From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Wed, 1 May 2024 15:21:04 +0000 (-0400)
Subject: Clean-up: modernize pretty_xml.cpp
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=HEAD;ds=sidebyside

Clean-up: modernize pretty_xml.cpp

Since pretty_xml was converted to C++, clang-tidy had a number of
grievances such as the use of NULL (instead of nullptr).

Since the file is very small, it is modernized to address those issues:
  - Wrap libxml2 resources in RAII wrappers
  - Use C++ IO APIs in lieu of fprintf

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ie90e3e05130f7916f411e0de36e8aac72a0f790c
---

diff --git a/tests/utils/xml-utils/common.hpp b/tests/utils/xml-utils/common.hpp
index 5acb1b1be..01a9b5207 100644
--- a/tests/utils/xml-utils/common.hpp
+++ b/tests/utils/xml-utils/common.hpp
@@ -13,8 +13,37 @@
 #include <libxml/parser.h>
 #include <memory>
 
-using xml_parser_ctx_uptr = std::unique_ptr<
+namespace lttng {
+namespace libxml {
+
+using parser_ctx_uptr = std::unique_ptr<
 	xmlParserCtxt,
 	lttng::memory::create_deleter_class<xmlParserCtxt, xmlFreeParserCtxt>::deleter>;
+using doc_uptr =
+	std::unique_ptr<xmlDoc, lttng::memory::create_deleter_class<xmlDoc, xmlFreeDoc>::deleter>;
+
+/*
+ * Manage the global parser context of libxml2.
+ * There should only be one instance of this class per process.
+ */
+class global_parser_context {
+public:
+	global_parser_context()
+	{
+		xmlInitParser();
+	}
+
+	~global_parser_context()
+	{
+		xmlCleanupParser();
+	}
 
+	/* Deactivate copy and assignment. */
+	global_parser_context(const global_parser_context&) = delete;
+	global_parser_context(global_parser_context&&) = delete;
+	global_parser_context& operator=(const global_parser_context&) = delete;
+	global_parser_context& operator=(global_parser_context&&) = delete;
+};
+} /* namespace libxml */
+} /* namespace lttng */
 #endif /* TESTS_UTILS_XML_UTILS_COMMON_HPP */
diff --git a/tests/utils/xml-utils/extract_xml.cpp b/tests/utils/xml-utils/extract_xml.cpp
index ad319d3c4..280f2ed02 100644
--- a/tests/utils/xml-utils/extract_xml.cpp
+++ b/tests/utils/xml-utils/extract_xml.cpp
@@ -38,6 +38,8 @@
 #include <string.h>
 #include <unistd.h>
 
+namespace ll = lttng::libxml;
+
 #if defined(LIBXML_XPATH_ENABLED)
 
 static int opt_verbose;
@@ -178,7 +180,7 @@ static int extract_xpath(const char *xml_path, const xmlChar *xpath)
 	LTTNG_ASSERT(xml_path);
 	LTTNG_ASSERT(xpath);
 
-	xml_parser_ctx_uptr parserCtx{ xmlNewParserCtxt() };
+	ll::parser_ctx_uptr parserCtx{ xmlNewParserCtxt() };
 
 	if (!parserCtx) {
 		fprintf(stderr, "ERR: could not allocate an XML parser context\n");
diff --git a/tests/utils/xml-utils/pretty_xml.cpp b/tests/utils/xml-utils/pretty_xml.cpp
index 7eb4710ca..8a6e967a7 100644
--- a/tests/utils/xml-utils/pretty_xml.cpp
+++ b/tests/utils/xml-utils/pretty_xml.cpp
@@ -12,34 +12,28 @@
 
 #include "common.hpp"
 
+#include <common/scope-exit.hpp>
+
+#include <iostream>
 #include <libxml/parser.h>
 #include <unistd.h>
 
+namespace ll = lttng::libxml;
+
 int main()
 {
-	xmlDocPtr doc = NULL;
-
-	/* Init libxml. */
-	xmlInitParser();
-
-	{
-		xml_parser_ctx_uptr parserCtx{ xmlNewParserCtxt() };
-
-		/* Parse the XML document from stdin. */
-		doc = xmlCtxtReadFd(
-			parserCtx.get(), STDIN_FILENO, nullptr, nullptr, XML_PARSE_NOBLANKS);
-		if (!doc) {
-			fprintf(stderr, "ERR parsing: xml input invalid");
-			return -1;
-		}
-
-		xmlDocFormatDump(stdout, doc, 1);
-
-		xmlFreeDoc(doc);
+	const ll::global_parser_context global_parser_context;
+	const ll::parser_ctx_uptr parserCtx{ xmlNewParserCtxt() };
+
+	/* Parse the XML document from stdin. */
+	const ll::doc_uptr doc{ xmlCtxtReadFd(
+		parserCtx.get(), STDIN_FILENO, nullptr, nullptr, XML_PARSE_NOBLANKS) };
+	if (!doc) {
+		std::cerr << "Error: invalid XML input on stdin\n";
+		return -1;
 	}
 
-	/* Shutdown libxml. */
-	xmlCleanupParser();
+	xmlDocFormatDump(stdout, doc.get(), 1);
 
 	return 0;
 }