Hi Alex,
On 9/25/20 9:31 AM, Alejandro Colomar wrote:
> Signed-off-by: Alejandro Colomar <colomar.6.4.3@xxxxxxxxx>
> ---
> man2/seccomp.2 | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/man2/seccomp.2 b/man2/seccomp.2
> index 58033da1c..d6b856c32 100644
> --- a/man2/seccomp.2
> +++ b/man2/seccomp.2
> @@ -1101,7 +1101,7 @@ install_filter(int syscall_nr, int t_arch, int f_errno)
> };
>
> struct sock_fprog prog = {
> - .len = (unsigned short) (sizeof(filter) / sizeof(filter[0])),
> + .len = sizeof(filter) / sizeof(filter[0]),
> .filter = filter,
> };
I have a small doubt about this change. With the change,
there are no compilation warnings.
But, if we change the code to something slightly different:
[[
size_t x = (sizeof(filter) / sizeof(filter[0]));
struct sock_fprog prog = {
.len = x,
.filter = filter,
};
]]
The "cc -Wconversion" gives us the following warning:
warning: conversion from ‘size_t’ {aka ‘long unsigned int’}
to ‘short unsigned int’ may change value
Presumably we don't get a warning for an assignment of the form
.len = (sizeof(filter) / sizeof(filter[0]))
because the compiler is smart enough to work out that the
value of the constant expression is within the range of
"unsigned short".
Your thoughts?
Thanks,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
