[PATCH 4/9] dtas-tl prune: cull missing files from tracklist

[Eric Wong]

This helps for folks creating and replacing many throwaway files
while editing with dtas-splitfx, or compulsive renamers.
---
 Documentation/dtas-tl.pod |  4 ++-
 bin/dtas-tl               | 52 ++++++++++++++++++++++++---------------
 2 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/Documentation/dtas-tl.pod b/Documentation/dtas-tl.pod
index ac1b47d..b5a4b31 100644
--- a/Documentation/dtas-tl.pod
+++ b/Documentation/dtas-tl.pod
@@ -60,6 +60,8 @@ optionally seek to POS.  POS should be a timestamp in 
HH:MM:SS.FRAC format.
 
 =item prev - play the previous track in the tracklist
 
+=item prune - cull non-existent pathnames from the tracklist
+
 =item repeat 1 - repeat the current track
 
 =item repeat false - disable repeat
@@ -120,7 +122,7 @@ No subscription is necessary to post to the mailing list.
 
 =head1 COPYRIGHT
 
-Copyright 2013-2020 all contributors L<mailto:dtas-all@nongnu.org>
+Copyright all contributors L<mailto:dtas-all@nongnu.org>
 
 License: GPL-3.0+ L<https://www.gnu.org/licenses/gpl-3.0.txt>
 
diff --git a/bin/dtas-tl b/bin/dtas-tl
index 2b34937..767b02d 100755
--- a/bin/dtas-tl
+++ b/bin/dtas-tl
@@ -21,6 +21,18 @@ def fix_enc!(str, enc)
   str.force_encoding(Encoding::ASCII_8BIT) unless str.valid_encoding?
 end
 
+def each_track(c)
+  enc = Encoding.default_external
+  get_track_ids(c).each_slice(128) do |track_ids|
+    res = c.req("tl get #{track_ids.join(' ')}")
+    res = Shellwords.split(res.sub!(/\A\d+ /, ''))
+    while line = res.shift
+      fix_enc!(line, enc)
+      yield line
+    end
+  end
+end
+
 def do_edit(c)
   require 'dtas/edit_client'
   require 'tempfile'
@@ -30,19 +42,13 @@ def do_edit(c)
   tmp_path = tmp.path
   orig = []
   orig_idx = {}
-  enc = Encoding.default_external
 
-  get_track_ids(c).each_slice(128) do |track_ids|
-    res = c.req("tl get #{track_ids.join(' ')}")
-    res = Shellwords.split(res.sub!(/\A\d+ /, ''))
-    while line = res.shift
-      line.sub!(/\A(\d+)=/n, '') or abort "unexpected line=#{line.inspect}\n"
-      fix_enc!(line, enc)
-      track_id = $1.to_i
-      orig_idx[track_id] = orig.size
-      orig << track_id
-      tmp.write("#{Shellwords.escape(line)} =#{track_id}\n")
-    end
+  each_track(c) do |line|
+    line.sub!(/\A(\d+)=/n, '') or abort "unexpected line=#{line.inspect}\n"
+    track_id = $1.to_i
+    orig_idx[track_id] = orig.size
+    orig << track_id
+    tmp.write("#{Shellwords.escape(line)} =#{track_id}\n")
   end
   tmp.flush
 
@@ -139,15 +145,21 @@ def add_after(c, argv, last_id)
 
 c = DTAS::UNIXClient.new
 case cmd = ARGV[0]
-when "cat"
-  enc = Encoding.default_external
-  get_track_ids(c).each_slice(128) do |track_ids|
-    res = c.req("tl get #{track_ids.join(' ')}")
-    res = Shellwords.split(res.sub!(/\A\d+ /, ''))
-    while line = res.shift
-      fix_enc!(line, enc)
-      print "#{line}\n"
+when 'cat'
+  each_track(c) { |line| print "#{line}\n" }
+when 'prune'
+  each_track(c) do |line|
+    line.sub!(/\A(\d+)=/n, '') or abort "unexpected line=#{line.inspect}\n"
+    track_id = $1.to_i
+    ok = false
+    begin
+      st = File.stat(line)
+      ok = st.readable? && st.size?
+    rescue Errno::ENOENT, Errno::ENOTDIR, Errno::EACCES => e
+      warn "# #{line}: #{e.class}"
+      # raise other exceptions
     end
+    c.req("tl remove #{track_id}") unless ok
   end
 when 'aac' # add-after-current
   ARGV.shift