Date: Tue, 14 Jun 2016 22:07:12 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 210288] File descriptors created by pipe are both read/write Message-ID: <bug-210288-8@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=210288 Bug ID: 210288 Summary: File descriptors created by pipe are both read/write Product: Base System Version: 11.0-CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: kwilliams@qnx.com Created attachment 171448 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=171448&action=edit test program demonstrating the issue pipe(2) is documented by as returning 2 file descriptors, one for reading the other for writing. "Data can be written to the file descriptor fildes[1] and read from the file descriptor fildes[0]. A read on the file descriptor fildes[0] shall access data written to the file descriptor fildes[1] on a first-in-first-out basis." The actual implementation ends up wiring fd[0] to fd[1] such that writes on fd[1] provide data that can be read on fd[0] (as required). Oddly writes to fd[0] provide data that can be read in fd[1]. This deviates from the Posix spec (or at least stomps fully into the 'grey' area), resulting in FBSD utilities being rendered portable between unix-like distros. The attached test program demonstrates this behavior. On strictly compliant distros the attached code will result in the child write and parent read failing. -- You are receiving this mail because: You are the assignee for the bug.home | help
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