3534 - [PP] PR_Seek should allow offsets past EOF

Status: VERIFIED FIXED

(NSPR :: NSPR, defect, P3)

Description

[gordon]

John McMullen reports that PR_Seek on other platforms actually allows an offset
past the end of file.  PR_Seek on macintosh should be
made to work the same way.

Comment 1

[Wan-Teh Chang]

Reassigned the bug to gordon.

Comment 2

[don]

Changed target milestone to M4.

I thought this was fixed already?

Comment 3

[mcmullen]

Don, pink fixed the only one known place (in the registry code) where this was
called with the win/unix assumption.  The real fix is to make the win/unix
assumption valid always in future.

Pink's fix was to write out enough bogus data to make the seek work.

Comment 4

[Mike Pinkerton (not reading bugmail)]

And i'm sure that I'm writing out random bits of memory to disk, so there are
certain privacy issues involved in that ;)

Comment 5

[srinivas]

Note that while PR_Seek on Unix/Win platforms allows setting the file pointer
beyond the current end of file, the file size itself is not changed by the seek
operation. The next PR_Write call causes the write to happen at the new pointer;
the data between the original end-of-file position and the position of the file
pointer after PR_Seek is zero-filled by the OS.

That is, if PR_Seek is used to seek beyond the end-of-file and the file is
closed, there will be no change to the contents of the file (or the file size)
on Unix/win platforms.

To emulate the same semantics on Mac, one can save the file pointer in nspr's fd
and extend the file on the next call to PR_Write. Also, file extension should be
done with zero-filled pages, rather than random data.

Comment 6

[don]

Changed target milestone to M6.

Comment 7

[Steve Dagley]

Offloading some of gordon's doomage

Comment 8

[Terry Weissman]

NSPR now has its own Bugzilla product.  Moving this bug to the NSPR product.

Comment 9

[Steve Dagley]

Fix checked in.  The old code would actually re-set the EOF on a seek past the
current EOF but did not advance the file mark after resetting EOF.

Comment 10

[phillip]

this fix is not visible to qa. if you think this bug should be reopened,
please do so.

will mark as verified.