feat: update config file load path

Signed-off-by: h1994st <[email protected]>

.gitignore

@@ -4,6 +4,7 @@
 *.manifest
 .*.o
 !.gitignore
+config.toml
 
 # Created by https://www.toptal.com/developers/gitignore/api/rust,macos,visualstudiocode
 # Edit at https://www.toptal.com/developers/gitignore?templates=rust,macos,visualstudiocode

README.md

@@ -22,7 +22,13 @@ llvm-dis hello.bc  # Obtain readable `hello.ll` file
 
 ### Configuration
 
-The default configuration file `~/.rllvm/config.toml` will be automatically created, if it does not exist, with the following entries:
+Users can specify the configuration file by setting the environment variable `RLLVM_CONFIG`.
+
+```bash
+export RLLVM_CONFIG=/absolute/path/to/config/file.toml
+```
+
+Otherwise, the default configuration file `~/.rllvm/config.toml` will be used. The configuration file will be automatically created, if it does not exist, with the following entries:
 
 | Configuration Key          | Required? | Notes                                                                                   |
 | -------------------------- | --------- | --------------------------------------------------------------------------------------- |

src/config.rs

@@ -8,7 +8,9 @@ use log::Level;
 use serde::{Deserialize, Serialize};
 
 use crate::{
-    constants::DEFAULT_CONF_FILEPATH_UNDER_HOME,
+    constants::{
+        DEFAULT_CONF_FILEPATH_UNDER_HOME, DEFAULT_RLLVM_CONF_FILEPATH_ENV_NAME, HOME_ENV_NAME,
+    },
     utils::{execute_llvm_config, find_llvm_config},
 };
 
@@ -109,8 +111,17 @@ impl RLLVMConfig {
 
 impl RLLVMConfig {
     pub fn new() -> Self {
-        let config_filepath = PathBuf::from(env::var("HOME").unwrap_or("".into()))
-            .join(DEFAULT_CONF_FILEPATH_UNDER_HOME);
+        let config_filepath = env::var(DEFAULT_RLLVM_CONF_FILEPATH_ENV_NAME).map_or_else(
+            |_| {
+                // Default config file
+                PathBuf::from(env::var(HOME_ENV_NAME).unwrap_or("".into()))
+                    .join(DEFAULT_CONF_FILEPATH_UNDER_HOME)
+            },
+            |x| {
+                // User-defined config file
+                PathBuf::from(x)
+            },
+        );
         Self::load_path(config_filepath)
     }
 

src/constants.rs

@@ -13,6 +13,10 @@ pub const DARWIN_SEGMENT_NAME: &str = "__RLLVM";
 pub const DARWIN_SECTION_NAME: &str = "__llvm_bc";
 pub const ELF_SECTION_NAME: &str = ".llvm_bc";
 
+/// Environment variables
+pub const DEFAULT_RLLVM_CONF_FILEPATH_ENV_NAME: &str = "RLLVM_CONFIG";
+pub const HOME_ENV_NAME: &str = "HOME";
+
 /// The default filepath of the configuration file
 pub const DEFAULT_CONF_FILEPATH_UNDER_HOME: &str = ".rllvm/config.toml";