summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorSerhiy Storchaka <storchaka@gmail.com>2013-02-10 12:31:07 (GMT)
committerSerhiy Storchaka <storchaka@gmail.com>2013-02-10 12:31:07 (GMT)
commit9fef188c9eea428a28e108c4ab6966c6c19a097a (patch)
tree8129ca8bb4e0d06bf44ac9eb2ae8bfc230fc97b1
parentd83c82440b85faa6aefdf56fce25f285d8164bb7 (diff)
parent88efc52d7451ab648c9659e6be47cee34bf0ce43 (diff)
downloadcpython-9fef188c9eea428a28e108c4ab6966c6c19a097a.zip
cpython-9fef188c9eea428a28e108c4ab6966c6c19a097a.tar.gz
cpython-9fef188c9eea428a28e108c4ab6966c6c19a097a.tar.bz2
Issue #1470548: XMLGenerator now works with binary output streams.
-rw-r--r--Lib/test/test_sax.py215
-rw-r--r--Lib/xml/sax/saxutils.py67
-rw-r--r--Misc/NEWS2
3 files changed, 192 insertions, 92 deletions
diff --git a/Lib/test/test_sax.py b/Lib/test/test_sax.py
index 968ffca..98cc58e 100644
--- a/Lib/test/test_sax.py
+++ b/Lib/test/test_sax.py
@@ -13,7 +13,7 @@ from xml.sax.saxutils import XMLGenerator, escape, unescape, quoteattr, \
from xml.sax.expatreader import create_parser
from xml.sax.handler import feature_namespaces
from xml.sax.xmlreader import InputSource, AttributesImpl, AttributesNSImpl
-from io import StringIO
+from io import BytesIO, StringIO
import os.path
import shutil
from test import support
@@ -173,31 +173,29 @@ class SaxutilsTest(unittest.TestCase):
# ===== XMLGenerator
-start = '<?xml version="1.0" encoding="iso-8859-1"?>\n'
-
-class XmlgenTest(unittest.TestCase):
+class XmlgenTest:
def test_xmlgen_basic(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result)
gen.startDocument()
gen.startElement("doc", {})
gen.endElement("doc")
gen.endDocument()
- self.assertEqual(result.getvalue(), start + "<doc></doc>")
+ self.assertEqual(result.getvalue(), self.xml("<doc></doc>"))
def test_xmlgen_basic_empty(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result, short_empty_elements=True)
gen.startDocument()
gen.startElement("doc", {})
gen.endElement("doc")
gen.endDocument()
- self.assertEqual(result.getvalue(), start + "<doc/>")
+ self.assertEqual(result.getvalue(), self.xml("<doc/>"))
def test_xmlgen_content(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result)
gen.startDocument()
@@ -206,10 +204,10 @@ class XmlgenTest(unittest.TestCase):
gen.endElement("doc")
gen.endDocument()
- self.assertEqual(result.getvalue(), start + "<doc>huhei</doc>")
+ self.assertEqual(result.getvalue(), self.xml("<doc>huhei</doc>"))
def test_xmlgen_content_empty(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result, short_empty_elements=True)
gen.startDocument()
@@ -218,10 +216,10 @@ class XmlgenTest(unittest.TestCase):
gen.endElement("doc")
gen.endDocument()
- self.assertEqual(result.getvalue(), start + "<doc>huhei</doc>")
+ self.assertEqual(result.getvalue(), self.xml("<doc>huhei</doc>"))
def test_xmlgen_pi(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result)
gen.startDocument()
@@ -230,10 +228,11 @@ class XmlgenTest(unittest.TestCase):
gen.endElement("doc")
gen.endDocument()
- self.assertEqual(result.getvalue(), start + "<?test data?><doc></doc>")
+ self.assertEqual(result.getvalue(),
+ self.xml("<?test data?><doc></doc>"))
def test_xmlgen_content_escape(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result)
gen.startDocument()
@@ -243,10 +242,10 @@ class XmlgenTest(unittest.TestCase):
gen.endDocument()
self.assertEqual(result.getvalue(),
- start + "<doc>&lt;huhei&amp;</doc>")
+ self.xml("<doc>&lt;huhei&amp;</doc>"))
def test_xmlgen_attr_escape(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result)
gen.startDocument()
@@ -260,13 +259,43 @@ class XmlgenTest(unittest.TestCase):
gen.endElement("doc")
gen.endDocument()
- self.assertEqual(result.getvalue(), start +
- ("<doc a='\"'><e a=\"'\"></e>"
- "<e a=\"'&quot;\"></e>"
- "<e a=\"&#10;&#13;&#9;\"></e></doc>"))
+ self.assertEqual(result.getvalue(), self.xml(
+ "<doc a='\"'><e a=\"'\"></e>"
+ "<e a=\"'&quot;\"></e>"
+ "<e a=\"&#10;&#13;&#9;\"></e></doc>"))
+
+ def test_xmlgen_encoding(self):
+ encodings = ('iso-8859-15', 'utf-8', 'utf-8-sig',
+ 'utf-16', 'utf-16be', 'utf-16le',
+ 'utf-32', 'utf-32be', 'utf-32le')
+ for encoding in encodings:
+ result = self.ioclass()
+ gen = XMLGenerator(result, encoding=encoding)
+
+ gen.startDocument()
+ gen.startElement("doc", {"a": '\u20ac'})
+ gen.characters("\u20ac")
+ gen.endElement("doc")
+ gen.endDocument()
+
+ self.assertEqual(result.getvalue(),
+ self.xml('<doc a="\u20ac">\u20ac</doc>', encoding=encoding))
+
+ def test_xmlgen_unencodable(self):
+ result = self.ioclass()
+ gen = XMLGenerator(result, encoding='ascii')
+
+ gen.startDocument()
+ gen.startElement("doc", {"a": '\u20ac'})
+ gen.characters("\u20ac")
+ gen.endElement("doc")
+ gen.endDocument()
+
+ self.assertEqual(result.getvalue(),
+ self.xml('<doc a="&#8364;">&#8364;</doc>', encoding='ascii'))
def test_xmlgen_ignorable(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result)
gen.startDocument()
@@ -275,10 +304,10 @@ class XmlgenTest(unittest.TestCase):
gen.endElement("doc")
gen.endDocument()
- self.assertEqual(result.getvalue(), start + "<doc> </doc>")
+ self.assertEqual(result.getvalue(), self.xml("<doc> </doc>"))
def test_xmlgen_ignorable_empty(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result, short_empty_elements=True)
gen.startDocument()
@@ -287,10 +316,10 @@ class XmlgenTest(unittest.TestCase):
gen.endElement("doc")
gen.endDocument()
- self.assertEqual(result.getvalue(), start + "<doc> </doc>")
+ self.assertEqual(result.getvalue(), self.xml("<doc> </doc>"))
def test_xmlgen_ns(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result)
gen.startDocument()
@@ -303,12 +332,12 @@ class XmlgenTest(unittest.TestCase):
gen.endPrefixMapping("ns1")
gen.endDocument()
- self.assertEqual(result.getvalue(), start + \
- ('<ns1:doc xmlns:ns1="%s"><udoc></udoc></ns1:doc>' %
+ self.assertEqual(result.getvalue(), self.xml(
+ '<ns1:doc xmlns:ns1="%s"><udoc></udoc></ns1:doc>' %
ns_uri))
def test_xmlgen_ns_empty(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result, short_empty_elements=True)
gen.startDocument()
@@ -321,12 +350,12 @@ class XmlgenTest(unittest.TestCase):
gen.endPrefixMapping("ns1")
gen.endDocument()
- self.assertEqual(result.getvalue(), start + \
- ('<ns1:doc xmlns:ns1="%s"><udoc/></ns1:doc>' %
+ self.assertEqual(result.getvalue(), self.xml(
+ '<ns1:doc xmlns:ns1="%s"><udoc/></ns1:doc>' %
ns_uri))
def test_1463026_1(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result)
gen.startDocument()
@@ -334,10 +363,10 @@ class XmlgenTest(unittest.TestCase):
gen.endElementNS((None, 'a'), 'a')
gen.endDocument()
- self.assertEqual(result.getvalue(), start+'<a b="c"></a>')
+ self.assertEqual(result.getvalue(), self.xml('<a b="c"></a>'))
def test_1463026_1_empty(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result, short_empty_elements=True)
gen.startDocument()
@@ -345,10 +374,10 @@ class XmlgenTest(unittest.TestCase):
gen.endElementNS((None, 'a'), 'a')
gen.endDocument()
- self.assertEqual(result.getvalue(), start+'<a b="c"/>')
+ self.assertEqual(result.getvalue(), self.xml('<a b="c"/>'))
def test_1463026_2(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result)
gen.startDocument()
@@ -358,10 +387,10 @@ class XmlgenTest(unittest.TestCase):
gen.endPrefixMapping(None)
gen.endDocument()
- self.assertEqual(result.getvalue(), start+'<a xmlns="qux"></a>')
+ self.assertEqual(result.getvalue(), self.xml('<a xmlns="qux"></a>'))
def test_1463026_2_empty(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result, short_empty_elements=True)
gen.startDocument()
@@ -371,10 +400,10 @@ class XmlgenTest(unittest.TestCase):
gen.endPrefixMapping(None)
gen.endDocument()
- self.assertEqual(result.getvalue(), start+'<a xmlns="qux"/>')
+ self.assertEqual(result.getvalue(), self.xml('<a xmlns="qux"/>'))
def test_1463026_3(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result)
gen.startDocument()
@@ -385,10 +414,10 @@ class XmlgenTest(unittest.TestCase):
gen.endDocument()
self.assertEqual(result.getvalue(),
- start+'<my:a xmlns:my="qux" b="c"></my:a>')
+ self.xml('<my:a xmlns:my="qux" b="c"></my:a>'))
def test_1463026_3_empty(self):
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result, short_empty_elements=True)
gen.startDocument()
@@ -399,7 +428,7 @@ class XmlgenTest(unittest.TestCase):
gen.endDocument()
self.assertEqual(result.getvalue(),
- start+'<my:a xmlns:my="qux" b="c"/>')
+ self.xml('<my:a xmlns:my="qux" b="c"/>'))
def test_5027_1(self):
# The xml prefix (as in xml:lang below) is reserved and bound by
@@ -416,13 +445,13 @@ class XmlgenTest(unittest.TestCase):
parser = make_parser()
parser.setFeature(feature_namespaces, True)
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result)
parser.setContentHandler(gen)
parser.parse(test_xml)
self.assertEqual(result.getvalue(),
- start + (
+ self.xml(
'<a:g1 xmlns:a="http://example.com/ns">'
'<a:g2 xml:lang="en">Hello</a:g2>'
'</a:g1>'))
@@ -435,7 +464,7 @@ class XmlgenTest(unittest.TestCase):
#
# This test demonstrates the bug by direct manipulation of the
# XMLGenerator.
- result = StringIO()
+ result = self.ioclass()
gen = XMLGenerator(result)
gen.startDocument()
@@ -450,15 +479,57 @@ class XmlgenTest(unittest.TestCase):
gen.endDocument()
self.assertEqual(result.getvalue(),
- start + (
+ self.xml(
'<a:g1 xmlns:a="http://example.com/ns">'
'<a:g2 xml:lang="en">Hello</a:g2>'
'</a:g1>'))
+ def test_no_close_file(self):
+ result = self.ioclass()
+ def func(out):
+ gen = XMLGenerator(out)
+ gen.startDocument()
+ gen.startElement("doc", {})
+ func(result)
+ self.assertFalse(result.closed)
+
+class StringXmlgenTest(XmlgenTest, unittest.TestCase):
+ ioclass = StringIO
+
+ def xml(self, doc, encoding='iso-8859-1'):
+ return '<?xml version="1.0" encoding="%s"?>\n%s' % (encoding, doc)
+
+ test_xmlgen_unencodable = None
+
+class BytesXmlgenTest(XmlgenTest, unittest.TestCase):
+ ioclass = BytesIO
+
+ def xml(self, doc, encoding='iso-8859-1'):
+ return ('<?xml version="1.0" encoding="%s"?>\n%s' %
+ (encoding, doc)).encode(encoding, 'xmlcharrefreplace')
+
+class WriterXmlgenTest(BytesXmlgenTest):
+ class ioclass(list):
+ write = list.append
+ closed = False
+
+ def seekable(self):
+ return True
+
+ def tell(self):
+ # return 0 at start and not 0 after start
+ return len(self)
+
+ def getvalue(self):
+ return b''.join(self)
+
+
+start = b'<?xml version="1.0" encoding="iso-8859-1"?>\n'
+
class XMLFilterBaseTest(unittest.TestCase):
def test_filter_basic(self):
- result = StringIO()
+ result = BytesIO()
gen = XMLGenerator(result)
filter = XMLFilterBase()
filter.setContentHandler(gen)
@@ -470,7 +541,7 @@ class XMLFilterBaseTest(unittest.TestCase):
filter.endElement("doc")
filter.endDocument()
- self.assertEqual(result.getvalue(), start + "<doc>content </doc>")
+ self.assertEqual(result.getvalue(), start + b"<doc>content </doc>")
# ===========================================================================
#
@@ -478,7 +549,7 @@ class XMLFilterBaseTest(unittest.TestCase):
#
# ===========================================================================
-with open(TEST_XMLFILE_OUT) as f:
+with open(TEST_XMLFILE_OUT, 'rb') as f:
xml_test_out = f.read()
class ExpatReaderTest(XmlTestBase):
@@ -487,11 +558,11 @@ class ExpatReaderTest(XmlTestBase):
def test_expat_file(self):
parser = create_parser()
- result = StringIO()
+ result = BytesIO()
xmlgen = XMLGenerator(result)
parser.setContentHandler(xmlgen)
- with open(TEST_XMLFILE) as f:
+ with open(TEST_XMLFILE, 'rb') as f:
parser.parse(f)
self.assertEqual(result.getvalue(), xml_test_out)
@@ -503,7 +574,7 @@ class ExpatReaderTest(XmlTestBase):
self.addCleanup(support.unlink, fname)
parser = create_parser()
- result = StringIO()
+ result = BytesIO()
xmlgen = XMLGenerator(result)
parser.setContentHandler(xmlgen)
@@ -547,13 +618,13 @@ class ExpatReaderTest(XmlTestBase):
def resolveEntity(self, publicId, systemId):
inpsrc = InputSource()
- inpsrc.setByteStream(StringIO("<entity/>"))
+ inpsrc.setByteStream(BytesIO(b"<entity/>"))
return inpsrc
def test_expat_entityresolver(self):
parser = create_parser()
parser.setEntityResolver(self.TestEntityResolver())
- result = StringIO()
+ result = BytesIO()
parser.setContentHandler(XMLGenerator(result))
parser.feed('<!DOCTYPE doc [\n')
@@ -563,7 +634,7 @@ class ExpatReaderTest(XmlTestBase):
parser.close()
self.assertEqual(result.getvalue(), start +
- "<doc><entity></entity></doc>")
+ b"<doc><entity></entity></doc>")
# ===== Attributes support
@@ -632,7 +703,7 @@ class ExpatReaderTest(XmlTestBase):
def test_expat_inpsource_filename(self):
parser = create_parser()
- result = StringIO()
+ result = BytesIO()
xmlgen = XMLGenerator(result)
parser.setContentHandler(xmlgen)
@@ -642,7 +713,7 @@ class ExpatReaderTest(XmlTestBase):
def test_expat_inpsource_sysid(self):
parser = create_parser()
- result = StringIO()
+ result = BytesIO()
xmlgen = XMLGenerator(result)
parser.setContentHandler(xmlgen)
@@ -657,7 +728,7 @@ class ExpatReaderTest(XmlTestBase):
self.addCleanup(support.unlink, fname)
parser = create_parser()
- result = StringIO()
+ result = BytesIO()
xmlgen = XMLGenerator(result)
parser.setContentHandler(xmlgen)
@@ -667,12 +738,12 @@ class ExpatReaderTest(XmlTestBase):
def test_expat_inpsource_stream(self):
parser = create_parser()
- result = StringIO()
+ result = BytesIO()
xmlgen = XMLGenerator(result)
parser.setContentHandler(xmlgen)
inpsrc = InputSource()
- with open(TEST_XMLFILE) as f:
+ with open(TEST_XMLFILE, 'rb') as f:
inpsrc.setByteStream(f)
parser.parse(inpsrc)
@@ -681,7 +752,7 @@ class ExpatReaderTest(XmlTestBase):
# ===== IncrementalParser support
def test_expat_incremental(self):
- result = StringIO()
+ result = BytesIO()
xmlgen = XMLGenerator(result)
parser = create_parser()
parser.setContentHandler(xmlgen)
@@ -690,10 +761,10 @@ class ExpatReaderTest(XmlTestBase):
parser.feed("</doc>")
parser.close()
- self.assertEqual(result.getvalue(), start + "<doc></doc>")
+ self.assertEqual(result.getvalue(), start + b"<doc></doc>")
def test_expat_incremental_reset(self):
- result = StringIO()
+ result = BytesIO()
xmlgen = XMLGenerator(result)
parser = create_parser()
parser.setContentHandler(xmlgen)
@@ -701,7 +772,7 @@ class ExpatReaderTest(XmlTestBase):
parser.feed("<doc>")
parser.feed("text")
- result = StringIO()
+ result = BytesIO()
xmlgen = XMLGenerator(result)
parser.setContentHandler(xmlgen)
parser.reset()
@@ -711,12 +782,12 @@ class ExpatReaderTest(XmlTestBase):
parser.feed("</doc>")
parser.close()
- self.assertEqual(result.getvalue(), start + "<doc>text</doc>")
+ self.assertEqual(result.getvalue(), start + b"<doc>text</doc>")
# ===== Locator support
def test_expat_locator_noinfo(self):
- result = StringIO()
+ result = BytesIO()
xmlgen = XMLGenerator(result)
parser = create_parser()
parser.setContentHandler(xmlgen)
@@ -730,7 +801,7 @@ class ExpatReaderTest(XmlTestBase):
self.assertEqual(parser.getLineNumber(), 1)
def test_expat_locator_withinfo(self):
- result = StringIO()
+ result = BytesIO()
xmlgen = XMLGenerator(result)
parser = create_parser()
parser.setContentHandler(xmlgen)
@@ -745,7 +816,7 @@ class ExpatReaderTest(XmlTestBase):
shutil.copyfile(TEST_XMLFILE, fname)
self.addCleanup(support.unlink, fname)
- result = StringIO()
+ result = BytesIO()
xmlgen = XMLGenerator(result)
parser = create_parser()
parser.setContentHandler(xmlgen)
@@ -766,7 +837,7 @@ class ErrorReportingTest(unittest.TestCase):
parser = create_parser()
parser.setContentHandler(ContentHandler()) # do nothing
source = InputSource()
- source.setByteStream(StringIO("<foo bar foobar>")) #ill-formed
+ source.setByteStream(BytesIO(b"<foo bar foobar>")) #ill-formed
name = "a file name"
source.setSystemId(name)
try:
@@ -857,7 +928,9 @@ class XmlReaderTest(XmlTestBase):
def test_main():
run_unittest(MakeParserTest,
SaxutilsTest,
- XmlgenTest,
+ StringXmlgenTest,
+ BytesXmlgenTest,
+ WriterXmlgenTest,
ExpatReaderTest,
ErrorReportingTest,
XmlReaderTest)
diff --git a/Lib/xml/sax/saxutils.py b/Lib/xml/sax/saxutils.py
index 625bc12..a62183a 100644
--- a/Lib/xml/sax/saxutils.py
+++ b/Lib/xml/sax/saxutils.py
@@ -4,18 +4,10 @@ convenience of application and driver writers.
"""
import os, urllib.parse, urllib.request
+import io
from . import handler
from . import xmlreader
-# See whether the xmlcharrefreplace error handler is
-# supported
-try:
- from codecs import xmlcharrefreplace_errors
- _error_handling = "xmlcharrefreplace"
- del xmlcharrefreplace_errors
-except ImportError:
- _error_handling = "strict"
-
def __dict_replace(s, d):
"""Replace substrings of a string using a dictionary."""
for key, value in d.items():
@@ -76,14 +68,50 @@ def quoteattr(data, entities={}):
return data
+def _gettextwriter(out, encoding):
+ if out is None:
+ import sys
+ return sys.stdout
+
+ if isinstance(out, io.TextIOBase):
+ # use a text writer as is
+ return out
+
+ # wrap a binary writer with TextIOWrapper
+ if isinstance(out, io.RawIOBase):
+ # Keep the original file open when the TextIOWrapper is
+ # destroyed
+ class _wrapper:
+ __class__ = out.__class__
+ def __getattr__(self, name):
+ return getattr(out, name)
+ buffer = _wrapper()
+ buffer.close = lambda: None
+ else:
+ # This is to handle passed objects that aren't in the
+ # IOBase hierarchy, but just have a write method
+ buffer = io.BufferedIOBase()
+ buffer.writable = lambda: True
+ buffer.write = out.write
+ try:
+ # TextIOWrapper uses this methods to determine
+ # if BOM (for UTF-16, etc) should be added
+ buffer.seekable = out.seekable
+ buffer.tell = out.tell
+ except AttributeError:
+ pass
+ return io.TextIOWrapper(buffer, encoding=encoding,
+ errors='xmlcharrefreplace',
+ newline='\n',
+ write_through=True)
+
class XMLGenerator(handler.ContentHandler):
def __init__(self, out=None, encoding="iso-8859-1", short_empty_elements=False):
- if out is None:
- import sys
- out = sys.stdout
handler.ContentHandler.__init__(self)
- self._out = out
+ out = _gettextwriter(out, encoding)
+ self._write = out.write
+ self._flush = out.flush
self._ns_contexts = [{}] # contains uri -> prefix dicts
self._current_context = self._ns_contexts[-1]
self._undeclared_ns_maps = []
@@ -91,12 +119,6 @@ class XMLGenerator(handler.ContentHandler):
self._short_empty_elements = short_empty_elements
self._pending_start_element = False
- def _write(self, text):
- if isinstance(text, str):
- self._out.write(text)
- else:
- self._out.write(text.encode(self._encoding, _error_handling))
-
def _qname(self, name):
"""Builds a qualified name from a (ns_url, localname) pair"""
if name[0]:
@@ -125,6 +147,9 @@ class XMLGenerator(handler.ContentHandler):
self._write('<?xml version="1.0" encoding="%s"?>\n' %
self._encoding)
+ def endDocument(self):
+ self._flush()
+
def startPrefixMapping(self, prefix, uri):
self._ns_contexts.append(self._current_context.copy())
self._current_context[uri] = prefix
@@ -157,9 +182,9 @@ class XMLGenerator(handler.ContentHandler):
for prefix, uri in self._undeclared_ns_maps:
if prefix:
- self._out.write(' xmlns:%s="%s"' % (prefix, uri))
+ self._write(' xmlns:%s="%s"' % (prefix, uri))
else:
- self._out.write(' xmlns="%s"' % uri)
+ self._write(' xmlns="%s"' % uri)
self._undeclared_ns_maps = []
for (name, value) in attrs.items():
diff --git a/Misc/NEWS b/Misc/NEWS
index 0e0cd0f..730eab1 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -172,6 +172,8 @@ Core and Builtins
Library
-------
+- Issue #1470548: XMLGenerator now works with binary output streams.
+
- Issue #6975: os.path.realpath() now correctly resolves multiple nested
symlinks on POSIX platforms.