Add sigaltstack() prototype - Round 2

[Joel Sherrill]

On 8/15/2014 9:32 AM, Corinna Vinschen wrote:
> On Aug 15 09:20, Joel Sherrill wrote:
>> On 8/15/2014 8:46 AM, Corinna Vinschen wrote:
>>> On Aug 15 08:26, Joel Sherrill wrote:
>>>> 2014-08-15 Joel Sherrill <...>
>>>>
>>>>     * libc/include/sys/signal.h: Add sigaltstack() support.
>>> Shouldn't this patch define the available flags, too?
>> You are correct. It should. Obviously the code we were compiling didn't
>> use them. :)
>>
>> Attached is v3. Values follow those in glibc. Same ChangeLog.
> Uhm, I'm sorry, but...
No reason to be sorry. It is a review. :)
>> Index: newlib/libc/include/sys/signal.h
>> ===================================================================
>> RCS file: /cvs/src/src/newlib/libc/include/sys/signal.h,v
>> retrieving revision 1.22
>> diff -u -r1.22 signal.h
>> --- newlib/libc/include/sys/signal.h	26 Oct 2012 09:23:46 -0000	1.22
>> +++ newlib/libc/include/sys/signal.h	15 Aug 2014 14:20:10 -0000
>> @@ -104,6 +104,23 @@
>>  #define sa_sigaction  _signal_handlers._sigaction
>>  #endif
>>  
>> +#if __BSD_VISIBLE || __XSI_VISIBLE || __POSIX_VISIBLE >= 200112
>> +/*
>> + * Possible values for ss_flags in stack_t below.
>> + */
>> +#define SS_ONSTACK 0x1
>> +#define SS_ONSTACK 0x2
> ...that's SS_DISABLE 0x2, right?

Right.

I need to slow down on a Friday morning. I am ready to get out in the
pretty weather. :(

And FWIW the use of tabs vs spaces in defining constants in this file
is very inconsistent.
> POSIX also defines SIGSTKSZ and MINSIGSTKSZ. 
And checking the signal.h Open Group page, there is also SA_ONSTACK. The
SA_xxx constants are in OS specific sections so I added this only to the
RTEMS section with the same guards.
>  I'm wondering if we
> shouldn't add default values here if the variables aren't already
> defined.  Or would that rather be something for the target specific
> config?
They should be target specific but we could default them if not defined
in <sys/features.h>. <sys/features.h> is already included so that is already
a dependency.

My CentOS 6.x defines them in <asm/signal.h> to this:

#define MINSIGSTKSZ     2048
#define SIGSTKSZ        8192

Those seem reasonable enough as defaults the target can override.

Attached is another revision. Don't fret over catching my mistakes. It
is part of the process.

>
> Corinna
>

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel.sherrill@OARcorp.com        On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
Support Available                (256) 722-9985

-------------- next part --------------
Index: newlib/libc/include/sys/signal.h
===================================================================
RCS file: /cvs/src/src/newlib/libc/include/sys/signal.h,v
retrieving revision 1.22
diff -u -r1.22 signal.h
--- newlib/libc/include/sys/signal.h	26 Oct 2012 09:23:46 -0000	1.22
+++ newlib/libc/include/sys/signal.h	15 Aug 2014 16:03:12 -0000
@@ -71,9 +71,12 @@
 
 /*  3.3.8 Synchronously Accept a Signal, P1003.1b-1993, p. 76 */
 
-#define SA_NOCLDSTOP 1   /* Do not generate SIGCHLD when children stop */
-#define SA_SIGINFO   2   /* Invoke the signal catching function with */
-                         /*   three arguments instead of one. */
+#define SA_NOCLDSTOP 0x1   /* Do not generate SIGCHLD when children stop */
+#define SA_SIGINFO   0x2   /* Invoke the signal catching function with */
+                           /*   three arguments instead of one. */
+#if __BSD_VISIBLE || __XSI_VISIBLE || __POSIX_VISIBLE >= 200112
+#define SA_ONSTACK   0x4   /* Signal delivery will be on a separate stack. */
+#endif
 
 /* struct sigaction notes from POSIX:
  *
@@ -104,6 +107,34 @@
 #define sa_sigaction  _signal_handlers._sigaction
 #endif
 
+#if __BSD_VISIBLE || __XSI_VISIBLE || __POSIX_VISIBLE >= 200112
+/*
+ * Minimum and default signal stack constants. Allow for target overrides
+ * from <sys/features.h>.
+ */
+#ifndef	MINSIGSTKSZ
+#define	MINSIGSTKSZ	2048
+#endif
+#ifndef	SIGSTKSZ
+#define	SIGSTKSZ	8192
+#endif
+
+/*
+ * Possible values for ss_flags in stack_t below.
+ */
+#define	SS_ONSTACK	0x1
+#define	SS_DISABLE	0x2
+
+/*
+ * Structure used in sigaltstack call.
+ */
+typedef struct sigaltstack {
+  void     *ss_sp;    /* Stack base or pointer.  */
+  int       ss_flags; /* Flags.  */
+  size_t    ss_size;  /* Stack size.  */
+} stack_t;
+#endif
+
 #elif defined(__CYGWIN__)
 #include <cygwin/signal.h>
 #else
@@ -161,6 +192,11 @@
 int _EXFUN(sigsuspend, (const sigset_t *));
 int _EXFUN(sigpause, (int));
 
+
+#if __BSD_VISIBLE || __XSI_VISIBLE || __POSIX_VISIBLE >= 200112
+int _EXFUN(sigaltstack, (const stack_t *__restrict, stack_t *__restrict));
+#endif
+
 #if defined(_POSIX_THREADS)
 #ifdef __CYGWIN__
 #  ifndef _CYGWIN_TYPES_H