lib/utils: fall back to env for configs and Ghidra plugins

src/cwe_checker_lib/src/utils/ghidra.rs

@@ -183,7 +183,7 @@ fn generate_ghidra_call_command(
         .ok_or_else(|| anyhow!("Invalid file name"))?
         .to_string_lossy()
         .to_string();
-    let ghidra_plugin_path = get_ghidra_plugin_path("p_code_extractor");
+    let ghidra_plugin_path = get_ghidra_plugin_path("p_code_extractor")?;
 
     let mut ghidra_command = Command::new(headless_path);
     ghidra_command

src/cwe_checker_lib/src/utils/mod.rs

@@ -10,21 +10,77 @@ pub mod symbol_utils;
 
 use crate::prelude::*;
 
+use std::{env, fs, path};
+
+use anyhow::bail;
+
+const ENV_CWE_CHECKER_CONFIGS_PATH: &str = "CWE_CHECKER_CONFIGS_PATH";
+const ENV_CWE_CHECKER_GHIDRA_PLUGINS_PATH: &str = "CWE_CHECKER_GHIDRA_PLUGINS_PATH";
+
 /// Get the contents of a configuration file.
+///
+/// We first search the file in our config directory. Then, we fall back to
+/// the CWE_CHECKER_CONFIG environment variable.
 pub fn read_config_file(filename: &str) -> Result<serde_json::Value, Error> {
-    let project_dirs = directories::ProjectDirs::from("", "", "cwe_checker")
-        .context("Could not discern location of configuration files.")?;
+    let config_path = if let Some(config_path) = get_config_path_from_project_dir(filename) {
+        config_path
+    } else if let Some(config_path) = get_path_from_env(ENV_CWE_CHECKER_CONFIGS_PATH, filename) {
+        config_path
+    } else {
+        bail!("Unable to find configuration file: {}.", filename)
+    };
+    let config_file = fs::read_to_string(config_path)
+        .context(format!("Could not read configuration file: {}", filename))?;
+    Ok(serde_json::from_str(&config_file)?)
+}
+
+fn get_config_path_from_project_dir(filename: &str) -> Option<path::PathBuf> {
+    let project_dirs = directories::ProjectDirs::from("", "", "cwe_checker")?;
     let config_dir = project_dirs.config_dir();
     let config_path = config_dir.join(filename);
-    let config_file =
-        std::fs::read_to_string(config_path).context("Could not read configuration file")?;
-    Ok(serde_json::from_str(&config_file)?)
+
+    if config_path.exists() {
+        Some(config_path)
+    } else {
+        None
+    }
+}
+
+/// Get the path to a Ghidra plugin that is bundled with the cwe_checker.
+///
+/// We first search the plugin in our data directory, then we fall back to
+/// the CWE_CHECKER_GHIDRA_PLUGIN_PATH environment variable.
+pub fn get_ghidra_plugin_path(plugin_name: &str) -> Result<path::PathBuf, Error> {
+    if let Some(ghidra_plugin_path) = get_ghidra_plugin_path_from_project_dirs(plugin_name) {
+        Ok(ghidra_plugin_path)
+    } else if let Some(ghidra_plugin_path) =
+        get_path_from_env(ENV_CWE_CHECKER_GHIDRA_PLUGINS_PATH, plugin_name)
+    {
+        Ok(ghidra_plugin_path)
+    } else {
+        bail!("Unable to find Ghidra plugin: {}", plugin_name)
+    }
 }
 
-/// Get the folder path to a Ghidra plugin bundled with the cwe_checker.
-pub fn get_ghidra_plugin_path(plugin_name: &str) -> std::path::PathBuf {
-    let project_dirs = directories::ProjectDirs::from("", "", "cwe_checker")
-        .expect("Could not discern location of data directory.");
+fn get_ghidra_plugin_path_from_project_dirs(plugin_name: &str) -> Option<path::PathBuf> {
+    let project_dirs = directories::ProjectDirs::from("", "", "cwe_checker")?;
     let data_dir = project_dirs.data_dir();
-    data_dir.join("ghidra").join(plugin_name)
+    let plugin_path = data_dir.join("ghidra").join(plugin_name);
+
+    if plugin_path.exists() {
+        Some(plugin_path)
+    } else {
+        None
+    }
+}
+
+fn get_path_from_env(var: &str, filename: &str) -> Option<path::PathBuf> {
+    let val = env::var(var).ok()?;
+    let path = path::PathBuf::from(val).join(filename);
+
+    if path.exists() {
+        Some(path)
+    } else {
+        None
+    }
 }