51056 - error in reading unreachable preferences file

Status: VERIFIED FIXED

(Core :: Preferences: Backend, defect, P3)

Description

[buster]

from the original posting by Nigel Cole <[e-mail]> on 
netscape.public.mozilla.seamonkey:

I think there's a problem in the code for reading the preferences file.

According to:

http://lxr.mozilla.org/seamonkey/source/modules/libpref/src/prefapi.c#265

the preferences file is read using an fread in pref_OpenFile, but the
return value isn't checked (line 291); in the event of a system problem,
the fread can return 0 and the code continues assuming a fileLength of 0.
(I'm bumping into this a lot with Communicator, which presumably uses
similar code).

I believe this can be fixed by simply adding:

        if (fileLength == 0)
                ok = PREF_ERROR;
        else

before line 293.

System: Networked Sun SPARCs running Solaris 2.6, though the problem
could affect any system where the fread can fail and return 0.

Comment 1

[Henrik Gemal]

Attachment: Diff to add "if (fileLength == 0)" check

Comment 2

[Daniel Veditz [:dveditz]]

Actually preferences backend, I'll take this.

Comment 3

[verah (gone)]

Nav triage team: reassigning to dveditz

Comment 4

[Daniel Veditz [:dveditz]]

Ick, prefs shouldn't be using raw fread() anyway, it should be using NSPR 
wrappers.

Comment 5

[Daniel Veditz [:dveditz]]

Patch checked in.

Comment 6

[Henrik Gemal]

Dan, you said that the prefs shouldn't be using raw fread(), they should be 
using NSPR wrappers. Did you file a bug on that, or should I do it?

Comment 7

[Daniel Veditz [:dveditz]]

No, I didn't file a but against the File i/o used in the low-level prefs.

Comment 8

[sairuh (rarely reading bugmail)]

backend fix, so rubberstamp vrfy.

Comment 9

[Henrik Gemal]

Bug 53021 filed on the use of fread() instead of NSPR wrappers....