Read config once

Signed-off-by: Vlad Volodkin <[email protected]>

Author: Vlad Volodkin

mountpoint-s3-fs/examples/mount_from_config.rs

@@ -1,4 +1,4 @@
-use std::{fs::File, io::BufReader, path::Path, time::Instant};
+use std::{fs::File, io::Read, path::Path, time::Instant};
 
 use anyhow::{Context, Result, anyhow};
 use clap::Parser;
@@ -173,15 +173,13 @@ impl ConfigOptions {
 }
 
 /// Reads the config_version field from a JSON config file and validates it against CONFIG_VERSION
-fn validate_config_version<P: AsRef<Path>>(path: P) -> Result<()> {
+fn validate_config_version(json_str: &str) -> Result<()> {
     #[derive(Deserialize)]
     struct VersionOnly {
         config_version: String,
     }
 
-    let file = File::open(&path)?;
-    let reader = BufReader::new(file);
-    let version_info: VersionOnly = serde_json::from_reader(reader)?;
+    let version_info: VersionOnly = serde_json::from_str(json_str)?;
 
     if version_info.config_version != CONFIG_VERSION {
         return Err(anyhow!(
@@ -194,10 +192,11 @@ fn validate_config_version<P: AsRef<Path>>(path: P) -> Result<()> {
 }
 
 fn load_config<P: AsRef<Path>>(path: P) -> Result<ConfigOptions> {
-    validate_config_version(path.as_ref())?;
-    let file = File::open(path)?;
-    let reader = BufReader::new(file);
-    let config: ConfigOptions = serde_json::from_reader(reader)?;
+    let mut file = File::open(path)?;
+    let mut json_str = String::new();
+    file.read_to_string(&mut json_str)?;
+    validate_config_version(&json_str)?;
+    let config: ConfigOptions = serde_json::from_str(&json_str)?;
     Ok(config)
 }