Added user configuration to utility module

burritos.cfg

@@ -0,0 +1,40 @@
+##################################################
+# BurritOS configuration file
+##################################################
+
+NumPhysPages      = 400
+UserStackSize     = 4096
+MaxFileNameSize   = 256
+NumDirEntries     = 30
+NumPortLoc        = 32009
+NumPortDist       = 32010
+ProcessorFrequency = 100
+SectorSize        = 128
+PageSize          = 128
+MaxVirtPages      = 200000
+
+# String values
+###############
+# WARNING: Copying can be very slow
+# because the system transferts data
+# by 10 byte chunks. The transfer file
+# can be set by changing the transfersize
+# constant in fstest.rs.
+
+TargetMachineName = localhost
+FileToCopy	  = test/halt /halt
+FileToCopy	  = test/hello /hello
+FileToCopy	  = test/sort /sort
+FileToCopy        = test/shell /shell
+
+# Boolean values
+################
+UseACIA		 = None
+PrintStat        = 1
+FormatDisk       = 1
+ListDir          = 1
+PrintFileSyst    = 0
+
+ProgramToRun     = /sort
+
+

src/utility/cfg.rs

@@ -0,0 +1,107 @@
+//! Functions for burritos.cfg configuration file parsing.
+//! Needed to set-up machine and system constants without
+//! recompiling.
+
+use std::{
+    fs::File, 
+    path::Path,
+    collections::HashMap,
+    io::{
+        BufReader,
+        BufRead,
+        Error
+    }
+};
+
+/// Aliases the rather long HashMap<MachineSettingKey, i32> type
+/// to a rather simpler to understand Settings.
+pub type Settings = HashMap<MachineSettingKey, i32>;
+
+/// Keys for the Settings HashMap, represented as enums for
+/// maintainability.
+#[derive(Eq, Hash, PartialEq, Debug)]
+pub enum MachineSettingKey {
+    /// Number of physical pages.
+    NumPhysPages,
+    /// Stack size.
+    UserStackSize,
+    /// Maximum size of a file name
+    MaxFileNameSize,
+    /// Number of directory entries
+    NumDirEntries,
+    /// Processor Frequency
+    ProcessorFrequency,
+    /// Disk sector size
+    SectorSize,
+    /// Memory page size
+    PageSize,
+    /// Maximum number of Virtual Pages
+    MaxVirtPages,
+    /// In case of unknown key in configuration file.
+    Unknown
+}
+
+/// Allows for converting string slices to correspoding MachineSettingKey
+/// enum value.
+impl From<&str> for MachineSettingKey {
+    fn from(s: &str) -> Self {
+        match s {
+            "NumPhysPages" => MachineSettingKey::NumPhysPages,
+            "UserStackSize" => MachineSettingKey::UserStackSize,
+            "MaxFileNameSize" => MachineSettingKey::MaxFileNameSize,
+            "NumDirEntries" => MachineSettingKey::NumDirEntries,
+            "ProcessorFrequency" => MachineSettingKey::ProcessorFrequency,
+            "SectorSize" => MachineSettingKey::SectorSize,
+            "PageSize" => MachineSettingKey::PageSize,
+            "MaxVirtPages" => MachineSettingKey::MaxVirtPages,
+            _ => MachineSettingKey::Unknown
+        }
+    }
+}
+
+/// Tries to return a HashMap containing the user defined burritos configuration
+/// in the burritos.cfg file.
+/// 
+/// If the file is not found, the function will return an io error.
+/// 
+/// If the configuration is invalid, the function may return a HashMap with missing or
+/// non-sensical settings.
+/// It is up to the caller to determine whether or not default values should be placed
+/// instead of halting the program.
+pub fn read_settings() -> Result<Settings, Error> {
+    // Opening file
+    let file = {
+        let file_path = "./burritos.cfg";
+        let file_path = Path::new(file_path);
+        match File::open(file_path) {
+            Ok(opened_file) => opened_file,
+            Err(error_message) => Err(error_message)?
+        }
+    };
+    let file_reader = BufReader::new(file);
+    let filtered_setting_strings = filter_garbage(file_reader);
+    let mut settings_map = Settings::new();
+    // Reading settings
+    for line in filtered_setting_strings {
+        let mut split_line = line.split_whitespace();
+        let key = split_line.next().unwrap_or("_");
+        split_line.next(); // Skipping '=' character
+        let setting = split_line.next().unwrap_or("_");
+        settings_map = update_settings_map(settings_map, key, setting);
+    }
+    Ok(settings_map)
+}
+
+fn filter_garbage<R: std::io::Read>(reader: BufReader<R>) -> Vec<String> {
+    reader.lines()
+        .map(|l| l.unwrap())
+        .filter(|l| !l.is_empty() && !l.starts_with("#"))
+        .collect()
+}
+
+fn update_settings_map(mut settings_map: Settings, key: &str, setting: &str) -> Settings {
+    let key = MachineSettingKey::from(key);
+    let setting = i32::from_str_radix(setting, 10).unwrap_or(0);
+    settings_map.insert(key, setting);
+    settings_map
+}

src/utility/mod.rs

@@ -1,2 +1,3 @@
 pub mod list;
 pub mod objaddr;
+pub mod cfg;