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// Copyright 2019 astonbitecode
//
// 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.
/*!
# java-locator
This is a small utility written in [Rust](https://www.rust-lang.org/).
It locates the active Java installation in the host.
## Usage
The utility can be used as a library, or as an executable:
### Library
```rust
extern crate java_locator;
fn main() -> java_locator::errors::Result<()> {
let java_home = java_locator::locate_java_home()?;
let dyn_lib_path = java_locator::locate_jvm_dyn_library()?;
let libjsig = java_locator::locate_file("libjsig.so")?;
println!("The java home is {}", java_home);
println!("The jvm dynamic library path is {}", dyn_lib_path);
println!("The file libjsig.so is located in {}", libjsig);
Ok(())
}
```
### Executable
Having rust [installed](https://www.rust-lang.org/tools/install), you may install the utility using cargo:
`cargo install java-locator --features build-binary`
And then, issuing
`java-locator`
you should have an output like:
> /usr/lib/jvm/java-11-openjdk-amd64
You may retrieve the location of the `jvm` shared library:
`java-locator --jvmlib`
should give an output like:
> /usr/lib/jvm/java-11-openjdk-amd64/lib/server
This may be used in cases when the `LD_LIBRARY_PATH` (or `PATH` in windows) should be populated.
You may also retrieve the location of any file inside the Java installation:
`java-locator --file libjsig.so`
and you can even use wildcards:
`java-locator --file libjsig*`
The latter two commands should return something like:
> /usr/lib/jvm/java-11-openjdk-amd64/lib
## License
At your option, under:
* Apache License, Version 2.0, (http://www.apache.org/licenses/LICENSE-2.0)
* MIT license (http://opensource.org/licenses/MIT)
*/
use std::env;
use std::path::PathBuf;
use std::process::Command;
use glob::{glob, Pattern};
use lazy_static::lazy_static;
pub mod errors;
const WINDOWS: &'static str = "windows";
const MACOS: &'static str = "macos";
const ANDROID: &'static str = "android";
const UNIX: &'static str = "unix";
lazy_static! {
static ref TARGET_OS: String = {
let target_os_res = env::var("CARGO_CFG_TARGET_OS");
let tos = target_os_res.as_ref().map(|x| &**x).unwrap_or_else(|_| {
if cfg!(windows) {
WINDOWS
} else if cfg!(target_os = "macos") {
MACOS
} else if cfg!(target_os = "android") {
ANDROID
} else {
UNIX
}
});
tos.to_string()
};
}
fn is_windows() -> bool {
&*TARGET_OS == WINDOWS
}
fn is_macos() -> bool {
&*TARGET_OS == MACOS
}
#[allow(dead_code)]
fn is_android() -> bool {
&*TARGET_OS == ANDROID
}
#[allow(dead_code)]
fn is_unix() -> bool {
&*TARGET_OS == UNIX
}
/// Returns the name of the jvm dynamic library:
///
/// * libjvm.so for Linux
///
/// * libjvm.dlyb for Macos
///
/// * jvm.dll for Windows
pub fn get_jvm_dyn_lib_file_name() -> &'static str {
if is_windows() {
"jvm.dll"
} else if is_macos() {
"libjvm.dylib"
} else {
"libjvm.so"
}
}
/// Returns the Java home path.
///
/// If `JAVA_HOME` env var is defined, the function returns it without any checks whether the var points to a valid directory or not.
///
/// If `JAVA_HOME` is not defined, the function tries to locate it using the `java` executable.
pub fn locate_java_home() -> errors::Result<String> {
match &env::var("JAVA_HOME") {
Ok(s) if s.is_empty() => do_locate_java_home(),
Ok(java_home_env_var) => Ok(java_home_env_var.clone()),
Err(_) => do_locate_java_home(),
}
}
fn do_locate_java_home() -> errors::Result<String> {
// Prepare the command depending on the host
let command_str = if is_windows() {
"where"
} else if is_macos() {
"/usr/libexec/java_home"
} else {
"which"
};
let mut command = Command::new(command_str);
if !is_macos() {
command.arg("java");
}
let output = command.output().map_err(|error| {
let message = format!(
"Command '{}' is not found in the system PATH ({})",
command_str, error
);
errors::JavaLocatorError::new(&message)
})?;
let java_exec_path = String::from_utf8(output.stdout).map(|jp| {
let mut lines: Vec<&str> = jp.lines().collect();
if lines.len() > 1 {
println!(
"WARNING: java_locator found {} possible java locations: {}. Using the last one.",
lines.len(),
lines.join(", ")
);
lines.remove(lines.len() - 1).to_string()
} else {
jp
}
})?;
// Return early in case that the java executable is not found
if java_exec_path.is_empty() {
Err(errors::JavaLocatorError::new(
"Java is not installed or not added in the system PATH",
))?
}
let mut test_path = PathBuf::from(java_exec_path.trim());
while let Ok(path) = test_path.read_link() {
test_path = if path.is_absolute() {
path
} else {
test_path.pop();
test_path.push(path);
test_path
};
}
if !is_macos() {
// Here we should have found ourselves in a directory like /usr/lib/jvm/java-8-oracle/jre/bin/java
test_path.pop();
test_path.pop();
}
match test_path.to_str() {
Some(s) => Ok(String::from(s)),
None => Err(errors::JavaLocatorError::new(&format!(
"Could not convert path {:?} to String",
test_path
))),
}
}
/// Returns the path that contains the `libjvm.so` (or `jvm.dll` in windows).
pub fn locate_jvm_dyn_library() -> errors::Result<String> {
let jvm_dyn_lib_file_name = if is_windows() { "jvm.dll" } else { "libjvm.*" };
locate_file(jvm_dyn_lib_file_name)
}
/// Returns the path that contains the file with the provided name.
///
/// This function argument can be a wildcard.
pub fn locate_file(file_name: &str) -> errors::Result<String> {
// Find the JAVA_HOME
let java_home = locate_java_home()?;
let query = format!("{}/**/{}", Pattern::escape(&java_home), file_name);
let paths_vec: Vec<String> = glob(&query)?
.filter_map(Result::ok)
.map(|path_buf| {
let mut pb = path_buf.clone();
pb.pop();
pb.to_str().unwrap_or("").to_string()
})
.filter(|s: &String| !s.is_empty())
.collect();
if paths_vec.is_empty() {
Err(errors::JavaLocatorError::new(&format!(
"Could not find the {} library in any subdirectory of {}",
file_name, java_home
)))
} else {
Ok(paths_vec[0].clone())
}
}
#[cfg(test)]
mod unit_tests {
use super::*;
#[test]
fn locate_java_home_test() {
println!("locate_java_home: {}", locate_java_home().unwrap());
println!(
"locate_jvm_dyn_library: {}",
locate_jvm_dyn_library().unwrap()
);
}
#[test]
fn locate_java_from_exec_test() {
println!("do_locate_java_home: {}", do_locate_java_home().unwrap());
}
}