other: clarify config file creation logic/code (#1518)

docs/content/configuration/config-file/index.md

@@ -12,8 +12,8 @@ If no config file argument is given, it will automatically look for a config fil
 | Linux   | `~/.config/bottom/bottom.toml` <br/> `$XDG_CONFIG_HOME/bottom/bottom.toml`                                                             |
 | Windows | `C:\Users\<USER>\AppData\Roaming\bottom\bottom.toml`                                                                                   |
 
-Like if a path is passed with `-C`/`--config`, if a file doesn't exist at the path, bottom will automatically create a
-new, default config file at that location.
+If the config file doesn't exist at the path, bottom will automatically try to create a new config file at the location
+with default values.
 
 ## JSON Schema
 

src/main.rs

@@ -27,7 +27,6 @@ use std::{
     boxed::Box,
     io::{stderr, stdout, Write},
     panic::{self, PanicInfo},
-    path::Path,
     sync::{
         mpsc::{self, Receiver, Sender},
         Arc, Condvar, Mutex,
@@ -36,7 +35,6 @@ use std::{
     time::{Duration, Instant},
 };
 
-use anyhow::Context;
 use app::{layout_manager::UsedWidgets, App, AppConfigFields, DataFilters};
 use crossterm::{
     event::{
@@ -49,7 +47,7 @@ use crossterm::{
 };
 use data_conversion::*;
 use event::{handle_key_event_or_break, handle_mouse_event, BottomEvent, CollectionThreadEvent};
-use options::{args, get_config_path, get_or_create_config, init_app};
+use options::{args, get_or_create_config, init_app};
 use tui::{backend::CrosstermBackend, Terminal};
 #[allow(unused_imports)]
 use utils::logging::*;
@@ -330,18 +328,8 @@ fn main() -> anyhow::Result<()> {
     }
 
     // Read from config file.
-    let config = {
-        let config_path = get_config_path(args.general.config_location.as_deref());
-        get_or_create_config(config_path.as_deref()).with_context(|| {
-            format!(
-                "Unable to parse or create the config file at: {}",
-                config_path
-                    .as_deref()
-                    .unwrap_or_else(|| Path::new("<failed locating>"))
-                    .display()
-            )
-        })?
-    };
+
+    let config = get_or_create_config(args.general.config_location.as_deref())?;
 
     // Create the "app" and initialize a bunch of stuff.
     let (mut app, widget_layout, styling) = init_app(args, config)?;

src/options.rs

@@ -68,7 +68,7 @@ macro_rules! is_flag_enabled {
 ///
 /// For more details on this, see [dirs](https://docs.rs/dirs/latest/dirs/fn.config_dir.html)'
 /// documentation.
-pub fn get_config_path(override_config_path: Option<&Path>) -> Option<PathBuf> {
+fn get_config_path(override_config_path: Option<&Path>) -> Option<PathBuf> {
     const DEFAULT_CONFIG_FILE_PATH: &str = "bottom/bottom.toml";
 
     if let Some(conf_loc) = override_config_path {
@@ -92,29 +92,73 @@ pub fn get_config_path(override_config_path: Option<&Path>) -> Option<PathBuf> {
     })
 }
 
-/// Get the config at `config_path`. If there is no config file at the specified
-/// path, it will try to create a new file with the default settings, and return
-/// the default config. If bottom fails to write a new config, it will silently
-/// just return the default config.
-pub fn get_or_create_config(config_path: Option<&Path>) -> OptionResult<Config> {
-    match &config_path {
-        Some(path) => {
-            if let Ok(config_string) = fs::read_to_string(path) {
-                Ok(toml_edit::de::from_str(&config_string)?)
-            } else {
+fn create_config_at_path(path: &Path) -> anyhow::Result<Config> {
     if let Some(parent_path) = path.parent() {
         fs::create_dir_all(parent_path)?;
     }
 
-                fs::File::create(path)?.write_all(CONFIG_TEXT.as_bytes())?;
+    let mut file = fs::File::create(path)?;
+    file.write_all(CONFIG_TEXT.as_bytes())?;
+
     Ok(Config::default())
+}
+
+/// Get the config at `config_path`. If there is no config file at the specified
+/// path, it will try to create a new file with the default settings, and return
+/// the default config.
+///
+/// We're going to use the following behaviour on when we'll return an error rather
+/// than just "silently" continuing on:
+/// - If the user passed in a path explicitly, then we will be loud and error out.
+/// - If the user does NOT pass in a path explicitly, then just show a warning,
+///   but continue. This is in case they do not want to write a default config file at
+///   the XDG locations, for example.
+pub fn get_or_create_config(config_path: Option<&Path>) -> anyhow::Result<Config> {
+    let adjusted_config_path = get_config_path(config_path);
+
+    match &adjusted_config_path {
+        Some(path) => {
+            if let Ok(config_string) = fs::read_to_string(path) {
+                Ok(toml_edit::de::from_str(&config_string)?)
+            } else {
+                match create_config_at_path(path) {
+                    Ok(cfg) => Ok(cfg),
+                    Err(err) => {
+                        if config_path.is_some() {
+                            Err(err.context(format!(
+                                "bottom could not create a new config file at '{}'.",
+                                path.display()
+                            )))
+                        } else {
+                            indoc::eprintdoc!(
+                                "Note: bottom couldn't create a default config file at '{}', and the \
+                                application has fallen back to the default configuration.
+                                    
+                                Caused by:
+                                    {err}
+                                ",
+                                path.display()
+                            );
+
+                            Ok(Config::default())
+                        }
+                    }
+                }
             }
         }
         None => {
             // If we somehow don't have any config path, then just assume the default config
             // but don't write to any file.
             //
-            // TODO: Maybe make this "show" an error, but don't crash.
+            // TODO: For now, just print a message to stderr indicating this. In the future,
+            // probably show in-app (too).
+
+            eprintln!(
+                "Note: bottom couldn't find a location to create or read a config file, so \
+                the application has fallen back to the default configuration. \
+                This could be for a variety of reasons, such as issues with file permissions."
+            );
+
             Ok(Config::default())
         }
     }