hello.rs: Add write/setattr and test reproducing zero reads

examples/hello.rs

@@ -7,7 +7,7 @@ use std::env;
 use std::ffi::OsStr;
 use libc::ENOENT;
 use time::Timespec;
-use fuse::{FileType, FileAttr, Filesystem, Request, ReplyData, ReplyEntry, ReplyAttr, ReplyDirectory};
+use fuse::{FileType, FileAttr, Filesystem, Request, ReplyData, ReplyEntry, ReplyAttr, ReplyDirectory, ReplyWrite, ReplyOpen, ReplyCreate, ReplyEmpty};
 
 const TTL: Timespec = Timespec { sec: 1, nsec: 0 };                     // 1 second
 
@@ -30,8 +30,6 @@ const HELLO_DIR_ATTR: FileAttr = FileAttr {
     flags: 0,
 };
 
-const HELLO_TXT_CONTENT: &'static str = "Hello World!\n";
-
 const HELLO_TXT_ATTR: FileAttr = FileAttr {
     ino: 2,
     size: 13,
@@ -49,12 +47,23 @@ const HELLO_TXT_ATTR: FileAttr = FileAttr {
     flags: 0,
 };
 
-struct HelloFS;
+struct HelloFS {
+    hello_txt_content: Vec<u8>,
+}
+
+impl HelloFS {
+    fn hello_txt_attr(&self) -> FileAttr {
+        let mut attr = HELLO_TXT_ATTR;
+        attr.size = self.hello_txt_content.len() as u64;
+        attr
+    }
+}
 
 impl Filesystem for HelloFS {
     fn lookup(&mut self, _req: &Request, parent: u64, name: &OsStr, reply: ReplyEntry) {
         if parent == 1 && name.to_str() == Some("hello.txt") {
-            reply.entry(&TTL, &HELLO_TXT_ATTR, 0);
+            let attr = self.hello_txt_attr();
+            reply.entry(&TTL, &attr, 0);
         } else {
             reply.error(ENOENT);
         }
@@ -63,14 +72,45 @@ impl Filesystem for HelloFS {
     fn getattr(&mut self, _req: &Request, ino: u64, reply: ReplyAttr) {
         match ino {
             1 => reply.attr(&TTL, &HELLO_DIR_ATTR),
-            2 => reply.attr(&TTL, &HELLO_TXT_ATTR),
+            2 => reply.attr(&TTL, &self.hello_txt_attr()),
+            _ => reply.error(ENOENT),
+        }
+    }
+
+    fn setattr(&mut self, _req: &Request, ino: u64, _mode: Option<u32>, _uid: Option<u32>, _gid: Option<u32>, _size: Option<u64>, _atime: Option<Timespec>, _mtime: Option<Timespec>, _fh: Option<u64>, _crtime: Option<Timespec>, _chgtime: Option<Timespec>, _bkuptime: Option<Timespec>, _flags: Option<u32>, reply: ReplyAttr) {
+        match ino {
+            1 => reply.attr(&TTL, &HELLO_DIR_ATTR),
+            2 => reply.attr(&TTL, &self.hello_txt_attr()),
             _ => reply.error(ENOENT),
         }
     }
 
-    fn read(&mut self, _req: &Request, ino: u64, _fh: u64, offset: i64, _size: u32, reply: ReplyData) {
+    fn open(&mut self, _req: &Request, ino: u64, flags: u32, reply: ReplyOpen) {
+        if ino == 2 {
+            reply.opened(0, flags)
+        } else {
+            reply.error(ENOENT);
+        }
+    }
+
+    fn read(&mut self, _req: &Request, ino: u64, _fh: u64, offset: i64, size: u32, reply: ReplyData) {
+        if ino == 2 {
+            let offset = offset as usize;
+            let size = size as usize;
+            let read_size = size.min(self.hello_txt_content.len() - offset);
+            reply.data(&self.hello_txt_content.as_slice()[offset .. offset + read_size]);
+        } else {
+            reply.error(ENOENT);
+        }
+    }
+
+    fn write(&mut self, _req: &Request, ino: u64, _fh: u64, offset: i64, data: &[u8], _flags: u32, reply: ReplyWrite) {
         if ino == 2 {
-            reply.data(&HELLO_TXT_CONTENT.as_bytes()[offset as usize..]);
+            let offset = offset as usize;
+            let overwrite_len = data.len().min(self.hello_txt_content.len() - offset);
+            self.hello_txt_content.as_mut_slice()[offset .. offset + overwrite_len].copy_from_slice(&data[.. overwrite_len]);
+            self.hello_txt_content.extend_from_slice(&data[overwrite_len ..]);
+            reply.written(data.len() as u32)
         } else {
             reply.error(ENOENT);
         }
@@ -93,5 +133,21 @@ impl Filesystem for HelloFS {
 fn main() {
     env_logger::init().unwrap();
     let mountpoint = env::args_os().nth(1).unwrap();
-    fuse::mount(HelloFS, &mountpoint, &[]).unwrap();
+    fuse::mount(HelloFS { hello_txt_content: vec![] }, &mountpoint, &[]).unwrap();
 }
+
+#[test]
+fn stale_data_bug() {
+    use std::io::Read;
+    use std::io::Write;
+    let mut file_read = std::fs::File::open("/tmp/mnt/hello.txt").unwrap();
+    let mut file_write = std::fs::File::create("/tmp/mnt/hello.txt").unwrap();
+    file_write.write_all("Init".as_bytes()).unwrap();
+    let mut buffer1 = vec![];
+    file_read.read_to_end(&mut buffer1).unwrap();
+    println!("buffer1 {:?}", buffer1);
+    file_write.write_all("Hello World!".as_bytes()).unwrap();
+    let mut buffer2 = vec![];
+    file_read.read_to_end(&mut buffer2).unwrap();
+    println!("buffer2 {:?}", buffer2);
+}