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Fix: memory leak in XML.parse and XML.parse_html methods #16414

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Merged
merged 2 commits into from
Nov 27, 2025
+28 −8
Merged

Fix: memory leak in XML.parse and XML.parse_html methods #16414

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df9cf99
Free parser context after use.
toddsundsted Nov 23, 2025
36c769a
Refactor parser context management into helpers.
toddsundsted Nov 24, 2025
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34 changes: 26 additions & 8 deletions src/xml.cr
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Original file line number Diff line number Diff line change
Expand Up @@ -51,13 +51,34 @@ require "./xml/libxml2"
# string # => "<?xml version=\"1.0\"?>\n<person id=\"1\">\n <firstname>Jane</firstname>\n <lastname>Doe</lastname>\n</person>\n"
# ```
module XML
# Wraps a block that uses a XML parser context. Allocates the
# context and ensures the context is freed after use.
private def self.parse_xml(&)
ctxt = LibXML.xmlNewParserCtxt
begin
from_ptr(ctxt) { yield ctxt }
ensure
LibXML.xmlFreeParserCtxt(ctxt)
end
end

# Wraps a block that uses a HTML parser context. Allocates the
# context and ensures the context is freed after use.
private def self.parse_html(&)
ctxt = LibXML.htmlNewParserCtxt
begin
from_ptr(ctxt) { yield ctxt }
ensure
LibXML.htmlFreeParserCtxt(ctxt)
end
end

# Parses an XML document from *string* with *options* into an `XML::Node`.
#
# See `ParserOptions.default` for default options.
def self.parse(string : String, options : ParserOptions = ParserOptions.default) : Document
raise XML::Error.new("Document is empty", 0) if string.empty?
ctxt = LibXML.xmlNewParserCtxt
from_ptr(ctxt) do
parse_xml do |ctxt|
LibXML.xmlCtxtReadMemory(ctxt, string, string.bytesize, nil, nil, options)
end
end
Expand All @@ -66,8 +87,7 @@ module XML
#
# See `ParserOptions.default` for default options.
def self.parse(io : IO, options : ParserOptions = ParserOptions.default) : Document
ctxt = LibXML.xmlNewParserCtxt
from_ptr(ctxt) do
parse_xml do |ctxt|
LibXML.xmlCtxtReadIO(ctxt, ->read_callback, ->close_callback, Box(IO).box(io), nil, nil, options)
end
end
Expand All @@ -77,8 +97,7 @@ module XML
# See `HTMLParserOptions.default` for default options.
def self.parse_html(string : String, options : HTMLParserOptions = HTMLParserOptions.default) : Document
raise XML::Error.new("Document is empty", 0) if string.empty?
ctxt = LibXML.htmlNewParserCtxt
from_ptr(ctxt) do
parse_html do |ctxt|
LibXML.htmlCtxtReadMemory(ctxt, string, string.bytesize, nil, "utf-8", options)
end
end
Expand All @@ -87,8 +106,7 @@ module XML
#
# See `HTMLParserOptions.default` for default options.
def self.parse_html(io : IO, options : HTMLParserOptions = HTMLParserOptions.default) : Document
ctxt = LibXML.htmlNewParserCtxt
from_ptr(ctxt) do
parse_html do |ctxt|
LibXML.htmlCtxtReadIO(ctxt, ->read_callback, ->close_callback, Box(IO).box(io), nil, "utf-8", options)
end
end
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2 changes: 2 additions & 0 deletions src/xml/libxml2.cr
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Original file line number Diff line number Diff line change
Expand Up @@ -175,10 +175,12 @@ lib LibXML
fun xmlNewParserCtxt : ParserCtxt
fun xmlCtxtReadIO(ParserCtxt, ioread : InputReadCallback, ioclose : InputCloseCallback, ioctx : Void*, url : UInt8*, encoding : UInt8*, options : XML::ParserOptions) : Doc*
fun xmlCtxtReadMemory(ParserCtxt, buffer : UInt8*, size : Int, url : UInt8*, encoding : UInt8*, options : XML::ParserOptions) : Doc*
fun xmlFreeParserCtxt(ctxt : ParserCtxt)

fun htmlNewParserCtxt : HTMLParserCtxt
fun htmlCtxtReadMemory(HTMLParserCtxt, buffer : UInt8*, size : Int, url : UInt8*, encoding : UInt8*, options : XML::HTMLParserOptions) : Doc*
fun htmlCtxtReadIO(HTMLParserCtxt, ioread : InputReadCallback, ioclose : InputCloseCallback, ioctx : Void*, url : UInt8*, encoding : UInt8*, options : XML::HTMLParserOptions) : Doc*
fun htmlFreeParserCtxt(ctxt : HTMLParserCtxt)

fun xmlDocGetRootElement(doc : Doc*) : Node*
fun xmlXPathNodeSetCreate(node : Node*) : NodeSet*
Expand Down