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pdf: added capability to extract metadata from XML packet

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This commit is contained in:
Jean-Francois Dockes 2017-05-12 10:27:12 +02:00
parent 5863d29e49
commit d87d410f11
1 changed files with 155 additions and 19 deletions
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174
src/filters/rclpdf.py
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@ -78,15 +78,27 @@ class PDFExtractor:
def __init__(self, em):
self.currentindex = 0
self.pdftotext = None
self.pdfinfo = None
self.pdftk = None
self.em = em
self.confdir = rclconfig.RclConfig().getConfDir()
cf_doocr = rclconfig.RclConfig().getConfParam("pdfocr")
cf_attach = rclconfig.RclConfig().getConfParam("pdfattach")
self.tesseract = None
self.pdftotext = rclexecm.which("pdftotext")
if not self.pdftotext:
self.pdftotext = rclexecm.which("poppler/pdftotext")
# No need for anything else. openfile() will return an
# error at once
return
cf = rclconfig.RclConfig()
self.confdir = cf.getConfDir()
# The user can set a list of meta tags to be extracted from
# the XMP metadata packet. These are specified as
# (xmltag,rcltag) pairs
self.extrameta = cf.getConfParam("pdfextrameta")
if self.extrameta:
self._initextrameta()
# Check if we need to escape portions of text where old
# versions of pdftotext output raw HTML special characters.
@ -106,6 +118,7 @@ class PDFExtractor:
# either the presence of a file in the config dir (historical)
# or a set config variable.
self.ocrpossible = False
cf_doocr = cf.getConfParam("pdfocr")
if cf_doocr or os.path.isfile(os.path.join(self.confdir, "ocrpdf")):
self.tesseract = rclexecm.which("tesseract")
if self.tesseract:
@ -116,17 +129,56 @@ class PDFExtractor:
# self.em.rclog("OCRPOSSIBLE: %d" % self.ocrpossible)
# Pdftk is optionally used to extract attachments. This takes
# a hit on perfmance even in the absence of any attachments,
# a hit on performance even in the absence of any attachments,
# so it can be disabled in the configuration.
self.attextractdone = False
self.attachlist = []
cf_attach = cf.getConfParam("pdfattach")
if cf_attach:
self.pdftk = rclexecm.which("pdftk")
else:
self.pdftk = None
if self.pdftk:
self.maybemaketmpdir()
def _initextrameta(self):
self.pdfinfo = rclexecm.which("pdfinfo")
if not self.pdfinfo:
self.pdfinfo = rclexecm.which("poppler/pdfinfo")
if not self.pdfinfo:
self.extrameta = None
return
# extrameta is like "samename metanm|rclnm ..."
# we turn it into a list of pairs
l = self.extrameta.split()
self.extrameta = []
for e in l:
l1 = e.split('|')
if len(l1) == 1:
l1.append(l1[0])
self.extrameta.append(l1)
# Using lxml because it is better with
# namespaces. With xml, we'd have to walk the XML tree
# first, extracting all xmlns attributes and
# constructing a tree (I tried and did not succeed in
# doing this actually). lxml does it partially for
# us. See http://stackoverflow.com/questions/14853243/
# parsing-xml-with-namespace-in-python-via-elementtree
global ET
#import xml.etree.ElementTree as ET
try:
import lxml.etree as ET
except Exception as err:
self.em.rclog("Can't import lxml etree: %s" % err)
self.extrameta = None
self.pdfinfo = None
return
self.re_head = re.compile(r'<head>', re.IGNORECASE)
self.re_xmlpacket = re.compile(r'<\?xpacket[ ]+begin.*\?>' +
r'(.*)' + r'<\?xpacket[ ]+end',
flags = re.DOTALL)
# Extract all attachments if any into temporary directory
def extractAttach(self):
if self.attextractdone:
@ -244,10 +296,13 @@ class PDFExtractor:
if not data:
return ""
return '''<html><head><meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\"></head><body><pre>''' + \
return '''<html><head>
<meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\">
</head><body><pre>''' + \
self.em.htmlescape(data) + \
'''</pre></body></html>'''
# pdftotext (used to?) badly escape text inside the header
# fields. We do it here. This is not an html parser, and depends a
# lot on the actual format output by pdftotext.
@ -299,8 +354,81 @@ class PDFExtractor:
output += line + b'\n'
return output, isempty
def _metatag(self, nm, val):
return "<meta name=\"" + nm + "\" content=\"" + \
self.em.htmlescape(val) + "\">"
# metaheaders is a list of (nm, value) pairs
def _injectmeta(self, html, metaheaders):
metatxt = ''
for nm, val in metaheaders:
metatxt += self._metatag(nm, val) + '\n'
if not metatxt:
return html
res = self.re_head.sub('<head>\n' + metatxt, html)
#self.em.rclog("Substituted html: [%s]"%res)
if res:
return res
else:
return html
def _xmltreetext(self, elt):
'''Extract all text content from subtree'''
text = ''
for e in elt.iter():
if e.text:
text += e.text + " "
return text.strip()
# or: return reduce((lambda t,p : t+p+' '),
# [e.text for e in elt.iter() if e.text]).strip()
def _setextrameta(self, html):
if not self.pdfinfo:
return
all = subprocess.check_output([self.pdfinfo, "-meta", self.filename])
# Extract the XML packet
res = self.re_xmlpacket.search(all)
xml = ''
if res:
xml = res.group(1)
# self.em.rclog("extrameta: XML: [%s]" % xml)
if not xml:
return html
metaheaders = []
# The namespace thing is a drag. Can't do it from the top. See
# the stackoverflow ref above. Maybe we'd be better off just
# walking the full tree and building the namespaces dict.
root = ET.fromstring(xml)
#self.em.rclog("NSMAP: %s"% root.nsmap)
namespaces = {'rdf' : "http://www.w3.org/1999/02/22-rdf-syntax-ns#"}
rdf = root.find("rdf:RDF", namespaces)
#self.em.rclog("RDF NSMAP: %s"% rdf.nsmap)
rdfdesclist = rdf.findall("rdf:Description", rdf.nsmap)
#self.em.rclog("RDFDESC NSMAP: %s"% rdfdesc.nsmap)
for metanm,rclnm in self.extrameta:
for rdfdesc in rdfdesclist:
try:
elt = rdfdesc.find(metanm, rdfdesc.nsmap)
except:
# We get an exception when this rdf:Description does not
# define the required namespace.
continue
if elt is not None:
text = self._xmltreetext(elt)
if text:
# Should we set empty values ?
# Can't use setfield as it only works for
# text/plain output at the moment.
metaheaders.append((rclnm, text))
if metaheaders:
return self._injectmeta(html, metaheaders)
def _selfdoc(self):
'''Extract the text from the pdf doc (as opposed to attachment)'''
self.em.setmimetype('text/html')
if self.attextractdone and len(self.attachlist) == 0:
@ -308,15 +436,23 @@ class PDFExtractor:
else:
eof = rclexecm.RclExecM.noteof
data = subprocess.check_output([self.pdftotext, "-htmlmeta", "-enc",
html = subprocess.check_output([self.pdftotext, "-htmlmeta", "-enc",
"UTF-8", "-eol", "unix", "-q",
self.filename, "-"])
data, isempty = self._fixhtml(data)
#self.em.rclog("ISEMPTY: %d : data: \n%s" % (isempty, data))
html, isempty = self._fixhtml(html)
#self.em.rclog("ISEMPTY: %d : data: \n%s" % (isempty, html))
if isempty and self.ocrpossible:
data = self.ocrpdf()
return (True, data, "", eof)
html = self.ocrpdf()
if self.extrameta:
try:
html = self._setextrameta(html)
except Exception as err:
self.em.rclog("Metadata extraction failed: %s" % err)
return (True, html, "", eof)
def maybemaketmpdir(self):
global tmpdir
@ -329,15 +465,15 @@ class PDFExtractor:
###### File type handler api, used by rclexecm ---------->
def openfile(self, params):
if not self.pdftotext:
print("RECFILTERROR HELPERNOTFOUND pdftotext")
sys.exit(1);
self.filename = params["filename:"]
#self.em.rclog("openfile: [%s]" % self.filename)
self.currentindex = -1
self.attextractdone = False
if not self.pdftotext:
print("RECFILTERROR HELPERNOTFOUND pdftotext")
sys.exit(1);
if self.pdftk:
preview = os.environ.get("RECOLL_FILTER_FORPREVIEW", "no")
if preview != "yes":