From 3b85a1d887900c83cb2557a05882984caaef65e1 Mon Sep 17 00:00:00 2001
From: 4lDO2 <4lDO2@protonmail.com>
Date: Sat, 20 Feb 2021 14:15:27 +0100
Subject: [PATCH] Finish kernel-facing API.

---
 src/lib.rs                        | 65 +++++++++++++++++++++++++++----
 src/types.rs                      |  6 +--
 utils/src/redox_initfs_package.rs |  2 +-
 3 files changed, 60 insertions(+), 13 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index df56dba28a..fdc683541c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -12,6 +12,9 @@ pub struct InitFs<'initfs> {
     base: &'initfs [u8],
 }
 
+#[derive(Clone, Copy, Debug)]
+pub struct Inode(u16);
+
 #[derive(Clone, Copy, Debug)]
 pub struct Error;
 
@@ -50,6 +53,59 @@ impl<'initfs> InodeDir<'initfs> {
     pub fn inode(self) -> InodeStruct<'initfs> {
         self.inner
     }
+    pub fn entry_count(&self) -> Result<u32> {
+        let len = self.entries()?.len();
+
+        // NOTE: Len is originally stored as a u32 in the struct, so it can never exceed u32
+        // despite first being converted to usize.
+        let len = len as u32;
+
+        Ok(len)
+    }
+    pub fn get_entry(&self, idx: u32) -> Result<Option<Entry<'initfs>>> {
+        let idx = usize::try_from(idx).map_err(|_| Error)?;
+
+        self.entries().map(|entries| {
+            let entry = entries.get(idx)?;
+
+            Some(Entry {
+                entry,
+                initfs: self.inner.initfs,
+            })
+        })
+    }
+    fn entries(&self) -> Result<&'initfs [DirEntry]> {
+        let bytes = self.inner.data()?;
+        let entries = plain::slice_from_bytes::<DirEntry>(bytes)
+            .expect("expected dir entry to have alignment 1");
+
+        Ok(entries)
+    }
+}
+
+pub struct Entry<'initfs> {
+    initfs: InitFs<'initfs>,
+    entry: &'initfs DirEntry,
+}
+
+impl<'initfs> Entry<'initfs> {
+    pub fn inode(&self) -> Inode {
+        Inode(self.entry.inode.get())
+    }
+    pub fn name(&self) -> Result<&'initfs [u8]> {
+        let name_offset: usize = self
+            .entry
+            .name_offset
+            .0
+            .get()
+            .try_into()
+            .map_err(|_| Error)?;
+        let name_length: usize = self.entry.name_len.get().try_into().map_err(|_| Error)?;
+
+        let name_end = name_offset.checked_add(name_length).ok_or(Error)?;
+
+        self.initfs.base.get(name_offset..name_end).ok_or(Error)
+    }
 }
 
 #[derive(Clone, Copy)]
@@ -153,11 +209,6 @@ impl<'initfs> InitFs<'initfs> {
             .try_into()
             .expect("expected inode struct size to fit within u8")
     }
-    fn direntry_struct_len_8() -> u8 {
-        core::mem::size_of::<DirEntry>()
-            .try_into()
-            .expect("expected dir entry struct size to fit within u8")
-    }
     fn inode_table_offset_usize(&self) -> usize {
         // NOTE: We have already validated that the inode table fits within the initfs slice, and
         // that this length, which must fit within usize, also fits within u32.
@@ -190,7 +241,7 @@ impl<'initfs> InitFs<'initfs> {
         plain::slice_from_bytes::<InodeHeader>(inode_table_bytes)
             .expect("expected inode struct alignment to be 1")
     }
-    pub const ROOT_INODE: Inode = Inode(U16::new(0));
+    pub const ROOT_INODE: Inode = Inode(0);
 
     pub fn inode_count(&self) -> u16 {
         self.get_header_assume_valid().inode_count.get()
@@ -199,7 +250,7 @@ impl<'initfs> InitFs<'initfs> {
         // NOTE: Even for 16-bit architectures (obviously edge-case, but some bootloaders may
         // perhaps use this code), we have already checked that the inode table can fit within
         // usize, and the table byte size is always larger than the count.
-        let inode_usize = inode.0.get() as usize;
+        let inode_usize = inode.0 as usize;
 
         let inode = self.inode_table().get(inode_usize)?;
 
diff --git a/src/types.rs b/src/types.rs
index cbddb7ed48..405387f1e3 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -50,10 +50,6 @@ pub struct Offset(pub U32);
 #[derive(Clone, Copy, Debug)]
 pub struct Length(pub U32);
 
-#[repr(transparent)]
-#[derive(Clone, Copy, Debug)]
-pub struct Inode(pub U16);
-
 #[repr(packed)]
 #[derive(Clone, Copy, Debug)]
 pub struct Timespec {
@@ -97,7 +93,7 @@ pub enum InodeType {
 #[repr(packed)]
 #[derive(Clone, Copy, Debug)]
 pub struct DirEntry {
-    pub inode: Inode,
+    pub inode: U16,
     pub name_len: U16,
     pub name_offset: Offset,
 }
diff --git a/utils/src/redox_initfs_package.rs b/utils/src/redox_initfs_package.rs
index d438c78e7f..447b73c947 100644
--- a/utils/src/redox_initfs_package.rs
+++ b/utils/src/redox_initfs_package.rs
@@ -294,7 +294,7 @@ fn allocate_and_write_dir(
             let inode = this_start_inode + index;
 
             *direntry = initfs::DirEntry {
-                inode: initfs::Inode(inode.into()),
+                inode: inode.into(),
                 name_len: name_len.into(),
                 name_offset: initfs::Offset(name_offset.into()),
             };