Add efi variable list command logic

Author: nvinson

meson.build

@@ -57,6 +57,14 @@ lib_refivar = static_library(
       lib_refivar_efi_guids_list_path_rs
     ],
     {
+      'efivarfs': [
+        'src/lib/efivar/efivarfs/efi_variables.rs',
+        'src/lib/efivar/efivarfs/mod.rs',
+      ],
+      'efivar': [
+        'src/lib/efivar/efivar/efi_variables.rs',
+        'src/lib/efivar/efivar/mod.rs',
+      ],
       'print_mode': [
         'src/lib/efivar/print_mode/decimal.rs',
         'src/lib/efivar/print_mode/mod.rs',

src/bin/efivar.rs

@@ -110,6 +110,11 @@ fn create_parser() -> clap::Command {
 }
 
 fn list_variables(parser_args: clap::ArgMatches) -> ExitCode {
+    let mut efi_variables: efivar::efivarfs::EfiVariables = Default::default();
+
+    for v in efi_variables.list() {
+        println!("{}", v);
+    }
     return std::process::ExitCode::from(0);
 }
 

src/lib/efivar/efivar/efi_variables.rs

@@ -0,0 +1,29 @@
+use crate::efivarfs;
+use std::path::PathBuf;
+
+const EFIVARS_PATH: &'static str = "/sys/firmware/efi/vars";
+
+pub struct EfiVariables {
+    path: PathBuf,
+}
+
+impl Default for EfiVariables {
+    fn default() -> Self {
+        return EfiVariables {
+            path: EFIVARS_PATH.into(),
+        };
+    }
+}
+
+impl EfiVariables {
+    pub fn set_path(&mut self, path: PathBuf) -> &EfiVariables {
+        self.path = path;
+        return self;
+    }
+
+    pub fn list(&self) -> efivarfs::EfiVariablesNameIter {
+        let mut e: efivarfs::EfiVariables = Default::default();
+        e.set_path(self.path.clone());
+        return e.list();
+    }
+}

src/lib/efivar/efivar/mod.rs

@@ -0,0 +1,12 @@
+/*
+ * DEPRECTATED
+ *
+ * This module relies on a Linux kernel interface that was removed in 6.0. The interface was
+ * deprecated with the 5.10 release of the Linux kernel.
+ *
+ * This module is included for support for kernels < 5.10. It should not be used for current or
+ * future Linux kernels.
+ */
+mod efi_variables;
+
+pub use efi_variables::EfiVariables;

src/lib/efivar/efivarfs/efi_variables.rs

@@ -0,0 +1,99 @@
+use crate::types::EfiGuid;
+use std::fs::{self, ReadDir};
+use std::path::PathBuf;
+
+const EFIVARFS_PATH: &'static str = "/sys/firmware/efi/efivars";
+
+// variable file names have 1 or more characters, a dash, then a UUID (36 characters)
+const MIN_VAR_FILE_NAME_LEN: usize = 38;
+
+pub struct EfiVariables {
+    path: PathBuf,
+}
+
+pub struct EfiVariablesNameIter {
+    dir_entry_iter: Option<ReadDir>,
+}
+
+fn convert_name(name: Option<&str>) -> Result<String, String> {
+    return match name {
+        Some(n) => {
+            if n.len() < MIN_VAR_FILE_NAME_LEN {
+                return Err(format!(
+                    "file name {n} does not represent an EFI variable name"
+                ));
+            }
+            if n.bytes().nth(n.len() - MIN_VAR_FILE_NAME_LEN + 1).unwrap() != b'-' {
+                return Err(format!(
+                    "file name {n} does not represent an EFI variable name"
+                ));
+            }
+            let guid_bytes = &n[n.len() - MIN_VAR_FILE_NAME_LEN + 2..n.len()];
+            let guid: Option<EfiGuid> = match guid_bytes.try_into() {
+                Ok(g) => Some(g),
+                Err(_) => None,
+            };
+            if guid.is_none() {
+                return Err(format!(
+                    "file name {n} does not represent an EFI variable name"
+                ));
+            }
+            let suffix = &n[0..n.len() - MIN_VAR_FILE_NAME_LEN + 1];
+
+            return Ok(String::new() + guid_bytes + &"-" + suffix);
+        }
+        None => Err("no name provided".to_string()),
+    };
+}
+
+impl Iterator for EfiVariablesNameIter {
+    type Item = String;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        return match &mut self.dir_entry_iter {
+            Some(iter) => {
+                for entry in iter {
+                    let converted_name = match entry {
+                        Ok(entry) => convert_name(entry.file_name().to_str()),
+                        Err(e) => Err(e.to_string()),
+                    };
+                    if converted_name.is_ok() {
+                        return converted_name.ok();
+                    }
+                }
+                return None;
+            }
+            None => None,
+        };
+    }
+}
+
+impl Default for EfiVariables {
+    fn default() -> Self {
+        return EfiVariables {
+            path: EFIVARFS_PATH.into(),
+        };
+    }
+}
+
+impl EfiVariables {
+    pub fn set_path(&mut self, path: PathBuf) -> &EfiVariables {
+        self.path = path;
+        return self;
+    }
+
+    pub fn list(&mut self) -> EfiVariablesNameIter {
+        if self.path.is_dir() {
+            let iter = fs::read_dir(&self.path);
+            return EfiVariablesNameIter {
+                dir_entry_iter: match iter {
+                    Ok(i) => Some(i),
+                    Err(_) => None,
+                },
+            };
+        }
+        return EfiVariablesNameIter {
+            dir_entry_iter: None,
+        };
+    }
+}

src/lib/efivar/efivarfs/mod.rs

@@ -0,0 +1,4 @@
+mod efi_variables;
+
+pub use crate::efivarfs::efi_variables::EfiVariables;
+pub use crate::efivarfs::efi_variables::EfiVariablesNameIter;

src/lib/efivar/mod.rs

@@ -1,5 +1,7 @@
 pub mod efi_guids;
+pub mod efivar;
 pub mod efivar_display;
+pub mod efivarfs;
 pub mod print_mode;
 pub mod types;
 

src/lib/efivar/types/mod.rs

@@ -8,6 +8,6 @@ mod print_mode;
 pub use self::efi_guid::EfiGuid;
 pub use self::efi_guid_error::EfiGuidError;
 pub use self::efi_guid_list_entry::EfiGuidListEntry;
-pub use self::efi_variable_attribute::EfiVariableAttribute;
 pub use self::efi_variable::EfiVariable;
+pub use self::efi_variable_attribute::EfiVariableAttribute;
 pub use self::print_mode::PrintMode;

src/lib/efivar/types/print_mode.rs

@@ -1,4 +1,4 @@
 pub enum PrintMode {
     VERBOSE,
-    DECIMAL
+    DECIMAL,
 }