Add --with-nonshared-cflags option to configure

ChangeLog

@@ -1,3 +1,13 @@
+2018-08-16  Florian Weimer  <fweimer@redhat.com>
+
+	* configure.ac: Add --with-nonshared-cflags option.
+	* config.make.in (extra-nonshared-cflags): Set variable.
+	* Makeconfig (CFLAGS-.oS): Use it.
+	* manual/install.texi (Configuring and compiling): Document
+	--with-nonshared-cflags.
+	* configure: Regenerate.
+	* INSTALL: Likewise.
+
 2018-08-16  Florian Weimer  <fweimer@redhat.com>
 
 	* Makeconfig (ASFLAGS): Always append required assembler flags.

INSTALL

@@ -90,6 +90,22 @@ if 'CFLAGS' is specified it must enable optimization.  For example:
      library will still be usable, but functionality may be lost--for
      example, you can't build a shared libc with old binutils.
 
+'--with-nonshared-cflags=CFLAGS'
+     Use additional compiler flags CFLAGS to build the parts of the
+     library which are always statically linked into applications and
+     libraries even with shared linking (that is, the object files
+     contained in 'lib*_nonshared.a' libraries).  The build process will
+     automatically use the appropriate flags, but this option can be
+     used to set additional flags required for building applications and
+     libraries, to match local policy.  For example, if such a policy
+     requires that all code linked into applications must be built with
+     source fortification,
+     '--with-nonshared-cflags=-Wp,-D_FORTIFY_SOURCE=2' will make sure
+     that the objects in 'libc_nonshared.a' are compiled with this flag
+     (although this will not affect the generated code in this
+     particular case and potentially change debugging information and
+     metadata only).
+
 '--disable-shared'
      Don't build shared libraries even if it is possible.  Not all
      systems support shared libraries; you need ELF support and

Makeconfig

@@ -1038,7 +1038,7 @@ object-suffixes-for-libc += .oS
 # Must build the routines as PIC, though, because they can end up in (users')
 # shared objects.  We don't want to use CFLAGS-os because users may, for
 # example, make that processor-specific.
-CFLAGS-.oS = $(CFLAGS-.o) $(PIC-ccflag)
+CFLAGS-.oS = $(CFLAGS-.o) $(PIC-ccflag) $(extra-nonshared-cflags)
 CPPFLAGS-.oS = $(CPPFLAGS-.o) -DPIC -DLIBC_NONSHARED=1
 libtype.oS = lib%_nonshared.a
 endif

config.make.in

@@ -110,6 +110,7 @@ BUILD_CC = @BUILD_CC@
 CFLAGS = @CFLAGS@
 CPPFLAGS-config = @CPPFLAGS@
 CPPUNDEFS = @CPPUNDEFS@
+extra-nonshared-cflags = @extra_nonshared_cflags@
 ASFLAGS-config = @ASFLAGS_config@
 AR = @AR@
 NM = @NM@

configure

@@ -684,6 +684,7 @@ force_install
 bindnow
 hardcoded_path_in_tests
 enable_timezone_tools
+extra_nonshared_cflags
 use_default_link
 sysheaders
 ac_ct_CXX
@@ -762,6 +763,7 @@ with_binutils
 with_selinux
 with_headers
 with_default_link
+with_nonshared_cflags
 enable_sanity_checks
 enable_shared
 enable_profile
@@ -1482,6 +1484,8 @@ Optional Packages:
   --with-headers=PATH     location of system headers to use (for example
                           /usr/src/linux/include) [default=compiler default]
   --with-default-link     do not use explicit linker scripts
+  --with-nonshared-cflags=CFLAGS
+                          build nonshared libraries with additional CFLAGS
   --with-cpu=CPU          select code for CPU variant
 
 Some influential environment variables:
@@ -3339,6 +3343,16 @@ else
 fi
 
 
+
+# Check whether --with-nonshared-cflags was given.
+if test "${with_nonshared_cflags+set}" = set; then :
+  withval=$with_nonshared_cflags; extra_nonshared_cflags=$withval
+else
+  extra_nonshared_cflags=
+fi
+
+
+
 # Check whether --enable-sanity-checks was given.
 if test "${enable_sanity_checks+set}" = set; then :
   enableval=$enable_sanity_checks; enable_sanity=$enableval

configure.ac

@@ -154,6 +154,14 @@ AC_ARG_WITH([default-link],
 	    [use_default_link=$withval],
 	    [use_default_link=default])
 
+dnl Additional build flags injection.
+AC_ARG_WITH([nonshared-cflags],
+	    AC_HELP_STRING([--with-nonshared-cflags=CFLAGS],
+			   [build nonshared libraries with additional CFLAGS]),
+	    [extra_nonshared_cflags=$withval],
+	    [extra_nonshared_cflags=])
+AC_SUBST(extra_nonshared_cflags)
+
 AC_ARG_ENABLE([sanity-checks],
 	      AC_HELP_STRING([--disable-sanity-checks],
 			     [really do not use threads (should not be used except in special situations) @<:@default=yes@:>@]),

manual/install.texi

@@ -117,6 +117,20 @@ problem and suppress these constructs, so that the library will still be
 usable, but functionality may be lost---for example, you can't build a
 shared libc with old binutils.
 
+@item --with-nonshared-cflags=@var{cflags}
+Use additional compiler flags @var{cflags} to build the parts of the
+library which are always statically linked into applications and
+libraries even with shared linking (that is, the object files contained
+in @file{lib*_nonshared.a} libraries).  The build process will
+automatically use the appropriate flags, but this option can be used to
+set additional flags required for building applications and libraries,
+to match local policy.  For example, if such a policy requires that all
+code linked into applications must be built with source fortification,
+@samp{--with-nonshared-cflags=-Wp,-D_FORTIFY_SOURCE=2} will make sure
+that the objects in @file{libc_nonshared.a} are compiled with this flag
+(although this will not affect the generated code in this particular
+case and potentially change debugging information and metadata only).
+
 @c disable static doesn't work currently
 @c @item --disable-static
 @c Don't build static libraries.  Static libraries aren't that useful these