btrfs_cli/inspect/
dump_super.rs

1use super::print_super;
2use crate::{Format, Runnable};
3use anyhow::{Context, Result, bail};
4use btrfs_disk::superblock::{self, SUPER_MIRROR_MAX};
5use clap::Parser;
6use std::{fs::File, path::PathBuf};
7
8/// Dump the btrfs superblock from a device or image file.
9///
10/// Reads and displays the superblock stored on a btrfs block device or
11/// filesystem image. By default only the primary superblock (mirror 0,
12/// at offset 64 KiB) is printed. Use -a to print all mirrors, or -s to
13/// select a specific one.
14#[derive(Parser, Debug)]
15pub struct DumpSuperCommand {
16    /// Path to a btrfs block device or image file
17    path: PathBuf,
18
19    /// Print full information including sys_chunk_array and backup roots
20    #[clap(short = 'f', long)]
21    full: bool,
22
23    /// Print all superblock mirrors (0, 1, 2)
24    #[clap(short = 'a', long)]
25    all: bool,
26
27    /// Print only this superblock mirror (0, 1, or 2)
28    #[clap(short = 's', long = "super", value_parser = clap::value_parser!(u32).range(..SUPER_MIRROR_MAX as i64))]
29    mirror: Option<u32>,
30
31    /// Read the superblock from this byte offset instead of using a mirror index
32    #[clap(long, conflicts_with_all = ["mirror", "all"])]
33    bytenr: Option<u64>,
34
35    /// Attempt to print superblocks with bad magic
36    #[clap(short = 'F', long)]
37    force: bool,
38}
39
40impl Runnable for DumpSuperCommand {
41    fn run(&self, _format: Format, _dry_run: bool) -> Result<()> {
42        let mut file = File::open(&self.path).with_context(|| {
43            format!("failed to open '{}'", self.path.display())
44        })?;
45
46        // Collect (offset, label) pairs for each superblock to print.
47        let offsets: Vec<(u64, String)> = if let Some(bytenr) = self.bytenr {
48            vec![(bytenr, format!("bytenr={bytenr}"))]
49        } else if self.all {
50            (0..SUPER_MIRROR_MAX)
51                .map(|m| {
52                    let off = superblock::super_mirror_offset(m);
53                    (off, format!("bytenr={off}"))
54                })
55                .collect()
56        } else {
57            let m = self.mirror.unwrap_or(0);
58            let off = superblock::super_mirror_offset(m);
59            vec![(off, format!("bytenr={off}"))]
60        };
61
62        for (i, (offset, label)) in offsets.iter().enumerate() {
63            if i > 0 {
64                println!();
65            }
66
67            println!("superblock: {label}, device={}", self.path.display());
68
69            let sb = match superblock::read_superblock_at(&mut file, *offset) {
70                Ok(sb) => sb,
71                Err(e) if e.kind() == std::io::ErrorKind::UnexpectedEof => {
72                    println!(
73                        "superblock at {label} beyond end of device, skipping"
74                    );
75                    continue;
76                }
77                Err(e) => {
78                    return Err(e).with_context(|| {
79                        format!(
80                            "failed to read superblock at {label} from '{}'",
81                            self.path.display()
82                        )
83                    });
84                }
85            };
86
87            if !sb.magic_is_valid() && !self.force {
88                if self.all {
89                    println!(
90                        "superblock at {label} has bad magic, skipping (use -F to force)"
91                    );
92                    continue;
93                }
94                bail!(
95                    "bad magic on superblock at {label} of '{}' (use -F to force)",
96                    self.path.display()
97                );
98            }
99
100            println!(
101                "---------------------------------------------------------"
102            );
103            print_super::print_superblock(&sb, self.full);
104        }
105
106        Ok(())
107    }
108}
btrfs_cli/inspect/dump_super.rs

btrfs_cli/inspect/
dump_super.rs
