This is the mail archive of the
mailing list for the glibc project.
Re: [PATCH v2 1/2] sysdeps/stat: Handle 64-bit ino_t types on 32-bit hosts
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Alistair Francis <alistair dot francis at wdc dot com>
- Cc: <libc-alpha at sourceware dot org>, <macro at wdc dot com>, <alistair23 at gmail dot com>
- Date: Thu, 19 Sep 2019 20:33:17 +0000
- Subject: Re: [PATCH v2 1/2] sysdeps/stat: Handle 64-bit ino_t types on 32-bit hosts
- Ironport-sdr: skC8WnfgGnIV1XpVMauiXXRZ+34LQFnpVfXqSYeNe7wIDEv7+yZ6GGhTfJt0NtPNEdAFZd4BIF LnNKfqAWOBu2L2rCCp7Jwof4gs7TyD2LU+SmkGUGoqF9YscokFrKeNY/V0spP3cg77OWCkdt6G xQ8q+qezBd6oZUFr2fQRextb6VWjtkVN6snaAz7GNw7AGMWsvTRoXlqgkpLNLuen9J+/9eLohp vqEmoNrBqZj4Tjd8aGZYZLsbkCs6xRgApdRjt2WGeEqxN+kf5u+i6ckplFoziahnTHT5iHgzX7 TWM=
- Ironport-sdr: xswZmTX+ucJkHbBInT9BYofqXkLgNXaySjI67CsbumfPZjBbYiqRe1afITU/u2W0eW2Hr3qddD 9cWsrOXHYUBgCE/5V9tv/P1dOEdAiiYfOy060bLhZAHtWrvOZlraDO/L+FMRcykepYzjN7wxiL ZSqOElnvST2j8Vm1jrHy6N+ecIcppSJHOGXIB28tGAvFegeaxBzT5XYDJy0P/U4YQrDkhFhRIi 31PRYoHiwzaxxHTkhbVX/0x34qKuedlFzCHwUGCqkWw/uiC+uTBtWNVHiLq9aysx96yaoqHhGy +gc=
- References: <firstname.lastname@example.org>
On Wed, 18 Sep 2019, Alistair Francis wrote:
> On a 32-bit platform with a 64-bit ino_t type (__INO_T_MATCHES_INO64_T
> defined) we want to update the stat struct to remove the padding as it
> isn't required. As we don't have the padding we also need to update the
> overflow checker to not access the undefined members.
When posting a patch, please *always* say how it was tested. Typically
that would include running the glibc testsuite for at least one
configuration (but there may be exceptions, e.g. documentation patches).
> -#if defined __USE_FILE_OFFSET64
> +#if defined(__USE_FILE_OFFSET64) || __INO_T_MATCHES_INO64_T == 1
> +# if __INO_T_MATCHES_INO64_T == 1 && __OFF_T_MATCHES_OFF64_T != 1
The rule in glibc is that we compile with -Wundef and do not rely on
undefined macros being interpreted as 0 in #if.
Both __INO_T_MATCHES_INO64_T and __OFF_T_MATCHES_OFF64_T are in fact
defined/undefined macros, not macros that might sometimes be defined to 1
and sometimes to 0. So testing with == there is problematic; I'd expect
it to cause -Wundef errors for any existing 32-bit linux/generic
architecture where those macros are undefined (i.e. csky and nios2).
There are two possible approaches to fixing this.
(a) Do a preliminary patch that changes these macros from defined /
undefined to always-defined with 1 / 0 values. This involves updating a
lot of places that use the macros (mainly using __OFF_T_MATCHES_OFF64_T),
as well as ensuring that all bits/typesizes.h headers provide appropriate
(b) Change this patch to do defined / undefined tests rather than testing
the macro values.
Also, when a macro is 0 / 1 I'd expect boolean tests just to test the
macro as a boolean (so plain "__INO_T_MATCHES_INO64_T" inside #if, not
"__INO_T_MATCHES_INO64_T == 1").
Also, if using "defined" with (), like a function call there should be a
space before '('.
Joseph S. Myers