Messages in this thread | | | Date | Wed, 15 Feb 2006 07:42:37 -0300 | From | Davi Arnaut <> | Subject | Re: [PATH 0/2] strndup_user, description |
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On Wed, 15 Feb 2006 02:53:10 +0000 Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> On Maw, 2006-02-14 at 21:47 -0300, Davi Arnaut wrote: > > This patch series creates a strndup_user() function in order to avoid duplicated > > and error-prone (userspace modifying the string after the strlen_user()) code. > > Well userspace can still modify in this case. So you could still get a > \0 mid buffer but that seems harmless.
Yes.
> However > > > +#define strdup_user(s) strndup_user(s, PAGE_SIZE) > > Better this doesn't exist as it is a wrapper for a bad habit that isnt > yet used so why encourage it. >
Ok, I will inline it. > > > + length = strlen_user(s); > > What if n is very large ? Should use strnlen_user clipped by n
That's what "if (length > n) length = n" is for. > Also say the length limit is 8 and the text is "hello\0" > > We get length = 5 5 < 8, alloc 5 bytes set 5th to \0 and return "hell > \0"
No, we would get length = 6, strlen_user returns the size of the string _including_ the terminating NUL.
-- Davi Arnaut
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