From d5021abc07a20689a582940ec50178f64e4d4d24 Mon Sep 17 00:00:00 2001
From: Milian Wolff <mail@milianw.de>
Date: Mon, 13 Nov 2017 15:14:57 +0100
Subject: [PATCH] Add --xdev capability to files.pl

This allows one to easily grasp the file sizes on a given mount point.
E.g. on my laptop, I'm running out of disk space on my root partition.
Now I can run the following command to easily find large files:

sudo files.pl --xdev / | flamegraph.pl > /tmp/out.svg

Previously, I'd have to find a custom whitelist of folders in / to
pass to `files.pl` explicitly.
---
 files.pl | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/files.pl b/files.pl
index 27654be6..50426b2e 100755
--- a/files.pl
+++ b/files.pl
@@ -16,25 +16,44 @@
 use File::Find;
 
 sub usage {
-	print STDERR "USAGE: $0 directory\n";
+	print STDERR "USAGE: $0 [--xdev] [DIRECTORY]...\n";
 	print STDERR "   eg, $0 /Users\n";
+	print STDERR "   To not descend directories on other filesystems:";
+	print STDERR "   eg, $0 --xdev /\n";
 	print STDERR "Intended to be piped to flamegraph.pl. Full example:\n";
 	print STDERR "   $0 /Users | flamegraph.pl " .
 	    "--hash --countname=bytes > files.svg\n";
 	print STDERR "   $0 /usr /home /root /etc | flamegraph.pl " .
 	    "--hash --countname=bytes > files.svg\n";
+	print STDERR "   $0 --xdev / | flamegraph.pl " .
+	    "--hash --countname=bytes > files.svg\n";
 	exit 1;
 }
 
 usage() if @ARGV == 0 or $ARGV[0] eq "--help" or $ARGV[0] eq "-h";
 
+my $filter_xdev = 0;
+my $xdev_id;
+
 foreach my $dir (@ARGV) {
-    find(\&wanted, $dir);
+	if ($dir eq "--xdev") {
+	    $filter_xdev = 1;
+	} else {
+	    find(\&wanted, $dir);
+	}
 }
 
 sub wanted {
 	my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size) = lstat($_);
 	return unless defined $size;
+	if ($filter_xdev) {
+		if (!$xdev_id) {
+			$xdev_id = $dev;
+		} elsif ($xdev_id ne $dev) {
+			$File::Find::prune = 1;
+			return;
+		}
+	}
 	my $path = $File::Find::name;
 	$path =~ tr/\//;/;		# delimiter
 	$path =~ tr/;.a-zA-Z0-9-/_/c;	# ditch whitespace and other chars