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cc-devel - Re: [cc-devel] [Tracker] Extracting Embedded Licenses

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  • From: Jon Phillips <jon AT rejon.org>
  • To: Jason Kivlighn <jkivlighn AT gmail.com>
  • Cc: CC Developer Mailing List <cc-devel AT lists.ibiblio.org>, tracker-list AT gnome.org, "Nathan R. Yergler" <nathan AT creativecommons.org>, jamie <jamiemcc AT blueyonder.co.uk>
  • Subject: Re: [cc-devel] [Tracker] Extracting Embedded Licenses
  • Date: Mon, 18 Jun 2007 14:33:46 -0700

On Mon, 2007-06-18 at 12:49 -0700, Jason Kivlighn wrote:
> Hi,
>
> imagemagick: Uses 'convert filename xmp:-' to output an image's embedded
> XMP. This works for at least JPEG and TIFF files. For JPEGs, however,
> Imagemagick outputs the namespace and XMP, seperated by \0. I'm not
> sure how I can handle this, without simply assuming that 'convert'
> returned two null-terminated strings. Nevertheless, this extracts the
> XMP from TIFF files.
>
> msoffice: Extends the msoffice extractor to also parse the
> DocumentSummeryInformation infile, which contains user-defined metadata,
> along with license metadata embedded by the MSOffice Creative Commons Add-in
>
> pdf: Extends the pdf extractor to read a PDF's metadata stream and parse
> it as XMP. I'm still awaiting poppler extending the glib bindings to
> allow reading the metadata stream. Until then, it will simply never
> find the metadata stream and go on without error.
>
> png: Adds a check for the XML:com:adobe:xmp iTXt field, and parses it as
> XMP.
>
> html: Adds a new html parser using libxml2. Parses the document,
> checking for RDFa licenses. It also checks for other basic HTML
> properties like title and author.
>
> There's also several XML formats I'd like to parse for license data,
> particularly SVG and SMIL. Would this be do-able, and if so, how should
> I go about it? Write new extractors for each format or is this too much
> overhead? These could use GMarkupParse, rather than bringing in libxml2
> like the HTML parser.
>
> Cheers,
> Jason

Nathan, what do you think about these as well?

Jon

> plain text document attachment (tracker-imagemagick-extract-xmp.patch)
> Index: src/tracker-extract/tracker-extract-imagemagick.c
> ===================================================================
> --- src/tracker-extract/tracker-extract-imagemagick.c (revision 598)
> +++ src/tracker-extract/tracker-extract-imagemagick.c (working copy)
> @@ -35,7 +35,7 @@
> gint exit_status;
>
> /* imagemagick crashes trying to extract from xcf files */
> - if (g_str_has_suffix (filename, '.xcf')) {
> + if (g_str_has_suffix (filename, ".xcf")) {
> return;
> }
>
> @@ -60,5 +60,16 @@
> g_hash_table_insert (metadata, g_strdup
> ("Image:Comments"), g_strdup (g_strescape (lines[2], "")));
> }
> }
> +
> + gchar *xmp;
> + argv[0] = g_strdup ("convert");
> + argv[1] = g_strdup (filename);
> + argv[2] = g_strdup ("xmp:-");
> + argv[3] = NULL;
> +
> + if (tracker_spawn (argv, 10, &xmp, &exit_status)) {
> + if (exit_status == EXIT_SUCCESS) {
> + tracker_read_xmp(xmp,strlen(xmp),metadata);
> + }
> + }
> }
> -
> plain text document attachment
> (tracker-msoffice-extract-license.patch)
> Index: src/tracker-extract/tracker-extract-msoffice.c
> ===================================================================
> --- src/tracker-extract/tracker-extract-msoffice.c (revision 598)
> +++ src/tracker-extract/tracker-extract-msoffice.c (working copy)
> @@ -118,7 +118,26 @@
> }
> }
>
> +static void
> +doc_metadata_cb (gpointer key, gpointer value, gpointer user_data)
> +{
> + gchar *name;
> + GsfDocProp *property;
> + GHashTable *metadata;
> + GValue const *val;
>
> + name = (gchar *) key;
> + property = (GsfDocProp *) value;
> + metadata = (GHashTable *) user_data;
> +
> + val = gsf_doc_prop_get_val (property);
> +
> + if (strcmp (name, "CreativeCommons_LicenseURL") == 0) {
> + add_gvalue_in_hash_table (metadata, "File:License", val);
> + }
> +}
> +
> +
> void
> tracker_extract_msoffice (gchar *filename, GHashTable *metadata)
> {
> @@ -145,25 +164,37 @@
> }
>
> stream = gsf_infile_child_by_name (infile, "\05SummaryInformation");
> - g_object_unref (G_OBJECT (infile));
> -
> - if (!stream) {
> - gsf_shutdown ();
> - return;
> + if (stream) {
> + md = gsf_doc_meta_data_new ();
> +
> + if (gsf_msole_metadata_read (stream, md)) {
> + gsf_shutdown ();
> + return;
> + }
> +
> + gsf_doc_meta_data_foreach (md, metadata_cb, metadata);
> +
> + g_object_unref (G_OBJECT (md));
> + g_object_unref (G_OBJECT (stream));
> }
>
> - md = gsf_doc_meta_data_new ();
> -
> - if (gsf_msole_metadata_read (stream, md)) {
> - gsf_shutdown ();
> - return;
> + stream = gsf_infile_child_by_name (infile,
> "\05DocumentSummaryInformation");
> + if (stream) {
> + md = gsf_doc_meta_data_new ();
> +
> + if (gsf_msole_metadata_read (stream, md)) {
> + gsf_shutdown ();
> + return;
> + }
> +
> + gsf_doc_meta_data_foreach (md, doc_metadata_cb, metadata);
> +
> + g_object_unref (G_OBJECT (md));
> + g_object_unref (G_OBJECT (stream));
> }
>
> - gsf_doc_meta_data_foreach (md, metadata_cb, metadata);
> + g_object_unref (G_OBJECT (infile));
>
> - g_object_unref (G_OBJECT (md));
> - g_object_unref (G_OBJECT (stream));
> -
> gsf_shutdown ();
> }
>
> plain text document attachment (tracker-pdf-extract-xmp.patch)
> Index: src/tracker-extract/tracker-extract-pdf.c
> ===================================================================
> --- src/tracker-extract/tracker-extract-pdf.c (revision 598)
> +++ src/tracker-extract/tracker-extract-pdf.c (working copy)
> @@ -26,6 +26,8 @@
> #include <string.h>
> #include <glib.h>
>
> +#include "tracker-extract.h"
> +
> void tracker_extract_pdf (gchar *filename, GHashTable *metadata)
> {
> PopplerDocument *document;
> @@ -34,6 +36,7 @@
> gchar *author;
> gchar *subject;
> gchar *keywords;
> + gchar *metadata_xml;
> GTime creation_date;
> GError *error = NULL;
>
> @@ -50,6 +53,7 @@
> "subject", &subject,
> "keywords", &keywords,
> "creation-date", &creation_date,
> + "metadata", &metadata_xml,
> NULL);
>
> if (title && strlen (title))
> @@ -71,10 +75,15 @@
> g_hash_table_insert (metadata, g_strdup ("Doc:PageCount"),
> g_strdup_printf ("%d", poppler_document_get_n_pages
> (document)));
>
> + if ( metadata_xml ) {
> + tracker_read_xmp (metadata_xml,strlen(metadata_xml),metadata);
> + }
> +
> g_free (title);
> g_free (author);
> g_free (subject);
> g_free (keywords);
> + g_free (metadata_xml);
> g_object_unref (document);
> }
>
> plain text document attachment (tracker-png-extract-xmp.patch)
> Index: src/tracker-extract/tracker-extract-png.c
> ===================================================================
> --- src/tracker-extract/tracker-extract-png.c (revision 598)
> +++ src/tracker-extract/tracker-extract-png.c (working copy)
> @@ -20,6 +20,8 @@
>
> #include "config.h"
>
> +#include "tracker-extract.h"
> +
> #include <stdio.h>
> #include <glib.h>
> #include <png.h>
> @@ -79,15 +81,23 @@
> g_strdup_printf ("%ld", height));
> }
>
> -
> if (png_get_text (png_ptr, info_ptr, &text_ptr, &num_text) >
> 0) {
> - for (i = 0; i < num_text; i++) {
> - for (j=0; tagmap[j].type; j++) {
> - if (strcasecmp (tagmap[j].name,
> text_ptr[i].key) == 0) {
> - if (text_ptr[i].text &&
> strlen (text_ptr[i].text) > 0) {
> - g_hash_table_insert
> (metadata, g_strdup (tagmap[j].type), g_strdup (text_ptr[i].text));
> + for (i = 0; i < num_text; i++) {
> + if ( text_ptr[i].key != NULL ) {
> + #if defined(HAVE_EXEMPI) &&
> defined(PNG_iTXt_SUPPORTED)
> + if
> (strcmp("XML:com.adobe.xmp",text_ptr[i].key) == 0) {
> +
> tracker_read_xmp(text_ptr[i].text,text_ptr[i].itxt_length,metadata);
> + continue;
> + }
> + #endif
> +
> + for (j=0; tagmap[j].type; j++) {
> + if (strcasecmp
> (tagmap[j].name, text_ptr[i].key) == 0) {
> + if (text_ptr[i].text
> && strlen (text_ptr[i].text) > 0) {
> +
> g_hash_table_insert (metadata, g_strdup (tagmap[j].type), g_strdup
> (text_ptr[i].text));
> + }
> + break;
> }
> - break;
> }
> }
> }
> plain text document attachment (tracker-extract-html.patch)
> Index: src/tracker-extract/tracker-extract.c
> ===================================================================
> --- src/tracker-extract/tracker-extract.c (revision 598)
> +++ src/tracker-extract/tracker-extract.c (working copy)
> @@ -52,6 +52,9 @@
> void tracker_extract_totem (gchar *, GHashTable *);
> void tracker_extract_oasis (gchar *, GHashTable *);
> void tracker_extract_ps (gchar *, GHashTable *);
> +#ifdef HAVE_LIBXML2
> +void tracker_extract_html (gchar *, GHashTable *);
> +#endif
> #ifdef HAVE_POPPLER
> void tracker_extract_pdf (gchar *, GHashTable *);
> #endif
> @@ -84,6 +87,10 @@
> /* Document extractors */
> { "application/vnd.oasis.opendocument.*", tracker_extract_oasis
> },
> { "application/postscript", tracker_extract_ps
> },
> +#ifdef HAVE_LIBXML2
> + { "text/html",
> tracker_extract_html },
> + { "application/xhtml+xml", tracker_extract_html },
> +#endif
> #ifdef HAVE_POPPLER
> { "application/pdf", tracker_extract_pdf
> },
> #endif
> Index: src/tracker-extract/Makefile.am
> ===================================================================
> --- src/tracker-extract/Makefile.am (revision 598)
> +++ src/tracker-extract/Makefile.am (working copy)
> @@ -5,6 +5,7 @@
> $(LIBGSF_CFLAGS) \
> $(LIBGSF_CFLAGS) \
> $(GSTREAMER_CFLAGS) \
> + $(LIBXML2_CFLAGS) \
> $(XINE_CFLAGS)
>
> bin_PROGRAMS = tracker-extract
> @@ -33,6 +34,7 @@
> tracker-extract-imagemagick.c \
> tracker-extract-mplayer.c \
> tracker-extract-totem.c \
> + tracker-extract-html.c \
> $(video_sources)
>
> tracker_extract_LDADD = $(GLIB2_LIBS) \
> @@ -41,4 +43,5 @@
> $(LIBEXIF_LIBS) \
> $(LIBGSF_LIBS) \
> $(GSTREAMER_LIBS) \
> + $(LIBXML2_LIBS) \
> $(XINE_LIBS)
> Index: configure.ac
> ===================================================================
> --- configure.ac (revision 598)
> +++ configure.ac (working copy)
> @@ -605,8 +605,25 @@
> [ AC_DEFINE(IOPRIO_SUPPORT,[],[Define ioprio support])
> ioprio_support=yes ])
> AC_MSG_RESULT([$ioprio_support])
>
> -#####################################################
> +##################################################################
> +# check for libxml2
> +##################################################################
>
> +LIBXML2_REQUIRED=0.6
> +
> +AC_ARG_ENABLE(libxml2, AC_HELP_STRING([--disable-libxml2],[Disable
> HTML/XML extractors (full-text will still be
> available)]),,[enable_libxml2=yes])
> +if test "x$enable_libxml2" = "xyes"; then
> + PKG_CHECK_MODULES(LIBXML2, [
> + libxml-2.0 >= $LIBXML2_REQUIRED],
> + [have_libxml2=yes] , [have_libxml2=no])
> + AC_SUBST(LIBXML2_CFLAGS)
> + AC_SUBST(LIBXML2_LIBS)
> +else
> + have_libxml2="no (disabled)"
> +fi
> +AM_CONDITIONAL(HAVE_LIBXML2, test "$have_libxml2" = "yes")
> +test "$have_libxml2" = "yes" && AC_DEFINE(HAVE_LIBXML2, [], [Define if we
> have libxml2])
> +
> AC_CONFIG_FILES([
> Makefile
> tracker.pc
> @@ -675,6 +692,7 @@
> exif (jpeg): $have_libexif
> gsf: $have_libgsf
> video files: $videos_are_handled
> ($videos_handler)
> + xml/html formats: $have_libxml2
>
> "
> if test "x$enable_external_sqlite" = "xyes"; then
> Index: src/tracker-extract/tracker-extract-html.c
> ===================================================================
> --- src/tracker-extract/tracker-extract-html.c (revision 0)
> +++ src/tracker-extract/tracker-extract-html.c (revision 0)
> @@ -0,0 +1,161 @@
> +/* Tracker Extract - extracts embedded metadata from files
> + * Copyright (C) 2007, Jason Kivlighn (jkivlighn AT gmail.com)
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public
> + * License along with this program; if not, write to the
> + * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
> + * Boston, MA 02110-1301, USA.
> + */
> +
> +#include "config.h"
> +
> +#ifdef HAVE_LIBXML2
> +
> +#include <string.h>
> +#include <glib.h>
> +#include <libxml/HTMLparser.h>
> +
> +typedef enum {
> + READ_TITLE,
> + } tag_type;
> +
> +typedef struct {
> + GHashTable *metadata;
> + tag_type current;
> +} HTMLParseInfo;
> +
> +gboolean
> +has_attribute( const xmlChar ** atts, const char *attr, const char*val )
> +{
> + int i;
> + for ( i = 0; atts[i]; i+=2 )
> + {
> + if ( strcmp((char*)atts[i],attr) == 0 ) {
> + if ( !val || strcmp((char*)atts[i+1],val) == 0 ) {
> + return TRUE;
> + }
> + }
> + }
> + return FALSE;
> +}
> +
> +const xmlChar *
> +lookup_attribute( const xmlChar **atts, const char *attr )
> +{
> + int i;
> + for ( i = 0; atts[i]; i+=2 )
> + {
> + if ( strcmp((char*)atts[i],attr) == 0 ) {
> + return atts[i+1];
> + }
> + }
> +
> + return NULL;
> +}
> +
> +void
> +startElement (void * info, const xmlChar * name, const xmlChar ** atts)
> +{
> + /* Look for RDFa triple describing the license */
> + if ( strcmp((char*)name,"a") == 0 ) {
> + /* This tag is a license. Ignore, however, if it is
> referring to another document */
> + if ( has_attribute(atts,"rel","license") &&
> !has_attribute(atts,"about",NULL) ) {
> + const xmlChar *href = lookup_attribute(atts,"href");
> + if ( href ) {
> + g_hash_table_insert (((HTMLParseInfo
> *)info)->metadata, g_strdup ("File:License"),
> + g_strdup( (char*)href ));
> + }
> + }
> + } else if ( strcmp((char*)name,"title") == 0 ) {
> + ((HTMLParseInfo *)info)->current = READ_TITLE;
> + } else if ( strcmp((char*)name,"meta") == 0 ) {
> + if ( has_attribute(atts,"name","Author") ) {
> + const xmlChar *author =
> lookup_attribute(atts,"content");
> + if ( author ) {
> + g_hash_table_insert (((HTMLParseInfo
> *)info)->metadata, g_strdup ("Doc:Author"),
> + g_strdup( (char*)author
> ));
> + }
> + }
> + if ( has_attribute(atts,"name","DC.Description") ) {
> + const xmlChar *desc =
> lookup_attribute(atts,"content");
> + if ( desc ) {
> + g_hash_table_insert (((HTMLParseInfo
> *)info)->metadata, g_strdup ("Doc:Comments"),
> + g_strdup( (char*)desc ));
> + }
> + }
> + }
> +}
> +
> +void
> +characters(void * info, const xmlChar * ch, int len)
> +{
> + switch(((HTMLParseInfo *)info)->current) {
> + case READ_TITLE:
> + g_hash_table_insert (((HTMLParseInfo
> *)info)->metadata, g_strdup ("Doc:Title"),
> + g_strdup( (char*)ch ));
> + break;
> + default: break;
> + }
> +
> + ((HTMLParseInfo *)info)->current = -1;
> +}
> +
> +void tracker_extract_html (gchar* filename, GHashTable *metadata)
> +{
> + xmlSAXHandler SAXHandlerStruct = {
> + NULL, /* internalSubset */
> + NULL, /* isStandalone */
> + NULL, /* hasInternalSubset */
> + NULL, /* hasExternalSubset */
> + NULL, /* resolveEntity */
> + NULL, /* getEntity */
> + NULL, /* entityDecl */
> + NULL, /* notationDecl */
> + NULL, /* attributeDecl */
> + NULL, /* elementDecl */
> + NULL, /* unparsedEntityDecl */
> + NULL, /* setDocumentLocator */
> + NULL, /* startDocument */
> + NULL, /* endDocument */
> + startElement, /* startElement */
> + NULL, /* endElement */
> + NULL, /* reference */
> + characters, /* characters */
> + NULL, /* ignorableWhitespace */
> + NULL, /* processingInstruction */
> + NULL, /* comment */
> + NULL, /* xmlParserWarning */
> + NULL, /* xmlParserError */
> + NULL, /* xmlParserError */
> + NULL, /* getParameterEntity */
> + NULL, /* cdataBlock */
> + NULL, /* externalSubset */
> + 1, /* initialized */
> + NULL, /* private */
> + NULL, /* startElementNsSAX2Func */
> + NULL, /* endElementNsSAX2Func */
> + NULL /* xmlStructuredErrorFunc */
> + };
> +
> + HTMLParseInfo info = { metadata, -1 };
> +
> + htmlDocPtr doc;
> + doc = htmlSAXParseFile(filename, NULL, &SAXHandlerStruct, &info);
> + if ( doc ) {
> + xmlFreeDoc(doc);
> + }
> +}
> +
> +#else
> +#warning "Not building HTML metadata extractor."
> +#endif
> _______________________________________________
> tracker-list mailing list
> tracker-list AT gnome.org
> http://mail.gnome.org/mailman/listinfo/tracker-list
--
Jon Phillips

San Francisco, CA
USA PH 510.499.0894
jon AT rejon.org
http://www.rejon.org

MSN, AIM, Yahoo Chat: kidproto
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