From 956dfd2dddfe9b88ce9643f5495bf9a746bcbcfd Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Sat, 27 Sep 2025 21:43:57 +0200
Subject: [PATCH] xmllint: Use zlib directly

This prepares xmllint for eventually removing decompression support from
libxml2.
---
 CMakeLists.txt |  3 +++
 Makefile.am    |  4 +--
 configure.ac   |  2 ++
 meson.build    |  4 +++
 xmllint.c      | 69 +++++++++++++++++++++++++++++++++++++++++++++-----
 5 files changed, 73 insertions(+), 9 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 116c77dd2..b9981fdc8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -455,6 +455,9 @@ if(LIBXML2_WITH_PROGRAMS)
         endif()
         install(TARGETS    ${PROGRAM} EXPORT LibXml2 RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR} COMPONENT programs)
     endforeach()
+    if(LIBXML2_WITH_ZLIB)
+        target_link_libraries(xmllint ZLIB::ZLIB)
+    endif()
 endif()
 
 if(LIBXML2_WITH_TESTS)
diff --git a/Makefile.am b/Makefile.am
index 19ec30550..f053b2f04 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -137,9 +137,9 @@ runsuite_DEPENDENCIES = $(DEPS)
 runsuite_LDADD= $(LDADDS)
 
 xmllint_SOURCES = xmllint.c shell.c lintmain.c
-xmllint_CFLAGS = $(AM_CFLAGS) $(RDL_CFLAGS)
+xmllint_CFLAGS = $(AM_CFLAGS) $(RDL_CFLAGS) $(Z_CFLAGS)
 xmllint_DEPENDENCIES = $(DEPS)
-xmllint_LDADD=  $(RDL_LIBS) $(LDADDS)
+xmllint_LDADD = $(RDL_LIBS) $(Z_LIBS) $(LDADDS)
 
 testModule_SOURCES=testModule.c
 testModule_DEPENDENCIES = $(DEPS)
diff --git a/configure.ac b/configure.ac
index 4eb629bb3..d8dc4e1b4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -838,6 +838,8 @@ if test "$with_zlib" != "no" && test "$with_zlib" != ""; then
     XML_PRIVATE_LIBS="${XML_PRIVATE_LIBS} ${Z_LIBS}"
 fi
 AC_SUBST(WITH_ZLIB)
+AC_SUBST(Z_CFLAGS)
+AC_SUBST(Z_LIBS)
 
 dnl
 dnl Checks for iconv library.
diff --git a/meson.build b/meson.build
index e0f1c729c..1d4b6c3b5 100644
--- a/meson.build
+++ b/meson.build
@@ -356,6 +356,10 @@ if want_history
     xmllint_deps += history_dep
 endif
 
+if want_zlib
+    xmllint_deps += dependency('zlib')
+endif
+
 ### crypto
 if sys_windows == true
     bcrypt_dep = cc.find_library('bcrypt', required: true)
diff --git a/xmllint.c b/xmllint.c
index 5140e9358..cd629ee11 100644
--- a/xmllint.c
+++ b/xmllint.c
@@ -33,6 +33,10 @@
   #endif
 #endif
 
+#ifdef LIBXML_ZLIB_ENABLED
+  #include <zlib.h>
+#endif
+
 #include <libxml/xmlmemory.h>
 #include <libxml/parser.h>
 #include <libxml/parserInternals.h>
@@ -329,10 +333,28 @@ xmllintResourceLoader(void *ctxt, const char *URL,
  *									*
  ************************************************************************/
 
+#ifdef LIBXML_ZLIB_ENABLED
+static int
+xmllintGzRead(void *ctxt, char *buf, int len) {
+    return gzread(ctxt, buf, len);
+}
+
+static int
+xmllintGzClose(void *ctxt) {
+    if (gzclose(ctxt) != Z_OK)
+        return -1;
+
+    return 0;
+}
+#endif
+
 static xmlDocPtr
 parseXml(xmllintState *lint, const char *filename) {
     xmlParserCtxtPtr ctxt = lint->ctxt;
     xmlDocPtr doc;
+#ifdef LIBXML_ZLIB_ENABLED
+    gzFile gz;
+#endif
 
 #ifdef LIBXML_PUSH_ENABLED
     if (lint->appOptions & XML_LINT_PUSH_ENABLED) {
@@ -380,12 +402,26 @@ parseXml(xmllintState *lint, const char *filename) {
     }
 #endif
 
+#ifdef LIBXML_ZLIB_ENABLED
     if (strcmp(filename, "-") == 0)
-        doc = xmlCtxtReadFd(ctxt, STDIN_FILENO, "-", NULL,
-                            lint->parseOptions | XML_PARSE_UNZIP);
+        gz = gzdopen(STDIN_FILENO, "rb");
     else
-        doc = xmlCtxtReadFile(ctxt, filename, NULL,
-                              lint->parseOptions | XML_PARSE_UNZIP);
+        gz = gzopen(filename, "rb");
+
+    if (gz == NULL) {
+        fprintf(lint->errStream, "Can't open %s\n", filename);
+        lint->progresult = XMLLINT_ERR_RDFILE;
+        return(NULL);
+    }
+
+    doc = xmlCtxtReadIO(ctxt, xmllintGzRead, xmllintGzClose, gz,
+                        filename, NULL, lint->parseOptions);
+#else
+    if (strcmp(filename, "-") == 0)
+        doc = xmlCtxtReadFd(ctxt, STDIN_FILENO, "-", NULL, lint->parseOptions);
+    else
+        doc = xmlCtxtReadFile(ctxt, filename, NULL, lint->parseOptions);
+#endif
 
     return(doc);
 }
@@ -1351,16 +1387,35 @@ static void streamFile(xmllintState *lint, const char *filename) {
     } else
 #endif
     {
+#ifdef LIBXML_ZLIB_ENABLED
+        gzFile gz;
+#endif
+
         xmlResetLastError();
 
+#ifdef LIBXML_ZLIB_ENABLED
+        if (strcmp(filename, "-") == 0)
+            gz = gzdopen(STDIN_FILENO, "rb");
+        else
+            gz = gzopen(filename, "rb");
+
+        if (gz == NULL) {
+            fprintf(lint->errStream, "Can't open %s\n", filename);
+            lint->progresult = XMLLINT_ERR_RDFILE;
+            return;
+        }
+
+        reader = xmlReaderForIO(xmllintGzRead, xmllintGzClose, gz,
+                                filename, NULL, lint->parseOptions);
+#else
         if (strcmp(filename, "-") == 0) {
             reader = xmlReaderForFd(STDIN_FILENO, "-", NULL,
-                                    lint->parseOptions | XML_PARSE_UNZIP);
+                                    lint->parseOptions);
         }
         else {
-            reader = xmlReaderForFile(filename, NULL,
-                                      lint->parseOptions | XML_PARSE_UNZIP);
+            reader = xmlReaderForFile(filename, NULL, lint->parseOptions);
         }
+#endif
         if (reader == NULL) {
             const xmlError *error = xmlGetLastError();