Support setattr (partially; only for truncation)

Cargo.lock

@@ -889,6 +889,7 @@ dependencies = [
  "dashmap 5.0.0",
  "env_logger",
  "futures-util",
+ "libc",
  "log",
  "olivefs_common",
  "path-absolutize",

olivefs/src/filesystem.rs

@@ -47,6 +47,13 @@ fn test_bits(haystack: i32, needle: i32) -> bool {
     (haystack & needle) == needle
 }
 
+fn absolutise_time_or_now(input: TimeOrNow) -> SystemTime {
+    match input {
+        TimeOrNow::SpecificTime(time) => time,
+        TimeOrNow::Now => SystemTime::now(),
+    }
+}
+
 impl Filesystem for OliveFilesystem {
     /// Initialize filesystem.
     /// Called before any other filesystem method.
@@ -164,8 +171,8 @@ impl Filesystem for OliveFilesystem {
         uid: Option<u32>,
         gid: Option<u32>,
         size: Option<u64>,
-        _atime: Option<TimeOrNow>,
-        _mtime: Option<TimeOrNow>,
+        atime: Option<TimeOrNow>,
+        mtime: Option<TimeOrNow>,
         _ctime: Option<SystemTime>,
         fh: Option<u64>,
         _crtime: Option<SystemTime>,
@@ -174,12 +181,44 @@ impl Filesystem for OliveFilesystem {
         flags: Option<u32>,
         reply: ReplyAttr,
     ) {
-        debug!(
-            "[Not Implemented] setattr(ino: {:#x?}, mode: {:?}, uid: {:?}, \
-            gid: {:?}, size: {:?}, fh: {:?}, flags: {:?})",
-            ino, mode, uid, gid, size, fh, flags
+        let requester = self.requester.clone();
+
+        self.spawn_with_error_handler(
+            async move {
+                let vnode = VnodeId(
+                    ino.try_into()
+                        .context("Converting u64 inode to u32 VnodeId.")?,
+                );
+
+                match requester
+                    .setattr(
+                        vnode,
+                        mode,
+                        uid,
+                        gid,
+                        size,
+                        atime.map(absolutise_time_or_now),
+                        mtime.map(absolutise_time_or_now),
+                    )
+                    .await?
+                {
+                    DataResponse::Success(file_metadata) => {
+                        reply.attr(&Duration::from_secs(5), &file_metadata.into());
+                    }
+                    DataResponse::Error { code, message } => {
+                        warn!(
+                            "setattr(ino: {:#x?}, mode: {:?}, uid: {:?}, \
+                            gid: {:?}, size: {:?}, fh: {:?}, flags: {:?}): {:?}",
+                            ino, mode, uid, gid, size, fh, flags, message
+                        );
+                        reply.error(code as c_int);
+                    }
+                }
+
+                Ok(())
+            },
+            "setattr",
         );
-        reply.error(ENOSYS);
     }
 
     /// Read symbolic link.

olivefs/src/requester.rs

@@ -12,7 +12,7 @@ use std::net::SocketAddr;
 use std::path::Path;
 use std::str::FromStr;
 use std::sync::Arc;
-use std::time::Duration;
+use std::time::{Duration, SystemTime};
 
 use crate::configuration::StreamingReaderConfig;
 use crate::requester::streaming_reader::StreamingReader;
@@ -269,6 +269,29 @@ impl Requester {
             .await
     }
 
+    pub async fn setattr(
+        &self,
+        vnode: VnodeId,
+        mode: Option<u32>,
+        uid: Option<u32>,
+        gid: Option<u32>,
+        size: Option<u64>,
+        atime: Option<SystemTime>,
+        mtime: Option<SystemTime>,
+    ) -> anyhow::Result<DataResponse<FileMetadata>> {
+        self.internal
+            .command(&DataCommand::SetAttr {
+                vnode,
+                mode,
+                uid,
+                gid,
+                size,
+                atime,
+                mtime,
+            })
+            .await
+    }
+
     pub async fn start_streaming_reader(
         &self,
         file_handle: u32,

olivefs_common/src/messages.rs

@@ -79,6 +79,15 @@ pub enum DataCommand {
     FlushFile {
         file_handle: u32,
     },
+    SetAttr {
+        vnode: VnodeId,
+        mode: Option<u32>,
+        uid: Option<u32>,
+        gid: Option<u32>,
+        size: Option<u64>,
+        atime: Option<SystemTime>,
+        mtime: Option<SystemTime>,
+    },
 }
 
 pub trait DataResponseBase: Serialize + DeserializeOwned + Debug + Clone + 'static {}

olivefsd/Cargo.toml

@@ -39,5 +39,8 @@ x509-parser = "0.12.0"
 # consider also: sharded-slab (concurrent access), thunderdome (generational indices)
 slab = "0.4.5"
 
+## System
+libc = "0.2.112"
+
 ## Common
 olivefs_common = { path = "../olivefs_common" }

olivefsd/src/server/connections.rs

@@ -94,6 +94,24 @@ pub async fn handle_command_stream(
                 )
                 .await?;
             }
+            DataCommand::SetAttr {
+                vnode,
+                mode,
+                uid,
+                gid,
+                size,
+                atime,
+                mtime,
+            } => {
+                send_bare_message(
+                    &mut tx,
+                    &file_access
+                        .setattr(vnode, mode, uid, gid, size, atime, mtime)
+                        .await
+                        .unwrap_or_else(error_to_response),
+                )
+                .await?;
+            }
         }
     }
 

olivefsd/src/server/file_access.rs

@@ -1,5 +1,5 @@
 use olivefs_common::error_codes;
-use olivefs_common::error_codes::{EBADFD, EFAULT, ENOENT};
+use olivefs_common::error_codes::{EBADFD, EFAULT, ENOENT, ENOSYS};
 use olivefs_common::messages::{
     DataResponse, DirectoryEntry, FileKind, FileMetadata, OpenMode, VnodeId,
 };
@@ -7,18 +7,23 @@ use path_absolutize::Absolutize;
 use slab::Slab;
 use std::borrow::Borrow;
 use std::collections::HashMap;
+use std::io;
 use std::io::SeekFrom;
 
-use anyhow::bail;
+use anyhow::{anyhow, bail};
+use libc::{ELOOP, O_NOFOLLOW};
+use log::{error, warn};
 use std::os::unix::fs::{MetadataExt, PermissionsExt};
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
-use std::time::{Duration, Instant};
-use log::{error, warn};
+use std::time::{Duration, Instant, SystemTime};
 use tokio::fs::{OpenOptions, ReadDir};
 use tokio::io::{AsyncReadExt, AsyncSeekExt, AsyncWriteExt};
 use tokio::sync::RwLock;
 
+// 4 symlinks ought to be enough for anybody!
+pub const MAX_SYMLINK_RESOLVE_TRIES: u32 = 4;
+
 /// Server-wide state that all clients might need to mess with
 #[derive(Default)]
 pub struct ServerwideState {
@@ -109,6 +114,7 @@ impl FileAccess {
         if let Some(inode_info) = inode_map.get(vnode.0 as usize) {
             Ok(inode_info.real_path.clone())
         } else {
+            // TODO just make this an io::Error.
             Err(DataResponse::Error {
                 code: error_codes::EFAULT,
                 message: "No inode info".to_string(),
@@ -116,6 +122,45 @@ impl FileAccess {
         }
     }
 
+    async fn resolve_vnode_including_follow_symlinks_safely_best_effort(
+        &self,
+        vnode: VnodeId,
+    ) -> anyhow::Result<PathBuf> {
+        let real_path = self
+            .resolve_vnode::<()>(vnode)
+            .await
+            .map_err(|_| anyhow!("No inode info"))?;
+        Ok(self.safely_resolve_symlinks_best_effort(real_path).await?)
+    }
+
+    /// Guarantees that the end file was not a symlink at the time of checking.
+    /// The caller must still prevent themselves from opening symlinks (but they may safely fail
+    /// on opening a symlink if it gets changed under their feet).
+    /// The symlinks will stop resolving if they ever point outside of the root directory, even
+    /// if they point to a symlink that points back into the restricted tree.
+    async fn safely_resolve_symlinks_best_effort(
+        &self,
+        path: PathBuf,
+    ) -> Result<PathBuf, io::Error> {
+        let mut path = path;
+        let root = self.client_info.root.clone();
+        tokio::task::spawn_blocking(move || -> Result<PathBuf, io::Error> {
+            for _ in 0..MAX_SYMLINK_RESOLVE_TRIES {
+                let abs_path = &path.absolutize_virtually(&root)?;
+                let metadata = abs_path.symlink_metadata()?;
+
+                if !metadata.file_type().is_symlink() {
+                    return Ok(abs_path.to_path_buf());
+                }
+
+                path = abs_path.read_link()?;
+            }
+            Err(io::Error::from_raw_os_error(ELOOP)).into()
+        })
+        .await
+        .map_err(|_| io::Error::from_raw_os_error(EFAULT))?
+    }
+
     async fn allocate_vnode(&self, path: PathBuf) -> anyhow::Result<VnodeId> {
         let paths_to_vnodes = self.client_state.existing_paths_to_inodes.read().await;
         if let Some(vi) = paths_to_vnodes.get(&path) {
@@ -314,6 +359,9 @@ impl FileAccess {
                         // We'll allocate the Vnode after we know the target doesn't already exist. Fill in 0 for now.
                         let mut open_options = OpenOptions::new();
 
+                        // IMPORTANT: Don't follow symlinks
+                        open_options.custom_flags(O_NOFOLLOW);
+
                         // Only create new files
                         open_options.create_new(true);
 
@@ -580,4 +628,37 @@ impl FileAccess {
             }),
         }
     }
+
+    pub async fn setattr(
+        &self,
+        vnode: VnodeId,
+        mode: Option<u32>,
+        uid: Option<u32>,
+        gid: Option<u32>,
+        size: Option<u64>,
+        atime: Option<SystemTime>,
+        mtime: Option<SystemTime>,
+    ) -> anyhow::Result<DataResponse<FileMetadata>> {
+        if mode.is_some() || uid.is_some() || gid.is_some() || atime.is_some() || mtime.is_some() {
+            return Err(io::Error::from_raw_os_error(ENOSYS).into());
+        }
+
+        let path = self
+            .resolve_vnode_including_follow_symlinks_safely_best_effort(vnode)
+            .await?;
+
+        if let Some(truncate_to) = size {
+            let mut open_options = OpenOptions::new();
+
+            // IMPORTANT: Don't follow symlinks
+            open_options.custom_flags(O_NOFOLLOW);
+            open_options.write(true);
+            let file = open_options.open(&path).await?;
+            file.set_len(truncate_to).await?;
+        }
+
+        let metadata = self.read_metadata(&path, vnode).await?;
+
+        Ok(DataResponse::Success(metadata))
+    }
 }