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Deprecate SIGSTKSZ/MINSIGSTKSZ with _SC_SIGSTKSZ_SOURCE

Message ID 20201015122653.GA319424@gmail.com
State Superseded
Headers show
Series Deprecate SIGSTKSZ/MINSIGSTKSZ with _SC_SIGSTKSZ_SOURCE | expand

Commit Message

H.J. Lu Oct. 15, 2020, 12:26 p.m. UTC
On Wed, Oct 14, 2020 at 06:47:01PM +0100, Dave Martin wrote:
> > +#ifndef _SIGNAL_H
> > +# error "Never include <bits/sigstksz.h> directly; use <signal.h> instead."
> > +#endif
> > +
> > +#if __USE_SC_SIGSTKSZ
> > +# include <unistd.h>
> > +
> > +/* Default stack size for a signal handler: sysconf (SC_SIGSTKSZ).  */
> > +# undef SIGSTKSZ
> > +# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
> > +
> > +/* Minimum stack size for a signal handler: SIGSTKSZ.  */
> > +# undef MINSIGSTKSZ
> > +# define MINSIGSTKSZ SIGSTKSZ
> > +#endif
> 
> To help raise awareness, is it worth adding deprecation warnings on
> these?
> 
> Could we still consider them deprecated even with _SC_SIGSTKSZ_SOURCE?
> Ideally they should be (or even removed), since even if these values are
> "correct", using them is still a potential portability problem when
> building for other library stacks.
> 
> I think the rule ought to be to use these only if _SC_SIGSTKSZ /
> _SC_MINSIGSTKSZ aren't available, and with the caveat that the values
> may be wrong --  similar to the situation with PAGESIZE.
> 
> 
> It could be worth making this feature test macro more general and
> harvesting any other broken legacy macros we're aware of (such as
> PAGESIZE, but there are probably others).  Probably out of scope for
> this patch, though.
> 

Here is the followup patch to deprecate SIGSTKSZ and MINSIGSTKSZ.


H.J.
----
When _SC_SIGSTKSZ_SOURCE is defined, deprecate SIGSTKSZ and MINSIGSTKSZ:

tst-minsigstksz-5.c:46:3: warning: ‘MINSIGSTKSZ_is_deprecated’ is deprecated: Use sysconf (_SC_MINSIGSTKSZ) instead [-Wdeprecated-declarations]
   35 | MINSIGSTKSZ_is_deprecated (void)
---
 sysdeps/unix/sysv/linux/Makefile        |  6 ++++--
 sysdeps/unix/sysv/linux/bits/sigstksz.h | 18 ++++++++++++++++--
 2 files changed, 20 insertions(+), 4 deletions(-)

Comments

Joseph Myers Oct. 15, 2020, 7:59 p.m. UTC | #1
On Thu, 15 Oct 2020, H.J. Lu via Libc-alpha wrote:

> +__attribute_deprecated_msg__ ("Use sysconf (_SC_SIGSTKSZ) instead")
> +__extern_always_inline long
> +SIGSTKSZ_is_deprecated (void)
> +{
> +  return sysconf (_SC_SIGSTKSZ);
> +}
> +
> +__attribute_deprecated_msg__ ("Use sysconf (_SC_MINSIGSTKSZ) instead")
> +__extern_always_inline long
> +MINSIGSTKSZ_is_deprecated (void)
> +{
> +  return sysconf (_SC_SIGSTKSZ);
> +}

Those function names should start with '__' rather than claiming the names 
SIGSTKSZ_is_deprecated and MINSIGSTKSZ_is_deprecated from the user's 
namespace.
diff mbox series

Patch

diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index b51a02a6e6..5576c729ae 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -189,9 +189,11 @@  sysdep_headers += sys/timex.h bits/timex.h
 sysdep_routines += ntp_gettime ntp_gettimex
 endif
 
+CFLAGS-SIGSTKSZ += -D_SC_SIGSTKSZ_SOURCE -Wno-error=deprecated-declarations
+
 ifeq ($(subdir),signal)
 # Compile tst-minsigstksz-5.c with _SC_SIGSTKSZ_SOURCE.
-CFLAGS-tst-minsigstksz-5.c += -D_SC_SIGSTKSZ_SOURCE
+CFLAGS-tst-minsigstksz-5.c += $(CFLAGS-SIGSTKSZ)
 
 tests-special += $(objpfx)tst-signal-numbers.out
 # Depending on signal.o* is a hack.  What we actually want is a dependency
@@ -233,7 +235,7 @@  endif
 
 ifeq ($(subdir),support)
 # Compile xsigstack.c with _SC_SIGSTKSZ_SOURCE.
-CFLAGS-xsigstack.c += -D_SC_SIGSTKSZ_SOURCE
+CFLAGS-xsigstack.c += $(CFLAGS-SIGSTKSZ)
 endif
 
 ifeq ($(subdir),termios)
diff --git a/sysdeps/unix/sysv/linux/bits/sigstksz.h b/sysdeps/unix/sysv/linux/bits/sigstksz.h
index cd5b3cc895..c3e17e2251 100644
--- a/sysdeps/unix/sysv/linux/bits/sigstksz.h
+++ b/sysdeps/unix/sysv/linux/bits/sigstksz.h
@@ -23,11 +23,25 @@ 
 #if __USE_SC_SIGSTKSZ
 # include <unistd.h>
 
+__attribute_deprecated_msg__ ("Use sysconf (_SC_SIGSTKSZ) instead")
+__extern_always_inline long
+SIGSTKSZ_is_deprecated (void)
+{
+  return sysconf (_SC_SIGSTKSZ);
+}
+
+__attribute_deprecated_msg__ ("Use sysconf (_SC_MINSIGSTKSZ) instead")
+__extern_always_inline long
+MINSIGSTKSZ_is_deprecated (void)
+{
+  return sysconf (_SC_SIGSTKSZ);
+}
+
 /* Default stack size for a signal handler: sysconf (SC_SIGSTKSZ).  */
 # undef SIGSTKSZ
-# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
+# define SIGSTKSZ SIGSTKSZ_is_deprecated ()
 
 /* Minimum stack size for a signal handler: SIGSTKSZ.  */
 # undef MINSIGSTKSZ
-# define MINSIGSTKSZ SIGSTKSZ
+# define MINSIGSTKSZ MINSIGSTKSZ_is_deprecated ()
 #endif