file-restore(-daemon): implement list API

Allows listing files and directories on a block device snapshot.
Hierarchy displayed is:

/archive.img.fidx/bucket/component/<path>
e.g.
/drive-scsi0.img.fidx/part/2/etc/passwd
(corresponding to /etc/passwd on the second partition of drive-scsi0)

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

src/bin/proxmox_restore_daemon/api.rs

@@ -1,19 +1,24 @@
 ///! File-restore API running inside the restore VM
-use anyhow::Error;
-use serde_json::Value;
+use anyhow::{bail, Error};
+use std::ffi::OsStr;
 use std::fs;
+use std::os::unix::ffi::OsStrExt;
+use std::path::{Path, PathBuf};
 
 use proxmox::api::{api, ApiMethod, Permission, Router, RpcEnvironment, SubdirMap};
 use proxmox::list_subdirs_api_method;
 
 use proxmox_backup::api2::types::*;
+use proxmox_backup::backup::DirEntryAttribute;
+use proxmox_backup::tools::fs::read_subdir;
 
-use super::{watchdog_remaining, watchdog_ping};
+use super::{disk::ResolveResult, watchdog_remaining, watchdog_ping};
 
 // NOTE: All API endpoints must have Permission::Superuser, as the configs for authentication do
 // not exist within the restore VM. Safety is guaranteed by checking a ticket via a custom ApiAuth.
 
 const SUBDIRS: SubdirMap = &[
+    ("list", &Router::new().get(&API_METHOD_LIST)),
     ("status", &Router::new().get(&API_METHOD_STATUS)),
     ("stop", &Router::new().get(&API_METHOD_STOP)),
 ];
@@ -72,3 +77,123 @@ fn stop() {
     println!("'reboot' syscall failed: {}", err);
     std::process::exit(1);
 }
+
+fn get_dir_entry(path: &Path) -> Result<DirEntryAttribute, Error> {
+    use nix::sys::stat;
+
+    let stat = stat::stat(path)?;
+    Ok(match stat.st_mode & libc::S_IFMT {
+        libc::S_IFREG => DirEntryAttribute::File {
+            size: stat.st_size as u64,
+            mtime: stat.st_mtime,
+        },
+        libc::S_IFDIR => DirEntryAttribute::Directory { start: 0 },
+        _ => bail!("unsupported file type: {}", stat.st_mode),
+    })
+}
+
+#[api(
+    input: {
+        properties: {
+            "path": {
+                type: String,
+                description: "base64-encoded path to list files and directories under",
+            },
+        },
+    },
+    access: {
+        description: "Permissions are handled outside restore VM.",
+        permission: &Permission::Superuser,
+    },
+)]
+/// List file details for given file or a list of files and directories under the given path if it
+/// points to a directory.
+fn list(
+    path: String,
+    _info: &ApiMethod,
+    _rpcenv: &mut dyn RpcEnvironment,
+) -> Result<Vec<ArchiveEntry>, Error> {
+    watchdog_ping();
+
+    let mut res = Vec::new();
+
+    let param_path = base64::decode(path)?;
+    let mut path = param_path.clone();
+    if let Some(b'/') = path.last() {
+        path.pop();
+    }
+    let path_str = OsStr::from_bytes(&path[..]);
+    let param_path_buf = Path::new(path_str);
+
+    let mut disk_state = crate::DISK_STATE.lock().unwrap();
+    let query_result = disk_state.resolve(&param_path_buf)?;
+
+    match query_result {
+        ResolveResult::Path(vm_path) => {
+            let root_entry = get_dir_entry(&vm_path)?;
+            match root_entry {
+                DirEntryAttribute::File { .. } => {
+                    // list on file, return details
+                    res.push(ArchiveEntry::new(&param_path, &root_entry));
+                }
+                DirEntryAttribute::Directory { .. } => {
+                    // list on directory, return all contained files/dirs
+                    for f in read_subdir(libc::AT_FDCWD, &vm_path)? {
+                        if let Ok(f) = f {
+                            let name = f.file_name().to_bytes();
+                            let path = &Path::new(OsStr::from_bytes(name));
+                            if path.components().count() == 1 {
+                                // ignore '.' and '..'
+                                match path.components().next().unwrap() {
+                                    std::path::Component::CurDir
+                                    | std::path::Component::ParentDir => continue,
+                                    _ => {}
+                                }
+                            }
+
+                            let mut full_vm_path = PathBuf::new();
+                            full_vm_path.push(&vm_path);
+                            full_vm_path.push(path);
+                            let mut full_path = PathBuf::new();
+                            full_path.push(param_path_buf);
+                            full_path.push(path);
+
+                            let entry = get_dir_entry(&full_vm_path);
+                            if let Ok(entry) = entry {
+                                res.push(ArchiveEntry::new(
+                                    full_path.as_os_str().as_bytes(),
+                                    &entry,
+                                ));
+                            }
+                        }
+                    }
+                }
+                _ => unreachable!(),
+            }
+        }
+        ResolveResult::BucketTypes(types) => {
+            for t in types {
+                let mut t_path = path.clone();
+                t_path.push(b'/');
+                t_path.extend(t.as_bytes());
+                res.push(ArchiveEntry::new(
+                    &t_path[..],
+                    &DirEntryAttribute::Directory { start: 0 },
+                ));
+            }
+        }
+        ResolveResult::BucketComponents(comps) => {
+            for c in comps {
+                let mut c_path = path.clone();
+                c_path.push(b'/');
+                c_path.extend(c.as_bytes());
+                res.push(ArchiveEntry::new(
+                    &c_path[..],
+                    &DirEntryAttribute::Directory { start: 0 },
+                ));
+            }
+        }
+    }
+
+    Ok(res)
+}