1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139

//! Module for [CommandLineTag].

use crate::{Tag, TagTrait, TagTypeId};

use core::fmt::{Debug, Formatter};
use core::mem;
use core::str;

#[cfg(feature = "builder")]
use {
    crate::builder::traits::StructAsBytes, crate::builder::BoxedDst, crate::TagType,
    alloc::vec::Vec, core::convert::TryInto,
};

pub(crate) const METADATA_SIZE: usize = mem::size_of::<TagTypeId>() + mem::size_of::<u32>();

/// This tag contains the command line string.
///
/// The string is a normal C-style UTF-8 zero-terminated string that can be
/// obtained via the `command_line` method.
#[derive(ptr_meta::Pointee, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
pub struct CommandLineTag {
    typ: TagTypeId,
    size: u32,
    /// Null-terminated UTF-8 string
    cmdline: [u8],
}

impl CommandLineTag {
    /// Create a new command line tag from the given string.
    #[cfg(feature = "builder")]
    pub fn new(command_line: &str) -> BoxedDst<Self> {
        let mut bytes: Vec<_> = command_line.bytes().collect();
        if !bytes.ends_with(&[0]) {
            // terminating null-byte
            bytes.push(0);
        }
        BoxedDst::new(TagType::Cmdline, &bytes)
    }

    /// Reads the command line of the kernel as Rust string slice without
    /// the null-byte.
    ///
    /// For example, this returns `"console=ttyS0"`.if the GRUB config
    /// contains  `"multiboot2 /mykernel console=ttyS0"`.
    ///
    /// If the function returns `Err` then perhaps the memory is invalid.
    ///
    /// # Examples
    ///
    /// ```rust,no_run
    /// # let boot_info = unsafe { multiboot2::load(0xdeadbeef).unwrap() };
    /// if let Some(tag) = boot_info.command_line_tag() {
    ///     let command_line = tag.cmdline();
    ///     assert_eq!(Ok("/bootarg"), command_line);
    /// }
    /// ```
    pub fn cmdline(&self) -> Result<&str, str::Utf8Error> {
        Tag::get_dst_str_slice(&self.cmdline)
    }
}

impl Debug for CommandLineTag {
    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
        f.debug_struct("CommandLineTag")
            .field("typ", &{ self.typ })
            .field("size", &{ self.size })
            .field("cmdline", &self.cmdline())
            .finish()
    }
}

impl TagTrait for CommandLineTag {
    fn dst_size(base_tag: &Tag) -> usize {
        assert!(base_tag.size as usize >= METADATA_SIZE);
        base_tag.size as usize - METADATA_SIZE
    }
}

#[cfg(feature = "builder")]
impl StructAsBytes for CommandLineTag {
    fn byte_size(&self) -> usize {
        self.size.try_into().unwrap()
    }
}

#[cfg(test)]
mod tests {
    use crate::{CommandLineTag, Tag, TagType};

    const MSG: &str = "hello";

    /// Returns the tag structure in bytes in little endian format.
    fn get_bytes() -> std::vec::Vec<u8> {
        // size is: 4 bytes for tag + 4 bytes for size + length of null-terminated string
        let size = (4 + 4 + MSG.as_bytes().len() + 1) as u32;
        [
            &((TagType::Cmdline.val()).to_le_bytes()),
            &size.to_le_bytes(),
            MSG.as_bytes(),
            // Null Byte
            &[0],
        ]
        .iter()
        .flat_map(|bytes| bytes.iter())
        .copied()
        .collect()
    }

    /// Tests to parse a string with a terminating null byte from the tag (as the spec defines).
    #[test]
    #[cfg_attr(miri, ignore)]
    fn test_parse_str() {
        let tag = get_bytes();
        let tag = unsafe { &*tag.as_ptr().cast::<Tag>() };
        let tag = tag.cast_tag::<CommandLineTag>();
        assert_eq!({ tag.typ }, TagType::Cmdline);
        assert_eq!(tag.cmdline().expect("must be valid UTF-8"), MSG);
    }

    /// Test to generate a tag from a given string.
    #[test]
    #[cfg(feature = "builder")]
    fn test_build_str() {
        use crate::builder::traits::StructAsBytes;

        let tag = CommandLineTag::new(MSG);
        let bytes = tag.struct_as_bytes();
        assert_eq!(bytes, get_bytes());
        assert_eq!(tag.cmdline(), Ok(MSG));

        // test also some bigger message
        let tag = CommandLineTag::new("AbCdEfGhUjK YEAH");
        assert_eq!(tag.cmdline(), Ok("AbCdEfGhUjK YEAH"));
        let tag = CommandLineTag::new("AbCdEfGhUjK YEAH".repeat(42).as_str());
        assert_eq!(tag.cmdline(), Ok("AbCdEfGhUjK YEAH".repeat(42).as_str()));
    }
}