m4 ChangeLog configure.ac src/m4.c src/stackovf.c [branch-1_4]

[Eric Blake]

CVSROOT:        /sources/m4
Module name:    m4
Branch:         branch-1_4
Changes by:     Eric Blake <ericb>      06/06/22 03:29:36

Modified files:
        .              : ChangeLog configure.ac 
        src            : m4.c stackovf.c 

Log message:
        Avoid obsolete sigstack when POSIX sigaltstack is available:
        * src/m4.c: Blindly assume signal.h, since stackovf.c and gnulib
        do likewise.
        * configure.ac (AC_CHECK_HEADERS): Likewise.
        (AC_CHECK_TYPES): New check for siginfo_t, since siginfo.h is
        obsolete and most hosts now have it in signal.h.
        (AC_CHECK_MEMBERS): New check for sigaction.sa_sigaction.
        (AC_CACHE_CHECK): Cache decision to use stackovf.
        (AC_EGREP_HEADER): Switch to AC_CHECK_TYPES.
        * src/stackovf.c (DEBUG_STACKOVF): Remove unused define.
        (SA_RESETHAND, SA_SIGINFO): Provide fallback definitions, to
        simplify later code.
        (PARAM_STACKOVF, PARAM_NOSTACKOVF): Move further away from NULL,
        in case of dereferencing a member of a NULL pointer.
        (sigsegv_handler) [HAVE_STRUCT_SIGACTION_SA_SIGACTION]: Define a
        POSIX handler.
        (setup_stackovf_trap): Use NULL instead of 0 for pointers, use
        EXIT_FAILURE in error, indent preprocessor directives.
        [HAVE_SIGALTSTACK && HAVE_SIGINFO_T]: Depend on siginfo_t, not
        siginfo.h.
        [HAVE_SIGACTION && defined SA_ONSTACK]: Prefer POSIX handler.
        Reported by Santiago Vila.

CVSWeb URLs:
http://cvs.savannah.gnu.org/viewcvs/m4/ChangeLog?cvsroot=m4&only_with_tag=branch-1_4&r1=1.1.1.1.2.76&r2=1.1.1.1.2.77
http://cvs.savannah.gnu.org/viewcvs/m4/configure.ac?cvsroot=m4&only_with_tag=branch-1_4&r1=1.36.2.14&r2=1.36.2.15
http://cvs.savannah.gnu.org/viewcvs/m4/src/m4.c?cvsroot=m4&only_with_tag=branch-1_4&r1=1.1.1.1.2.10&r2=1.1.1.1.2.11
http://cvs.savannah.gnu.org/viewcvs/m4/src/stackovf.c?cvsroot=m4&only_with_tag=branch-1_4&r1=1.1.1.1.2.1&r2=1.1.1.1.2.2