On 2/12/19 3:38 PM, Al Viro wrote: > On Tue, Feb 12, 2019 at 09:54:47AM -0500, demiobenour@xxxxxxxxx wrote: >> From: "Demi M. Obenour" <demiobenour@xxxxxxxxx> >> >> While testing the O_PATHSTATIC patch, I discovered that Linux does not >> return any error if an invalid flag is passed to open(2). This prevents >> adding new flags without a (minor) risk of breaking userspace. >> Therefore, add a check for invalid flags, and return -EINVAL if any are >> found. > > ... which would qualtify as userland ABI breakage all by itself. > I suspect that very few (if any) programs pass invalid flags to open(). Additionally, O_DIRECT was added in Linux 2.4, even though it had previously been ignored. If someone knows of a real program that does, I can instead create an open2() syscall, but I would prefer to avoid that.
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