K 10
svn:author
V 5
tegge
K 8
svn:date
V 27
1999-12-13T02:55:47.000000Z
K 7
svn:log
V 651
Fix two problems with pipe_write():

 1. Data written beyond end of pipe buffer, causing kernel memory corruption.

    - Check that space is still valid after obtaining the pipe lock.

    - Defer the calculation of transfer size until the pipe
      lock has been obtained.

    - Update the pipe buffer pointers while holding the pipe lock.

 2. Writes of size <= PIPE_BUF not always atomic.

    - Allow an internal write to span two contiguous segments,
      so writes of size <= PIPE_BUF can be kept atomic
      when wrapping around from the end to the start of the
      pipe buffer.

PR:		15235
Reviewed by:	Matt Dillon <dillon@FreeBSD.org>

END