[libpng16] Allow unversioned links created on install to be disabled in

configure.  In configure builds 'make install' changes/adds links like png.h
and libpng.a to point to the newly installed, versioned, files (e.g.
libpng17/png.h and libpng17.a). Three new configure options and some
rearrangement of Makefile.am allow creation of these links to be disabled.

ANNOUNCE

@@ -1,5 +1,5 @@
 
-Libpng 1.6.9beta02 - December 29, 2013
+Libpng 1.6.9beta02 - December 30, 2013
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -42,7 +42,7 @@ Version 1.6.9beta01 [December 26, 2013]
   Rebuilt configure scripts with automake-1.14.1 and autoconf-2.69
     in the tar distributions.
 
-Version 1.6.9beta02 [December 29, 2013]
+Version 1.6.9beta02 [December 30, 2013]
   Added checks for libpng 1.5 to pngvalid.c.  This supports the use of
     this version of pngvalid in libpng 1.5
   Merged with pngvalid.c from libpng-1.7 changes to create a single
@@ -54,6 +54,11 @@ Version 1.6.9beta02 [December 29, 2013]
   Revised pngvalid.c to support libpng 1.5, which does not support the
     PNG_MAXIMUM_INFLATE_WINDOW option, so #define it out when appropriate in
     pngvalid.c
+  Allow unversioned links created on install to be disabled in configure.
+    In configure builds 'make install' changes/adds links like png.h
+    and libpng.a to point to the newly installed, versioned, files (e.g.
+    libpng17/png.h and libpng17.a). Three new configure options and some
+    rearrangement of Makefile.am allow creation of these links to be disabled.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

CHANGES

@@ -4767,7 +4767,7 @@ Version 1.6.9beta01 [December 26, 2013]
   Rebuilt configure scripts with automake-1.14.1 and autoconf-2.69
     in the tar distributions.
 
-Version 1.6.9beta02 [December 29, 2013]
+Version 1.6.9beta02 [December 30, 2013]
   Added checks for libpng 1.5 to pngvalid.c.  This supports the use of
     this version of pngvalid in libpng 1.5
   Merged with pngvalid.c from libpng-1.7 changes to create a single
@@ -4779,6 +4779,11 @@ Version 1.6.9beta02 [December 29, 2013]
   Revised pngvalid.c to support libpng 1.5, which does not support the
     PNG_MAXIMUM_INFLATE_WINDOW option, so #define it out when appropriate in
     pngvalid.c
+  Allow unversioned links created on install to be disabled in configure.
+    In configure builds 'make install' changes/adds links like png.h
+    and libpng.a to point to the newly installed, versioned, files (e.g.
+    libpng17/png.h and libpng17.a). Three new configure options and some
+    rearrangement of Makefile.am allow creation of these links to be disabled.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

Makefile.am

@@ -81,7 +81,7 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = png.c pngerror.c\
 	png.h pngconf.h pngdebug.h pnginfo.h pngpriv.h pngstruct.h pngusr.dfa
 
 if PNG_ARM_NEON
-  libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/arm_init.c\
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/arm_init.c\
 	arm/filter_neon.S arm/filter_neon_intrinsics.c
 endif
 
@@ -287,43 +287,74 @@ check: scripts/symbols.chk
 dist-hook:
 	cd '$(top_distdir)'; rm -f $(SCRIPT_CLEANFILES)
 
-# install the .../include headers as links to the new ones
+# Make links between installed files with release-specific names and the generic
-install-data-hook:
+# file names.  If this install rule is run the generic names will be deleted and
-	cd '$(DESTDIR)$(includedir)'; rm -f png.h pngconf.h pnglibconf.h
+# recreated - this has obvious issues for systems with multiple installations.
-	cd '$(DESTDIR)$(includedir)'; $(LN_S) $(PNGLIB_BASENAME)/png.h png.h
-	cd '$(DESTDIR)$(includedir)'; $(LN_S) $(PNGLIB_BASENAME)/pngconf.h \
-		pngconf.h
-	cd '$(DESTDIR)$(includedir)'; $(LN_S) $(PNGLIB_BASENAME)/pnglibconf.h \
-		pnglibconf.h
-	cd '$(DESTDIR)$(pkgconfigdir)'; rm -f libpng.pc
-	cd '$(DESTDIR)$(pkgconfigdir)'; $(LN_S) $(PNGLIB_BASENAME).pc libpng.pc
 
-# do evil things to libpng to cause libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@ to be used
+install-header-links:
-install-exec-hook:
+	@set -ex; cd '$(DESTDIR)$(includedir)'; for f in $(HEADERS); do \
-	cd '$(DESTDIR)$(bindir)'; rm -f libpng-config
+	   rm -f "$$f"; $(LN_S) "$(PNGLIB_BASENAME)/$$f" "$$f"; done
-	cd '$(DESTDIR)$(bindir)';\
+
-	   $(LN_S) $(PNGLIB_BASENAME)-config libpng-config
+uninstall-header-links:
-	@set -x;\
+	cd '$(DESTDIR)$(includedir)'; rm -f $(HEADERS)
-	cd '$(DESTDIR)$(libdir)';\
+
-	for ext in a la so so.@PNGLIB_MAJOR@@PNGLIB_MINOR@.@PNGLIB_RELEASE@\
+install-libpng-pc:
-	   sl dylib dll.a; do\
+	@set -ex; cd '$(DESTDIR)$(pkgconfigdir)'; rm -f libpng.pc; \
-		rm -f libpng.$$ext;\
+	   $(LN_S) '$(PNGLIB_BASENAME).pc' libpng.pc
-                if test -f $(PNGLIB_BASENAME).$$ext; then\
+
-                       $(LN_S) $(PNGLIB_BASENAME).$$ext libpng.$$ext;\
+uninstall-libpng-pc:
-                fi;\
+	rm -f '$(DESTDIR)$(pkgconfigdir)/libpng.pc'
+
+# EXT_LIST is a list of the possibly library directory extensions, this exists
+# because we can't find a good way of discovering the file extensions that are
+# actually installed on a given system, so instead we check for every extension
+# we have seen.
+
+EXT_LIST = a dll.a so so.@PNGLIB_MAJOR@@PNGLIB_MINOR@.@PNGLIB_RELEASE@ la sl dylib
+
+install-library-links:
+	@set -x; cd '$(DESTDIR)$(libdir)';\
+	for ext in $(EXT_LIST); do\
+	   rm -f "libpng.$$ext";\
+           if test -f "$(PNGLIB_BASENAME).$$ext"; then\
+              $(LN_S) "$(PNGLIB_BASENAME).$$ext" "libpng.$$ext" || exit 1;\
+           fi;\
 	done
 
-uninstall-hook:
+uninstall-library-links:
-	cd '$(DESTDIR)$(includedir)'; rm -f png.h pngconf.h pnglibconf.h
+	@set -x; cd '$(DESTDIR)$(libdir)'; for ext in $(EXT_LIST); do\
-	rm -f '$(DESTDIR)$(pkgconfigdir)/libpng.pc'
+	   rm -f "libpng.$$ext"; done
+
+install-libpng-config:
+	@set -ex; cd '$(DESTDIR)$(bindir)'; rm -f libpng-config; \
+	   $(LN_S) '$(PNGLIB_BASENAME)-config' libpng-config
+
+uninstall-libpng-config:
 	rm -f '$(DESTDIR)$(bindir)/libpng-config'
-	rm -f '$(DESTDIR)$(libdir)/libpng.a'
+
-	rm -f '$(DESTDIR)$(libdir)/libpng.la'
+if DO_INSTALL_LINKS
-	rm -f '$(DESTDIR)$(libdir)/libpng.so'
+# If --enable-unversioned-links is specified the header and lib file links
-	rm -f '$(DESTDIR)$(libdir)/libpng.so.@PNGLIB_MAJOR@@PNGLIB_MINOR@.@PNGLIB_RELEASE@'
+# will be automatically made on a 'make install':
-	rm -f '$(DESTDIR)$(libdir)/libpng.sl'
+
-	rm -f '$(DESTDIR)$(libdir)/libpng.dylib'
+install-data-hook: install-header-links
-	rm -f '$(DESTDIR)$(libdir)/libpng.dll.a'
+uninstall-hook: uninstall-header-links
+install-exec-hook: install-library-links
+uninstall-hook: uninstall-library-links
+endif
+
+if DO_INSTALL_LIBPNG_PC
+# Likewise, --install-pc causes libpng.pc to be constructed:
+
+install-data-hook: install-libpng-pc
+uninstall-hook: uninstall-libpng-pc
+endif
+
+if DO_INSTALL_LIBPNG_CONFIG
+# And --install-config:
+
+install-exec-hook: install-libpng-config
+uninstall-hook: uninstall-libpng-config
+endif
 
 # The following addition ensures that 'make all' always builds the test programs
 # too.  It used to, but some change either in libpng or configure stopped this

configure.ac

@@ -226,6 +226,45 @@ AC_ARG_WITH(libpng-prefix,
     fi])
 AM_CONDITIONAL([DO_PNG_PREFIX], [test "${with_libpng_prefix:-no}" != "no"])
 
+# Control over what links are made for installed files.  Versioned files are
+# always installed, when the following options are turned on corresponding
+# unversioned links are also created (normally as symbolic links):
+AC_ARG_ENABLE([unversioned-links],
+   AS_HELP_STRING([[[--enable-unversioned-links]]],
+      [Installed libpng header files are placed in a versioned subdirectory]
+      [and installed libpng library (including DLL) files are versioned.]
+      [If this option is enabled unversioned links will be created pointing to]
+      [the corresponding installed files.  If you use libpng.pc or]
+      [libpng-config for all builds you do not need these links, but if you]
+      [compile programs directly they will typically #include <png.h> and]
+      [link with -lpng; in that case you need the links.]
+      [The links can be installed manually using 'make install-header-links']
+      [and 'make install-library-links' and can be removed using the]
+      [corresponding uninstall- targets.  If you do enable this option every]
+      [libpng 'make install' will recreate the links to point to the just]
+      [installed version of libpng.  The default is to create the links;]
+      [use --disable-unversioned-links to change this]))
+
+# The AM_CONDITIONAL test is written so that the default is enabled;
+# --disable-unversioned-links must be given to turn the option off.
+AM_CONDITIONAL([DO_INSTALL_LINKS],[test "$enable_unversioned_links" != "no"])
+
+AC_ARG_ENABLE([unversioned-libpng-pc],
+   AS_HELP_STRING([[[--enable-unversioned-libpng-pc]]],
+      [Install the configuration file 'libpng.pc' as a link to the versioned]
+      [version.  This is done by default - use --disable-unversioned-libpng-pc]
+      [to change this.]))
+AM_CONDITIONAL([DO_INSTALL_LIBPNG_PC],
+   [test "$enable_unversioned_libpng_pc" != "no"])
+
+AC_ARG_ENABLE([unversioned-libpng-config],
+   AS_HELP_STRING([[[--enable-unversioned-libpng-config]]],
+      [Install the configuration file 'libpng-config' as a link to the]
+      [versioned version.  This is done by default - use]
+      [--disable-unversioned-libpng-config to change this.]))
+AM_CONDITIONAL([DO_INSTALL_LIBPNG_CONFIG],
+   [test "$enable_unversioned_libpng_config" != "no"])
+
 # HOST SPECIFIC OPTIONS
 # =====================
 #