android toolchain: add the missing xmllint tool

MODULE.bazel

@@ -9,6 +9,7 @@ bazel_dep(name = "rules_license", version = "1.0.0")
 bazel_dep(name = "rules_java", version = "9.3.0")
 bazel_dep(name = "rules_cc", version = "0.2.14")
 bazel_dep(name = "rules_shell", version = "0.6.1")
+bazel_dep(name = "libxml2", version = "2.15.3")
 
 bazel_dep(name = "stardoc", version = "0.8.0", dev_dependency = True)
 
@@ -58,6 +59,7 @@ python.toolchain(
 bazel_dep(name = "rules_proto", version = "7.1.0", repo_name = "rules_proto")
 
 maven = use_extension("@rules_jvm_external//:extensions.bzl", "maven")
+
 # Maven for android_ide_common need to be separated into their own separate maven_install for now
 # due to compatibility issues with newer versions.
 maven.install(

prereqs.bzl

@@ -212,6 +212,18 @@ def rules_android_prereqs(dev_mode = False):
         ],
     )
 
+    maybe(
+        http_archive,
+        name = "libxml2",
+        sha256 = "0da50c1415f4ec0364569d2119b1436ba837b31df44af28569d234272c23cf1f",
+        strip_prefix = "libxml2-v2.15.3",
+        build_file = Label("//third_party/libxml2:BUILD.bazel"),
+        patches = [Label("//third_party/libxml2:00_config_h.patch")],
+        urls = [
+            "https://gitlab.gnome.org/GNOME/libxml2/-/archive/v2.15.3/libxml2-v2.15.3.tar.gz",
+        ],
+    )
+
     _apksig_archive()
     _com_android_dex_archive()
 

third_party/libxml2/00_config_h.patch

@@ -0,0 +1,76 @@
+This patch injects the libxml2 config.h file required for the build. It was generated using the
+overlay from the Bazel Central Registry from
+https://github.com/bazelbuild/bazel-central-registry/tree/main/modules/libxml2/2.15.3/overlay/config.h
+
+To update or regenerate this patch:
+1. Download config.h from https://raw.githubusercontent.com/bazelbuild/bazel-central-registry/main/modules/libxml2/<VERSION>/overlay/config.h
+2. Run: diff -u --label /dev/null /dev/null --label b/config.h config.h > 00_config_h.patch
+3. Re-add this comments to the patch file.
+
+--- /dev/null
++++ b/config.h
+@@ -0,0 +1,64 @@
++/* config.h.  Generated from config.h.in by configure.  */
++/* config.h.in.  Generated from configure.ac by autoheader.  */
++
++/* Define to 1 if you have the <dlfcn.h> header file. */
++#define HAVE_DLFCN_H 1
++
++/* Define to 1 if you have the <inttypes.h> header file. */
++#define HAVE_INTTYPES_H 1
++
++/* Define to 1 if you have the <stdint.h> header file. */
++#define HAVE_STDINT_H 1
++
++/* Define to 1 if you have the <stdio.h> header file. */
++#define HAVE_STDIO_H 1
++
++/* Define to 1 if you have the <stdlib.h> header file. */
++#define HAVE_STDLIB_H 1
++
++/* Define to 1 if you have the <string.h> header file. */
++#define HAVE_STRING_H 1
++
++/* Define to 1 if you have the <sys/stat.h> header file. */
++#define HAVE_SYS_STAT_H 1
++
++/* Define to 1 if you have the <sys/types.h> header file. */
++#define HAVE_SYS_TYPES_H 1
++
++/* Define to the sub-directory where libtool stores uninstalled libraries. */
++#define LT_OBJDIR ".libs/"
++
++/* Name of package */
++#define PACKAGE "libxml2"
++
++/* Define to the address where bug reports for this package should be sent. */
++#define PACKAGE_BUGREPORT ""
++
++/* Define to the full name of this package. */
++#define PACKAGE_NAME "libxml2"
++
++/* Define to the full name and version of this package. */
++#define PACKAGE_STRING "libxml2 2.15.3"
++
++/* Define to the one symbol short name of this package. */
++#define PACKAGE_TARNAME "libxml2"
++
++/* Define to the home page for this package. */
++#define PACKAGE_URL ""
++
++/* Define to the version of this package. */
++#define PACKAGE_VERSION "2.15.3"
++
++/* Define to 1 if all of the C90 standard headers exist (not just the ones
++   required in a freestanding environment). This macro is provided for
++   backward compatibility; new code need not use it. */
++#define STDC_HEADERS 1
++
++/* Version number of package */
++#define VERSION "2.15.3"
++
++/* System configuration directory (/etc) */
++#define XML_SYSCONFDIR "/usr/local/etc"
++
++/* TLS specifier */
++/* #undef XML_THREAD_LOCAL */

third_party/libxml2/BUILD.bazel

@@ -0,0 +1,165 @@
+# Copied from https://github.com/bazelbuild/bazel-central-registry/blob/main/modules/libxml2/2.15.3/overlay/BUILD.bazel.
+
+load("@rules_cc//cc:cc_binary.bzl", "cc_binary")
+load("@rules_cc//cc:cc_library.bzl", "cc_library")
+load("@rules_cc//cc:cc_test.bzl", "cc_test")
+
+config_setting(
+    name = "is_windows_clang_mingw",
+    constraint_values = ["@platforms//os:windows"],
+    flag_values = {"@rules_cc//cc/compiler:compiler": "clang"},
+)
+
+config_setting(
+    name = "is_windows_clang_cl",
+    constraint_values = ["@platforms//os:windows"],
+    flag_values = {"@rules_cc//cc/compiler:compiler": "clang-cl"},
+)
+
+config_setting(
+    name = "is_windows_msvc",
+    constraint_values = ["@platforms//os:windows"],
+    flag_values = {"@rules_cc//cc/compiler:compiler": "msvc-cl"},
+)
+
+UNIX_DEFINES = [
+    "HAVE_DECL_GETENTROPY",
+    "HAVE_DECL_GLOB",
+    "HAVE_DECL_MMAP",
+    "HAVE_DLOPEN",
+    "HAVE_FUNC_ATTRIBUTE_DESTRUCTOR",
+    "HAVE_PTHREAD_H",
+    "HAVE_STRINGS_H",
+    "HAVE_UNISTD_H",
+]
+
+cc_library(
+    name = "xml2",
+    srcs = [
+        "HTMLparser.c",
+        "HTMLtree.c",
+        "SAX2.c",
+        "buf.c",
+        "c14n.c",
+        "catalog.c",
+        "chvalid.c",
+        "debugXML.c",
+        "dict.c",
+        "encoding.c",
+        "entities.c",
+        "error.c",
+        "globals.c",
+        "hash.c",
+        "list.c",
+        "nanohttp.c",
+        "parser.c",
+        "parserInternals.c",
+        "pattern.c",
+        "relaxng.c",
+        "schematron.c",
+        "threads.c",
+        "tree.c",
+        "uri.c",
+        "valid.c",
+        "xinclude.c",
+        "xlink.c",
+        "xmlIO.c",
+        "xmlmemory.c",
+        "xmlmodule.c",
+        "xmlreader.c",
+        "xmlregexp.c",
+        "xmlsave.c",
+        "xmlschemas.c",
+        "xmlschemastypes.c",
+        "xmlstring.c",
+        "xmlwriter.c",
+        "xpath.c",
+        "xpointer.c",
+    ] + glob(["include/private/*.h"]),
+    hdrs = glob([
+        "include/libxml/*.h",
+        "*.h",
+    ]),
+    defines = select({
+        "@platforms//os:linux": UNIX_DEFINES + [
+            "HAVE_POLL_H",
+        ],
+        "@platforms//os:macos": UNIX_DEFINES,
+        "@platforms//os:windows": [
+            "LIBXML_STATIC",
+            '"XML_THREAD_LOCAL=__declspec(thread)"',
+        ],
+        "//conditions:default": [],
+    }),
+    includes = ["include"],
+    linkopts = select({
+        ":is_windows_clang_cl": [
+            "bcrypt.lib",
+        ],
+        ":is_windows_msvc": [
+            "bcrypt.lib",
+        ],
+        ":is_windows_clang_mingw": [
+            "-lbcrypt",
+        ],
+        "//conditions:default": [
+            "-lm",
+            "-pthread",
+            "-ldl",
+        ],
+    }),
+    textual_hdrs = [
+        "codegen/charset.inc",
+        "codegen/escape.inc",
+        "codegen/html5ent.inc",
+        "codegen/ranges.inc",
+        "codegen/unicode.inc",
+    ],
+    visibility = ["//visibility:public"],
+)
+
+alias(
+    name = "libxml2",
+    actual = ":xml2",
+    visibility = ["//visibility:public"],
+)
+
+cc_binary(
+    name = "xmllint",
+    srcs = [
+        "lintmain.c",
+        "shell.c",
+        "xmllint.c",
+    ],
+    visibility = ["//visibility:public"],
+    deps = ["//:libxml2"],
+)
+
+cc_binary(
+    name = "xmlcatalog",
+    srcs = ["xmlcatalog.c"],
+    visibility = ["//visibility:public"],
+    deps = ["//:libxml2"],
+)
+
+DATA = glob([
+    "test/**",
+])
+
+[
+    cc_test(
+        name = test.removeprefix("test") + "_test",
+        srcs = [test + ".c"],
+        data = DATA,
+        deps = ["//:libxml2"],
+    )
+    for test in [
+        "testapi",
+        "testchar",
+        "testdict",
+        "testlimits",
+        # TODO(zbarsky): Figure out why these two fail in BCR CI but work locally...
+        # "testparser",
+        # "testrecurse",
+    ]
+]

toolchains/android/toolchain.bzl

@@ -269,6 +269,12 @@ _ATTRS = dict(
         default = "//toolchains/android:unzip",
         executable = True,
     ),
+    xmllint_tool = attr.label(
+        cfg = "exec",
+        default = "@libxml2//:xmllint",
+        allow_files = True,
+        executable = True,
+    ),
     xsltproc_tool = attr.label(
         cfg = "exec",
         default = Label("//tools/android/xslt:xslt"),