pg_waldump: Add support for archived WAL decoding.

pg_waldump can now accept the path to a tar archive containing WAL
files and decode them. This feature was added primarily for
pg_verifybackup, which previously disabled WAL parsing for
tar-formatted backups.

Note that this patch requires that the WAL files within the archive be
in sequential order; an error will be reported otherwise. The next
patch is planned to remove this restriction.

Author: amulsul

doc/src/sgml/ref/pg_waldump.sgml

@@ -141,13 +141,17 @@ PostgreSQL documentation
       <term><option>--path=<replaceable>path</replaceable></option></term>
       <listitem>
        <para>
-        Specifies a directory to search for WAL segment files or a
-        directory with a <literal>pg_wal</literal> subdirectory that
+        Specifies a tar archive or a directory to search for WAL segment files
+        or a directory with a <literal>pg_wal</literal> subdirectory that
         contains such files.  The default is to search in the current
         directory, the <literal>pg_wal</literal> subdirectory of the
         current directory, and the <literal>pg_wal</literal> subdirectory
         of <envar>PGDATA</envar>.
        </para>
+       <para>
+        If a tar archive is provided, its WAL segment files must be in
+        sequential order; otherwise, an error will be reported.
+       </para>
       </listitem>
      </varlistentry>
 

src/bin/pg_waldump/Makefile

@@ -3,20 +3,25 @@
 PGFILEDESC = "pg_waldump - decode and display WAL"
 PGAPPICON=win32
 
+# make these available to TAP test scripts
+export TAR
+
 subdir = src/bin/pg_waldump
 top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
 OBJS = \
 	$(RMGRDESCOBJS) \
 	$(WIN32RES) \
+	archive_waldump.o \
 	compat.o \
 	pg_waldump.o \
 	rmgrdesc.o \
 	xlogreader.o \
 	xlogstats.o
 
-override CPPFLAGS := -DFRONTEND $(CPPFLAGS)
+override CPPFLAGS := -DFRONTEND -I$(libpq_srcdir) $(CPPFLAGS)
+LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils
 
 RMGRDESCSOURCES = $(sort $(notdir $(wildcard $(top_srcdir)/src/backend/access/rmgrdesc/*desc*.c)))
 RMGRDESCOBJS = $(patsubst %.c,%.o,$(RMGRDESCSOURCES))