From 1775e74030da0071f8c49b60d076afdea06a8cd6 Mon Sep 17 00:00:00 2001
From: Matthijs Kooijman <matthijs@stdin.nl>
Date: Thu, 1 Jan 2009 15:02:23 +0100
Subject: [PATCH] tools: Add a interpolate function that can interpolate %
 variables into a path.

This allows handlers to turn a single path configuration variable into
different paths, based on the vserver used.
---
 lib/tools.in   | 43 +++++++++++++++++++++++++++++++++++++++++++
 man/backup.d.5 | 29 +++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/lib/tools.in b/lib/tools.in
index 0005be9..fe7d54a 100644
--- a/lib/tools.in
+++ b/lib/tools.in
@@ -46,3 +46,46 @@ function getconf() {
 	# because it is in an 'eval' statement.
 	eval $1='$ret'
 }
+
+#
+# Replaces escape sequences in $1 with the proper values for the vserver $2.
+# The result is put on stdout.  If $2 is empty, values for the host are
+# replaced. The following values are replaced:
+#
+# %%  Literal %
+# %h  The short hostname (as returned by hostname -s)
+# %H  The full hostname (as returned by hostname --fqdn)
+# %n  The vserver name, or empty for the host
+# %N  The vserver name, or "host" for the host
+# %v  The vserver root directory, or empty for the host
+#
+# Note that the given vserver must be running!
+#
+function interpolate() {
+	path=$1
+	vsname=$2
+	vexec=${vsname:+$VSERVER $vsname exec }
+	# Find the values to replace
+	h=`$vexec hostname -s`
+	H=`$vexec hostname --fqdn`
+	n=$vsname
+	N=${vsname:-host}
+	v=${vsname:+$VROOTDIR/$vsname}
+
+	expr=''
+	for var in h H n N v; do
+		# Do indirect lookup of the value to replace
+		val=${!var}
+		# Escape slashes (twice, bash seems to eat one somewhere)
+		val=`echo "$val" | sed 's#/#\\\\/#g'`
+		# Add replacement pattern. The first part checks that there is
+		# an odd number of percent signs before the variable, so
+		# double % is properly left alone.
+		expr="${expr}s/\(\(^\|[^%]\)\(%%\)*\)%$var/\1$val/g;"
+	done
+	# Finally replace literal % signs
+	expr="${expr}s/%%/%/g"
+
+	# Do the actual interpolation
+	echo $path | sed "$expr"
+}
diff --git a/man/backup.d.5 b/man/backup.d.5
index 5090051..80f0ce8 100644
--- a/man/backup.d.5
+++ b/man/backup.d.5
@@ -97,6 +97,35 @@ The file format of the action configuration files is "ini style." Sections are c
    pear = no thanks \\
    i will not have a pear.
 
+.SH INTERPOLATION
+
+Some handlers will support path interpolation for some of their configuration variables. Interpolation allows you to give a config variable a different value, depending on the host or vserver it is used in. See the documentation for each handler for which variables are interpolated.
+
+The following interpolation variables are available:
+
+.IP %h
+The short hostname (output of `hostname -s`).
+
+.IP %h
+The full hostname (output of `hostname --fqdn`).
+
+.IP %n
+The name of the vserver running in, or the empty string when running on the host.
+
+.IP %N
+The name of the vserver running in, or "host" when running on the host.
+
+.IP %v
+The root direcotry of the vserver running in, or the empty string when running on the host.  
+
+.IP %%
+A literal %.
+
+For example, the following would backup the foo and bar vservers to /var/backups/foo and /var/backups/bar respectively.
+
+   backupdir = /var/backups/%n
+   vsnames   = foo bar
+
 .SH SEE ALSO
 .BR backupninja (1), 
 .BR ninjahelper (1), 
-- 
2.30.2