18949 - file buffering in nsIFileStream ignores seeks.

Status: VERIFIED FIXED

(SeaMonkey :: UI Design, defect, P3)

Description

[David :Bienvenu]

Local mail folders were getting corrupted because the buffering added to
nsIFileStream ignores seeks. So the sequence of calls need to corrupt a file is
as simple as this:

stream->write(buf)...
seek (somewhere else)
close

the output buffers will get written out at close time, at the location we've
seeked to, not the location we thought we were at when we did the write.

A simple fix for this is to make seek do a flush. I've changed my code to do a
flush after every write, but other clients could get bit in very painful ways.

Comment 1

[David :Bienvenu]

I've marked this critical since it can corrupt files.

Comment 2

[Doug Turner (:dougt)]

sounds like a regression.  At one point seek would flush buffers.  Blame does
not see though some code rearragement.  Adding people to cc list.  Warren,
Simon, do you think any of your changes could have cause this directly or
indirectly?

Comment 3

[Simon Fraser [no longer active]]

The only changes I made were to un-inline some methods in nsFileImpl, and not do
PR_Sync on read-only file close.

Comment 4

[Doug Turner (:dougt)]

it is a simple fix.  We need to make seek() call flush().

Comment 5

[Doug Turner (:dougt)]

thats what you said!!..  :-)  fixed.

Comment 6

[sairuh (rarely reading bugmail)]

rubberstamp vrfy.