Installed-header hygiene (BZ#20366): stack_t.

sys/ucontext.h unconditionally uses stack_t, and it does not make
sense to change that.  But signal.h only declares stack_t under
__USE_XOPEN_EXTENDED || __USE_XOPEN2K8.  The actual definition is
already in a bits header, bits/sigstack.h, but that header insists on
only being included by signal.h, so we have to change that as well as
all of the sys/ucontext.h variants.  (Some but not all variants of
bits/sigcontext.h, which sys/ucontext.h may also need, had already
received this adjustment; for consistency, I made them all the same,
even if that's not strictly necessary in some configurations.)
bits/sigcontext.h and bits/sigstack.h also all need to receive
multiple inclusion guards.

	* sysdeps/generic/sys/ucontext.h
	* sysdeps/arm/sys/ucontext.h
	* sysdeps/i386/sys/ucontext.h
	* sysdeps/m68k/sys/ucontext.h
	* sysdeps/mips/sys/ucontext.h
	* sysdeps/unix/sysv/linux/aarch64/sys/ucontext.h
	* sysdeps/unix/sysv/linux/alpha/sys/ucontext.h
	* sysdeps/unix/sysv/linux/arm/sys/ucontext.h
	* sysdeps/unix/sysv/linux/hppa/sys/ucontext.h
	* sysdeps/unix/sysv/linux/ia64/sys/ucontext.h
	* sysdeps/unix/sysv/linux/m68k/sys/ucontext.h
	* sysdeps/unix/sysv/linux/mips/sys/ucontext.h
	* sysdeps/unix/sysv/linux/nios2/sys/ucontext.h
	* sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h
	* sysdeps/unix/sysv/linux/s390/sys/ucontext.h
	* sysdeps/unix/sysv/linux/sh/sys/ucontext.h
	* sysdeps/unix/sysv/linux/sparc/sys/ucontext.h
	* sysdeps/unix/sysv/linux/tile/sys/ucontext.h
	* sysdeps/unix/sysv/linux/x86/sys/ucontext.h:
	Include both bits/sigcontext.h and bits/sigstack.h.
	Fix grammar error in comment, if present.

	* bits/sigstack.h
	* sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h
	* sysdeps/unix/sysv/linux/alpha/bits/sigstack.h
	* sysdeps/unix/sysv/linux/bits/sigstack.h
	* sysdeps/unix/sysv/linux/ia64/bits/sigstack.h
	* sysdeps/unix/sysv/linux/mips/bits/sigstack.h
	* sysdeps/unix/sysv/linux/powerpc/bits/sigstack.h
	* sysdeps/unix/sysv/linux/sparc/bits/sigstack.h
	* bits/sigcontext.h
	* sysdeps/mach/hurd/i386/bits/sigcontext.h
	* sysdeps/unix/sysv/linux/bits/sigcontext.h
	* sysdeps/unix/sysv/linux/ia64/bits/sigcontext.h
	* sysdeps/unix/sysv/linux/sparc/bits/sigcontext.h:
	Add multiple inclusion guard.  Permit inclusion by sys/ucontext.h
	as well as signal.h, if this was not already allowed.  Request
	definition of size_t if necessary.  Minimize semantically-null
	differences across files.

33 files changed, 271 insertions, 108 deletions

diff --git a/ChangeLog b/ChangeLog
index b428ba42ee..47ea83666f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,47 @@
 2016-09-23  Zack Weinberg  <zackw@panix.com>
 
+	* sysdeps/generic/sys/ucontext.h
+	* sysdeps/arm/sys/ucontext.h
+	* sysdeps/i386/sys/ucontext.h
+	* sysdeps/m68k/sys/ucontext.h
+	* sysdeps/mips/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/aarch64/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/alpha/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/arm/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/hppa/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/ia64/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/m68k/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/mips/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/nios2/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/s390/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/sh/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/sparc/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/tile/sys/ucontext.h
+	* sysdeps/unix/sysv/linux/x86/sys/ucontext.h:
+	Include both bits/sigcontext.h and bits/sigstack.h.
+	Fix grammar error in comment, if present.
+
+	* bits/sigstack.h
+	* sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h
+	* sysdeps/unix/sysv/linux/alpha/bits/sigstack.h
+	* sysdeps/unix/sysv/linux/bits/sigstack.h
+	* sysdeps/unix/sysv/linux/ia64/bits/sigstack.h
+	* sysdeps/unix/sysv/linux/mips/bits/sigstack.h
+	* sysdeps/unix/sysv/linux/powerpc/bits/sigstack.h
+	* sysdeps/unix/sysv/linux/sparc/bits/sigstack.h
+	* bits/sigcontext.h
+	* sysdeps/mach/hurd/i386/bits/sigcontext.h
+	* sysdeps/unix/sysv/linux/bits/sigcontext.h
+	* sysdeps/unix/sysv/linux/ia64/bits/sigcontext.h
+	* sysdeps/unix/sysv/linux/sparc/bits/sigcontext.h:
+	Add multiple inclusion guard.  Permit inclusion by sys/ucontext.h
+	as well as signal.h, if this was not already allowed.  Request
+	definition of size_t if necessary.  Minimize semantically-null
+	differences across files.
+
+2016-09-23  Zack Weinberg  <zackw@panix.com>
+
 	* time/time.h, bits/time.h, sysdeps/unix/sysv/linux/bits/time.h:
 	Remove all logic conditional on __need macros.	Move all the
 	conditionally defined types to their own headers...
diff --git a/bits/sigcontext.h b/bits/sigcontext.h
index 85b2a96d9f..ddc4966d6b 100644
--- a/bits/sigcontext.h
+++ b/bits/sigcontext.h
@@ -16,7 +16,10 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifndef _SIGNAL_H
+#ifndef _BITS_SIGCONTEXT_H
+#define _BITS_SIGCONTEXT_H 1
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never use <bits/sigcontext.h> directly; include <signal.h> instead."
 #endif
 
@@ -30,3 +33,5 @@ struct sigcontext
   };
 
 /* Signal subcodes should be defined here.  */
+
+#endif /* bits/sigcontext.h */
diff --git a/bits/sigstack.h b/bits/sigstack.h
index b4b911e7d1..62020b396e 100644
--- a/bits/sigstack.h
+++ b/bits/sigstack.h
@@ -16,7 +16,10 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifndef _SIGNAL_H
+#ifndef _BITS_SIGSTACK_H
+#define _BITS_SIGSTACK_H 1
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never include this file directly.  Use <signal.h> instead"
 #endif
 
@@ -52,3 +55,5 @@ enum
 
 /* System default stack size.  */
 #define SIGSTKSZ	(MINSIGSTKSZ + 32768)
+
+#endif /* bits/sigstack.h */
diff --git a/sysdeps/arm/sys/ucontext.h b/sysdeps/arm/sys/ucontext.h
index 744cb538cf..28bf860100 100644
--- a/sysdeps/arm/sys/ucontext.h
+++ b/sysdeps/arm/sys/ucontext.h
@@ -23,6 +23,12 @@
 #include <features.h>
 #include <signal.h>
 
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
+#include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
+
 typedef int greg_t;
 
 /* Number of general registers.  */
diff --git a/sysdeps/generic/sys/ucontext.h b/sysdeps/generic/sys/ucontext.h
index f08cec04cc..b5ec972a91 100644
--- a/sysdeps/generic/sys/ucontext.h
+++ b/sysdeps/generic/sys/ucontext.h
@@ -25,9 +25,11 @@
 #include <features.h>
 #include <signal.h>
 
-/* We need the signal context definitions even if they are not used
-   included in <signal.h>.  */
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
 #include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
 
 typedef struct sigcontext mcontext_t;
 
diff --git a/sysdeps/i386/sys/ucontext.h b/sysdeps/i386/sys/ucontext.h
index d08e1a7f56..882173ba57 100644
--- a/sysdeps/i386/sys/ucontext.h
+++ b/sysdeps/i386/sys/ucontext.h
@@ -23,6 +23,12 @@
 #include <features.h>
 #include <signal.h>
 
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
+#include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
+
 /* Type for general register.  */
 typedef int greg_t;
 
diff --git a/sysdeps/m68k/sys/ucontext.h b/sysdeps/m68k/sys/ucontext.h
index ef85368cb2..1c363a8c31 100644
--- a/sysdeps/m68k/sys/ucontext.h
+++ b/sysdeps/m68k/sys/ucontext.h
@@ -23,6 +23,12 @@
 #include <features.h>
 #include <signal.h>
 
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
+#include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
+
 /* Type for general register.  */
 typedef int greg_t;
 
diff --git a/sysdeps/mach/hurd/i386/bits/sigcontext.h b/sysdeps/mach/hurd/i386/bits/sigcontext.h
index 6d15b039ef..73585e18d1 100644
--- a/sysdeps/mach/hurd/i386/bits/sigcontext.h
+++ b/sysdeps/mach/hurd/i386/bits/sigcontext.h
@@ -16,12 +16,13 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef _BITS_SIGCONTEXT_H
+#define _BITS_SIGCONTEXT_H 1
+
 #if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never use <bits/sigcontext.h> directly; include <signal.h> instead."
 #endif
 
-#ifndef sc_pc
-
 /* Signal handlers are actually called:
    void handler (int sig, int code, struct sigcontext *scp);  */
 
@@ -116,4 +117,4 @@ struct sigcontext
 #define DBG_SINGLE_TRAP		0x1 /* single step */
 #define DBG_BRKPNT_FAULT	0x2 /* breakpoint instruction */
 
-#endif /* sc_pc */
+#endif /* bits/sigcontext.h */
diff --git a/sysdeps/mips/sys/ucontext.h b/sysdeps/mips/sys/ucontext.h
index b3d752bc46..89970a8337 100644
--- a/sysdeps/mips/sys/ucontext.h
+++ b/sysdeps/mips/sys/ucontext.h
@@ -21,9 +21,16 @@
 #define _SYS_UCONTEXT_H	1
 
 #include <features.h>
-#include <sgidefs.h>
 #include <signal.h>
 
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
+#include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
+#include <sgidefs.h>
+
+
 /* Type for general register.  */
 #if _MIPS_SIM == _ABIO32
 typedef __uint32_t greg_t;
diff --git a/sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h b/sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h
index 5b09b7c8c3..cb3e97d90d 100644
--- a/sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h
+++ b/sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h
@@ -16,10 +16,15 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifndef _SIGNAL_H
+#ifndef _BITS_SIGSTACK_H
+#define _BITS_SIGSTACK_H 1
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never include this file directly.  Use <signal.h> instead"
 #endif
 
+#define __need_size_t
+#include <stddef.h>
 
 /* Structure describing a signal stack (obsolete).  */
 struct sigstack
@@ -28,8 +33,15 @@ struct sigstack
     int ss_onstack;		/* Nonzero if executing on this stack.  */
   };
 
+/* Alternate, preferred interface.  */
+typedef struct sigaltstack
+  {
+    void *ss_sp;
+    int ss_flags;
+    size_t ss_size;
+  } stack_t;
 
-/* Possible values for `ss_flags.'.  */
+/* Possible values for `ss_flags'.  */
 enum
 {
   SS_ONSTACK = 1,
@@ -44,11 +56,4 @@ enum
 /* System default stack size.  */
 #define SIGSTKSZ	16384
 
-
-/* Alternate, preferred interface.  */
-typedef struct sigaltstack
-  {
-    void *ss_sp;
-    int ss_flags;
-    size_t ss_size;
-  } stack_t;
+#endif /* bits/sigstack.h */
diff --git a/sysdeps/unix/sysv/linux/aarch64/sys/ucontext.h b/sysdeps/unix/sysv/linux/aarch64/sys/ucontext.h
index 01da3ca858..2e3e1ee87d 100644
--- a/sysdeps/unix/sysv/linux/aarch64/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/aarch64/sys/ucontext.h
@@ -23,11 +23,14 @@
 
 #include <features.h>
 #include <signal.h>
-#include <sys/procfs.h>
 
-/* We need the signal context definitions even if they are not used
-   included in <signal.h>.  */
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
 #include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
+#include <sys/procfs.h>
+
 
 typedef elf_greg_t greg_t;
 
diff --git a/sysdeps/unix/sysv/linux/alpha/bits/sigstack.h b/sysdeps/unix/sysv/linux/alpha/bits/sigstack.h
index 6ad3363ddf..b2de7a1d3e 100644
--- a/sysdeps/unix/sysv/linux/alpha/bits/sigstack.h
+++ b/sysdeps/unix/sysv/linux/alpha/bits/sigstack.h
@@ -16,10 +16,15 @@
    License along with the GNU C Library.  If not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifndef _SIGNAL_H
+#ifndef _BITS_SIGSTACK_H
+#define _BITS_SIGSTACK_H 1
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never include this file directly.  Use <signal.h> instead"
 #endif
 
+#define __need_size_t
+#include <stddef.h>
 
 /* Structure describing a signal stack (obsolete).  */
 struct sigstack
@@ -28,8 +33,15 @@ struct sigstack
     int ss_onstack;		/* Nonzero if executing on this stack.  */
   };
 
+/* Alternate, preferred interface.  */
+typedef struct sigaltstack
+  {
+    __ptr_t ss_sp;
+    int ss_flags;
+    size_t ss_size;
+  } stack_t;
 
-/* Possible values for `ss_flags.'.  */
+/* Possible values for `ss_flags'.  */
 enum
 {
   SS_ONSTACK = 1,
@@ -44,11 +56,4 @@ enum
 /* System default stack size.  */
 #define SIGSTKSZ	16384
 
-
-/* Alternate, preferred interface.  */
-typedef struct sigaltstack
-  {
-    __ptr_t ss_sp;
-    int ss_flags;
-    size_t ss_size;
-  } stack_t;
+#endif /* bits/sigstack.h */
diff --git a/sysdeps/unix/sysv/linux/alpha/sys/ucontext.h b/sysdeps/unix/sysv/linux/alpha/sys/ucontext.h
index a42e662cf5..0fa4c1f996 100644
--- a/sysdeps/unix/sysv/linux/alpha/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/alpha/sys/ucontext.h
@@ -21,7 +21,10 @@
 #include <features.h>
 #include <signal.h>
 
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
 #include <bits/sigcontext.h>
+#include <bits/sigstack.h>
 
 
 /* Type for general register.  */
diff --git a/sysdeps/unix/sysv/linux/arm/sys/ucontext.h b/sysdeps/unix/sysv/linux/arm/sys/ucontext.h
index f32eadc099..c7aceadb7d 100644
--- a/sysdeps/unix/sysv/linux/arm/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/arm/sys/ucontext.h
@@ -23,9 +23,11 @@
 #include <features.h>
 #include <signal.h>
 
-/* We need the signal context definitions even if they are not used
-   included in <signal.h>.  */
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
 #include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
 
 typedef int greg_t;
 
diff --git a/sysdeps/unix/sysv/linux/bits/sigcontext.h b/sysdeps/unix/sysv/linux/bits/sigcontext.h
index 46cacb7b2c..bdeaae8ad2 100644
--- a/sysdeps/unix/sysv/linux/bits/sigcontext.h
+++ b/sysdeps/unix/sysv/linux/bits/sigcontext.h
@@ -15,6 +15,9 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef _BITS_SIGCONTEXT_H
+#define _BITS_SIGCONTEXT_H 1
+
 #if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never use <bits/sigcontext.h> directly; include <signal.h> instead."
 #endif
@@ -30,3 +33,5 @@
 # define __need_NULL
 # include <stddef.h>
 #endif
+
+#endif /* bits/sigcontext.h */
diff --git a/sysdeps/unix/sysv/linux/bits/sigstack.h b/sysdeps/unix/sysv/linux/bits/sigstack.h
index 115a98ec6b..d858f09b73 100644
--- a/sysdeps/unix/sysv/linux/bits/sigstack.h
+++ b/sysdeps/unix/sysv/linux/bits/sigstack.h
@@ -16,10 +16,15 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifndef _SIGNAL_H
+#ifndef _BITS_SIGSTACK_H
+#define _BITS_SIGSTACK_H 1
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never include this file directly.  Use <signal.h> instead"
 #endif
 
+#define __need_size_t
+#include <stddef.h>
 
 /* Structure describing a signal stack (obsolete).  */
 struct sigstack
@@ -28,8 +33,15 @@ struct sigstack
     int ss_onstack;		/* Nonzero if executing on this stack.  */
   };
 
+/* Alternate, preferred interface.  */
+typedef struct sigaltstack
+  {
+    void *ss_sp;
+    int ss_flags;
+    size_t ss_size;
+  } stack_t;
 
-/* Possible values for `ss_flags.'.  */
+/* Possible values for `ss_flags'.  */
 enum
 {
   SS_ONSTACK = 1,
@@ -44,11 +56,4 @@ enum
 /* System default stack size.  */
 #define SIGSTKSZ	8192
 
-
-/* Alternate, preferred interface.  */
-typedef struct sigaltstack
-  {
-    void *ss_sp;
-    int ss_flags;
-    size_t ss_size;
-  } stack_t;
+#endif /* bits/sigstack.h */
diff --git a/sysdeps/unix/sysv/linux/hppa/sys/ucontext.h b/sysdeps/unix/sysv/linux/hppa/sys/ucontext.h
index f6fd367bd9..fa2bd8c048 100644
--- a/sysdeps/unix/sysv/linux/hppa/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/hppa/sys/ucontext.h
@@ -23,9 +23,10 @@
 #include <features.h>
 #include <signal.h>
 
-/* We need the signal context definitions even if they are not used
-   included in <signal.h>.  */
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
 #include <bits/sigcontext.h>
+#include <bits/sigstack.h>
 
 
 /* Type for general register.  */
diff --git a/sysdeps/unix/sysv/linux/ia64/bits/sigcontext.h b/sysdeps/unix/sysv/linux/ia64/bits/sigcontext.h
index 591e7a22f0..af15ee856b 100644
--- a/sysdeps/unix/sysv/linux/ia64/bits/sigcontext.h
+++ b/sysdeps/unix/sysv/linux/ia64/bits/sigcontext.h
@@ -16,13 +16,13 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef _BITS_SIGCONTEXT_H
+#define _BITS_SIGCONTEXT_H 1
+
 #if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never use <bits/sigcontext.h> directly; include <signal.h> instead."
 #endif
 
-#ifndef _BITS_SIGCONTEXT_H
-#define _BITS_SIGCONTEXT_H 1
-
 #define __need_size_t
 #include <stddef.h>
 #include <bits/sigstack.h>
diff --git a/sysdeps/unix/sysv/linux/ia64/bits/sigstack.h b/sysdeps/unix/sysv/linux/ia64/bits/sigstack.h
index 0cd5e84043..f22e503f48 100644
--- a/sysdeps/unix/sysv/linux/ia64/bits/sigstack.h
+++ b/sysdeps/unix/sysv/linux/ia64/bits/sigstack.h
@@ -16,12 +16,15 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifndef _SIGNAL_H
+#ifndef _BITS_SIGSTACK_H
+#define _BITS_SIGSTACK_H 1
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never include this file directly.  Use <signal.h> instead"
 #endif
 
-#ifndef _SIGSTACK_H
-#define _SIGSTACK_H	1
+#define __need_size_t
+#include <stddef.h>
 
 /* Structure describing a signal stack (obsolete).  */
 struct sigstack
@@ -30,8 +33,15 @@ struct sigstack
     int ss_onstack;		/* Nonzero if executing on this stack.  */
   };
 
+/* Alternate, preferred interface.  */
+typedef struct sigaltstack
+  {
+    __ptr_t ss_sp;
+    int ss_flags;
+    size_t ss_size;
+  } stack_t;
 
-/* Possible values for `ss_flags.'.  */
+/* Possible values for `ss_flags'.  */
 enum
 {
   SS_ONSTACK = 1,
@@ -50,13 +60,4 @@ enum
 /* System default stack size.  */
 #define SIGSTKSZ	262144
 
-
-/* Alternate, preferred interface.  */
-typedef struct sigaltstack
-  {
-    __ptr_t ss_sp;
-    int ss_flags;
-    size_t ss_size;
-  } stack_t;
-
-#endif	/* bits/sigstack.h */
+#endif /* bits/sigstack.h */
diff --git a/sysdeps/unix/sysv/linux/ia64/sys/ucontext.h b/sysdeps/unix/sysv/linux/ia64/sys/ucontext.h
index c79fced452..730aa78fda 100644
--- a/sysdeps/unix/sysv/linux/ia64/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/ia64/sys/ucontext.h
@@ -21,7 +21,11 @@
 #include <features.h>
 #include <signal.h>
 
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
 #include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
 
 /*
  * These are here mostly for backwards compatibility with older Unices.
diff --git a/sysdeps/unix/sysv/linux/m68k/sys/ucontext.h b/sysdeps/unix/sysv/linux/m68k/sys/ucontext.h
index d8ee5423a5..66f4b55307 100644
--- a/sysdeps/unix/sysv/linux/m68k/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/m68k/sys/ucontext.h
@@ -23,6 +23,12 @@
 #include <features.h>
 #include <signal.h>
 
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
+#include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
+
 /* Type for general register.  */
 typedef int greg_t;
 
diff --git a/sysdeps/unix/sysv/linux/mips/bits/sigstack.h b/sysdeps/unix/sysv/linux/mips/bits/sigstack.h
index 2e9665444a..9e1ace9fdd 100644
--- a/sysdeps/unix/sysv/linux/mips/bits/sigstack.h
+++ b/sysdeps/unix/sysv/linux/mips/bits/sigstack.h
@@ -16,10 +16,15 @@
    License along with the GNU C Library.  If not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifndef _SIGNAL_H
+#ifndef _BITS_SIGSTACK_H
+#define _BITS_SIGSTACK_H 1
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never include this file directly.  Use <signal.h> instead"
 #endif
 
+#define __need_size_t
+#include <stddef.h>
 
 /* Structure describing a signal stack (obsolete).  */
 struct sigstack
@@ -28,8 +33,15 @@ struct sigstack
     int ss_onstack;		/* Nonzero if executing on this stack.  */
   };
 
+/* Alternate, preferred interface.  */
+typedef struct sigaltstack
+  {
+    void *ss_sp;
+    size_t ss_size;
+    int ss_flags;
+  } stack_t;
 
-/* Possible values for `ss_flags.'.  */
+/* Possible values for `ss_flags'.  */
 enum
 {
   SS_ONSTACK = 1,
@@ -44,11 +56,4 @@ enum
 /* System default stack size.  */
 #define SIGSTKSZ	8192
 
-
-/* Alternate, preferred interface.  */
-typedef struct sigaltstack
-  {
-    void *ss_sp;
-    size_t ss_size;
-    int ss_flags;
-  } stack_t;
+#endif /* bits/sigstack.h */
diff --git a/sysdeps/unix/sysv/linux/mips/sys/ucontext.h b/sysdeps/unix/sysv/linux/mips/sys/ucontext.h
index b5d2e2ab10..1ab0c686ef 100644
--- a/sysdeps/unix/sysv/linux/mips/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/mips/sys/ucontext.h
@@ -20,12 +20,15 @@
 #define _SYS_UCONTEXT_H	1
 
 #include <features.h>
-#include <sgidefs.h>
 #include <signal.h>
 
-/* We need the signal context definitions even if they are not used
-   included in <signal.h>.  */
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
 #include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
+#include <sgidefs.h>
+
 
 /* Type for general register.  Even in o32 we assume 64-bit registers,
    like the kernel.  */
diff --git a/sysdeps/unix/sysv/linux/nios2/sys/ucontext.h b/sysdeps/unix/sysv/linux/nios2/sys/ucontext.h
index a44ec61fa0..26c55de312 100644
--- a/sysdeps/unix/sysv/linux/nios2/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/nios2/sys/ucontext.h
@@ -24,6 +24,12 @@
 #include <features.h>
 #include <signal.h>
 
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
+#include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
+
 /* These definitions must be in sync with the kernel.  */
 
 #define MCONTEXT_VERSION 2
diff --git a/sysdeps/unix/sysv/linux/powerpc/bits/sigstack.h b/sysdeps/unix/sysv/linux/powerpc/bits/sigstack.h
index 5b9c0c1be9..b06f439306 100644
--- a/sysdeps/unix/sysv/linux/powerpc/bits/sigstack.h
+++ b/sysdeps/unix/sysv/linux/powerpc/bits/sigstack.h
@@ -16,10 +16,15 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifndef _SIGNAL_H
+#ifndef _BITS_SIGSTACK_H
+#define _BITS_SIGSTACK_H 1
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never include this file directly.  Use <signal.h> instead"
 #endif
 
+#define __need_size_t
+#include <stddef.h>
 
 /* Structure describing a signal stack (obsolete).  */
 struct sigstack
@@ -28,8 +33,15 @@ struct sigstack
     int ss_onstack;		/* Nonzero if executing on this stack.  */
   };
 
+/* Alternate, preferred interface.  */
+typedef struct sigaltstack
+  {
+    void *ss_sp;
+    int ss_flags;
+    size_t ss_size;
+  } stack_t;
 
-/* Possible values for `ss_flags.'.  */
+/* Possible values for `ss_flags'.  */
 enum
 {
   SS_ONSTACK = 1,
@@ -44,11 +56,4 @@ enum
 /* System default stack size.  */
 #define SIGSTKSZ	16384
 
-
-/* Alternate, preferred interface.  */
-typedef struct sigaltstack
-  {
-    void *ss_sp;
-    int ss_flags;
-    size_t ss_size;
-  } stack_t;
+#endif /* bits/sigstack.h */
diff --git a/sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h b/sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h
index 2b97bc71bd..c4634f68b5 100644
--- a/sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h
@@ -21,9 +21,11 @@
 #include <features.h>
 #include <signal.h>
 
-/* We need the signal context definitions even if they are not used
-   included in <signal.h>.  */
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
 #include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
 
 #if __WORDSIZE == 32
 
diff --git a/sysdeps/unix/sysv/linux/s390/sys/ucontext.h b/sysdeps/unix/sysv/linux/s390/sys/ucontext.h
index 78f5fd77a1..0128d1fa55 100644
--- a/sysdeps/unix/sysv/linux/s390/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/s390/sys/ucontext.h
@@ -18,15 +18,15 @@
 
 #ifndef _SYS_UCONTEXT_H
 #define _SYS_UCONTEXT_H	1
-/* Forward definition to avoid parse errors */
-struct ucontext;
-typedef struct ucontext ucontext_t;
+
 #include <features.h>
 #include <signal.h>
 
-/* We need the signal context definitions even if they are not used
-   included in <signal.h>.  */
+/* We need the signal context definitions even if they are not exposed
+   by in <signal.h>.  */
 #include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
 
 /* Type for a program status word.  */
 typedef struct
diff --git a/sysdeps/unix/sysv/linux/sh/sys/ucontext.h b/sysdeps/unix/sysv/linux/sh/sys/ucontext.h
index ab9a7e66bf..2c5fa0431c 100644
--- a/sysdeps/unix/sysv/linux/sh/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/sh/sys/ucontext.h
@@ -23,9 +23,10 @@
 #include <features.h>
 #include <signal.h>
 
-/* We need the signal context definitions even if they are not used
-   included in <signal.h>.  */
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
 #include <bits/sigcontext.h>
+#include <bits/sigstack.h>
 
 
 typedef int greg_t;
diff --git a/sysdeps/unix/sysv/linux/sparc/bits/sigcontext.h b/sysdeps/unix/sysv/linux/sparc/bits/sigcontext.h
index 43253f2c99..8794dddfa4 100644
--- a/sysdeps/unix/sysv/linux/sparc/bits/sigcontext.h
+++ b/sysdeps/unix/sysv/linux/sparc/bits/sigcontext.h
@@ -15,6 +15,9 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef _BITS_SIGCONTEXT_H
+#define _BITS_SIGCONTEXT_H 1
+
 #if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never use <bits/sigcontext.h> directly; include <signal.h> instead."
 #endif
@@ -75,3 +78,5 @@ struct sigcontext
 };
 
 #endif /* sparc64 */
+
+#endif /* bits/sigcontext.h */
diff --git a/sysdeps/unix/sysv/linux/sparc/bits/sigstack.h b/sysdeps/unix/sysv/linux/sparc/bits/sigstack.h
index 5b9c0c1be9..b06f439306 100644
--- a/sysdeps/unix/sysv/linux/sparc/bits/sigstack.h
+++ b/sysdeps/unix/sysv/linux/sparc/bits/sigstack.h
@@ -16,10 +16,15 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifndef _SIGNAL_H
+#ifndef _BITS_SIGSTACK_H
+#define _BITS_SIGSTACK_H 1
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never include this file directly.  Use <signal.h> instead"
 #endif
 
+#define __need_size_t
+#include <stddef.h>
 
 /* Structure describing a signal stack (obsolete).  */
 struct sigstack
@@ -28,8 +33,15 @@ struct sigstack
     int ss_onstack;		/* Nonzero if executing on this stack.  */
   };
 
+/* Alternate, preferred interface.  */
+typedef struct sigaltstack
+  {
+    void *ss_sp;
+    int ss_flags;
+    size_t ss_size;
+  } stack_t;
 
-/* Possible values for `ss_flags.'.  */
+/* Possible values for `ss_flags'.  */
 enum
 {
   SS_ONSTACK = 1,
@@ -44,11 +56,4 @@ enum
 /* System default stack size.  */
 #define SIGSTKSZ	16384
 
-
-/* Alternate, preferred interface.  */
-typedef struct sigaltstack
-  {
-    void *ss_sp;
-    int ss_flags;
-    size_t ss_size;
-  } stack_t;
+#endif /* bits/sigstack.h */
diff --git a/sysdeps/unix/sysv/linux/sparc/sys/ucontext.h b/sysdeps/unix/sysv/linux/sparc/sys/ucontext.h
index d7bf2aedb9..5856398e62 100644
--- a/sysdeps/unix/sysv/linux/sparc/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/sparc/sys/ucontext.h
@@ -20,8 +20,15 @@
 
 #include <features.h>
 #include <signal.h>
+
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
+#include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
 #include <bits/wordsize.h>
 
+
 #if __WORDSIZE == 64
 
 #define MC_TSTATE	0
diff --git a/sysdeps/unix/sysv/linux/tile/sys/ucontext.h b/sysdeps/unix/sysv/linux/tile/sys/ucontext.h
index d930a1fea6..59c9bd1c4c 100644
--- a/sysdeps/unix/sysv/linux/tile/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/tile/sys/ucontext.h
@@ -22,13 +22,15 @@
 #include <features.h>
 #include <signal.h>
 
-/* We need the signal context definitions even if they are not used
-   included in <signal.h>.  */
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
 #include <bits/sigcontext.h>
+#include <bits/sigstack.h>
 
 /* Get register type and register names. */
 #include <arch/abi.h>
 
+
 /* Type for general register.  */
 typedef uint_reg_t greg_t;
 
diff --git a/sysdeps/unix/sysv/linux/x86/sys/ucontext.h b/sysdeps/unix/sysv/linux/x86/sys/ucontext.h
index 062063526b..99ee9463ea 100644
--- a/sysdeps/unix/sysv/linux/x86/sys/ucontext.h
+++ b/sysdeps/unix/sysv/linux/x86/sys/ucontext.h
@@ -21,9 +21,11 @@
 #include <features.h>
 #include <signal.h>
 
-/* We need the signal context definitions even if they are not used
-   included in <signal.h>.  */
+/* We need the signal context definitions even if they are not exposed
+   by <signal.h>.  */
 #include <bits/sigcontext.h>
+#include <bits/sigstack.h>
+
 
 #ifdef __x86_64__