POSIX: generic wrappers for all setjmp.h symbols

This patch extends the generic wrappers of sigsetjmp to all of the *jmp
wrapper functions in <setjmp.h>

The C standard allows these to be defined as macros, rather than
explicit functions, which cannot be referenced by Fortran C bindings, so
we cannot assume that these functions exist, even when using a compliant
libc.

As with sigsetjmp, these functions are now disabled on default, and
raise a runtime error if called by the program.  Realistically, they
will only be defined by an autoconf-configured build.

This is required for older Linux distributions where libc does not
define longjmp.  Some Cray compilers also report incompatible longjmp
function signatures, which may indicate a similar problem (although this
needs further investigation).

ac/configure.ac

@@ -235,12 +235,24 @@ AC_CONFIG_COMMANDS(Makefile.dep, [make depend])
 
 # POSIX verification tests
 
-# These symbols may be defined as macros, making them inaccessible by Fortran.
-# These three exist in modern BSD and Linux libc, so we just confirm them.
-# But one day, we many need to handle them more carefully.
-AX_FC_CHECK_BIND_C([setjmp], [], [AC_MSG_ERROR([Could not find setjmp.])])
-AX_FC_CHECK_BIND_C([longjmp], [], [AC_MSG_ERROR([Could not find longjmp.])])
-AX_FC_CHECK_BIND_C([siglongjmp], [], [AC_MSG_ERROR([Could not find siglongjmp.])])
+# Symbols in <setjmp.h> may be defined as macros, making them inaccessible by
+# Fortran C bindings.  `sigsetjmp` is known to have an internal symbol in
+# glibc, so we check for this possibility.  For the others, we only check for
+# existence.
+
+# If the need arises, we may want to define these under a standalone macro.
+
+# Validate the setjmp symbol
+AX_FC_CHECK_BIND_C([setjmp],
+  [SETJMP="setjmp"], [SETJMP="setjmp_missing"]
+)
+AC_DEFINE_UNQUOTED([SETJMP_NAME], ["${SETJMP}"])
+
+# Validate the longjmp symbol
+AX_FC_CHECK_BIND_C([longjmp],
+  [LONGJMP="longjmp"], [LONGJMP="longjmp_missing"]
+)
+AC_DEFINE_UNQUOTED([LONGJMP_NAME], ["${LONGJMP}"])
 
 # Determine the sigsetjmp symbol.  If missing, then point to sigsetjmp_missing.
 #
@@ -256,6 +268,13 @@ for sigsetjmp_fn in sigsetjmp __sigsetjmp; do
 done
 AC_DEFINE_UNQUOTED([SIGSETJMP_NAME], ["${SIGSETJMP}"])
 
+# Validate the siglongjmp symbol
+AX_FC_CHECK_BIND_C([siglongjmp],
+  [SIGLONGJMP="siglongjmp"], [SETJMP="siglongjmp_missing"]
+)
+AC_DEFINE_UNQUOTED([SIGLONGJMP_NAME], ["${SIGLONGJMP}"])
+
+
 # Verify the size of nonlocal jump buffer structs
 # NOTE: This requires C compiler, but can it be done with a Fortran compiler?
 AC_LANG_PUSH([C])

src/framework/posix.F90

@@ -137,7 +137,7 @@ function sleep_posix(seconds) result(rc) bind(c, name="sleep")
   !! returns 0.  When `longjmp` is later called, the program is restored to the
   !! point where `setjmp` was called, except it now returns a value (rc) as
   !! specified by `longjmp`.
-  function setjmp(env) result(rc) bind(c, name="setjmp")
+  function setjmp(env) result(rc) bind(c, name=SETJMP_NAME)
     ! #include <setjmp.h>
     ! int setjmp(jmp_buf env);
     import :: jmp_buf, c_int
@@ -175,7 +175,7 @@ end function sigsetjmp
 
   !> C interface to POSIX longjmp()
   !! Users should use the Fortran-defined longjmp() function.
-  subroutine longjmp_posix(env, val) bind(c, name="longjmp")
+  subroutine longjmp_posix(env, val) bind(c, name=LONGJMP_NAME)
     ! #include <setjmp.h>
     ! int longjmp(jmp_buf env, int val);
     import :: jmp_buf, c_int
@@ -188,7 +188,7 @@ end subroutine longjmp_posix
 
   !> C interface to POSIX siglongjmp()
   !! Users should use the Fortran-defined siglongjmp() function.
-  subroutine siglongjmp_posix(env, val) bind(c, name="longjmp")
+  subroutine siglongjmp_posix(env, val) bind(c, name=SIGLONGJMP_NAME)
     ! #include <setjmp.h>
     ! int siglongjmp(jmp_buf env, int val);
     import :: sigjmp_buf, c_int
@@ -344,11 +344,36 @@ subroutine siglongjmp(env, val)
   call siglongjmp_posix(env, val_c)
 end subroutine siglongjmp
 
+
+! Symbols in <setjmp.h> may be platform-dependent and may not exist if defined
+! as a macro.  The following functions permit compilation when they are
+! unavailable, and report a runtime error if used in the program.
+
+!> Placeholder function for a missing or unconfigured setjmp
+function setjmp_missing(env) result(rc) bind(c)
+  type(jmp_buf), intent(in) :: env
+    !< Current process state (unused)
+  integer(kind=c_int) :: rc
+    !< Function return code (unused)
+
+  print '(a)', 'ERROR: setjmp() is not implemented in this build.'
+  print '(a)', 'Recompile with autoconf or -DSETJMP_NAME=\"<symbol name>\".'
+  error stop
+end function setjmp_missing
+
+!> Placeholder function for a missing or unconfigured longjmp
+subroutine longjmp_missing(env, val) bind(c)
+  type(jmp_buf), intent(in) :: env
+    !< Current process state (unused)
+  integer(kind=c_int), value, intent(in) :: val
+    !< Enable signal state flag (unused)
+
+  print '(a)', 'ERROR: longjmp() is not implemented in this build.'
+  print '(a)', 'Recompile with autoconf or -DLONGJMP_NAME=\"<symbol name>\".'
+  error stop
+end subroutine longjmp_missing
+
 !> Placeholder function for a missing or unconfigured sigsetjmp
-!!
-!! The symbol for sigsetjmp can be platform-dependent and may not exist if
-!! defined as a macro.  This function allows compilation, and reports a runtime
-!! error if used in the program.
 function sigsetjmp_missing(env, savesigs) result(rc) bind(c)
   type(sigjmp_buf), intent(in) :: env
     !< Current process state (unused)
@@ -362,4 +387,16 @@ function sigsetjmp_missing(env, savesigs) result(rc) bind(c)
   error stop
 end function sigsetjmp_missing
 
+!> Placeholder function for a missing or unconfigured siglongjmp
+subroutine siglongjmp_missing(env, val) bind(c)
+  type(sigjmp_buf), intent(in) :: env
+    !< Current process state (unused)
+  integer(kind=c_int), value, intent(in) :: val
+    !< Enable signal state flag (unused)
+
+  print '(a)', 'ERROR: siglongjmp() is not implemented in this build.'
+  print '(a)', 'Recompile with autoconf or -DSIGLONGJMP_NAME=\"<symbol name>\".'
+  error stop
+end subroutine siglongjmp_missing
+
 end module posix

src/framework/posix.h

@@ -12,12 +12,24 @@
 #define SIZEOF_SIGJMP_BUF SIZEOF_JMP_BUF
 #endif
 
-! glibc defines sigsetjmp as __sigsetjmp via macro readable from <setjmp.h>.
+! Wrappers to <setjmp.h> are disabled on default.
+#ifndef SETJMP_NAME
+#define SETJMP_NAME "setjmp_missing"
+#endif
+
+#ifndef LONGJMP_NAME
+#define LONGJMP_NAME "longjmp_missing"
+#endif
+
 #ifndef SIGSETJMP_NAME
 #define SIGSETJMP_NAME "sigsetjmp_missing"
 #endif
 
-! This should be defined by /usr/include/signal.h
+#ifndef SIGLONGJMP_NAME
+#define SIGLONGJMP_NAME "siglongjmp_missing"
+#endif
+
+! This should be defined by <signal.h>;
 ! If unset, we use the most common (x86) value
 #ifndef POSIX_SIGUSR1
 #define POSIX_SIGUSR1 10