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Merged
ryanbreen merged 1 commit into from
Feb 19, 2026
Merged

feat: replace b-prefixed Rust coreutils with BusyBox #234

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27 changes: 18 additions & 9 deletions kernel/src/arch_impl/aarch64/elf.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -477,31 +477,40 @@ fn load_segment_into_page_table(
}
}

// Calculate offset within the page where data should go.
// For the first page of a non-page-aligned segment (p_vaddr not aligned),
// data starts partway into the page.
let page_offset = if vaddr.as_u64() > page_vaddr.as_u64() {
(vaddr.as_u64() - page_vaddr.as_u64()) as usize
} else {
0usize
};

// Calculate which part of the file data maps to this page
let page_file_offset = if page_vaddr.as_u64() >= vaddr.as_u64() {
page_vaddr.as_u64() - vaddr.as_u64()
} else {
0
};

// Limit copy to the remaining space in this page to prevent buffer overflow.
// Without this, non-page-aligned segments (e.g., BusyBox data at 0x4005ff78)
// would write past the end of the physical frame, corrupting adjacent memory.
let bytes_available_in_page = (4096 - page_offset) as u64;
let copy_start_in_file = page_file_offset;
let copy_end_in_file = core::cmp::min(page_file_offset + 4096, file_size as u64);
let copy_end_in_file = core::cmp::min(
page_file_offset + bytes_available_in_page,
file_size as u64,
);

if copy_start_in_file < file_size as u64 && copy_end_in_file > copy_start_in_file {
let file_data_start = (file_start as u64 + copy_start_in_file) as usize;
let copy_size = (copy_end_in_file - copy_start_in_file) as usize;

// Calculate offset within the page where data should go
let page_offset = if vaddr.as_u64() > page_vaddr.as_u64() {
vaddr.as_u64() - page_vaddr.as_u64()
} else {
0
};

// Copy data using physical memory access (Linux-style approach)
unsafe {
let src = data.as_ptr().add(file_data_start);
let dst = phys_ptr.add(page_offset as usize);
let dst = phys_ptr.add(page_offset);
core::ptr::copy_nonoverlapping(src, dst, copy_size);
}

Expand Down
27 changes: 18 additions & 9 deletions kernel/src/elf.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -523,31 +523,40 @@ fn load_segment_into_page_table(
// Copy data if this page overlaps with file data
let page_start_vaddr = page.start_address();

// Calculate offset within the page where data should go.
// For the first page of a non-page-aligned segment (p_vaddr not aligned),
// data starts partway into the page.
let page_offset = if vaddr > page_start_vaddr {
(vaddr.as_u64() - page_start_vaddr.as_u64()) as usize
} else {
0usize
};

// Calculate which part of the file data maps to this page
let page_file_offset = if page_start_vaddr >= vaddr {
page_start_vaddr.as_u64() - vaddr.as_u64()
} else {
0
};

// Limit copy to the remaining space in this page to prevent buffer overflow.
// Without this, non-page-aligned segments (e.g., BusyBox data at 0x4005ff78)
// would write past the end of the physical frame, corrupting adjacent memory.
let bytes_available_in_page = (4096 - page_offset) as u64;
let copy_start_in_file = page_file_offset;
let copy_end_in_file = core::cmp::min(page_file_offset + 4096, file_size as u64);
let copy_end_in_file = core::cmp::min(
page_file_offset + bytes_available_in_page,
file_size as u64,
);

if copy_start_in_file < file_size as u64 && copy_end_in_file > copy_start_in_file {
let file_data_start = (file_start as u64 + copy_start_in_file) as usize;
let copy_size = (copy_end_in_file - copy_start_in_file) as usize;

// Calculate offset within the page where data should go
let page_offset = if vaddr > page_start_vaddr {
vaddr.as_u64() - page_start_vaddr.as_u64()
} else {
0
};

// Copy using physical memory access (Linux-style approach)
unsafe {
let src = data.as_ptr().add(file_data_start);
let dst = phys_ptr.add(page_offset as usize);
let dst = phys_ptr.add(page_offset);
core::ptr::copy_nonoverlapping(src, dst, copy_size);
}

Expand Down
78 changes: 73 additions & 5 deletions kernel/src/syscall/fs.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -93,8 +93,14 @@ pub const S_IFDIR: u32 = 0o040000; // Directory
pub const S_IFCHR: u32 = 0o020000; // Character device
pub const S_IFIFO: u32 = 0o010000; // FIFO (pipe)

/// stat structure (Linux compatible)
/// Note: The layout is the same for x86_64 and aarch64 Linux.
/// stat structure (Linux x86_64 compatible - 144 bytes)
///
/// x86_64 and aarch64 Linux have different struct stat layouts.
/// x86_64 uses the layout from arch/x86/include/uapi/asm/stat.h (144 bytes).
/// aarch64 uses the generic layout from include/uapi/asm-generic/stat.h (128 bytes).
/// Key differences: field order (nlink/mode swapped), nlink width (u64 vs u32),
/// blksize width (i64 vs i32), and trailing reserved space (24 vs 8 bytes).
#[cfg(target_arch = "x86_64")]
#[repr(C)]
pub struct Stat {
pub st_dev: u64,
Expand All @@ -117,6 +123,10 @@ pub struct Stat {
_reserved: [i64; 3],
}

#[cfg(target_arch = "x86_64")]
const _: () = assert!(core::mem::size_of::<Stat>() == 144);

#[cfg(target_arch = "x86_64")]
impl Stat {
/// Create a zeroed Stat structure
pub fn zeroed() -> Self {
Expand All @@ -143,6 +153,64 @@ impl Stat {
}
}

/// stat structure (Linux aarch64 compatible - 128 bytes)
///
/// Layout from include/uapi/asm-generic/stat.h used by aarch64 Linux.
#[cfg(target_arch = "aarch64")]
#[repr(C)]
pub struct Stat {
pub st_dev: u64,
pub st_ino: u64,
pub st_mode: u32,
pub st_nlink: u32,
pub st_uid: u32,
pub st_gid: u32,
pub st_rdev: u64,
_pad1: u64,
pub st_size: i64,
pub st_blksize: i32,
_pad2: i32,
pub st_blocks: i64,
pub st_atime: i64,
pub st_atime_nsec: i64,
pub st_mtime: i64,
pub st_mtime_nsec: i64,
pub st_ctime: i64,
pub st_ctime_nsec: i64,
_reserved: [u32; 2],
}

#[cfg(target_arch = "aarch64")]
const _: () = assert!(core::mem::size_of::<Stat>() == 128);

#[cfg(target_arch = "aarch64")]
impl Stat {
/// Create a zeroed Stat structure
pub fn zeroed() -> Self {
Self {
st_dev: 0,
st_ino: 0,
st_mode: 0,
st_nlink: 0,
st_uid: 0,
st_gid: 0,
st_rdev: 0,
_pad1: 0,
st_size: 0,
st_blksize: 0,
_pad2: 0,
st_blocks: 0,
st_atime: 0,
st_atime_nsec: 0,
st_mtime: 0,
st_mtime_nsec: 0,
st_ctime: 0,
st_ctime_nsec: 0,
_reserved: [0; 2],
}
}
}

/// sys_open - Open a file or directory
///
/// Helper: sys_open write path (O_CREAT/O_TRUNC) — works on any Ext2Fs instance.
Expand Down Expand Up @@ -696,7 +764,7 @@ pub fn sys_fstat(fd: i32, statbuf: u64) -> SyscallResult {
stat.st_uid = inode_stat.uid;
stat.st_gid = inode_stat.gid;
stat.st_size = inode_stat.size;
stat.st_nlink = inode_stat.nlink;
stat.st_nlink = inode_stat.nlink as _;
stat.st_atime = inode_stat.atime;
stat.st_mtime = inode_stat.mtime;
stat.st_ctime = inode_stat.ctime;
Expand All @@ -716,7 +784,7 @@ pub fn sys_fstat(fd: i32, statbuf: u64) -> SyscallResult {
stat.st_uid = inode_stat.uid;
stat.st_gid = inode_stat.gid;
stat.st_size = inode_stat.size;
stat.st_nlink = inode_stat.nlink;
stat.st_nlink = inode_stat.nlink as _;
stat.st_atime = inode_stat.atime;
stat.st_mtime = inode_stat.mtime;
stat.st_ctime = inode_stat.ctime;
Expand Down Expand Up @@ -3362,7 +3430,7 @@ pub fn sys_newfstatat(dirfd: i32, pathname: u64, statbuf: u64, _flags: u32) -> S
stat.st_uid = inode_stat.uid;
stat.st_gid = inode_stat.gid;
stat.st_size = inode_stat.size;
stat.st_nlink = inode_stat.nlink;
stat.st_nlink = inode_stat.nlink as _;
stat.st_atime = inode_stat.atime;
stat.st_mtime = inode_stat.mtime;
stat.st_ctime = inode_stat.ctime;
Expand Down
48 changes: 24 additions & 24 deletions kernel/src/test_exec.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3000,11 +3000,11 @@ pub fn test_shell_pipe() {
}
}

/// Test the `btrue` coreutil
/// Test the `true` coreutil
///
/// Verifies that /bin/btrue correctly exits with code 0.
/// Verifies that /sbin/true correctly exits with code 0.
pub fn test_true_coreutil() {
log::info!("Testing btrue coreutil (exit code 0)");
log::info!("Testing true coreutil (exit code 0)");

#[cfg(feature = "testing")]
let true_test_elf_buf = crate::userspace_test::get_test_binary("true_test");
Expand Down Expand Up @@ -3033,11 +3033,11 @@ pub fn test_true_coreutil() {
}
}

/// Test the `bfalse` coreutil
/// Test the `false` coreutil
///
/// Verifies that /bin/bfalse correctly exits with code 1.
/// Verifies that /bin/false correctly exits with code 1.
pub fn test_false_coreutil() {
log::info!("Testing bfalse coreutil (exit code 1)");
log::info!("Testing false coreutil (exit code 1)");

#[cfg(feature = "testing")]
let false_test_elf_buf = crate::userspace_test::get_test_binary("false_test");
Expand Down Expand Up @@ -3066,11 +3066,11 @@ pub fn test_false_coreutil() {
}
}

/// Test the `bhead` coreutil
/// Test the `head` coreutil
///
/// Verifies that /bin/bhead correctly outputs the first N lines of files.
/// Verifies that /bin/head correctly outputs the first N lines of files.
pub fn test_head_coreutil() {
log::info!("Testing bhead coreutil (first N lines)");
log::info!("Testing head coreutil (first N lines)");

#[cfg(feature = "testing")]
let head_test_elf_buf = crate::userspace_test::get_test_binary("head_test");
Expand Down Expand Up @@ -3099,11 +3099,11 @@ pub fn test_head_coreutil() {
}
}

/// Test the `btail` coreutil
/// Test the `tail` coreutil
///
/// Verifies that /bin/btail correctly outputs the last N lines of files.
/// Verifies that /bin/tail correctly outputs the last N lines of files.
pub fn test_tail_coreutil() {
log::info!("Testing btail coreutil (last N lines)");
log::info!("Testing tail coreutil (last N lines)");

#[cfg(feature = "testing")]
let tail_test_elf_buf = crate::userspace_test::get_test_binary("tail_test");
Expand Down Expand Up @@ -3132,11 +3132,11 @@ pub fn test_tail_coreutil() {
}
}

/// Test the `bwc` coreutil
/// Test the `wc` coreutil
///
/// Verifies that /bin/bwc correctly counts lines, words, and bytes.
/// Verifies that /bin/wc correctly counts lines, words, and bytes.
pub fn test_wc_coreutil() {
log::info!("Testing bwc coreutil (line/word/byte counts)");
log::info!("Testing wc coreutil (line/word/byte counts)");

#[cfg(feature = "testing")]
let wc_test_elf_buf = crate::userspace_test::get_test_binary("wc_test");
Expand Down Expand Up @@ -3165,11 +3165,11 @@ pub fn test_wc_coreutil() {
}
}

/// Test the `bwhich` coreutil
/// Test the `which` coreutil
///
/// Verifies that /bin/bwhich correctly locates commands in PATH.
/// Verifies that /bin/which correctly locates commands in PATH.
pub fn test_which_coreutil() {
log::info!("Testing bwhich coreutil (command location)");
log::info!("Testing which coreutil (command location)");

#[cfg(feature = "testing")]
let which_test_elf_buf = crate::userspace_test::get_test_binary("which_test");
Expand Down Expand Up @@ -3198,11 +3198,11 @@ pub fn test_which_coreutil() {
}
}

/// Test the `bcat` coreutil
/// Test the `cat` coreutil
///
/// Verifies that /bin/bcat correctly outputs file contents.
/// Verifies that /bin/cat correctly outputs file contents.
pub fn test_cat_coreutil() {
log::info!("Testing bcat coreutil (file concatenation)");
log::info!("Testing cat coreutil (file concatenation)");

#[cfg(feature = "testing")]
let cat_test_elf_buf = crate::userspace_test::get_test_binary("cat_test");
Expand Down Expand Up @@ -3231,11 +3231,11 @@ pub fn test_cat_coreutil() {
}
}

/// Test the `bls` coreutil
/// Test the `ls` coreutil
///
/// Verifies that /bin/bls correctly lists directory contents.
/// Verifies that /bin/ls correctly lists directory contents.
pub fn test_ls_coreutil() {
log::info!("Testing bls coreutil (directory listing)");
log::info!("Testing ls coreutil (directory listing)");

#[cfg(feature = "testing")]
let ls_test_elf_buf = crate::userspace_test::get_test_binary("ls_test");
Expand Down
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