linux-kernel - alternatives to null-terminated byte arrays in syscalls in the future?

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Message-ID: <CACXN+=QLJLaSnqLtbbfdFxq9kyUv+ea-m_SpcbZTeaUDTFxy7g@mail.gmail.com>
Date:	Fri, 8 Apr 2016 14:04:00 -0700
From:	Andrew Kelley <superjoe30@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: alternatives to null-terminated byte arrays in syscalls in the future?

The open syscall looks like this:

SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)

filename is a null terminated byte array. Null termination is one way
to handle lengths of byte arrays, but arguably a better way is to keep
track of the length in a separate field. Many programming languages
use pointer + length instead of null termination for various reasons.

When it's time to make a syscall such as open, software which does not
have a null character at the end of byte arrays are forced to allocate
memory, do a memcpy, insert a null byte, perform the open syscall,
then deallocate the memory.

What are the chances that in the future, Linux will have alternate
syscalls which accept byte array parameters where one can pass the
length of the byte array explicitly instead of using a null byte?

Regards,
Andrew Kelley