diff --git a/src/filesys/openfile.rs b/src/filesys/openfile.rs
index deafa89..f013dc6 100644
--- a/src/filesys/openfile.rs
+++ b/src/filesys/openfile.rs
@@ -76,19 +76,14 @@ impl OpenFile {
         }
 
         first_sector = div_round_down(position,disk::SECTOR_SIZE);
-        last_sector = div_round_up(position + num_bytes - 1, disk::SECTOR_SIZE);
+        last_sector = div_round_down(position + num_bytes - 1, disk::SECTOR_SIZE);
         num_sectors = last_sector - first_sector + 1;
 
         let mut buffer = vec![0_u8; (num_sectors * disk::SECTOR_SIZE) as usize];
-        let mut sector_buffer = vec![0_u8; disk::SECTOR_SIZE as usize];
 
         for i in first_sector..(last_sector + 1){
             
-            DrvDisk::read_sector(driver_disk, i, &mut sector_buffer);
-
-            for j in 0..sector_buffer.len(){
-                buffer.push(sector_buffer[j]);
-            }
+            DrvDisk::read_sector(driver_disk, i, &mut buffer);
         }
 
         start = position%disk::SECTOR_SIZE;
@@ -133,7 +128,46 @@ impl OpenFile {
         else if position + num_bytes > file_length{
             file.hdr.change_file_length(position + num_bytes);
         }
-        0
+
+        first_sector = div_round_down(position, disk::SECTOR_SIZE);
+        last_sector = div_round_down(position + nbr_octet_ecrit - 1, disk::SECTOR_SIZE);
+        nbr_sectors = last_sector + first_sector + 1;
+
+        let mut buffer = vec![0_u8; (nbr_sectors * disk::SECTOR_SIZE) as usize];
+        let mut sector_buffer = vec![0_u8; disk::SECTOR_SIZE as usize];
+
+        first_aligned = position == first_sector*disk::SECTOR_SIZE;//to use
+        last_aligned = position + nbr_octet_ecrit == (last_sector + 1)*disk::SECTOR_SIZE;//to use
+
+        /*
+        A CHANGER
+        les read & write de disk prenant en param des vec, on ne peut pour l'instant pas copier premier et dernier secteur si mauvais alignement
+        par defaut, on reconpie tout les secteur du disk de premier a dernier dans buffer, puis on ecrase avec les données dans from
+         */
+
+        //on recopie tous les secteurs dans buffer
+        for i in first_sector..(last_sector + 1){
+            driver_disk.read_sector(i, &mut buffer)
+        }
+
+        //on ecrase dans buffer avec les données de from
+        let start = position%disk::SECTOR_SIZE;
+        let end = start + nbr_octet_ecrit - 1;
+
+        for i in start..(end + 1){
+            buffer[i as usize] = from[(i-start) as usize];
+        }
+
+        //on ecrit, secteur par secteur, en segmentant buffer en secteurs
+        for i in 0..(nbr_sectors + 1){
+
+            let j = i*disk::SECTOR_SIZE;
+            let k = i + disk::SECTOR_SIZE - 1;
+            //driver_disk.write_sector(i + first_sector, &buffer[i..=k]);
+            //BESOIN DE CHANGER VEC U8 EN SLICE DANS les fonctions read & write de drv_disk & disk
+        }
+
+        nbr_octet_ecrit
     }
 
     pub fn read(driver_disk : &mut DrvDisk, file : &mut OpenFile, into : &mut Vec<u8>, num_bytes : i32) -> i32 {