Limit length of filenames

[fiete201]

I recently bought some CDs with Music from the Barock age. Those have sometimes Track names longer than 255 chars resulting in ripping Error MAX_RETRIES since file cant be written because in ext4 Filesystems 255 is the maximum length for filenames.

It would be nice to just cut off the track name or give an additional option to limit the length of the filename.

Thanks and best regards
Fritz

[RecursiveForest]

I think this is a good idea, we should automatically truncate track names to the filesystem length limit. I'll have to check what the most pythonic & portable way to inherit this limit from the OS is.

[JoeLametta]

I'll have to check what the most pythonic & portable way to inherit this limit from the OS is.

What about something like this? (using PC_NAME_MAX and PC_PATH_MAX as name arguments).
For example we can define a function which takes two arguments (filename, fullpath) and checks if both are within the aforementioned limits.

from os import pathconf


def check_path_limits(filename, fullpath):
    """Return true if both the lengths of the filename and fullpath arguments
    are within the limits provided by the OS, false otherwise.
    """
    flen_limit = pathconf(fullpath, 'PC_NAME_MAX')
    plen_limit = pathconf(fullpath, 'PC_PATH_MAX')
    return len(filename) < flen_limit and len(fullpath) < plen_limit

[JoeLametta]

@RecursiveForest What about this? (it only truncates filenames)

from os import pathconf


def truncate_filename(filename, extension, path):
    """Truncate filename to the max. len. allowed by the path's filesystem"""
    fn_lim = pathconf(path, 'PC_NAME_MAX')
    length = fn_lim - len(extension)
    return filename[:length]

It should be portable enough.

Availability: Unix.

[JoeLametta]

Completely untested patch:

From: JoeLametta <JoeLametta@users.noreply.github.com>
Date: Wed, 20 Jun 2018 08:00:00 +0000
Subject: [PATCH] Truncate filenames longer than filesystem's limit

---
 whipper/common/common.py      |  7 +++++++
 whipper/common/program.py     | 12 +++++++++---
 whipper/program/cdparanoia.py |  4 ++++
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/whipper/common/common.py b/whipper/common/common.py
index c8aefd4..ff23f50 100644
--- a/whipper/common/common.py
+++ b/whipper/common/common.py
@@ -153,6 +153,13 @@ class MissingFrames(Exception):
     pass
 
 
+def truncate_filename(path, filename, extension):
+    """Truncate filename to the max. len. allowed by the path's filesystem"""
+    fn_lim = os.pathconf(path, 'PC_NAME_MAX')
+    length = fn_lim - len(extension)
+    return filename[:length] + extension
+
+
 def shrinkPath(path):
     """
     Shrink a full path to a shorter version.
diff --git a/whipper/common/program.py b/whipper/common/program.py
index c16a660..f0297ec 100644
--- a/whipper/common/program.py
+++ b/whipper/common/program.py
@@ -571,7 +571,9 @@ class Program:
         return accurip.verify_result(self.result, responses, checksums)
 
     def write_m3u(self, discname):
-        m3uPath = u'%s.m3u' % discname
+        p, f = os.path.split(os.path.normpath(discname))
+        safe_name = common.truncate_filename(p, f, '.m3u')
+        m3uPath = os.path.join(p, safe_name)
         with open(m3uPath, 'w') as f:
             f.write(u'#EXTM3U\n'.encode('utf-8'))
             for track in self.result.tracks:
@@ -593,7 +595,9 @@ class Program:
 
     def writeCue(self, discName):
         assert self.result.table.canCue()
-        cuePath = '%s.cue' % discName
+        p, f = os.path.split(os.path.normpath(discName))
+        safe_name = common.truncate_filename(p, f, '.cue')
+        cuePath = os.path.join(p, safe_name)
         logger.debug('write .cue file to %s', cuePath)
         handle = open(cuePath, 'w')
         # FIXME: do we always want utf-8 ?
@@ -605,7 +609,9 @@ class Program:
         return cuePath
 
     def writeLog(self, discName, logger):
-        logPath = '%s.log' % discName
+        p, f = os.path.split(os.path.normpath(discName))
+        safe_name = common.truncate_filename(p, f, '.log')
+        logPath = os.path.join(p, safe_name)
         handle = open(logPath, 'w')
         log = logger.log(self.result)
         handle.write(log.encode('utf-8'))
diff --git a/whipper/program/cdparanoia.py b/whipper/program/cdparanoia.py
index 3163dc7..39cc8fc 100644
--- a/whipper/program/cdparanoia.py
+++ b/whipper/program/cdparanoia.py
@@ -482,6 +482,10 @@ class ReadVerifyTrackTask(task.MultiSeparateTask):
             if errno.ENAMETOOLONG != e.errno:
                 raise
             path = common.shrinkPath(path)
+            p, f = os.path.split(os.path.normpath(path))
+            f, e = os.path.splitext(f)
+            safe_name = common.truncate_filename(p, f, e)
+            path = os.path.join(p, safe_name)
             tmpoutpath = path + u'.part'
             open(tmpoutpath, 'wb').close()
         self._tmppath = tmpoutpath