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Re: [PATCH 64bit] ssize_t
On 02/20/2013 05:06 PM, Corinna Vinschen wrote:
On Feb 20 16:42, Ralf Corsepius wrote:
On 02/20/2013 04:17 PM, Corinna Vinschen wrote:
On Feb 20 16:08, Ralf Corsepius wrote:
On 02/20/2013 03:14 PM, Corinna Vinschen wrote:
On Feb 20 03:23, Yaakov (Cygwin/X) wrote:
I just discovered an issue resulting from this commit:
2002-06-27 Jeff Johnston <jjohnstn@...>
* libc/include/sys/_types.h: Define _ssize_t as int if int is
32-bits, otherwise define it as long.
On x86_64-cygwin (as on Linux), int is still 32 bits, but size_t is a
64bit unsigned long and ssize_t should be as large but signed.
Possible patch for newlib attached; corresponding patches for
cygwin-64bit-branch on cygwin-patches@.
Thanks for the patch. I'm just wondering if ssize_t shouldn't ideally
be based on size_t, at least when using GCC. GCC has a predefined
What I'm thinking of is something like
Does that make sense?
GCC requires exact symmetry of types between ssize_t and size_t.
I.e. checking for sizes of types is not sufficient for [s]size_t.
Do you have a code suggestion then?
So far, the best I have been able to come up with for RTEMS, was a
pretty unpleasant, error prone and lacking generality preprocessor
ATM, it looks like this:
Right, but GCC (IIRC, since 4.4) defines size_t (__SIZE_T_TYPE__)
GCC doesn't define ssize_t
That's what I pasted in my previous mail.
and also comes with pretty aggressive fprintf-format strings checks
related to [s]size_t.
That said, IMO, in an ideal world, GCC also would define a
Unfortunately we're not living in an ideal world. That said, I'm
willing to go with the obvious as I outlined above. Since size_t is
*likely* defined as int if int == long, and defined as long if int <
long, this should match most cases. Oh, and then there are the
potential LLP64 systems which define sizeof size_t == sizeof long long.
An additional elif would catch that:
# if defined (__SIZEOF_INT__) && __SIZEOF_SIZE_T__ == __SIZEOF_INT__
typedef int ssize_t;
# elif defined (__SIZEOF_LONG__) && __SIZEOF_SIZE_T__ == __SIZEOF_LONG__
typedef long ssize_t
typedef long long ssize_t;
Sorry, I think, I did not communicate my point accurately.
Let me try again:
GCC doesn't apply a size-based logic to define size_t, but applies
hard-coded predefined types for size_t, likely based on historic
I.e. any type-size based logic will sometimes fail:
E.g. for targets with sizeof(size_t) == sizeof(int) == sizeof(long). on
some targets GCC uses "typedef unsigned int size_t" and on other targets
GCC uses "typedef unsigned long size_t".
Now, if you choose "typedef int ssize_t" on targets, which use "typedef
long size_t", GCC will raise warnings related to fprintfs.