else. --- D.E.Knuth - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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