Fixes for shm handling

ipcd/src/shm.rs

@@ -5,13 +5,15 @@ use std::{
     rc::Rc,
 };
 use syscall::{
-    error::*, schemev2::NewFdFlags, Error, Map, MapFlags, Result, MAP_PRIVATE, PAGE_SIZE,
+    error::*, schemev2::NewFdFlags, Error, Map, MapFlags, Result, MAP_PRIVATE, MAP_SHARED,
+    PAGE_SIZE, PROT_READ, PROT_WRITE,
 };
 
 #[derive(Default)]
 pub struct ShmHandle {
     buffer: Option<MmapGuard>,
     refs: usize,
+    unlinked: bool,
 }
 pub struct ShmScheme {
     maps: HashMap<Rc<str>, ShmHandle>,
@@ -29,12 +31,23 @@ impl ShmScheme {
 }
 
 impl SchemeSync for ShmScheme {
-    fn open(&mut self, path: &str, _flags: usize, _ctx: &CallerCtx) -> Result<OpenResult> {
+    //FIXME: Handle O_RDONLY/O_WRONLY/O_RDWR
+    fn open(&mut self, path: &str, flags: usize, _ctx: &CallerCtx) -> Result<OpenResult> {
         let path = Rc::from(path);
-        let entry = self
-            .maps
-            .entry(Rc::clone(&path))
-            .or_insert(ShmHandle::default());
+        let entry = match self.maps.entry(Rc::clone(&path)) {
+            Entry::Occupied(mut e) => {
+                if flags & syscall::O_EXCL != 0 && flags & syscall::O_CREAT != 0 {
+                    return Err(Error::new(EEXIST));
+                }
+                e.into_mut()
+            }
+            Entry::Vacant(e) => {
+                if flags & syscall::O_CREAT == 0 {
+                    return Err(Error::new(ENOENT));
+                }
+                e.insert(ShmHandle::default())
+            }
+        };
         entry.refs += 1;
         self.handles.insert(self.next_id, path);
 
@@ -42,12 +55,12 @@ impl SchemeSync for ShmScheme {
         self.next_id += 1;
         Ok(OpenResult::ThisScheme {
             number: id,
-            flags: NewFdFlags::empty(),
+            flags: NewFdFlags::POSITIONED,
         })
     }
     fn fpath(&mut self, id: usize, buf: &mut [u8], _ctx: &CallerCtx) -> Result<usize> {
         // Write scheme name
-        const PREFIX: &[u8] = b"shm:";
+        const PREFIX: &[u8] = b"/scheme/shm/";
         let len = cmp::min(PREFIX.len(), buf.len());
         buf[..len].copy_from_slice(&PREFIX[..len]);
         if len < PREFIX.len() {
@@ -68,10 +81,32 @@ impl SchemeSync for ShmScheme {
             Entry::Vacant(_) => panic!("handle pointing to nothing"),
         };
         entry.get_mut().refs -= 1;
+        if entry.get().refs == 0 && entry.get().unlinked {
+            // There is no other reference to this entry, drop
+            entry.remove_entry();
+        }
+    }
+    fn unlink(&mut self, path: &str, ctx: &CallerCtx) -> Result<()> {
+        let path = Rc::from(path);
+        let mut entry = match self.maps.entry(Rc::clone(&path)) {
+            Entry::Occupied(e) => e,
+            Entry::Vacant(_) => return Err(Error::new(ENOENT)),
+        };
+
+        entry.get_mut().unlinked = true;
         if entry.get().refs == 0 {
             // There is no other reference to this entry, drop
             entry.remove_entry();
         }
+        Ok(())
+    }
+    fn ftruncate(&mut self, id: usize, len: u64, _ctx: &CallerCtx) -> Result<()> {
+        let path = self.handles.get(&id).ok_or(Error::new(EBADF))?;
+        self.maps
+            .get_mut(path)
+            .expect("handle pointing to nothing")
+            .buffer = Some(MmapGuard::alloc((len as usize).div_ceil(PAGE_SIZE))?);
+        Ok(())
     }
     fn mmap_prep(
         &mut self,
@@ -95,12 +130,51 @@ impl SchemeSync for ShmScheme {
                 }
                 Ok(buf.as_ptr() + offset as usize)
             }
+            //TODO: this should be only handled by ftruncate
             ref mut buf @ None => {
                 *buf = Some(MmapGuard::alloc(size.div_ceil(PAGE_SIZE))?);
                 Ok(buf.as_mut().unwrap().as_ptr() + offset as usize)
             }
         }
     }
+    fn read(
+        &mut self,
+        id: usize,
+        buf: &mut [u8],
+        offset: u64,
+        fcntl_flags: u32,
+        ctx: &CallerCtx,
+    ) -> Result<usize> {
+        let path = self.handles.get(&id).ok_or(Error::new(EBADF))?;
+        match self
+            .maps
+            .get_mut(path)
+            .expect("handle pointing to nothing")
+            .buffer
+        {
+            Some(ref mut map) => map.read(offset as usize, buf),
+            None => Err(Error::new(ERANGE)),
+        }
+    }
+    fn write(
+        &mut self,
+        id: usize,
+        buf: &[u8],
+        offset: u64,
+        fcntl_flags: u32,
+        ctx: &CallerCtx,
+    ) -> Result<usize> {
+        let path = self.handles.get(&id).ok_or(Error::new(EBADF))?;
+        match self
+            .maps
+            .get_mut(path)
+            .expect("handle pointing to nothing")
+            .buffer
+        {
+            Some(ref mut map) => map.write(offset as usize, buf),
+            None => Err(Error::new(ERANGE)),
+        }
+    }
 }
 
 pub struct MmapGuard {
@@ -116,7 +190,7 @@ impl MmapGuard {
                 &Map {
                     offset: 0,
                     size,
-                    flags: MAP_PRIVATE,
+                    flags: MAP_PRIVATE | PROT_READ | PROT_WRITE,
                     address: 0,
                 },
             )
@@ -130,6 +204,44 @@ impl MmapGuard {
     pub fn as_ptr(&self) -> usize {
         self.base
     }
+    pub fn as_slice(&self) -> &[u8] {
+        unsafe { core::slice::from_raw_parts(self.base as *const u8, self.size) }
+    }
+    pub fn as_slice_mut(&mut self) -> &mut [u8] {
+        unsafe { core::slice::from_raw_parts_mut(self.base as *mut u8, self.size) }
+    }
+    pub fn read(&self, offset: usize, buf: &mut [u8]) -> Result<usize> {
+        let read_len = buf.len();
+        let end = offset
+            .checked_add(read_len)
+            .ok_or_else(|| Error::new(ERANGE))?;
+
+        if end > self.size {
+            return Err(Error::new(ERANGE));
+        }
+
+        let mmap_slice = Self::as_slice(self);
+        let source_slice = &mmap_slice[offset..end];
+        buf.copy_from_slice(source_slice);
+
+        Ok(read_len)
+    }
+    pub fn write(&mut self, offset: usize, buf: &[u8]) -> Result<usize> {
+        let write_len = buf.len();
+        let end = offset
+            .checked_add(write_len)
+            .ok_or_else(|| Error::new(ERANGE))?;
+
+        if end > self.size {
+            return Err(Error::new(ERANGE));
+        }
+
+        let mmap_slice = Self::as_slice_mut(self);
+        let dest_slice = &mut mmap_slice[offset..end];
+        dest_slice.copy_from_slice(buf);
+
+        Ok(write_len)
+    }
 }
 impl Drop for MmapGuard {
     fn drop(&mut self) {