impl WasiFile for cap_std::fs::File

Cargo.lock

@@ -205,6 +205,31 @@ version = "1.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "08c48aae112d48ed9f069b33538ea9e3e90aa263cfa3d1c24309612b1f7472de"
 
+[[package]]
+name = "cap-primitives"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f9069ed88e23a3fff56577518a238e6975920620cd5d00be8ca73aa46a96d5f5"
+dependencies = [
+ "errno",
+ "fs-set-times",
+ "ipnet",
+ "libc",
+ "once_cell",
+ "posish",
+ "winapi",
+ "winx 0.20.0",
+]
+
+[[package]]
+name = "cap-std"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eacf34fea6948253011b8771b7ae6258a2ae15c7ba38e78b7dd60a785af354d2"
+dependencies = [
+ "cap-primitives",
+]
+
 [[package]]
 name = "capstone"
 version = "0.7.0"
@@ -897,6 +922,16 @@ version = "1.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
+[[package]]
+name = "fs-set-times"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4a37c11eb7933093dd2a56c9c4d934a754b56e672fb8c2b46d50997dd2b4392d"
+dependencies = [
+ "posish",
+ "winapi",
+]
+
 [[package]]
 name = "fst"
 version = "0.4.5"
@@ -1042,6 +1077,12 @@ dependencies = [
  "regex",
 ]
 
+[[package]]
+name = "ipnet"
+version = "2.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "47be2f14c678be2fdcab04ab1171db51b2762ce6f0a8ee87c8dd4a04ed216135"
+
 [[package]]
 name = "iter-enum"
 version = "0.2.4"
@@ -2311,6 +2352,7 @@ name = "wasi-c2"
 version = "0.21.0"
 dependencies = [
  "anyhow",
+ "cap-std",
  "getrandom 0.2.0",
  "libc",
  "system-interface",

crates/wasi-c2/Cargo.toml

@@ -20,6 +20,7 @@ getrandom = { version = "0.2.0", features = ["std"] }
 wiggle = { path = "../wiggle", default-features = false, version = "0.21.0" }
 tracing = "0.1.19"
 system-interface = { path = "../../../system-interface" }
+cap-std = "*"
 
 [badges]
 maintenance = { status = "actively-developed" }

crates/wasi-c2/src/ctx.rs

@@ -22,7 +22,6 @@ impl WasiCtx {
         file: Box<dyn WasiFile>,
         base_caps: FileCaps,
         inheriting_caps: FileCaps,
-        path: Option<PathBuf>,
     ) {
         let e = FileEntry {
             base_caps,

crates/wasi-c2/src/dir.rs

@@ -1,3 +1,5 @@
+// this file is extremely wip
+#![allow(dead_code, unused_variables)]
 use std::path::PathBuf;
 
 pub trait WasiDir {}

crates/wasi-c2/src/file.rs

@@ -3,37 +3,20 @@ use std::ops::Deref;
 use system_interface::fs::FileIoExt;
 
 pub trait WasiFile: FileIoExt {
-    fn allocate(&self, _offset: u64, _len: u64) -> Result<(), Error> {
+    fn datasync(&self) -> Result<(), Error>;
-        todo!("to implement fd_allocate, FileIoExt needs methods to get and set length of a file")
+    fn sync(&self) -> Result<(), Error>;
-    }
+    fn get_filetype(&self) -> Result<Filetype, Error>;
-    fn datasync(&self) -> Result<(), Error> {
+    fn get_fdflags(&self) -> Result<FdFlags, Error>;
-        todo!("FileIoExt has no facilities for sync");
+    fn get_oflags(&self) -> Result<OFlags, Error>;
-    }
+    fn set_oflags(&self, _flags: OFlags) -> Result<(), Error>;
-    fn filetype(&self) -> Filetype {
+    fn get_filestat(&self) -> Result<Filestat, Error>;
-        todo!("FileIoExt has no facilities for filetype");
+    fn set_filestat_times(
-    }
-    fn oflags(&self) -> OFlags {
-        todo!("FileIoExt has no facilities for oflags");
-    }
-    fn set_oflags(&self, _flags: OFlags) -> Result<(), Error> {
-        todo!("FileIoExt has no facilities for oflags");
-    }
-    fn filestat_get(&self) -> Result<Filestat, Error> {
-        todo!()
-    }
-    fn filestat_set_times(
         &self,
         _atim: Option<FilestatSetTime>,
         _mtim: Option<FilestatSetTime>,
-    ) -> Result<(), Error> {
+    ) -> Result<(), Error>;
-        todo!()
+    fn set_filestat_size(&self, _size: u64) -> Result<(), Error>;
-    }
+    fn allocate(&self, _offset: u64, _len: u64) -> Result<(), Error>;
-    fn filestat_set_size(&self, _size: u64) -> Result<(), Error> {
-        todo!()
-    }
-    fn sync(&self) -> Result<(), Error> {
-        todo!("FileIoExt has no facilities for sync")
-    }
 }
 
 #[derive(Debug, Copy, Clone)]
@@ -45,6 +28,24 @@ pub enum Filetype {
     SocketStream,
 }
 
+pub struct FdFlags {
+    flags: u32,
+}
+
+impl FdFlags {
+    /// Checks if `other` is a subset of those capabilties:
+    pub fn contains(&self, other: &Self) -> bool {
+        self.flags & other.flags == other.flags
+    }
+
+    pub const APPEND: FdFlags = FdFlags { flags: 1 };
+    pub const DSYNC: FdFlags = FdFlags { flags: 2 };
+    pub const NONBLOCK: FdFlags = FdFlags { flags: 4 };
+    pub const RSYNC: FdFlags = FdFlags { flags: 8 };
+    pub const SYNC: FdFlags = FdFlags { flags: 16 };
+    // etc
+}
+
 pub struct OFlags {
     flags: u32,
 }
@@ -75,7 +76,7 @@ pub struct Filestat {
     inode: u64,
     filetype: Filetype,
     nlink: u64,
-    size: usize,
+    size: u64,
     atim: std::time::SystemTime,
     mtim: std::time::SystemTime,
     ctim: std::time::SystemTime,
@@ -101,6 +102,15 @@ impl FileEntry {
             Err(Error::FileNotCapable(caps))
         }
     }
+
+    pub fn get_fdstat(&self) -> Result<FdStat, Error> {
+        Ok(FdStat {
+            filetype: self.file.get_filetype()?,
+            base_caps: self.base_caps,
+            inheriting_caps: self.inheriting_caps,
+            flags: self.file.get_fdflags()?,
+        })
+    }
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -146,3 +156,91 @@ impl std::fmt::Display for FileCaps {
         todo!()
     }
 }
+
+pub struct FdStat {
+    pub filetype: Filetype,
+    pub base_caps: FileCaps,
+    pub inheriting_caps: FileCaps,
+    pub flags: FdFlags,
+}
+
+impl WasiFile for cap_std::fs::File {
+    fn datasync(&self) -> Result<(), Error> {
+        self.sync_data()?;
+        Ok(())
+    }
+    fn sync(&self) -> Result<(), Error> {
+        self.sync_all()?;
+        Ok(())
+    }
+    fn get_filetype(&self) -> Result<Filetype, Error> {
+        let meta = self.metadata()?;
+        // cap-std's Metadata/FileType only offers booleans indicating whether a file is a directory,
+        // symlink, or regular file.
+        // Directories should be excluded by the type system.
+        if meta.is_file() {
+            Ok(Filetype::RegularFile)
+        } else {
+            Err(Error::Badf) // XXX idk what to do here
+        }
+    }
+    fn get_fdflags(&self) -> Result<FdFlags, Error> {
+        // XXX cap-std doesnt expose append, dsync, nonblock, rsync, sync
+        todo!()
+    }
+    fn get_oflags(&self) -> Result<OFlags, Error> {
+        // XXX what if it was opened append, async, nonblock...
+        let perms = self.metadata()?.permissions();
+        if perms.readonly() {
+            Ok(OFlags::RDONLY)
+        } else {
+            Ok(OFlags::RDWR)
+        }
+    }
+    fn set_oflags(&self, _flags: OFlags) -> Result<(), Error> {
+        // XXX cap-std::fs::Permissions does not export a constructor to build this out of
+        #[allow(unreachable_code)]
+        self.set_permissions(todo!())?;
+        Ok(())
+    }
+    fn get_filestat(&self) -> Result<Filestat, Error> {
+        // XXX cap-std does not expose every part of filestat
+        #![allow(unreachable_code, unused_variables)]
+        let meta = self.metadata()?;
+        Ok(Filestat {
+            device_id: todo!(),
+            inode: todo!(),
+            filetype: self.get_filetype()?,
+            nlink: todo!(),
+            size: meta.len(),
+            atim: meta.accessed()?.into_std(),
+            mtim: meta.modified()?.into_std(),
+            ctim: meta.created()?.into_std(),
+        })
+    }
+    fn set_filestat_times(
+        &self,
+        _atim: Option<FilestatSetTime>,
+        _mtim: Option<FilestatSetTime>,
+    ) -> Result<(), Error> {
+        // XXX cap-std does not expose a way to set accessed time or modified time
+        todo!()
+    }
+    fn set_filestat_size(&self, size: u64) -> Result<(), Error> {
+        self.set_len(size)?;
+        Ok(())
+    }
+    fn allocate(&self, offset: u64, len: u64) -> Result<(), Error> {
+        let metadata = self.metadata()?;
+        let current_size = metadata.len();
+        let wanted_size = offset.checked_add(len).ok_or(Error::TooBig)?;
+        // This check will be unnecessary when rust-lang/rust#63326 is fixed
+        if wanted_size > i64::max_value() as u64 {
+            return Err(Error::TooBig);
+        }
+        if wanted_size > current_size {
+            self.set_len(wanted_size)?;
+        }
+        Ok(())
+    }
+}

crates/wasi-c2/src/snapshots/preview_1.rs

@@ -1,6 +1,8 @@
 #![allow(unused_variables)]
 use crate::dir::{DirEntry, TableDirExt};
-use crate::file::{FileCaps, FileEntry, Filestat, FilestatSetTime, Filetype, OFlags};
+use crate::file::{
+    FdFlags, FdStat, FileCaps, FileEntry, Filestat, FilestatSetTime, Filetype, OFlags,
+};
 use crate::{Error, WasiCtx};
 use std::cell::RefMut;
 use std::convert::TryFrom;
@@ -191,7 +193,8 @@ impl<'a> wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
     fn fd_fdstat_get(&self, fd: types::Fd) -> Result<types::Fdstat, Error> {
         let table = self.table();
         let file_entry: RefMut<FileEntry> = table.get(u32::from(fd))?;
-        Ok(types::Fdstat::from(file_entry.deref()))
+        let fdstat = file_entry.get_fdstat()?;
+        Ok(types::Fdstat::from(&fdstat))
     }
 
     fn fd_fdstat_set_flags(&self, fd: types::Fd, flags: types::Fdflags) -> Result<(), Error> {
@@ -227,7 +230,7 @@ impl<'a> wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
         let table = self.table();
         let file_entry: RefMut<FileEntry> = table.get(u32::from(fd))?;
         let f = file_entry.get_cap(FileCaps::FILESTAT_GET)?;
-        let filestat = f.filestat_get()?;
+        let filestat = f.get_filestat()?;
         Ok(filestat.into())
     }
 
@@ -235,7 +238,7 @@ impl<'a> wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
         let table = self.table();
         let file_entry: RefMut<FileEntry> = table.get(u32::from(fd))?;
         let f = file_entry.get_cap(FileCaps::FILESTAT_SET_SIZE)?;
-        f.filestat_set_size(size)?;
+        f.set_filestat_size(size)?;
         Ok(())
     }
 
@@ -278,7 +281,7 @@ impl<'a> wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
             None
         };
 
-        f.filestat_set_times(atim, mtim)?;
+        f.set_filestat_times(atim, mtim)?;
         Ok(())
     }
 
@@ -649,13 +652,13 @@ impl From<types::Advice> for system_interface::fs::Advice {
     }
 }
 
-impl From<&FileEntry> for types::Fdstat {
+impl From<&FdStat> for types::Fdstat {
-    fn from(entry: &FileEntry) -> types::Fdstat {
+    fn from(fdstat: &FdStat) -> types::Fdstat {
         types::Fdstat {
-            fs_filetype: types::Filetype::from(&entry.file.filetype()),
+            fs_filetype: types::Filetype::from(&fdstat.filetype),
-            fs_rights_base: types::Rights::from(&entry.base_caps),
+            fs_rights_base: types::Rights::from(&fdstat.base_caps),
-            fs_rights_inheriting: types::Rights::from(&entry.base_caps),
+            fs_rights_inheriting: types::Rights::from(&fdstat.inheriting_caps),
-            fs_flags: types::Fdflags::from(&entry.file.oflags()),
+            fs_flags: types::Fdflags::from(&fdstat.flags),
         }
     }
 }
@@ -686,9 +689,9 @@ impl From<&Filetype> for types::Filetype {
         }
     }
 }
-impl From<&OFlags> for types::Fdflags {
+impl From<&FdFlags> for types::Fdflags {
-    fn from(caps: &OFlags) -> types::Fdflags {
+    fn from(fdflags: &FdFlags) -> types::Fdflags {
-        todo!("translate OFlags flags to Fdflags flags")
+        todo!("translate internal to Fdflags")
     }
 }