[libxml2] Fix a bug on name parsing at the end of current input buffer

[Daniel Veillard <veillard src gnome org>]

commit 51f02b0a03ea1fa6c65b3f9fd88cf60fb5803783
Author: Daniel Veillard <veillard redhat com>
Date:   Tue Sep 15 16:50:32 2015 +0800

    Fix a bug on name parsing at the end of current input buffer
    
    For https://bugzilla.gnome.org/show_bug.cgi?id=754946
    
    When hitting the end of the current input buffer while parsing
    a name we could end up loosing the beginning of the name, which
    led to various issues.

 parser.c                     |   29 ++++++++++++++++++++---------
 result/errors/754946.xml.err |   16 ++++++++++++++++
 result/errors/754946.xml.str |    4 ++++
 test/errors/754946.xml       |    1 +
 4 files changed, 41 insertions(+), 9 deletions(-)
---
diff --git a/parser.c b/parser.c
index 0edd53b..fd29a39 100644
--- a/parser.c
+++ b/parser.c
@@ -3491,7 +3491,14 @@ xmlParseNCNameComplex(xmlParserCtxtPtr ctxt) {
        c = CUR_CHAR(l);
        if (c == 0) {
            count = 0;
+           /*
+            * when shrinking to extend the buffer we really need to preserve
+            * the part of the name we already parsed. Hence rolling back
+            * by current lenght.
+            */
+           ctxt->input->cur -= l;
            GROW;
+           ctxt->input->cur += l;
             if (ctxt->instate == XML_PARSER_EOF)
                 return(NULL);
            end = ctxt->input->cur;
@@ -3523,7 +3530,7 @@ xmlParseNCNameComplex(xmlParserCtxtPtr ctxt) {
 
 static const xmlChar *
 xmlParseNCName(xmlParserCtxtPtr ctxt) {
-    const xmlChar *in;
+    const xmlChar *in, *e;
     const xmlChar *ret;
     int count = 0;
 
@@ -3535,16 +3542,19 @@ xmlParseNCName(xmlParserCtxtPtr ctxt) {
      * Accelerator for simple ASCII names
      */
     in = ctxt->input->cur;
-    if (((*in >= 0x61) && (*in <= 0x7A)) ||
-       ((*in >= 0x41) && (*in <= 0x5A)) ||
-       (*in == '_')) {
+    e = ctxt->input->end;
+    if ((((*in >= 0x61) && (*in <= 0x7A)) ||
+        ((*in >= 0x41) && (*in <= 0x5A)) ||
+        (*in == '_')) && (in < e)) {
        in++;
-       while (((*in >= 0x61) && (*in <= 0x7A)) ||
-              ((*in >= 0x41) && (*in <= 0x5A)) ||
-              ((*in >= 0x30) && (*in <= 0x39)) ||
-              (*in == '_') || (*in == '-') ||
-              (*in == '.'))
+       while ((((*in >= 0x61) && (*in <= 0x7A)) ||
+               ((*in >= 0x41) && (*in <= 0x5A)) ||
+               ((*in >= 0x30) && (*in <= 0x39)) ||
+               (*in == '_') || (*in == '-') ||
+               (*in == '.')) && (in < e))
            in++;
+       if (in >= e)
+           goto complex;
        if ((*in > 0) && (*in < 0x80)) {
            count = in - ctxt->input->cur;
             if ((count > XML_MAX_NAME_LENGTH) &&
@@ -3562,6 +3572,7 @@ xmlParseNCName(xmlParserCtxtPtr ctxt) {
            return(ret);
        }
     }
+complex:
     return(xmlParseNCNameComplex(ctxt));
 }
 
diff --git a/result/errors/754946.xml b/result/errors/754946.xml
new file mode 100644
index 0000000..e69de29
diff --git a/result/errors/754946.xml.err b/result/errors/754946.xml.err
new file mode 100644
index 0000000..423dff5
--- /dev/null
+++ b/result/errors/754946.xml.err
@@ -0,0 +1,16 @@
+Entity: line 1: parser error : internal error: xmlParseInternalSubset: error detected in Markup declaration
+
+ %SYSTEM; 
+         ^
+Entity: line 1: 
+A<lbbbbbbbbbbbbbbbbbbb_
+^
+Entity: line 1: parser error : DOCTYPE improperly terminated
+ %SYSTEM; 
+         ^
+Entity: line 1: 
+A<lbbbbbbbbbbbbbbbbbbb_
+^
+./test/errors/754946.xml:1: parser error : Extra content at the end of the document
+<!DOCTYPEA[<!ENTITY %
+  ^
diff --git a/result/errors/754946.xml.str b/result/errors/754946.xml.str
new file mode 100644
index 0000000..3b748cc
--- /dev/null
+++ b/result/errors/754946.xml.str
@@ -0,0 +1,4 @@
+./test/errors/754946.xml:1: parser error : Extra content at the end of the document
+<!DOCTYPEA[<!ENTITY %
+          ^
+./test/errors/754946.xml : failed to parse
diff --git a/test/errors/754946.xml b/test/errors/754946.xml
new file mode 100644
index 0000000..6b5f9b0
--- /dev/null
+++ b/test/errors/754946.xml
@@ -0,0 +1 @@
+<!DOCTYPEA[<!ENTITY %SYSTEM "A<lbbbbbbbbbbbbbbbbbbb_">%SYSTEM;<![
\ No newline at end of file