127 lines
4.2 KiB
Rust
127 lines
4.2 KiB
Rust
//! Functions for burritos.cfg configuration file parsing.
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//! Needed to set-up machine and system constants without
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//! recompiling.
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use std::{
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fs::File,
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path::Path,
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collections::HashMap,
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io::{
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BufReader,
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BufRead,
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Error
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}
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};
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/// Aliases the rather long HashMap<MachineSettingKey, i32> type
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/// to a rather simpler to understand Settings.
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pub type Settings = HashMap<MachineSettingKey, u64>;
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/// Keys for the Settings HashMap, represented as enums for
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/// maintainability.
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#[derive(Eq, Hash, PartialEq, Debug)]
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pub enum MachineSettingKey {
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/// Number of physical pages.
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NumPhysPages,
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/// Stack size.
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UserStackSize,
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/// Maximum size of a file name
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MaxFileNameSize,
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/// Number of directory entries
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NumDirEntries,
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/// Processor Frequency
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ProcessorFrequency,
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/// Disk sector size
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SectorSize,
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/// Memory page size
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PageSize,
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/// Maximum number of Virtual Pages
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MaxVirtPages,
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/// In case of unknown key in configuration file.
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Unknown
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}
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/// Allows for converting string slices to correspoding MachineSettingKey
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/// enum value.
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impl From<&str> for MachineSettingKey {
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fn from(s: &str) -> Self {
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match s {
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"NumPhysPages" => MachineSettingKey::NumPhysPages,
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"UserStackSize" => MachineSettingKey::UserStackSize,
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"MaxFileNameSize" => MachineSettingKey::MaxFileNameSize,
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"NumDirEntries" => MachineSettingKey::NumDirEntries,
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"ProcessorFrequency" => MachineSettingKey::ProcessorFrequency,
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"SectorSize" => MachineSettingKey::SectorSize,
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"PageSize" => MachineSettingKey::PageSize,
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"MaxVirtPages" => MachineSettingKey::MaxVirtPages,
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_ => MachineSettingKey::Unknown
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}
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}
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}
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/// Tries to return a HashMap containing the user defined burritos configuration
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/// in the burritos.cfg file.
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///
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/// If the file is not found, the function will return an io error.
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///
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/// If the configuration is invalid, the function may return a HashMap with missing or
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/// non-sensical settings.
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/// It is up to the caller to determine whether or not default values should be placed
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/// instead of halting the program.
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pub fn read_settings() -> Result<Settings, Error> {
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// Opening file
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let file = {
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let file_path = "./burritos.cfg";
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let file_path = Path::new(file_path);
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match File::open(file_path) {
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Ok(opened_file) => opened_file,
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Err(error_message) => Err(error_message)?
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}
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};
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let file_reader = BufReader::new(file);
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let filtered_setting_strings = filter_garbage(file_reader);
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let mut settings_map = Settings::new();
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// Reading settings
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for line in filtered_setting_strings {
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let mut split_line = line.split_whitespace();
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let key = split_line.next().unwrap_or("_");
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split_line.next(); // Skipping '=' character
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let setting = split_line.next().unwrap_or("_");
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settings_map = update_settings_map(settings_map, key, setting);
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}
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Ok(settings_map)
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}
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/// Returns a mock configuration for Machine unit testing
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///
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/// FIXME: Does not cover the whole configuration yet
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pub fn get_debug_configuration() -> Settings {
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let mut settings_map = Settings::new();
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settings_map.insert(MachineSettingKey::PageSize, 2048);
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settings_map.insert(MachineSettingKey::NumPhysPages, 8192);
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settings_map.insert(MachineSettingKey::UserStackSize, 4096);
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settings_map
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}
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/// Removes comments and empty lines
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/// Filters out empty lines and comments from the reader `BufReader`.
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///
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/// Returns a [`Vec<String>`], each entry containing a valid
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/// line from the input file.
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fn filter_garbage<R: std::io::Read>(reader: BufReader<R>) -> Vec<String> {
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reader.lines()
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.map(|l| l.unwrap())
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.filter(|l| !l.is_empty() && !l.starts_with('#'))
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.collect()
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}
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/// Inserts user settings into setting map
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/// Adds a <K, V> pair to a [`Settings`] map.
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///
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/// Returns the updated [`Settings`].
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fn update_settings_map(mut settings_map: Settings, key: &str, setting: &str) -> Settings {
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let key = MachineSettingKey::from(key);
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let setting = str::parse::<u64>(setting).unwrap_or(0);
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settings_map.insert(key, setting);
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settings_map
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} |