blkmap

Query file physical extents (FIEMAP) for a given range on disk.

This crate provides a Rust interface to the Linux FIEMAP ioctl, which allows querying the physical block mapping of files on disk. It works on both x86 and ARM Linux platforms.

Features

• Query complete file extent mapping
• Query extent mapping for a specific byte range
• Cross-platform support for x86 and ARM Linux
• Strongly-typed extent flags using bitflags
• Easy-to-use trait-based API
• CLI tool for quick extent queries

Installation

Add this to your Cargo.toml:

[dependencies]
blkmap = "0.1"

Or install the CLI tool:

cargo install blkmap

Library Usage

Query full file extent map

use blkmap::Fiemap;
use std::fs::File;

let file = File::open("/path/to/file")?;
let extents = file.fiemap()?;

for extent in extents {
    println!("Logical: {:#x}, Physical: {:#x}, Length: {:#x}",
             extent.logical, extent.physical, extent.length);
    println!("Flags: {:?}", extent.flags);
}

Query extent map for a specific range

use blkmap::Fiemap;
use std::fs::File;

let file = File::open("/path/to/file")?;
// Query extents for bytes 0-4096
let extents = file.fiemap_range(0, 4096)?;

Using with paths

The Fiemap trait is also implemented for path types:

use blkmap::Fiemap;
use std::path::Path;

// Using a Path
let extents = Path::new("/path/to/file").fiemap()?;

// Using a PathBuf
let path = std::path::PathBuf::from("/path/to/file");
let extents = path.fiemap()?;

Checking extent flags

use blkmap::{Fiemap, ExtentFlags};
use std::fs::File;

let file = File::open("/path/to/file")?;
let extents = file.fiemap()?;

for extent in extents {
    if extent.flags.is_shared() {
        println!("Extent is shared (reflinked/deduplicated)");
    }
    if extent.flags.is_unwritten() {
        println!("Extent is preallocated but not yet written");
    }
    if extent.is_last() {
        println!("This is the last extent in the file");
    }
}

CLI Usage

# Query all extents for a file
blkmap /path/to/file

# Query extents starting from offset 1024
blkmap /path/to/file --offset 1024

# Query extents for a specific range
blkmap /path/to/file --offset 0 --length 4096

# Short options
blkmap /path/to/file -o 1024 -l 8192

Example output:

Index  Logical            Physical           Length             Flags
--------------------------------------------------------------------------------
0      0x0000000000000000 0x00000000c8a01000 0x0000000000001000 LAST
--------------------------------------------------------------------------------
Total: 1 extent(s)

Extent Flags

The following extent flags are supported:

Platform Support

This crate only works on Linux systems. It has been tested on:

• x86_64 (Intel/AMD)
• aarch64 (ARM64)

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.