refactor: move ipfs_unixfs::dir::walk to top level

http/src/v0/root_files.rs

@@ -12,9 +12,9 @@ use bytes::{Bytes, BytesMut, buf::BufMut};
 use tar::{Header, EntryType};
 use futures::stream::TryStream;
 use ipfs::unixfs::ll::file::FileMetadata;
-use ipfs::unixfs::{ll::file::FileReadFailed, TraversalFailed, ll::file::visit::Cache};
+use ipfs::unixfs::{ll::file::FileReadFailed, TraversalFailed};
 use crate::v0::refs::{walk_path, IpfsPath};
-use ipfs::unixfs::ll::dir::walk::{self, Walker, ContinuedWalk};
+use ipfs::unixfs::ll::walk::{self, Walker, ContinuedWalk};
 use ipfs::Block;
 use async_stream::try_stream;
 
@@ -104,7 +104,7 @@ async fn get_inner<T: IpfsTypes>(ipfs: Ipfs<T>, args: GetArgs) -> Result<impl Re
 fn walk<Types: IpfsTypes>(ipfs: Ipfs<Types>, root: Cid)
     -> impl TryStream<Ok = Bytes, Error = GetError> + 'static
 {
-    let mut cache: Option<Cache> = None;
+    let mut cache = None;
     let mut tar_helper = TarHelper::with_buffer_sizes(16 * 1024);
 
     let mut root = Some(root);

unixfs/examples/get.rs

@@ -1,5 +1,4 @@
 use cid::Cid;
-use ipfs_unixfs::file::{FileReadFailed};
 use std::convert::TryFrom;
 use std::fmt;
 use std::io::{Error as IoError, Read};
@@ -57,7 +56,7 @@ fn main() {
 }
 
 fn walk(blocks: ShardedBlockStore, start: &Cid) -> Result<(), Error> {
-    use ipfs_unixfs::dir::walk::{Walker, ContinuedWalk};
+    use ipfs_unixfs::walk::{Walker, ContinuedWalk};
     use std::io::{stdout, Write};
 
     let stdout = stdout();
@@ -75,11 +74,11 @@ fn walk(blocks: ShardedBlockStore, start: &Cid) -> Result<(), Error> {
 
     let mut cache = None;
 
-    let mut visit = match Walker::start(&buf, "", &mut cache).unwrap() {
+    let mut visit = match Walker::start(&buf, "", &mut cache)? {
         ContinuedWalk::Directory(item) => {
             item.into_inner()
         },
-        x => unreachable!("{:?}", x),
+        x => todo!("Only root level directories are supported in this exporter, not: {:?}", x),
     };
 
     let mut header = tar::Header::new_gnu();
@@ -114,7 +113,7 @@ fn walk(blocks: ShardedBlockStore, start: &Cid) -> Result<(), Error> {
         // call to continue_walk.
         let (next, _) = walker.pending_links();
         blocks.as_file(&next.to_bytes())?.read_to_end(&mut buf)?;
-        visit = match walker.continue_walk(&buf, &mut cache).unwrap() {
+        visit = match walker.continue_walk(&buf, &mut cache)? {
             ContinuedWalk::File(segment, item) => {
 
                 let total_size = item.as_entry().total_file_size().unwrap();
@@ -372,7 +371,7 @@ fn path2bytes(p: &Path) -> &[u8] {
 enum Error {
     OpeningFailed(IoError),
     Other(IoError),
-    Traversal(ipfs_unixfs::file::FileReadFailed),
+    Walk(ipfs_unixfs::walk::Error),
 }
 
 impl From<IoError> for Error {
@@ -381,9 +380,9 @@ impl From<IoError> for Error {
     }
 }
 
-impl From<FileReadFailed> for Error {
-    fn from(e: FileReadFailed) -> Error {
-        Error::Traversal(e)
+impl From<ipfs_unixfs::walk::Error> for Error {
+    fn from(e: ipfs_unixfs::walk::Error) -> Error {
+        Error::Walk(e)
     }
 }
 
@@ -393,7 +392,7 @@ impl fmt::Display for Error {
         match self {
             OpeningFailed(e) => write!(fmt, "File opening failed: {}", e),
             Other(e) => write!(fmt, "Other file related io error: {}", e),
-            Traversal(e) => write!(fmt, "Traversal failed, please report this as a bug: {}", e),
+            Walk(e) => write!(fmt, "Walk failed, please report this as a bug: {}", e),
         }
     }
 }

unixfs/examples/resolve.rs

@@ -0,0 +1,291 @@
+use cid::Cid;
+use ipfs_unixfs::dir::{resolve, LookupError, ResolveError};
+use std::convert::TryFrom;
+use std::fmt;
+use std::io::{Error as IoError, Read};
+use std::path::PathBuf;
+
+fn main() {
+    let path = match std::env::args()
+        .nth(1)
+        .map(|s| IpfsPath::try_from(s.as_str()))
+    {
+        Some(Ok(path)) => path,
+        Some(Err(e)) => {
+            eprintln!("Invalid path given as argument: {}", e);
+            std::process::exit(1);
+        }
+        None => {
+            eprintln!("USAGE: {} IPFSPATH\n", std::env::args().next().unwrap());
+            eprintln!(
+                "Will resolve the given IPFSPATH to a CID through any UnixFS \
+                directories or HAMT shards from default go-ipfs 0.5 \
+                configuration flatfs blockstore and write the final CID into \
+                stdout"
+            );
+            std::process::exit(0);
+        }
+    };
+
+    let ipfs_path = match std::env::var("IPFS_PATH") {
+        Ok(s) => s,
+        Err(e) => {
+            eprintln!("IPFS_PATH is not set or could not be read: {}", e);
+            std::process::exit(1);
+        }
+    };
+
+    let mut blocks = PathBuf::from(ipfs_path);
+    blocks.push("blocks");
+
+    let blockstore = ShardedBlockStore { root: blocks };
+
+    match walk(blockstore, path) {
+        Ok(Some(cid)) => {
+            println!("{}", cid);
+        }
+        Ok(None) => {
+            eprintln!("not found");
+        }
+        Err(Error::OpeningFailed(e)) => {
+            eprintln!("{}\n", e);
+            eprintln!("This is likely caused by either:");
+            eprintln!(" - ipfs does not have the block");
+            eprintln!(" - ipfs is configured to use non-flatfs storage");
+            eprintln!(" - ipfs is configured to use flatfs with different sharding");
+            std::process::exit(1);
+        }
+        Err(e) => {
+            eprintln!("Failed to walk the merkle tree: {}", e);
+            std::process::exit(1);
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum PathError {
+    InvalidCid(cid::Error),
+    InvalidPath,
+}
+
+impl fmt::Display for PathError {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            PathError::InvalidCid(e) => write!(fmt, "{}", e),
+            PathError::InvalidPath => write!(fmt, "invalid path"),
+        }
+    }
+}
+
+impl std::error::Error for PathError {}
+
+/// Ipfs path following https://github.com/ipfs/go-path/
+#[derive(Debug)]
+pub struct IpfsPath {
+    /// Option to support moving the cid
+    root: Option<Cid>,
+    path: std::vec::IntoIter<String>,
+}
+
+impl From<Cid> for IpfsPath {
+    /// Creates a new IpfsPath from just the Cid, which is the same as parsing from a string
+    /// representation of a Cid but cannot fail.
+    fn from(root: Cid) -> IpfsPath {
+        IpfsPath {
+            root: Some(root),
+            path: Vec::new().into_iter(),
+        }
+    }
+}
+
+impl TryFrom<&str> for IpfsPath {
+    type Error = PathError;
+
+    fn try_from(path: &str) -> Result<Self, Self::Error> {
+        let mut split = path.splitn(2, "/ipfs/");
+        let first = split.next();
+        let (_root, path) = match first {
+            Some("") => {
+                /* started with /ipfs/ */
+                if let Some(x) = split.next() {
+                    // was /ipfs/x
+                    ("ipfs", x)
+                } else {
+                    // just the /ipfs/
+                    return Err(PathError::InvalidPath);
+                }
+            }
+            Some(x) => {
+                /* maybe didn't start with /ipfs/, need to check second */
+                if split.next().is_some() {
+                    // x/ipfs/_
+                    return Err(PathError::InvalidPath);
+                }
+
+                ("", x)
+            }
+            None => return Err(PathError::InvalidPath),
+        };
+
+        let mut split = path.splitn(2, '/');
+        let root = split
+            .next()
+            .expect("first value from splitn(2, _) must exist");
+
+        let path = split
+            .next()
+            .iter()
+            .flat_map(|s| s.split('/').filter(|s| !s.is_empty()).map(String::from))
+            .collect::<Vec<_>>()
+            .into_iter();
+
+        let root = Some(Cid::try_from(root).map_err(PathError::InvalidCid)?);
+
+        Ok(IpfsPath { root, path })
+    }
+}
+
+impl IpfsPath {
+    pub fn take_root(&mut self) -> Option<Cid> {
+        self.root.take()
+    }
+}
+
+fn walk(blocks: ShardedBlockStore, mut path: IpfsPath) -> Result<Option<Cid>, Error> {
+    use ipfs_unixfs::dir::MaybeResolved::*;
+
+    let mut buf = Vec::new();
+    let mut root = path.take_root().unwrap();
+
+    let mut cache = None;
+
+    for segment in path.path {
+        println!("cache {:?}", cache);
+        buf.clear();
+        eprintln!("reading {} to resolve {:?}", root, segment);
+        blocks.as_file(&root.to_bytes())?.read_to_end(&mut buf)?;
+
+        let mut walker = match resolve(&buf, segment.as_str(), &mut cache)? {
+            Found(cid) => {
+                // either root was a Directory or we got lucky with a HAMT directory.
+                // With HAMTDirectories the top level can contain a direct link to the target, but
+                // it's more likely it will be found under some bucket, which would be the third
+                // case in this match.
+                println!("got lucky: found {} for {:?}", cid, segment);
+                println!("cache {:?}", cache);
+                root = cid;
+                continue;
+            }
+
+            NotFound => return Ok(None),
+
+            // when we stumble upon a HAMT shard, we'll need to look up other blocks in order to
+            // find the final link. The current implementation cannot lookup the directory by
+            // hashing the name and looking it up, but the implementation can be changed underneath
+            // but the API would stay the same.
+            //
+            // HAMTDirecotories or HAMT shards are multi-block directories where the entires are
+            // bucketed per their hash value.
+            NeedToLoadMore(walker) => walker,
+        };
+
+        eprintln!("walking {} on {:?}", root, segment);
+
+        let mut other_blocks = 1;
+
+        loop {
+            let (first, _) = walker.pending_links();
+            buf.clear();
+            eprintln!("  -> reading {} while searching for {:?}", first, segment);
+            blocks.as_file(&first.to_bytes())?.read_to_end(&mut buf)?;
+
+            match walker.continue_walk(&buf, &mut cache)? {
+                NotFound => {
+                    println!("cache {:?}", cache);
+                    return Ok(None);
+                }
+                Found(cid) => {
+                    eprintln!(
+                        "     resolved {} from {} after {} blocks to {}",
+                        segment, root, other_blocks, cid
+                    );
+                    root = cid;
+                    break;
+                }
+                NeedToLoadMore(next) => walker = next,
+            }
+            other_blocks += 1;
+        }
+    }
+
+    println!("cache {:?}", cache);
+    Ok(Some(root))
+}
+
+enum Error {
+    OpeningFailed(IoError),
+    Other(IoError),
+    Traversal(ResolveError),
+}
+
+impl From<IoError> for Error {
+    fn from(e: IoError) -> Error {
+        Error::Other(e)
+    }
+}
+
+impl From<ResolveError> for Error {
+    fn from(e: ResolveError) -> Error {
+        Error::Traversal(e)
+    }
+}
+
+impl From<LookupError> for Error {
+    fn from(e: LookupError) -> Error {
+        Error::Traversal(e.into())
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        use Error::*;
+        match self {
+            OpeningFailed(e) => write!(fmt, "File opening failed: {}", e),
+            Other(e) => write!(fmt, "Other file related io error: {}", e),
+            Traversal(e) => write!(fmt, "Walking failed, please report this as a bug: {:?}", e),
+        }
+    }
+}
+
+struct ShardedBlockStore {
+    root: PathBuf,
+}
+
+impl ShardedBlockStore {
+    fn as_path(&self, key: &[u8]) -> PathBuf {
+        // assume that we have a block store with second-to-last/2 sharding
+        // files in Base32Upper
+
+        let encoded = multibase::Base::Base32Upper.encode(key);
+        let len = encoded.len();
+
+        // this is safe because base32 is ascii
+        let dir = &encoded[(len - 3)..(len - 1)];
+        assert_eq!(dir.len(), 2);
+
+        let mut path = self.root.clone();
+        path.push(dir);
+        path.push(encoded);
+        path.set_extension("data");
+        path
+    }
+
+    fn as_file(&self, key: &[u8]) -> Result<std::fs::File, Error> {
+        let path = self.as_path(key);
+
+        std::fs::OpenOptions::new()
+            .read(true)
+            .open(path)
+            .map_err(Error::OpeningFailed)
+    }
+}

unixfs/src/dir.rs

@@ -7,9 +7,6 @@ use std::fmt;
 mod sharded_lookup;
 pub use sharded_lookup::{Cache, LookupError, ShardError, ShardedLookup};
 
-/// Support for walking over all UnixFs trees. TODO: This needs to be moved to top-level.
-pub mod walk;
-
 /// Resolves a single path segment on `dag-pb` or UnixFS directories (normal, sharded).
 ///
 /// The third parameter can always be substituted with a None but when repeatedly resolving over

unixfs/src/lib.rs

@@ -18,6 +18,9 @@ use crate::pb::UnixFsType;
 /// Support operations for the dag-pb, the outer shell of UnixFS.
 pub mod dagpb;
 
+/// Support for walking over all UnixFs trees.
+pub mod walk;
+
 /// A link could not be transformed into a Cid.
 #[derive(Debug)]
 pub struct InvalidCidInLink {