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bug#21694: 'clone' syscall binding unreliable
From: |
Ludovic Courtès |
Subject: |
bug#21694: 'clone' syscall binding unreliable |
Date: |
Sun, 25 Oct 2015 21:59:45 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Mark H Weaver <address@hidden> skribis:
> address@hidden (Ludovic Courtès) writes:
[...]
>> ;; The libc interface to sys_clone is not useful for Scheme programs, so the
>> -;; low-level system call is wrapped instead.
>> +;; low-level system call is wrapped instead. The 'syscall' function is
>> +;; declared in <unistd.h> as a variadic function; in practice, it expects 6
>> +;; pointer-sized arguments, as shown in, e.g., x86_64/syscall.S.
>> (define clone
>> (let* ((ptr (dynamic-func "syscall" (dynamic-link)))
>> - (proc (pointer->procedure int ptr (list int int '*)))
>> + (proc (pointer->procedure long ptr
>> + (list long ;sysno
>> + unsigned-long ;flags
>
> 'long' and 'unsigned long' might not be the same size as a pointer.
> Better to use 'size_t' for both of these. While not strictly guaranteed
> to be the same size as a pointer, in practice they should be the same
> except on architectures with segmented memory models.
>
> What do you think?
I had the same reaction, but posix/unistd.h in libc really uses these
types for ‘syscall’ so I thought it’d be best to stick to them.
WDYT?
Ludo’.