Fix problem generating file names in send-to-device and possibly save-to-disk. The original code assumed that the last component always had an extension, which isn't true when evaluating templates to generate a file name. If the resulting string was too long and if last segment of the string contained a period then the remainder of the string after the period was assumed to be an extension. If that remainder was longer than permitted, shorten_components_to generated a path consisting of a single letter.

Example: if the template generated this string:
"Some of the Best From Tor.com, 2013 Edition_ A Tor.Com Original - A. B. C. Personn & Aa Angstrom & Anne McCaffrey & Banks, Iain M & Bruce Sterling & Cajkovskij, Petr Ilic & Chacko, David & Charlie Huston & Collins, Wilkie & D'Ansey, Leigh & Dahl, Roland & Edward Elmer _Doc_ Smith & Eric Flint & George Charon & Jules Verne (1422)"
then the "extension" was everything after the A. B. C., with a length that can easily exceed the max path len.

src/calibre/devices/smart_device_app/driver.py

@@ -453,7 +453,8 @@ class SMART_DEVICE_APP(DeviceConfig, DevicePlugin):
         app_id = str(getattr(mdata, 'application_id', ''))
         id_ = mdata.get('id', fname)
         extra_components = get_components(template, mdata, id_,
-                timefmt=opts.send_timefmt, length=maxlen-len(app_id)-1)
+                timefmt=opts.send_timefmt, length=maxlen-len(app_id)-1,
+                last_has_extension=False)
         if not extra_components:
             extra_components.append(sanitize(fname))
         else:

src/calibre/devices/utils.py

@@ -100,7 +100,7 @@ def create_upload_path(mdata, fname, template, sanitize,
     id_ = mdata.get('id', fname)
     extra_components = get_components(template, mdata, id_,
             timefmt=opts.send_timefmt, length=maxlen-len(app_id)-1,
-            sanitize_func=sanitize)
+            sanitize_func=sanitize, last_has_extension=False)
     if not extra_components:
         extra_components.append(sanitize(filename_callback(fname,
             mdata)))

src/calibre/library/save_to_disk.py

@@ -169,7 +169,7 @@ class Formatter(TemplateFormatter):
 
 def get_components(template, mi, id, timefmt='%b %Y', length=250,
         sanitize_func=ascii_filename, replace_whitespace=False,
-        to_lowercase=False, safe_format=True):
+        to_lowercase=False, safe_format=True, last_has_extension=True):
 
     tsorder = tweaks['save_template_title_series_sorting']
     format_args = FORMAT_ARGS.copy()
@@ -248,7 +248,7 @@ def get_components(template, mi, id, timefmt='%b %Y', length=250,
     if replace_whitespace:
         components = [re.sub(r'\s', '_', x) for x in components]
 
-    return shorten_components_to(length, components)
+    return shorten_components_to(length, components, last_has_extension=last_has_extension)
 
 
 def save_book_to_disk(id_, db, root, opts, length):
@@ -286,7 +286,8 @@ def get_path_components(opts, mi, book_id, path_length):
         components = get_components(opts.template, mi, book_id, opts.timefmt, path_length,
             ascii_filename if opts.asciiize else sanitize_file_name_unicode,
             to_lowercase=opts.to_lowercase,
-            replace_whitespace=opts.replace_whitespace, safe_format=False)
+            replace_whitespace=opts.replace_whitespace, safe_format=False,
+            last_has_extension=False)
     except Exception, e:
         raise ValueError(_('Failed to calculate path for '
             'save to disk. Template: %(templ)s\n'

src/calibre/utils/filenames.py

@@ -52,7 +52,7 @@ def shorten_component(s, by_what):
         return s
     return s[:l] + s[-l:]
 
-def shorten_components_to(length, components, more_to_take=0):
+def shorten_components_to(length, components, more_to_take=0, last_has_extension=True):
     filepath = os.sep.join(components)
     extra = len(filepath) - (length - more_to_take)
     if extra < 1:
@@ -68,7 +68,7 @@ def shorten_components_to(length, components, more_to_take=0):
         if delta > len(x):
             r = x[0] if x is components[-1] else ''
         else:
-            if x is components[-1]:
+            if last_has_extension and x is components[-1]:
                 b, e = os.path.splitext(x)
                 if e == '.':
                     e = ''