image_index.rs: write header

src/backup/image_index.rs

@@ -2,9 +2,20 @@ use failure::*;
 
 use super::chunk_store::*;
 
+use std::io::Write;
 use std::path::{Path, PathBuf};
 use std::os::unix::io::AsRawFd;
+use uuid::Uuid;
 
+#[repr(C)]
+pub struct ImageIndexHeader {
+    pub magic: [u8; 12],
+    pub version: u32,
+    pub uuid: [u8; 16],
+    pub ctime: i64,
+    pub size: u64,
+    reserved: [u8; 4048], // oversall size is one page (4096 bytes)
+}
 
 // split image into fixed size chunks
 
@@ -13,6 +24,8 @@ pub struct ImageIndex<'a> {
     chunk_size: usize,
     size: usize,
     index: *mut u8,
+    uuid: [u8; 16],
+    ctime: i64,
 }
 
 impl <'a> ImageIndex<'a> {
@@ -23,15 +36,39 @@ impl <'a> ImageIndex<'a> {
         println!("FULLPATH: {:?} {}", full_path, size);
 
         let mut file = std::fs::OpenOptions::new()
-            .create_new(true)
+        //FIXME: use .create_new(true)
+            .create(true).truncate(true)
             .read(true)
             .write(true)
             .open(&full_path)?;
 
         let chunk_size = 64*1024;
+
+        let header_size = std::mem::size_of::<ImageIndexHeader>();
+
+        // todo: use static assertion when available in rust
+        if header_size != 4096 { panic!("got unexpected header size"); }
+
+        let ctime = std::time::SystemTime::now().duration_since(
+            std::time::SystemTime::UNIX_EPOCH)?.as_secs() as i64;
+
+        let uuid = Uuid::new_v4();
+
+        let mut buffer = vec![0u8; header_size];
+        let header = unsafe { &mut * (buffer.as_ptr() as *mut ImageIndexHeader) };
+
+        header.magic = *b"PROXMOX-BIDX";
+        header.version = u32::to_be(1);
+        header.ctime = i64::to_be(ctime);
+        header.size = u64::to_be(size as u64);
+        header.uuid = *uuid.as_bytes();
+
+        file.write_all(&buffer);
+
         let index_size = ((size + chunk_size - 1)/chunk_size)*32;
-        nix::unistd::ftruncate(file.as_raw_fd(), index_size as i64)?;
-        println!("SIZES: {}", index_size);
+        nix::unistd::ftruncate(file.as_raw_fd(), (header_size + index_size) as i64)?;
+
+        println!("SIZES: {} {}", index_size, header_size);
 
         let data = unsafe { nix::sys::mman::mmap(
             std::ptr::null_mut(),
@@ -39,13 +76,16 @@ impl <'a> ImageIndex<'a> {
             nix::sys::mman::ProtFlags::PROT_READ | nix::sys::mman::ProtFlags::PROT_WRITE,
             nix::sys::mman::MapFlags::MAP_SHARED,
             file.as_raw_fd(),
-            0) }? as *mut u8;
+            header_size as i64) }? as *mut u8;
+
 
         Ok(Self {
             store,
             chunk_size,
             size,
             index: data,
+            ctime,
+            uuid: *uuid.as_bytes(),
         })
     }