Re: [Libguestfs] [PATCH] hivexml

I've made some changes to hivexml.c, that I think addresses the invalid XML that is being generated (as of version 1.3.3). I'm only addressing invalid XML characters in string values and string-lists. As I saw mentioned in earlier forum messages (https://www.redhat.com/archives/libguestfs/2011-September/msg00082.html), there could be invalid XML character issues in keys as well, but that is not addressed in this patch. Secondly, I slightly modified the string element in that I used a value attribute to more closely align with the earlier change that Alex did to singular string values. I've addressed the three of you because you all commented on the earlier patch, and I would like to get your feedback on mine. If you'd like me to post to the libguestfs mailing list, I could do so... let me know if there are patch standards that I should use. The approach I took was toI use XMLisCharQ() to check each UTF-8 string value in value_string and value_mulitple_string. The issue I encountered was that the following UTF-8 string was occurring in a clean Win7 install -- e689a4 02 eb8288c 7937 46 5 The 02 (^B) is an invalid XML character in the 1.0 spec, and was causing xmllint to fail in the following manner [hivex-1.3.3-orig]# xmllint xmlout.orig xmlout.orig:2: parser error : PCDATA invalid Char value 2 18T02:23:42Z</mtime><value type="string-list" key="Autorecover MOFs"><string>æ¤ ^ After the patch, ...with all the surrounding stuff cut away [hivex-1.3.3-new]# xmllint xmlout.new | tidy -raw -xml -i <?xml version="1.0" encoding="utf-8"?> <hive> <mtime>2011-02-18T02:23:42Z</mtime> <value type="string-list" key="Autorecover MOFs"> <string encoding="base64" value="5omkAuuCiMeTdGU=" /> </value> </hive> And the patch itself... [hivex]# cat hivexml.patch diff -uprN hivex-1.3.3-orig/xml/hivexml.c hivex-1.3.3-new/xml/hivexml.c --- hivex-1.3.3-orig/xml/hivexml.c 2011-09-22 09:17:09.000000000 -0400 +++ hivex-1.3.3-new/xml/hivexml.c 2012-01-30 23:39:14.995639422 -0500 @@ -33,6 +33,7 @@ #endif #include <libxml/xmlwriter.h> +#include <libxml/chvalid.h> #include "hivex.h" @@ -209,6 +210,22 @@ filetime_to_8601 (int64_t windows_ticks) } static int +isValidXMLString(const char *string)

+{ + int c; + int len = strlen(string); + int pos = 0; + int charlen = len; + while ((c = xmlGetUTF8Char(string+pos, &charlen)) >= 0) { + if (xmlIsCharQ(c) == 0) + return 0; + pos += charlen; + charlen = len - pos; + } + return 1; +} + +static int node_start (hive_h *h, void *writer_v, hive_node_h node, const char *name) { int64_t last_modified; @@ -265,6 +282,20 @@ end_value (xmlTextWriterPtr writer) XML_CHECK (xmlTextWriterEndElement, (writer)); } +static void +start_string(xmlTextWriterPtr writer, const char *encoding) +{ + XML_CHECK (xmlTextWriterStartElement, (writer, BAD_CAST "string")); + if (encoding) + XML_CHECK (xmlTextWriterWriteAttribute, (writer, BAD_CAST "encoding", BAD_CAST encoding)); +} + +static void +end_string(xmlTextWriterPtr writer) +{ + XML_CHECK (xmlTextWriterEndElement, (writer)); +} + static int value_string (hive_h *h, void *writer_v, hive_node_h node, hive_value_h value, hive_type t, size_t len, const char *key, const char *str) @@ -292,9 +323,14 @@ value_string (hive_h *h, void *writer_v, type = "unknown"; } - start_value (writer, key, type, NULL); + int validXML = isValidXMLString(str); + start_value (writer, key, type, validXML ? NULL : "base64"); XML_CHECK (xmlTextWriterStartAttribute, (writer, BAD_CAST "value")); - XML_CHECK (xmlTextWriterWriteString, (writer, BAD_CAST str)); + if (validXML) + XML_CHECK (xmlTextWriterWriteString, (writer, BAD_CAST str)); + else + XML_CHECK (xmlTextWriterWriteBase64, (writer, str, 0, strlen(str))); + XML_CHECK (xmlTextWriterEndAttribute, (writer)); end_value (writer); return 0; @@ -310,9 +346,14 @@ value_multiple_strings (hive_h *h, void size_t i; for (i = 0; argv[i] != NULL; ++i) { - XML_CHECK (xmlTextWriterStartElement, (writer, BAD_CAST "string")); - XML_CHECK (xmlTextWriterWriteString, (writer, BAD_CAST argv[i])); - XML_CHECK (xmlTextWriterEndElement, (writer)); + int validXML = isValidXMLString(argv[i]); + start_string(writer, validXML ? NULL : "base64"); + XML_CHECK (xmlTextWriterStartAttribute, (writer, BAD_CAST "value")); + if (validXML) + XML_CHECK (xmlTextWriterWriteString, (writer, BAD_CAST argv[i])); + else + XML_CHECK (xmlTextWriterWriteBase64, (writer, argv[i], 0, strlen(argv[i]))); + end_string(writer); } end_value (writer); [hivex]#