diff --git a/zipfuse/src/inode.rs b/zipfuse/src/inode.rs
new file mode 100644
index 0000000..ec00565
--- /dev/null
+++ b/zipfuse/src/inode.rs
@@ -0,0 +1,419 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+use anyhow::{anyhow, bail, Result};
+use std::collections::HashMap;
+use std::ffi::{OsStr, OsString};
+use std::io;
+
+/// `InodeTable` is a table of `InodeData` indexed by `Inode`.
+#[derive(Debug)]
+pub struct InodeTable {
+    table: Vec<InodeData>,
+}
+
+/// `Inode` is the handle (or index in the table) to `InodeData` which represents an inode.
+pub type Inode = u64;
+
+const INVALID: Inode = 0;
+const ROOT: Inode = 1;
+
+/// `InodeData` represents an inode which has metadata about a file or a directory
+#[derive(Debug)]
+pub struct InodeData {
+    /// Size of the file that this inode represents. In case when the file is a directory, this
+    // is zero.
+    pub size: u64,
+    /// unix mode of this inode. It may not have `S_IFDIR` and `S_IFREG` in case the original zip
+    /// doesn't have the information in the external_attributes fields. To test if this inode
+    /// is for a regular file or a directory, use `is_dir`.
+    pub mode: u32,
+    data: InodeDataData,
+}
+
+type ZipIndex = usize;
+
+/// `InodeDataData` is the actual data (or a means to access the data) of the file or the directory
+/// that an inode is representing. In case of a directory, this data is the hash table of the
+/// directory entries. In case of a file, this data is the index of the file in `ZipArchive` which
+/// can be used to retrieve `ZipFile` that provides access to the content of the file.
+#[derive(Debug)]
+enum InodeDataData {
+    Directory(HashMap<OsString, DirectoryEntry>),
+    File(ZipIndex),
+}
+
+#[derive(Debug, Clone)]
+pub struct DirectoryEntry {
+    pub inode: Inode,
+    pub kind: InodeKind,
+}
+
+#[derive(Debug, Clone, PartialEq, Copy)]
+pub enum InodeKind {
+    Directory,
+    File,
+}
+
+impl InodeData {
+    pub fn is_dir(&self) -> bool {
+        matches!(&self.data, InodeDataData::Directory(_))
+    }
+
+    pub fn get_directory(&self) -> Option<&HashMap<OsString, DirectoryEntry>> {
+        match &self.data {
+            InodeDataData::Directory(hash) => Some(hash),
+            _ => None,
+        }
+    }
+
+    pub fn get_zip_index(&self) -> Option<ZipIndex> {
+        match &self.data {
+            InodeDataData::File(zip_index) => Some(*zip_index),
+            _ => None,
+        }
+    }
+
+    // Below methods are used to construct the inode table when initializing the filesystem. Once
+    // the initialization is done, these are not used because this is a read-only filesystem.
+
+    fn new_dir(mode: u32) -> InodeData {
+        InodeData { mode, size: 0, data: InodeDataData::Directory(HashMap::new()) }
+    }
+
+    fn new_file(zip_index: ZipIndex, zip_file: &zip::read::ZipFile) -> InodeData {
+        InodeData {
+            mode: zip_file.unix_mode().unwrap_or(0),
+            size: zip_file.size(),
+            data: InodeDataData::File(zip_index),
+        }
+    }
+
+    fn add_to_directory(&mut self, name: OsString, entry: DirectoryEntry) {
+        match &mut self.data {
+            InodeDataData::Directory(hashtable) => {
+                let existing = hashtable.insert(name, entry);
+                assert!(existing.is_none());
+            }
+            _ => {
+                panic!("can't add a directory entry to a file inode");
+            }
+        }
+    }
+}
+
+impl InodeTable {
+    /// Gets `InodeData` at a specific index.
+    pub fn get(&self, inode: Inode) -> Option<&InodeData> {
+        match inode {
+            INVALID => None,
+            _ => self.table.get(inode as usize),
+        }
+    }
+
+    fn get_mut(&mut self, inode: Inode) -> Option<&mut InodeData> {
+        match inode {
+            INVALID => None,
+            _ => self.table.get_mut(inode as usize),
+        }
+    }
+
+    fn put(&mut self, data: InodeData) -> Inode {
+        let inode = self.table.len() as Inode;
+        self.table.push(data);
+        inode
+    }
+
+    /// Finds the inode number of a file named `name` in the `parent` inode. The `parent` inode
+    /// must exist and be a directory.
+    fn find(&self, parent: Inode, name: &OsStr) -> Option<Inode> {
+        let data = self.get(parent).unwrap();
+        match data.get_directory().unwrap().get(name) {
+            Some(DirectoryEntry { inode, .. }) => Some(*inode),
+            _ => None,
+        }
+    }
+
+    // Adds the inode `data` to the inode table and also links it to the `parent` inode as a file
+    // named `name`. The `parent` inode must exist and be a directory.
+    fn add(&mut self, parent: Inode, name: &OsStr, data: InodeData) -> Inode {
+        assert!(self.find(parent, name).is_none());
+
+        let kind = if data.is_dir() { InodeKind::Directory } else { InodeKind::File };
+        // Add the inode to the table
+        let inode = self.put(data);
+
+        // ... and then register it to the directory of the parent inode
+        self.get_mut(parent)
+            .unwrap()
+            .add_to_directory(OsString::from(name), DirectoryEntry { inode, kind });
+        inode
+    }
+
+    /// Constructs `InodeTable` from a zip archive `archive`.
+    pub fn from_zip<R: io::Read + io::Seek>(
+        archive: &mut zip::ZipArchive<R>,
+    ) -> Result<InodeTable> {
+        let mut table = InodeTable { table: Vec::new() };
+
+        // Add the inodes for the invalid and the root directory
+        assert_eq!(INVALID, table.put(InodeData::new_dir(0)));
+        assert_eq!(ROOT, table.put(InodeData::new_dir(0)));
+
+        // For each zip file in the archive, create an inode and add it to the table. If the file's
+        // parent directories don't have corresponding inodes in the table, handle them too.
+        for i in 0..archive.len() {
+            let file = archive.by_index(i)?;
+            let path = file
+                .enclosed_name()
+                .ok_or_else(|| anyhow!("{} is an invalid name", file.name()))?;
+            // TODO(jiyong): normalize this (e.g. a/b/c/../d -> a/b/d). We can't use
+            // fs::canonicalize as this is a non-existing path yet.
+
+            let mut parent = ROOT;
+            let mut iter = path.iter().peekable();
+            while let Some(name) = iter.next() {
+                // TODO(jiyong): remove this check by canonicalizing `path`
+                if name == ".." {
+                    bail!(".. is not allowed");
+                }
+
+                let is_leaf = iter.peek().is_none();
+                let is_file = file.is_file() && is_leaf;
+
+                // The happy path; the inode for `name` is already in the `parent` inode. Move on
+                // to the next path element.
+                if let Some(found) = table.find(parent, name) {
+                    parent = found;
+                    // Update the mode if this is a directory leaf.
+                    if !is_file && is_leaf {
+                        let mut inode = table.get_mut(parent).unwrap();
+                        inode.mode = file.unix_mode().unwrap_or(0);
+                    }
+                    continue;
+                }
+
+                const DEFAULT_DIR_MODE: u32 = libc::S_IRUSR | libc::S_IXUSR;
+
+                // No inode found. Create a new inode and add it to the inode table.
+                let inode = if is_file {
+                    InodeData::new_file(i, &file)
+                } else if is_leaf {
+                    InodeData::new_dir(file.unix_mode().unwrap_or(DEFAULT_DIR_MODE))
+                } else {
+                    InodeData::new_dir(DEFAULT_DIR_MODE)
+                };
+                let new = table.add(parent, name, inode);
+                parent = new;
+            }
+        }
+        Ok(table)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::inode::*;
+    use std::io::{Cursor, Write};
+    use zip::write::FileOptions;
+
+    // Creates an in-memory zip buffer, adds some files to it, and converts it to InodeTable
+    fn setup(add: fn(&mut zip::ZipWriter<&mut std::io::Cursor<Vec<u8>>>)) -> InodeTable {
+        let mut buf: Cursor<Vec<u8>> = Cursor::new(Vec::new());
+        let mut writer = zip::ZipWriter::new(&mut buf);
+        add(&mut writer);
+        assert!(writer.finish().is_ok());
+        drop(writer);
+
+        let zip = zip::ZipArchive::new(buf);
+        assert!(zip.is_ok());
+        let it = InodeTable::from_zip(&mut zip.unwrap());
+        assert!(it.is_ok());
+        it.unwrap()
+    }
+
+    fn check_dir(it: &InodeTable, parent: Inode, name: &str) -> Inode {
+        let inode = it.find(parent, &OsString::from(name));
+        assert!(inode.is_some());
+        let inode = inode.unwrap();
+        let inode_data = it.get(inode);
+        assert!(inode_data.is_some());
+        let inode_data = inode_data.unwrap();
+        assert_eq!(0, inode_data.size);
+        assert!(inode_data.is_dir());
+        inode
+    }
+
+    fn check_file<'a>(it: &'a InodeTable, parent: Inode, name: &str) -> &'a InodeData {
+        let inode = it.find(parent, &OsString::from(name));
+        assert!(inode.is_some());
+        let inode = inode.unwrap();
+        let inode_data = it.get(inode);
+        assert!(inode_data.is_some());
+        let inode_data = inode_data.unwrap();
+        assert!(!inode_data.is_dir());
+        inode_data
+    }
+
+    #[test]
+    fn empty_zip_has_two_inodes() {
+        let it = setup(|_| {});
+        assert_eq!(2, it.table.len());
+        assert!(it.get(INVALID).is_none());
+        assert!(it.get(ROOT).is_some());
+    }
+
+    #[test]
+    fn one_file() {
+        let it = setup(|zip| {
+            zip.start_file("foo", FileOptions::default()).unwrap();
+            zip.write_all(b"0123456789").unwrap();
+        });
+        let inode_data = check_file(&it, ROOT, "foo");
+        assert_eq!(b"0123456789".len() as u64, inode_data.size);
+    }
+
+    #[test]
+    fn one_dir() {
+        let it = setup(|zip| {
+            zip.add_directory("foo", FileOptions::default()).unwrap();
+        });
+        let inode = check_dir(&it, ROOT, "foo");
+        // The directory doesn't have any entries
+        assert_eq!(0, it.get(inode).unwrap().get_directory().unwrap().len());
+    }
+
+    #[test]
+    fn one_file_in_subdirs() {
+        let it = setup(|zip| {
+            zip.start_file("a/b/c/d", FileOptions::default()).unwrap();
+            zip.write_all(b"0123456789").unwrap();
+        });
+
+        assert_eq!(6, it.table.len());
+        let a = check_dir(&it, ROOT, "a");
+        let b = check_dir(&it, a, "b");
+        let c = check_dir(&it, b, "c");
+        let d = check_file(&it, c, "d");
+        assert_eq!(10, d.size);
+    }
+
+    #[test]
+    fn complex_hierarchy() {
+        // root/
+        //   a/
+        //    b1/
+        //    b2/
+        //      c1 (file)
+        //      c2/
+        //          d1 (file)
+        //          d2 (file)
+        //          d3 (file)
+        //  x/
+        //    y1 (file)
+        //    y2 (file)
+        //    y3/
+        //
+        //  foo (file)
+        //  bar (file)
+        let it = setup(|zip| {
+            let opt = FileOptions::default();
+            zip.add_directory("a/b1", opt).unwrap();
+
+            zip.start_file("a/b2/c1", opt).unwrap();
+
+            zip.start_file("a/b2/c2/d1", opt).unwrap();
+            zip.start_file("a/b2/c2/d2", opt).unwrap();
+            zip.start_file("a/b2/c2/d3", opt).unwrap();
+
+            zip.start_file("x/y1", opt).unwrap();
+            zip.start_file("x/y2", opt).unwrap();
+            zip.add_directory("x/y3", opt).unwrap();
+
+            zip.start_file("foo", opt).unwrap();
+            zip.start_file("bar", opt).unwrap();
+        });
+
+        assert_eq!(16, it.table.len()); // 8 files, 6 dirs, and 2 (for root and the invalid inode)
+        let a = check_dir(&it, ROOT, "a");
+        let _b1 = check_dir(&it, a, "b1");
+        let b2 = check_dir(&it, a, "b2");
+        let _c1 = check_file(&it, b2, "c1");
+
+        let c2 = check_dir(&it, b2, "c2");
+        let _d1 = check_file(&it, c2, "d1");
+        let _d2 = check_file(&it, c2, "d3");
+        let _d3 = check_file(&it, c2, "d3");
+
+        let x = check_dir(&it, ROOT, "x");
+        let _y1 = check_file(&it, x, "y1");
+        let _y2 = check_file(&it, x, "y2");
+        let _y3 = check_dir(&it, x, "y3");
+
+        let _foo = check_file(&it, ROOT, "foo");
+        let _bar = check_file(&it, ROOT, "bar");
+    }
+
+    #[test]
+    fn file_size() {
+        let it = setup(|zip| {
+            let opt = FileOptions::default();
+            zip.start_file("empty", opt).unwrap();
+
+            zip.start_file("10bytes", opt).unwrap();
+            zip.write_all(&[0; 10]).unwrap();
+
+            zip.start_file("1234bytes", opt).unwrap();
+            zip.write_all(&[0; 1234]).unwrap();
+
+            zip.start_file("2^20bytes", opt).unwrap();
+            zip.write_all(&[0; 2 << 20]).unwrap();
+        });
+
+        let f = check_file(&it, ROOT, "empty");
+        assert_eq!(0, f.size);
+
+        let f = check_file(&it, ROOT, "10bytes");
+        assert_eq!(10, f.size);
+
+        let f = check_file(&it, ROOT, "1234bytes");
+        assert_eq!(1234, f.size);
+
+        let f = check_file(&it, ROOT, "2^20bytes");
+        assert_eq!(2 << 20, f.size);
+    }
+
+    #[test]
+    fn rejects_invalid_paths() {
+        let invalid_paths = [
+            "a/../../b",   // escapes the root
+            "a/..",        // escapes the root
+            "a/../../b/c", // escape the root
+            "a/b/../c",    // doesn't escape the root, but not normalized
+        ];
+        for path in invalid_paths.iter() {
+            let mut buf: Cursor<Vec<u8>> = Cursor::new(Vec::new());
+            let mut writer = zip::ZipWriter::new(&mut buf);
+            writer.start_file(*path, FileOptions::default()).unwrap();
+            assert!(writer.finish().is_ok());
+            drop(writer);
+
+            let zip = zip::ZipArchive::new(buf);
+            assert!(zip.is_ok());
+            let it = InodeTable::from_zip(&mut zip.unwrap());
+            assert!(it.is_err());
+        }
+    }
+}