feat(iso): add read function

k/iso.c

@@ -49,7 +49,10 @@ int open(const char *pathname, int flags)
 
         // we found the file
         if (!length)
-            return register_fd(curr->data_blk.le, curr->data_size.le);
+        {
+            return register_fd(curr->data_blk.le, curr->file_size.le,
+                    (curr->type == ISO_FILE_ISDIR));
+        }
 
         // iteration for one directory
         while (curr->dir_size != 0)
@@ -72,6 +75,34 @@ int open(const char *pathname, int flags)
     return -1;
 }
 
+s64 read(int fd, void *buf, size_t count)
+{
+    if (fd > MAX_FD)
+        return -1;
+
+    struct file_entry *f = &fd_table[fd];
+    if (!f->open)
+        return -1;
+
+    u32 nb_block = f->file_offset / ISO_BLOCK_SIZE;
+    char *content = read_block(f->lba + nb_block);
+
+    size_t i = 0;
+    for (; i < count && f->file_offset < f->file_size; ++i)
+    {
+        ((char *)buf)[i] = content[f->file_offset];
+        ++(f->file_offset);
+
+        if (f->file_offset / ISO_BLOCK_SIZE > nb_block)
+        {
+            ++nb_block;
+            content = read_block(f->lba + nb_block);
+        }
+    }
+
+    return i;
+}
+
 int close(int fd)
 {
     return destroy_fd(fd);

k/iso.h

@@ -6,5 +6,7 @@
 #define O_RDONLY    0
 
 int open(const char *path, int flags);
+s64 read(int fd, void *buf, size_t count);
+int close(int fd);
 
 #endif /* !ISO_H */