error: Make sure that error messages are valid UTF-8

This has caused issues with the Python bindings for a long time.

Should fix #64.

error.c

@@ -163,7 +163,7 @@ xmlParserPrintFileInfo(xmlParserInputPtr input) {
 }
 
 /**
- * xmlParserPrintFileContext:
+ * xmlParserPrintFileContextInternal:
  * @input:  an xmlParserInputPtr input
  *
  * Displays current context within the input content for error tracking
@@ -172,7 +172,7 @@ xmlParserPrintFileInfo(xmlParserInputPtr input) {
 static void
 xmlParserPrintFileContextInternal(xmlParserInputPtr input ,
 		xmlGenericErrorFunc channel, void *data ) {
-    const xmlChar *cur, *base;
+    const xmlChar *cur, *base, *start;
     unsigned int n, col;	/* GCC warns if signed, because compared with sizeof() */
     xmlChar  content[81]; /* space for 80 chars + line terminator */
     xmlChar *ctnt;
@@ -191,19 +191,30 @@ xmlParserPrintFileContextInternal(xmlParserInputPtr input ,
     while ((n++ < (sizeof(content)-1)) && (cur > base) &&
 	   (*(cur) != '\n') && (*(cur) != '\r'))
         cur--;
-    if ((*(cur) == '\n') || (*(cur) == '\r')) cur++;
+    if ((*(cur) == '\n') || (*(cur) == '\r')) {
+        cur++;
+    } else {
+        /* skip over continuation bytes */
+        while ((cur < input->cur) && ((*cur & 0xC0) == 0x80))
+            cur++;
+    }
     /* calculate the error position in terms of the current position */
     col = input->cur - cur;
     /* search forward for end-of-line (to max buff size) */
     n = 0;
-    ctnt = content;
+    start = cur;
     /* copy selected text to our buffer */
-    while ((*cur != 0) && (*(cur) != '\n') &&
-	   (*(cur) != '\r') && (n < sizeof(content)-1)) {
-		*ctnt++ = *cur++;
-	n++;
+    while ((*cur != 0) && (*(cur) != '\n') && (*(cur) != '\r')) {
+        int len = input->end - cur;
+        int c = xmlGetUTF8Char(cur, &len);
+
+        if ((c < 0) || (n + len > sizeof(content)-1))
+            break;
+        cur += len;
+	n += len;
     }
-    *ctnt = 0;
+    memcpy(content, start, n);
+    content[n] = 0;
     /* print out the selected text */
     channel(data ,"%s\n", content);
     /* create blank line with problem pointer */

result/HTML/utf8bug.html.err

@@ -11,5 +11,5 @@
 ز همکاران است. روی آن کلیک کند.</FONT></FONT></STRONG><S1
                                                                                ^
 ./test/HTML/utf8bug.html:177: HTML parser error : htmlParseEntityRef: expecting ';'
-§ÛŒÙ† پاسخ را برای نویسنده مقاله رجانیوز copy&paste
+ین پاسخ را برای نویسنده مقاله رجانیوز copy&paste 
                                                                                ^

result/errors/754947.xml.ent

@@ -1,7 +1,7 @@
 ./test/errors/754947.xml:1: parser error : Input is not proper UTF-8, indicate encoding !
 Bytes: 0xEE 0x5D 0x5D 0x3E
-<d><![CDATA[0000000000000î]]>
+<d><![CDATA[0000000000000
                          ^
 ./test/errors/754947.xml:1: parser error : Premature end of data in tag d line 1
-<d><![CDATA[0000000000000î]]>
+<d><![CDATA[0000000000000
                          ^

result/errors/754947.xml.err

@@ -1,7 +1,7 @@
 ./test/errors/754947.xml:1: parser error : Input is not proper UTF-8, indicate encoding !
 Bytes: 0xEE 0x5D 0x5D 0x3E
-<d><![CDATA[0000000000000î]]>
+<d><![CDATA[0000000000000
                          ^
 ./test/errors/754947.xml:1: parser error : Premature end of data in tag d line 1
-<d><![CDATA[0000000000000î]]>
+<d><![CDATA[0000000000000
                          ^

result/errors/754947.xml.str

@@ -1,5 +1,5 @@
 ./test/errors/754947.xml:1: parser error : Input is not proper UTF-8, indicate encoding !
 Bytes: 0xEE 0x5D 0x5D 0x3E
-<d><![CDATA[0000000000000î]]>
+<d><![CDATA[0000000000000
                          ^
 ./test/errors/754947.xml : failed to parse

result/errors/759573-2.xml.ent

@@ -18,18 +18,18 @@ Entity: line 1:
                    ^
 ./test/errors/759573-2.xml:6: parser error : internal error: xmlParseInternalSubset: error detected in Markup declaration
 
-%xx;ÿggKENSMYNT#MENTD&#372zz;'>
+%xx;
     ^
 Entity: line 2: 
 <![INCLUDE[
   ^
 ./test/errors/759573-2.xml:6: parser error : internal error: xmlParseInternalSubset: error detected in Markup declaration
 
-%xx;ÿggKENSMYNT&#35;MENTD&#372zz;'>
+%xx;
     ^
 ./test/errors/759573-2.xml:6: parser error : DOCTYPE improperly terminated
-%xx;ÿggKENSMYNT&#35;MENTD&#372zz;'>
+%xx;
     ^
 ./test/errors/759573-2.xml:6: parser error : Start tag expected, '<' not found
-%xx;ÿggKENSMYNT&#35;MENTD&#372zz;'>
+%xx;
     ^

result/errors/759573-2.xml.err

@@ -18,18 +18,18 @@ Entity: line 1:
                    ^
 ./test/errors/759573-2.xml:6: parser error : internal error: xmlParseInternalSubset: error detected in Markup declaration
 
-%xx;ÿggKENSMYNT#MENTD&#372zz;'>
+%xx;
     ^
 Entity: line 2: 
 <![INCLUDE[
   ^
 ./test/errors/759573-2.xml:6: parser error : internal error: xmlParseInternalSubset: error detected in Markup declaration
 
-%xx;ÿggKENSMYNT&#35;MENTD&#372zz;'>
+%xx;
     ^
 ./test/errors/759573-2.xml:6: parser error : DOCTYPE improperly terminated
-%xx;ÿggKENSMYNT&#35;MENTD&#372zz;'>
+%xx;
     ^
 ./test/errors/759573-2.xml:6: parser error : Start tag expected, '<' not found
-%xx;ÿggKENSMYNT&#35;MENTD&#372zz;'>
+%xx;
     ^

result/errors/759573-2.xml.str

@@ -18,16 +18,16 @@ Entity: line 1:
                    ^
 ./test/errors/759573-2.xml:6: parser error : internal error: xmlParseInternalSubset: error detected in Markup declaration
 
-%xx;ÿggKENSMYNT#MENTD&#372zz;'>
+%xx;
     ^
 Entity: line 2: 
 <![INCLUDE[
   ^
 ./test/errors/759573-2.xml:6: parser error : internal error: xmlParseInternalSubset: error detected in Markup declaration
 
-%xx;ÿggKENSMYNT&#35;MENTD&#372zz;'>
+%xx;
     ^
 ./test/errors/759573-2.xml:6: parser error : DOCTYPE improperly terminated
-%xx;ÿggKENSMYNT&#35;MENTD&#372zz;'>
+%xx;
     ^
 ./test/errors/759573-2.xml : failed to parse

result/errors/cdata.xml.ent

@@ -1,4 +1,4 @@
 ./test/errors/cdata.xml:2: parser error : Input is not proper UTF-8, indicate encoding !
 Bytes: 0xE1 0x72 0x5D 0x5D
-<A><![CDATA[Cár]]></A>
+<A><![CDATA[C
              ^

result/errors/cdata.xml.err

@@ -1,4 +1,4 @@
 ./test/errors/cdata.xml:2: parser error : Input is not proper UTF-8, indicate encoding !
 Bytes: 0xE1 0x72 0x5D 0x5D
-<A><![CDATA[Cár]]></A>
+<A><![CDATA[C
              ^

result/errors/cdata.xml.str

@@ -1,5 +1,5 @@
 ./test/errors/cdata.xml:2: parser error : Input is not proper UTF-8, indicate encoding !
 Bytes: 0xE1 0x72 0x5D 0x5D
-<A><![CDATA[Cár]]></A>
+<A><![CDATA[C
              ^
 ./test/errors/cdata.xml : failed to parse

result/errors/utf8-1.xml.ent

@@ -0,0 +1,9 @@
+./test/errors/utf8-1.xml:1: parser error : StartTag: invalid element name
+..............................................................................<<
+                                                                               ^
+./test/errors/utf8-1.xml:1: parser error : StartTag: invalid element name
+..............................................................................<<
+                                                                               ^
+./test/errors/utf8-1.xml:2: parser error : Premature end of data in tag d line 1
+
+^

result/errors/utf8-1.xml.err

@@ -0,0 +1,9 @@
+./test/errors/utf8-1.xml:1: parser error : StartTag: invalid element name
+..............................................................................<<
+                                                                               ^
+./test/errors/utf8-1.xml:1: parser error : StartTag: invalid element name
+..............................................................................<<
+                                                                               ^
+./test/errors/utf8-1.xml:2: parser error : Premature end of data in tag d line 1
+
+^

result/errors/utf8-1.xml.str

@@ -0,0 +1,4 @@
+./test/errors/utf8-1.xml:1: parser error : StartTag: invalid element name
+..............................................................................<<
+                                                                               ^
+./test/errors/utf8-1.xml : failed to parse

result/errors/utf8-2.xml.ent

@@ -0,0 +1,9 @@
+./test/errors/utf8-2.xml:1: parser error : StartTag: invalid element name
+<d>.<<€€€€€€€€€€€€€€€€€€€€€€€€
+     ^
+./test/errors/utf8-2.xml:2: parser error : Couldn't find end of Start Tag €€€€€€€€€€€€€€€€€€€€€€€€€ line 1
+
+^
+./test/errors/utf8-2.xml:2: parser error : Premature end of data in tag d line 1
+
+^

result/errors/utf8-2.xml.err

@@ -0,0 +1,9 @@
+./test/errors/utf8-2.xml:1: parser error : StartTag: invalid element name
+<d>.<<€€€€€€€€€€€€€€€€€€€€€€€€
+     ^
+./test/errors/utf8-2.xml:2: parser error : Couldn't find end of Start Tag €€€€€€€€€€€€€€€€€€€€€€€€€ line 1
+
+^
+./test/errors/utf8-2.xml:2: parser error : Premature end of data in tag d line 1
+
+^

result/errors/utf8-2.xml.str

@@ -0,0 +1,4 @@
+./test/errors/utf8-2.xml:1: parser error : StartTag: invalid element name
+<d>.<<€€€€€€€€€€€€€€€€€€€€€€€€
+     ^
+./test/errors/utf8-2.xml : failed to parse

runtest.c

@@ -292,7 +292,7 @@ channel(void *ctx  ATTRIBUTE_UNUSED, const char *msg, ...) {
 }
 
 /**
- * xmlParserPrintFileContext:
+ * xmlParserPrintFileContextInternal:
  * @input:  an xmlParserInputPtr input
  *
  * Displays current context within the input content for error tracking
@@ -301,12 +301,14 @@ channel(void *ctx  ATTRIBUTE_UNUSED, const char *msg, ...) {
 static void
 xmlParserPrintFileContextInternal(xmlParserInputPtr input ,
 		xmlGenericErrorFunc chanl, void *data ) {
-    const xmlChar *cur, *base;
+    const xmlChar *cur, *base, *start;
     unsigned int n, col;	/* GCC warns if signed, because compared with sizeof() */
     xmlChar  content[81]; /* space for 80 chars + line terminator */
     xmlChar *ctnt;
 
-    if (input == NULL) return;
+    if ((input == NULL) || (input->cur == NULL))
+        return;
+
     cur = input->cur;
     base = input->base;
     /* skip backwards over any end-of-lines */
@@ -318,19 +320,30 @@ xmlParserPrintFileContextInternal(xmlParserInputPtr input ,
     while ((n++ < (sizeof(content)-1)) && (cur > base) &&
 	   (*(cur) != '\n') && (*(cur) != '\r'))
         cur--;
-    if ((*(cur) == '\n') || (*(cur) == '\r')) cur++;
+    if ((*(cur) == '\n') || (*(cur) == '\r')) {
+        cur++;
+    } else {
+        /* skip over continuation bytes */
+        while ((cur < input->cur) && ((*cur & 0xC0) == 0x80))
+            cur++;
+    }
     /* calculate the error position in terms of the current position */
     col = input->cur - cur;
     /* search forward for end-of-line (to max buff size) */
     n = 0;
-    ctnt = content;
+    start = cur;
     /* copy selected text to our buffer */
-    while ((*cur != 0) && (*(cur) != '\n') &&
-   (*(cur) != '\r') && (n < sizeof(content)-1)) {
-		*ctnt++ = *cur++;
-	n++;
+    while ((*cur != 0) && (*(cur) != '\n') && (*(cur) != '\r')) {
+        int len = input->end - cur;
+        int c = xmlGetUTF8Char(cur, &len);
+
+        if ((c < 0) || (n + len > sizeof(content)-1))
+            break;
+        cur += len;
+	n += len;
     }
-    *ctnt = 0;
+    memcpy(content, start, n);
+    content[n] = 0;
     /* print out the selected text */
     chanl(data ,"%s\n", content);
     /* create blank line with problem pointer */

test/errors/utf8-1.xml

@@ -0,0 +1 @@
+<d>Ä..............................................................................<<

test/errors/utf8-2.xml

@@ -0,0 +1 @@
+<d>.<<€€€€€€€€€€€€€€€€€€€€€€€€€