/*

* Copyright © 2016-2025 The LmdbJava Open Source Project

*

* Licensed under the Apache License, Version 2.0 (the "License");

* you may not use this file except in compliance with the License.

* You may obtain a copy of the License at

*

* http://www.apache.org/licenses/LICENSE-2.0

*

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

*/

package org.lmdbjava;

import static java.lang.System.getProperty;

import static java.util.Locale.ENGLISH;

import java.io.IOException;

import java.nio.file.Files;

import java.nio.file.Paths;

import java.util.stream.Stream;

/**

* Determines the name of the target LMDB native library.

*

* <p>Users will typically use an LMDB native library that is embedded within the LmdbJava JAR.

* Embedded libraries are built by a Zig cross-compilation step as part of the release process. The

* naming convention reflects the Zig target name plus a common filename extension. This simplifies

* support for future Zig targets (eg with different toolchains etc).

*

* <p>Users can set two system properties to override the automatic resolution of an embedded

* library. Setting {@link #LMDB_NATIVE_LIB_PROP} will force use of that external LMDB library.

* Setting {@link #LMDB_EMBEDDED_LIB_PROP} will force use of that embedded LMDB library. If both are

* set, the former property will take precedence. Most users do not need to set either property.

*/

public final class TargetName {

/**

* True if the resolved native filename is an external file (conversely false indicates the file

* should be considered a classpath resource).

*/

public static final boolean IS_EXTERNAL;

/**

* Java system property name that can be set to override the embedded library that will be used.

* This is likely to be required if automatic resolution fails but the user still prefers to use

* an LmdbJava-bundled library. This path must include the classpath prefix (usually <code>

* org/lmdbjava/native</code>).

*/

public static final String LMDB_EMBEDDED_LIB_PROP = "lmdbjava.embedded.lib";

/**

* Java system property name that can be set to provide a custom path to an external LMDB system

* library.

*/

public static final String LMDB_NATIVE_LIB_PROP = "lmdbjava.native.lib";

/** Resolved target native filename or fully-qualified classpath location. */

public static final String RESOLVED_FILENAME;

private static final String ARCH = getProperty("os.arch");

private static final String EMBED = getProperty(LMDB_EMBEDDED_LIB_PROP);

private static final String EXTERNAL = getProperty(LMDB_NATIVE_LIB_PROP);

private static final String OS = getProperty("os.name");

static {

IS_EXTERNAL = isExternal(EXTERNAL);

RESOLVED_FILENAME = resolveFilename(EXTERNAL, EMBED, ARCH, OS);

}

private TargetName() {}

/**

* Resolves the filename extension of the bundled LMDB library for a given operating system.

*

* @param os typically the <code>os.name</code> system property

* @return extension of the LMDB system library bundled with LmdbJava

*/

public static String resolveExtension(final String os) {

return check(os, "Windows") ? "dll" : "so";

}

static boolean isExternal(final String external) {

return external != null && !external.isEmpty();

}

static String resolveFilename(

final String external, final String embed, final String arch, final String os) {

if (external != null && !external.isEmpty()) {

return external;

}

if (embed != null && !embed.isEmpty()) {

return embed;

}

final String pkg = TargetName.class.getPackage().getName().replace('.', '/');

return pkg

+ "/native/"

+ resolveArch(arch)

+ "-"

+ resolveOs(os)

+ "-"

+ resolveToolchain(os)

+ "."

+ resolveExtension(os);

}

/**

* Case insensitively checks whether the passed string starts with any of the candidate strings.

*

* @param string the string being checked

* @param candidates one or more candidate strings

* @return true if the string starts with any of the candidates

*/

private static boolean check(final String string, final String... candidates) {

if (string == null) {

return false;

}

final String strLower = string.toLowerCase(ENGLISH);

for (final String c : candidates) {

if (strLower.startsWith(c.toLowerCase(ENGLISH))) {

return true;

}

}

return false;

}

private static String err(final String reason) {

return reason

+ " (please set system property "

+ LMDB_NATIVE_LIB_PROP

+ " to the path of an external LMDB native library,"

+ " or simply 'lmdb' if LMDB is installed in standard system paths;"

+ " alternatively set property "

+ LMDB_EMBEDDED_LIB_PROP

+ " to the name of an LmdbJava embedded library;"

+ " os.arch='"

+ ARCH

+ "' os.name='"

+ OS

+ "')";

}

private static String resolveArch(final String arch) {

if (check(arch, "aarch64")) {

return "aarch64";

} else if (check(arch, "x86_64", "amd64")) {

return "x86_64";

}

throw new UnsupportedOperationException(err("Unsupported os.arch"));

}

private static String resolveOs(final String os) {

if (check(os, "Linux")) {

return "linux";

} else if (check(os, "Mac OS")) {

return "macos";

} else if (check(os, "Windows")) {

return "windows";

}

throw new UnsupportedOperationException(err("Unsupported os.name"));

}

private static String resolveToolchain(final String os) {

if (check(os, "Mac OS")) {

return "none";

}

return isMuslLibc() ? "musl" : "gnu";

}

private static boolean isMuslLibc() {

try (Stream<String> lines = Files.lines(Paths.get("/proc/self/maps"))) {

return lines.anyMatch(line -> line.contains("/ld-musl"));

} catch (final IOException e) {

return false;

}

}

}