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-rw-r--r--macros/texinfo/texinfo/gnulib/m4/gnulib-common.m438
1 files changed, 34 insertions, 4 deletions
diff --git a/macros/texinfo/texinfo/gnulib/m4/gnulib-common.m4 b/macros/texinfo/texinfo/gnulib/m4/gnulib-common.m4
index 7c0e3e8fa4..57b94ed532 100644
--- a/macros/texinfo/texinfo/gnulib/m4/gnulib-common.m4
+++ b/macros/texinfo/texinfo/gnulib/m4/gnulib-common.m4
@@ -1,4 +1,4 @@
-# gnulib-common.m4 serial 41
+# gnulib-common.m4 serial 44
dnl Copyright (C) 2007-2019 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -17,10 +17,13 @@ AC_DEFUN([gl_COMMON_BODY], [
AH_VERBATIM([_Noreturn],
[/* The _Noreturn keyword of C11. */
#ifndef _Noreturn
-# if 201103 <= (defined __cplusplus ? __cplusplus : 0)
+# if (defined __cplusplus \
+ && ((201103 <= __cplusplus && !(__GNUC__ == 4 && __GNUC_MINOR__ == 7)) \
+ || (defined _MSC_VER && 1900 <= _MSC_VER)))
# define _Noreturn [[noreturn]]
-# elif (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) \
- || 4 < __GNUC__ + (7 <= __GNUC_MINOR__))
+# elif ((!defined __cplusplus || defined __clang__) \
+ && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) \
+ || 4 < __GNUC__ + (7 <= __GNUC_MINOR__)))
/* _Noreturn works as-is. */
# elif 2 < __GNUC__ + (8 <= __GNUC_MINOR__) || 0x5110 <= __SUNPRO_C
# define _Noreturn __attribute__ ((__noreturn__))
@@ -85,6 +88,33 @@ AC_DEFUN([gl_COMMON_BODY], [
# define _GL_ATTRIBUTE_MALLOC /* empty */
#endif
])
+ AH_VERBATIM([async_safe],
+[/* The _GL_ASYNC_SAFE marker should be attached to functions that are
+ signal handlers (for signals other than SIGABRT, SIGPIPE) or can be
+ invoked from such signal handlers. Such functions have some restrictions:
+ * All functions that it calls should be marked _GL_ASYNC_SAFE as well,
+ or should be listed as async-signal-safe in POSIX
+ <http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04>
+ section 2.4.3. Note that malloc(), sprintf(), and fwrite(), in
+ particular, are NOT async-signal-safe.
+ * All memory locations (variables and struct fields) that these functions
+ access must be marked 'volatile'. This holds for both read and write
+ accesses. Otherwise the compiler might optimize away stores to and
+ reads from such locations that occur in the program, depending on its
+ data flow analysis. For example, when the program contains a loop
+ that is intended to inspect a variable set from within a signal handler
+ while (!signal_occurred)
+ ;
+ the compiler is allowed to transform this into an endless loop if the
+ variable 'signal_occurred' is not declared 'volatile'.
+ Additionally, recall that:
+ * A signal handler should not modify errno (except if it is a handler
+ for a fatal signal and ends by raising the same signal again, thus
+ provoking the termination of the process). If it invokes a function
+ that may clobber errno, it needs to save and restore the value of
+ errno. */
+#define _GL_ASYNC_SAFE
+])
dnl Preparation for running test programs:
dnl Tell glibc to write diagnostics from -D_FORTIFY_SOURCE=2 to stderr, not
dnl to /dev/tty, so they can be redirected to log files. Such diagnostics