760209 - nsIZipWriter should fail if none of PR_WRONLY, PR_RDONLY, PR_RDWR are given

Status: NEW

(Core :: Networking: JAR, defect, P5)

Description

[Tim Taubert [:ttaubert] (inactive)]

Attachment: patch v1

It took me quite some time to find out I was accidentally passing a read-only file to nsIZipWriter.open(). ftruncate (on Linux) fails when calling zw.close() and the file is empty.

I was not passing any of RDONLY and WRONLY so I think we should extend the check at the beginning of the method.

Comment 1

[Tim Taubert [:ttaubert] (inactive)]

(Forget the summary please.)

I want to create a ZipWriter that creates a file if it doesn't exist, yet. If it exists I want to add/modify entries in that file. I'm now using:

> nsIZipWriter.open(file, PR_CREATE);

I add some entries and call nsIZipWriter.close(). Now ftruncate() in nsFileStreamBase::SetEOF() fails somehow and leaves a broken zip file. If I use:

> nsIZipWriter.open(file, PR_CREATE | PR_WRONLY);

it all works well but it overwrites the file every time which isn't what I want.

ftruncate() returns EINVAL which (as offset == 0) can only mean that "The fildes argument is not a file descriptor open for writing."

> ----------------------------------------

Ok, so I totally forgot about PR_RDWR. I of course need to specify that... ZW.open() should bail if none of the Read/Write flags is given.

Comment 2

[Firefox Bug Husbandry Bot]

Bulk change to priority: https://bugzilla.mozilla.org/show_bug.cgi?id=1399258