file_system/fundamentals/identifiers/
file.rs

1//! File identifier types for opened files.
2//!
3//! This module provides file identifier types used to identify opened files
4//! within a task's file descriptor table, similar to file descriptors in
5//! Unix-like systems.
6
7/// File identifier inner type.
8///
9/// This is the underlying numeric type used for file identifiers. The size
10/// is architecture-dependent to optimize memory usage while providing sufficient
11/// identifier space:
12/// - 16 bits (0-65,535) on 32-bit systems  
13/// - 32 bits (0-4,294,967,295) on 64-bit systems
14///
15/// This provides a good balance between memory efficiency and identifier space.
16#[cfg(target_pointer_width = "32")]
17pub type FileIdentifierInner = u16;
18#[cfg(target_pointer_width = "64")]
19pub type FileIdentifierInner = u32;
20
21/// Type-safe wrapper for file identifiers.
22///
23/// File identifiers are used to reference opened files within a task's context,
24/// similar to file descriptors in Unix-like systems. Each task maintains its own
25/// file identifier space, allowing for task isolation and security.
26///
27/// # Standard File Identifiers
28///
29/// The following standard identifiers are predefined:
30/// - [`FileIdentifier::STANDARD_IN`] (0) - Standard input
31/// - [`FileIdentifier::STANDARD_OUT`] (1) - Standard output  
32/// - [`FileIdentifier::STANDARD_ERROR`] (2) - Standard error
33/// - [`FileIdentifier::MINIMUM`] (3) - First available identifier for regular files
34///
35/// # Examples
36///
37/// ```rust
38/// use file_system::File_identifier_type;
39///
40/// // Standard file identifiers
41/// assert_eq!(File_identifier_type::Standard_in.Into_inner(), 0);
42/// assert_eq!(File_identifier_type::Standard_out.Into_inner(), 1);
43/// assert_eq!(File_identifier_type::Standard_error.Into_inner(), 2);
44///
45/// // Create a custom file identifier
46/// let file_id = File_identifier_type::new(42);
47/// assert_eq!(file_id.Into_inner(), 42);
48/// ```
49#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Ord, PartialOrd)]
50#[repr(transparent)]
51pub struct FileIdentifier(FileIdentifierInner);
52
53impl FileIdentifier {
54    /// Size in bits of the underlying identifier type.
55    pub const SIZE_BITS: u8 = core::mem::size_of::<FileIdentifierInner>() as u8 * 8;
56
57    /// Standard input file identifier (traditionally 0).
58    pub const STANDARD_IN: FileIdentifier = FileIdentifier::new(0);
59
60    /// Standard output file identifier (traditionally 1).
61    pub const STANDARD_OUT: FileIdentifier = FileIdentifier::new(1);
62
63    /// Standard error file identifier (traditionally 2).
64    pub const STANDARD_ERROR: FileIdentifier = FileIdentifier::new(2);
65
66    /// Minimum file identifier available for regular files.
67    ///
68    /// Regular files should use identifiers starting from this value to avoid
69    /// conflicts with standard file identifiers.
70    pub const MINIMUM: FileIdentifier = FileIdentifier::new(3);
71
72    /// Maximum possible file identifier value.
73    pub const MAXIMUM: FileIdentifier = FileIdentifier::new(FileIdentifierInner::MAX);
74
75    /// Create a new file identifier from a raw value.
76    ///
77    /// # Arguments
78    ///
79    /// * `Identifier` - The raw identifier value
80    ///
81    /// # Examples
82    ///
83    /// ```rust
84    /// use file_system::File_identifier_type;
85    ///
86    /// let file_id = File_identifier_type::new(5);
87    /// assert_eq!(file_id.Into_inner(), 5);
88    /// ```
89    pub const fn new(identifier: FileIdentifierInner) -> Self {
90        Self(identifier)
91    }
92
93    /// Get the raw identifier value.
94    ///
95    /// # Returns
96    ///
97    /// The underlying raw identifier value.
98    ///
99    /// # Examples
100    ///
101    /// ```rust
102    /// use file_system::File_identifier_type;
103    ///
104    /// let file_id = File_identifier_type::new(42);
105    /// assert_eq!(file_id.Into_inner(), 42);
106    /// ```
107    pub const fn into_inner(self) -> FileIdentifierInner {
108        self.0
109    }
110}
111
112impl From<FileIdentifierInner> for FileIdentifier {
113    fn from(internal_file_identifier: FileIdentifierInner) -> Self {
114        FileIdentifier(internal_file_identifier)
115    }
116}
117
118impl From<FileIdentifier> for FileIdentifierInner {
119    fn from(internal_file_identifier: FileIdentifier) -> Self {
120        internal_file_identifier.0
121    }
122}
123
124#[cfg(test)]
125mod tests {
126    use super::*;
127
128    #[test]
129    fn test_file_identifier() {
130        let identifier = FileIdentifier::from(0x1234);
131        assert_eq!(identifier, FileIdentifier::new(0x1234));
132        assert_eq!(FileIdentifierInner::from(identifier), 0x1234);
133    }
134}
file_system/fundamentals/identifiers/file.rs

file_system/fundamentals/identifiers/
file.rs
