Add blockdev.rs to parse block device

Author: HuijingHei

src/blockdev.rs

@@ -0,0 +1,208 @@
+use std::collections::HashMap;
+use std::path::Path;
+use std::process::Command;
+use std::sync::OnceLock;
+
+use crate::util;
+use anyhow::{bail, Context, Result};
+use fn_error_context::context;
+use regex::Regex;
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize, Debug)]
+struct BlockDevices {
+    blockdevices: Vec<Device>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+struct Device {
+    path: String,
+    pttype: Option<String>,
+    parttype: Option<String>,
+    parttypename: Option<String>,
+}
+
+impl Device {
+    #[allow(dead_code)]
+    pub(crate) fn is_esp_part(&self) -> bool {
+        const ESP_TYPE_GUID: &str = "c12a7328-f81f-11d2-ba4b-00a0c93ec93b";
+        if let Some(parttype) = &self.parttype {
+            if parttype.to_lowercase() == ESP_TYPE_GUID {
+                return true;
+            }
+        }
+        false
+    }
+
+    pub(crate) fn is_bios_boot_part(&self) -> bool {
+        const BIOS_BOOT_TYPE_GUID: &str = "21686148-6449-6e6f-744e-656564454649";
+        if let Some(parttype) = &self.parttype {
+            if parttype.to_lowercase() == BIOS_BOOT_TYPE_GUID
+                && self.pttype.as_deref() == Some("gpt")
+            {
+                return true;
+            }
+        }
+        false
+    }
+}
+
+/// Parse key-value pairs from lsblk --pairs.
+/// Newer versions of lsblk support JSON but the one in CentOS 7 doesn't.
+fn split_lsblk_line(line: &str) -> HashMap<String, String> {
+    static REGEX: OnceLock<Regex> = OnceLock::new();
+    let regex = REGEX.get_or_init(|| Regex::new(r#"([A-Z-_]+)="([^"]+)""#).unwrap());
+    let mut fields: HashMap<String, String> = HashMap::new();
+    for cap in regex.captures_iter(line) {
+        fields.insert(cap[1].to_string(), cap[2].to_string());
+    }
+    fields
+}
+
+/// This is a bit fuzzy, but... this function will return every block device in the parent
+/// hierarchy of `device` capable of containing other partitions. So e.g. parent devices of type
+/// "part" doesn't match, but "disk" and "mpath" does.
+pub(crate) fn find_parent_devices(device: &str) -> Result<Vec<String>> {
+    let mut cmd = Command::new("lsblk");
+    // Older lsblk, e.g. in CentOS 7.6, doesn't support PATH, but --paths option
+    cmd.arg("--pairs")
+        .arg("--paths")
+        .arg("--inverse")
+        .arg("--output")
+        .arg("NAME,TYPE")
+        .arg(device);
+    let output = util::cmd_output(&mut cmd)?;
+    let mut parents = Vec::new();
+    // skip first line, which is the device itself
+    for line in output.lines().skip(1) {
+        let dev = split_lsblk_line(line);
+        let name = dev
+            .get("NAME")
+            .with_context(|| format!("device in hierarchy of {device} missing NAME"))?;
+        let kind = dev
+            .get("TYPE")
+            .with_context(|| format!("device in hierarchy of {device} missing TYPE"))?;
+        if kind == "disk" {
+            parents.push(name.clone());
+        } else if kind == "mpath" {
+            parents.push(name.clone());
+            // we don't need to know what disks back the multipath
+            break;
+        }
+    }
+    if parents.is_empty() {
+        bail!("no parent devices found for {}", device);
+    }
+    Ok(parents)
+}
+
+#[context("get backing devices from mountpoint boot")]
+pub fn get_backing_devices<P: AsRef<Path>>(target_root: P) -> Result<Vec<String>> {
+    let target_root = target_root.as_ref();
+    let bootdir = target_root.join("boot");
+    if !bootdir.exists() {
+        bail!("{} does not exist", bootdir.display());
+    }
+    let bootdir = openat::Dir::open(&bootdir)?;
+    let fsinfo = crate::filesystem::inspect_filesystem(&bootdir, ".")?;
+    // Find the real underlying backing device for the root.
+    let backing_devices = find_parent_devices(&fsinfo.source)
+        .with_context(|| format!("while looking for backing devices of {}", fsinfo.source))?;
+    log::debug!("Find backing devices: {backing_devices:?}");
+    Ok(backing_devices)
+}
+
+#[context("Listing parttype for device {device}")]
+fn list_dev(device: &str) -> Result<BlockDevices> {
+    let mut cmd = Command::new("lsblk");
+    cmd.args([
+        "--json",
+        "--output",
+        "PATH,PTTYPE,PARTTYPE,PARTTYPENAME",
+        device,
+    ]);
+    let output = util::cmd_output(&mut cmd)?;
+    // Parse the JSON string into the `BlockDevices` struct
+    let Ok(devs) = serde_json::from_str::<BlockDevices>(&output) else {
+        bail!("Could not deserialize JSON output from lsblk");
+    };
+    Ok(devs)
+}
+
+/// Find esp partition on the same device
+pub fn get_esp_partition(device: &str) -> Result<Option<String>> {
+    let dev = list_dev(&device)?;
+    // Find the ESP part on the disk
+    for part in dev.blockdevices {
+        if part.is_esp_part() {
+            return Ok(Some(part.path));
+        }
+    }
+    log::debug!("Not found any esp partition");
+    Ok(None)
+}
+
+/// Find all ESP partitions on the backing devices with mountpoint boot
+#[allow(dead_code)]
+pub fn find_colocated_esps<P: AsRef<Path>>(target_root: P) -> Result<Vec<String>> {
+    // first, get the parent device
+    let backing_devices =
+        get_backing_devices(&target_root).with_context(|| "while looking for colocated ESPs")?;
+
+    // now, look for all ESPs on those devices
+    let mut esps = Vec::new();
+    for parent_device in backing_devices {
+        if let Some(esp) = get_esp_partition(&parent_device)? {
+            esps.push(esp)
+        }
+    }
+    log::debug!("Find esp partitions: {esps:?}");
+    Ok(esps)
+}
+
+/// Find bios_boot partition on the same device
+pub fn get_bios_boot_partition(device: &str) -> Result<Option<String>> {
+    let dev = list_dev(&device)?;
+    // Find the BIOS BOOT part on the disk
+    for part in dev.blockdevices {
+        if part.is_bios_boot_part() {
+            return Ok(Some(part.path));
+        }
+    }
+    log::debug!("Not found any bios_boot partition");
+    Ok(None)
+}
+
+/// Find all bios_boot partitions on the backing devices with mountpoint boot
+#[allow(dead_code)]
+pub fn find_colocated_bios_boot<P: AsRef<Path>>(target_root: P) -> Result<Vec<String>> {
+    // first, get the parent device
+    let backing_devices = get_backing_devices(&target_root)
+        .with_context(|| "looking for colocated bios_boot parts")?;
+
+    // now, look for all bios_boot parts on those devices
+    let mut bios_boots = Vec::new();
+    for parent_device in backing_devices {
+        if let Some(bios) = get_bios_boot_partition(&parent_device)? {
+            bios_boots.push(bios)
+        }
+    }
+    log::debug!("Find bios_boot partitions: {bios_boots:?}");
+    Ok(bios_boots)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_deserialize_lsblk_output() {
+        let data = include_str!("../tests/fixtures/example-lsblk-output.json");
+        let devices: BlockDevices =
+            serde_json::from_str(&data).expect("JSON was not well-formatted");
+        assert_eq!(devices.blockdevices.len(), 7);
+        assert_eq!(devices.blockdevices[0].path, "/dev/sr0");
+        assert!(devices.blockdevices[0].pttype.is_none());
+        assert!(devices.blockdevices[0].parttypename.is_none());
+    }
+}

src/main.rs

@@ -18,6 +18,7 @@ Refs:
 mod backend;
 #[cfg(any(target_arch = "x86_64", target_arch = "powerpc64"))]
 mod bios;
+mod blockdev;
 mod bootupd;
 mod cli;
 mod component;