1 files changed, 96 insertions, 0 deletions
diff --git a/pg_getwal b/pg_getwal
new file mode 100755
index 0000000..8e64e87
--- /dev/null
+++ b/pg_getwal
@@ -0,0 +1,96 @@
+#!/bin/sh
+
+# retrieve a WAL file from a pg_receivewal archive
+#
+# Copyright (C) 2021-2022 Christoph Berg <myon@debian.org>
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+
+set -eu
+
+binroot="/usr/lib/postgresql/"
+#redhat# binroot="/usr/pgsql-"
+
+if [ -z "${2:-}" ]; then
+    echo "Syntax: $0 /path/to/wal/%f %p" >&2
+    exit 1
+fi
+
+file="$1"
+path="$2"
+
+# sanity-check the first argument
+waldir="$(dirname $file)"
+if ! [ -d "$waldir" ]; then
+    echo "$0: $waldir is not a directory" >&2
+    exit 129
+fi
+
+if [ -f "$file.gz" ]; then
+    gunzip < "$file.gz" > "$path" || exit 129
+
+elif [ -f "$file.lz4" ]; then
+    unlz4 < "$file.lz4" > "$path" || exit 129
+
+elif [ -f "$file" ]; then
+    cp "$file" "$path" || exit 129
+
+elif [ -f "$file.gz.partial" ] || [ -f "$file.lz4.partial" ]; then
+    if [ -s "$file.gz.partial" ]; then
+        gunzip < "$file.gz.partial" > "$path" || exit 129
+    elif [ -s "$file.lz4.partial" ]; then
+        unlz4 < "$file.lz4.partial" > "$path" || exit 129
+    else
+        # .gz.partial starts completely empty, gunzip doesn't like that
+        touch "$path" || exit 129
+    fi
+
+    # expand file to original size
+    version=$(cat PG_VERSION) || exit 129
+    wal_file_size=$(LC_ALL=C "$binroot$version/bin/pg_controldata" . | awk '/^Bytes per WAL segment:/ { print $5 }') || exit 129
+    [ "$wal_file_size" -gt 0 ] || exit 129
+    truncate --size="$wal_file_size" "$path" || exit 129
+
+elif [ -f "$file.partial" ]; then
+    cp "$file.partial" "$path" || exit 129
+
+else
+    # file not found, exit silently in order not to spam the server log with errors
+    exit 1
+fi
+
+exit 0
+
+: <<=cut
+
+=head1 NAME
+
+pg_getwal - retrieve a WAL file from a pg_receivewal archive
+
+=head1 SYNOPSIS
+
+B<pg_getwal> I</path/to/wal/%f> I<%p>
+
+=head1 DESCRIPTION
+
+B<pg_getwal> retrieves and decompresses files from a WAL archive maintained by
+B<pg_receivewal> and B<pg_backupcluster>. It is put into PostgreSQL's
+B<restore_command> by B<pg_restorecluster>.
+
+=head1 SEE ALSO
+
+L<pg_restorecluster(1)>, L<pg_backupcluster(1)>.
+
+=head1 AUTHOR
+
+Christoph Berg L<E<lt>myon@debian.orgE<gt>>
+
+=cut