128798 - Use of FILE_FLAG_OVERLAPPED in ntio.c for _PR_MD_OPEN causes stdio redirect problems

Status: RESOLVED WORKSFORME

(NSPR :: NSPR, defect)

Description

[Mike Jones]

I want to redirect process output/error to a file.
I use the following sequence (loosely)
  PR_OpenFile (as writable)
  PR_SetFDInheritable (using handle from open above)
  PR_NewProcessAttr
  PR_SetStdioRedirect (using same handle and new process attr struct)
  PR_CreateProcess (using process attr struct)
The file is created and the process runs. However any writes to the file
don't work and nothing ends up in the file.

The problem seems to be with the use of the FILE_FLAG_OVERLAPPED flag when
opening files on Windows NT (see ntio.c around line 2086).
If this flag is not used then the writes in the child process end up in the
file and everything is fine. The problem is how to prevent the use of
FILE_FLAG_OVERLAPPED when the file is a target of a stdio redirection.

Comment 1

[Wan-Teh Chang]

Thanks for the bug report.  This is a known problem.
I didn't come up with a solution when I worked on this.

One workaround is to use the "WIN95" version of NSPR.
You build the "WIN95" version by passing OS_TARGET=WIN95
to gmake.

The only solution I can come up with is to add a new
flag to PR_Open and PR_OpenFile that says this file
descriptor will be inheritable.  On Windows, the
FILE_FLAG_OVERLAPPED flag must be passed to CreateFile()
at file open time, and can't be changed later.  So
the NSPR API will be subject to these constraints.

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

The bug assignee didn't login in Bugzilla in the last 7 months.
:KaiE, could you have a look please?
For more information, please visit auto_nag documentation.

Comment 3

[Kai Engert [:KaiE:]]

(In reply to Wan-Teh Chang from comment #1)

One workaround is to use the "WIN95" version of NSPR.

That seems to be the default nowadays, so no further action seems necessary.