Move wchar.c and encnames.c to src/common/.

Formerly, various frontend directories symlinked these two sources
and then built them locally.  That's an ancient, ugly hack, and
we now have a much better way: put them into libpgcommon.
So do that.  (The immediate motivation for this is the prospect
of having to introduce still more symlinking if we don't.)

This commit moves these two files absolutely verbatim, for ease of
reviewing the git history.  There's some follow-on work to be done
that will modify them a bit.

Robert Haas, Tom Lane

Discussion: https://postgr.es/m/CA+TgmoYO8oq-iy8E02rD8eX25T-9SmyxKWqqks5OMHxKvGXpXQ@mail.gmail.com

src/backend/utils/mb/Makefile

@@ -14,10 +14,8 @@ include $(top_builddir)/src/Makefile.global
 
 OBJS = \
 	conv.o \
-	encnames.o \
 	mbutils.o \
 	stringinfo_mb.o \
-	wchar.o \
 	wstrcmp.o \
 	wstrncmp.o
 

src/backend/utils/mb/README

@@ -3,12 +3,8 @@ src/backend/utils/mb/README
 Encodings
 =========
 
-encnames.c:	public functions for both the backend and the frontend.
 conv.c:		static functions and a public table for code conversion
-wchar.c:	mostly static functions and a public table for mb string and
-		multibyte conversion
 mbutils.c:	public functions for the backend only.
-		requires conv.c and wchar.c
 stringinfo_mb.c: public backend-only multibyte-aware stringinfo functions
 wstrcmp.c:	strcmp for mb
 wstrncmp.c:	strncmp for mb
@@ -16,6 +12,12 @@ win866.c:	a tool to generate KOI8 <--> CP866 conversion table
 iso.c:		a tool to generate KOI8 <--> ISO8859-5 conversion table
 win1251.c:	a tool to generate KOI8 <--> CP1251 conversion table
 
+See also in src/common/:
+
+encnames.c:	public functions for encoding names
+wchar.c:	mostly static functions and a public table for mb string and
+		multibyte conversion
+
 Introduction
 ------------
 	http://www.cprogramming.com/tutorial/unicode.html

src/bin/initdb/.gitignore

@@ -1,4 +1,3 @@
-/encnames.c
 /localtime.c
 
 /initdb

src/bin/initdb/Makefile

@@ -18,7 +18,12 @@ include $(top_builddir)/src/Makefile.global
 
 override CPPFLAGS := -DFRONTEND -I$(libpq_srcdir) -I$(top_srcdir)/src/timezone $(CPPFLAGS)
 
-# note: we need libpq only because fe_utils does
+# Note: it's important that we link to encnames.o from libpgcommon, not
+# from libpq, else we have risks of version skew if we run with a libpq
+# shared library from a different PG version.  The libpq_pgport macro
+# should ensure that that happens.
+#
+# We need libpq only because fe_utils does.
 LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport)
 
 # use system timezone data?
@@ -28,7 +33,6 @@ endif
 
 OBJS = \
 	$(WIN32RES) \
-	encnames.o \
 	findtimezone.o \
 	initdb.o \
 	localtime.o
@@ -38,15 +42,7 @@ all: initdb
 initdb: $(OBJS) | submake-libpq submake-libpgport submake-libpgfeutils
 	$(CC) $(CFLAGS) $(OBJS) $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@$(X)
 
-# We used to pull in all of libpq to get encnames.c, but that
-# exposes us to risks of version skew if we link to a shared library.
-# Do it the hard way, instead, so that we're statically linked.
-
-encnames.c: % : $(top_srcdir)/src/backend/utils/mb/%
-	rm -f $@ && $(LN_S) $< .
-
-# Likewise, pull in localtime.c from src/timezones
-
+# We must pull in localtime.c from src/timezones
 localtime.c: % : $(top_srcdir)/src/timezone/%
 	rm -f $@ && $(LN_S) $< .
 
@@ -60,7 +56,7 @@ uninstall:
 	rm -f '$(DESTDIR)$(bindir)/initdb$(X)'
 
 clean distclean maintainer-clean:
-	rm -f initdb$(X) $(OBJS) encnames.c localtime.c
+	rm -f initdb$(X) $(OBJS) localtime.c
 	rm -rf tmp_check
 
 # ensure that changes in datadir propagate into object file

src/common/Makefile

@@ -51,6 +51,7 @@ OBJS_COMMON = \
 	config_info.o \
 	controldata_utils.o \
 	d2s.o \
+	encnames.o \
 	exec.o \
 	f2s.o \
 	file_perm.o \
@@ -70,7 +71,8 @@ OBJS_COMMON = \
 	stringinfo.o \
 	unicode_norm.o \
 	username.o \
-	wait_error.o
+	wait_error.o \
+	wchar.o
 
 ifeq ($(with_openssl),yes)
 OBJS_COMMON += sha2_openssl.o

src/common/saslprep.c

@@ -27,12 +27,6 @@
 
 #include "common/saslprep.h"
 #include "common/unicode_norm.h"
-
-/*
- * Note: The functions in this file depend on functions from
- * src/backend/utils/mb/wchar.c, so in order to use this in frontend
- * code, you will need to link that in, too.
- */
 #include "mb/pg_wchar.h"
 
 /*

src/include/mb/pg_wchar.h

@@ -222,8 +222,8 @@ typedef unsigned int pg_wchar;
  * PostgreSQL encoding identifiers
  *
  * WARNING: the order of this enum must be same as order of entries
- *			in the pg_enc2name_tbl[] array (in mb/encnames.c), and
- *			in the pg_wchar_table[] array (in mb/wchar.c)!
+ *			in the pg_enc2name_tbl[] array (in src/common/encnames.c), and
+ *			in the pg_wchar_table[] array (in src/common/wchar.c)!
  *
  *			If you add some encoding don't forget to check
  *			PG_ENCODING_BE_LAST macro.

src/interfaces/libpq/.gitignore

@@ -1,4 +1 @@
 /exports.list
-# .c files that are symlinked in from elsewhere
-/encnames.c
-/wchar.c

src/interfaces/libpq/Makefile

@@ -45,11 +45,6 @@ OBJS = \
 	pqexpbuffer.o \
 	fe-auth.o
 
-# src/backend/utils/mb
-OBJS += \
-	encnames.o \
-	wchar.o
-
 ifeq ($(with_openssl),yes)
 OBJS += \
 	fe-secure-common.o \
@@ -102,17 +97,7 @@ include $(top_srcdir)/src/Makefile.shlib
 backend_src = $(top_srcdir)/src/backend
 
 
-# We use a few backend modules verbatim, but since we need
-# to compile with appropriate options to build a shared lib, we can't
-# use the same object files built for the backend.
-# Instead, symlink the source files in here and build our own object files.
-# When you add a file here, remember to add it in the "clean" target below.
-
-encnames.c wchar.c: % : $(backend_src)/utils/mb/%
-	rm -f $@ && $(LN_S) $< .
-
-
-# Make dependencies on pg_config_paths.h visible, too.
+# Make dependencies on pg_config_paths.h visible in all builds.
 fe-connect.o: fe-connect.c $(top_builddir)/src/port/pg_config_paths.h
 fe-misc.o: fe-misc.c $(top_builddir)/src/port/pg_config_paths.h
 
@@ -144,8 +129,6 @@ clean distclean: clean-lib
 	rm -f $(OBJS) pthread.h
 # Might be left over from a Win32 client-only build
 	rm -f pg_config_paths.h
-# Remove files we (may have) symlinked in from other places
-	rm -f encnames.c wchar.c
 
 maintainer-clean: distclean
 	$(MAKE) -C test $@

src/tools/msvc/Mkvcbuild.pm

@@ -120,11 +120,12 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c exec.c f2s.c file_perm.c ip.c
+	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
+	  f2s.c file_perm.c ip.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
-	  wait_error.c);
+	  wait_error.c wchar.c);
 
 	if ($solution->{options}->{openssl})
 	{