Entities which reference out-of-scope namespace have always been broken.
xmlParseBalancedChunkMemoryInternal tried to reuse the namespaces
currently in scope but these namespaces were ignored by the SAX handler.
Besides, there could be different namespaces in scope when expanding the
entity again. For example:
<!DOCTYPE doc [
<!ENTITY ent "<ns:elem/>">
]>
<doc>
<decl1 xmlns:ns="urn:ns1">
&ent;
</decl1>
<decl2 xmlns:ns="urn:ns2">
&ent;
</decl2>
</doc>
Add some comments outlining possible solutions to this problem.
For now, we stop copying namespaces to the temporary parser context
in xmlParseBalancedChunkMemoryInternal. This has never really worked
and the recent changes contained a partial fix which uncovered other
problems like a use-after-free with the XML Reader interface, found
by OSS-Fuzz.
Use a hash table to lookup namespaces by prefix. The hash table stores
an index into the namespace table. Auxiliary data for namespaces is
stored in a separate array along the main namespace table.
Use a hash table to verify attribute uniqueness. The hash table stores
an index into the attribute table.
Reuse hash value from the dictionary to avoid computing them twice.
See #346.
When decoding input data, check whether the "raw" buffer is empty after
parsing the document. Otherwise, the input ends with a truncated
multi-byte sequence which shouldn't be silently ignored.
Even with flush set to true, xmlCharEncInput didn't guarantee to decode
all data. This complicated the push parser.
Remove the flush flag and always decode all available data.
Also fix ICU code where the flush flag has a different meaning. Always
set flush to false and retry even with empty input buffers.
Don't create a copy of the whole input buffer. Read the data chunk by
chunk to save memory.
Historically, it was probably envisioned to read data from memory
without additional copying. This doesn't work reliably with the current
design of the XML parser which requires a terminating null byte at the
end of input buffers. This lead to xmlReadMemory interfaces, which
expect pointer and size arguments, being changed to make a
zero-terminated copy of the input buffer. Interfaces based on
xmlReadDoc, which actually expect a zero-terminated string and
would make zero-copy operation work, were then simplified to rely on
xmlReadMemoryi, resulting in an unnecessary copy.
To avoid copying (possibly gigabytes) of memory temporarily, we now
stream in-memory input just like content read from files in a
chunk-by-chunk fashion (using a somewhat outdated INPUT_CHUNK size of
250 bytes). As a side effect, we also avoid another copy of the whole
input when handling non-UTF-8 data which was made possible by some
earlier commits.
Interfaces expecting zero-terminated strings now make use of strnlen
which unfortunately isn't part of the standard C library and only
mandated since POSIX 2008.
Introduce XML_INPUT_HAS_ENCODING flag for xmlParserInput which is set
when xmlSwitchEncoding is called. The parser can use the flag to
reliably detect whether an encoding was already set via user override,
BOM or other auto-detection. In this case, the encoding declaration
won't be used to switch the encoding.
Before, an inscrutable mix of ctxt->charset, ctxt->input->encoding
and ctxt->input->buf->encoder was used.
Introduce private helper functions to switch encodings used by both the
XML and HTML parser:
- xmlDetectEncoding which skips over the BOM, allowing to remove the
BOM checks from other encoding functions.
- xmlSetDeclaredEncoding, replacing htmlCheckEncodingDirect, which warns
about encoding mismatches.
If users override the encoding, store the declared instead of the actual
encoding in xmlDoc. In this case, the actual encoding is known and the
raw value from the doc is more useful.
Also use the input flags to store the ISO-8859-1 fallback state.
Restrict the fallback to cases where no encoding was specified. (The
fallback is only useful in recovery mode and these days broken UTF-8 is
probably more likely than ISO-8859-1, so it might eventually be removed
completely.)
The 'charset' member of xmlParserCtxt is now unused. The 'encoding'
member of xmlParserInput is now unused.
The 'standalone' member of xmlParserInput is renamed to 'flags'.
A new parser state XML_PARSER_XML_DECL is added for the push parser.
It seems that this code path could only be triggered after an encoding
error in recovery mode. Creating char-ref nodes is unnecessary and
typically unexpected.
Follow-up to commit d0c3f01e. A parser context will be initialized to
SAX version 2, but this can be overridden with XML_PARSE_SAX1 later,
so we must initialize the SAX1 element handlers as well.
Change the check in xmlDetectSAX2 to only look for XML_SAX2_MAGIC, so
we don't switch to SAX1 if the SAX2 element handlers are NULL.
