linuxkpi: seq_read: Fix one by one error

[manu]

Summary

strscpy needs the buffer length not the string length (so including
the '\0').

Fixes: f697b9432d9c ("linuxkpi: drm-kmod debugfs support")
Sponsored by: Beckhoff Automation GmbH & Co. KG

[jfree]

Thanks for finding this. I was under the impression the sbuf_len returned
the entire length of the sbuf including the null terminator. On second
thought, you're certainly right. This same fix should really be put on top
of this review, though.

https://reviews.freebsd.org/D37101

[bz]

Or set SBUF_INCLUDENUL which will then return the + 1? Without looking based on @jfree 's comment is the logic between sbuf_len and the strscpy correct without the SBUF_INCLUDENUL?

[bz]

Ignore me; the sbuf is finished further up (Phabricator had hid that) so we'll always get the len without the +1.

sys/compat/linuxkpi/common/src/linux_seq_file.c

66

That size < 1 check could go to the top as well?

[manu]

In D37771#859135, @jfree wrote:

Thanks for finding this. I was under the impression the sbuf_len returned
the entire length of the sbuf including the null terminator. On second
thought, you're certainly right. This same fix should really be put on top
of this review, though.

https://reviews.freebsd.org/D37101

Wasn't aware of this one, it seems that there is still some questions about it so I'll commit this in the meantime so debugfs can work with drm.