feat(file-system): implement read and write FAT32 File System and basic shell

3 files changed, 50 insertions, 3 deletions

diff --git a/include/fs/fat32.h b/include/fs/fat32.h
index c794bd7..1bd60ef 100644
--- a/include/fs/fat32.h
+++ b/include/fs/fat32.h
@@ -74,6 +74,8 @@ public:
     uint32 first_clus;  // The starting cluster number of the file
     uint32 parent_clus; // Starting cluster number of the parent directory
     uint32 dir_offset;  // The byte offset of this directory entry in the parent directory
+    uint32 ent_sec;     // Sector number of the directory entry
+    uint32 ent_off;     // Offset of the directory entry within the sector
 
     FAT32Inode() : fs(nullptr), first_clus(0) {}
     // Implement VFS Interface
@@ -83,6 +85,7 @@ public:
     Inode *lookup(const char *name) override;
     Inode *create(const char *name, short type, short major, short minor) override;
     void truncate() override;
+    int unlink(const char *name) override;
 };
 
 class FAT32FileSystem : public FileSystem
@@ -93,17 +96,20 @@ public:
     uint32 root_cluster;
     uint32 sectors_per_cluster;
     uint32 bytes_per_cluster;
+    uint32 fat_sz;                  // Size of the FAT table (number of sectors)
 
     void init() override;
     Inode* root() override;
 
     // Helper functions
-    uint32 next_cluster(uint32 cluster); // Check the FAT table for the next cluster
-    uint32 alloc_cluster();              // Assign a new cluster
+    uint32 next_cluster(uint32 cluster);    // Check the FAT table for the next cluster
+    uint32 alloc_cluster();                 // Assign a new cluster
     uint32 cluster_to_sector(uint32 cluster);
 
     // directory entry parsing
     void read_dir_ent(struct FAT32_DirEnt *de, char *filename);
+    // Release the entire cluster chain starting from the cluster
+    void free_cluster_chain(uint32 cluster);
 };
 
 extern FAT32FileSystem fat32_fs;
diff --git a/include/fs/file.h b/include/fs/file.h
index 2f23176..a92d8f8 100644
--- a/include/fs/file.h
+++ b/include/fs/file.h
@@ -10,6 +10,8 @@ enum FileType
     FD_PIPE
 };
 
+class Pipe;
+
 struct file
 {
     enum FileType type;
@@ -17,11 +19,46 @@ struct file
     char readable;
     char writable;
 
-    struct pipe *pipe; // pipeline pointer
+    Pipe *pipe; // pipeline pointer
     Inode *ip;         // VFS Inode
     uint32 off;        // Current Offset
 };
 
+class Pipe
+{
+public:
+    static constexpr uint32_t SIZE = 512;
+
+    Pipe() : nread(0), nwrite(0), read_open(true), write_open(true)
+    {
+        lock.init("pipe");
+    }
+
+    // forbid copy
+    Pipe(const Pipe &) = delete;
+    Pipe &operator=(const Pipe &) = delete;
+
+    ~Pipe()
+    {
+        //
+    }
+
+    // creates a pair of connected file objects
+    static int create_pair(struct file **f0, struct file **f1);
+
+    int read(uint64_t addr, int n);
+    int write(uint64_t addr, int n);
+    void close(bool is_writer);
+
+private:
+    Spinlock lock;
+    char data[SIZE];
+    uint32_t nread;  // read
+    uint32_t nwrite; // write
+    bool read_open;
+    bool write_open;
+};
+
 namespace FileTable
 {
     void init();
diff --git a/include/fs/fs.h b/include/fs/fs.h
index f40bc0c..235ec80 100644
--- a/include/fs/fs.h
+++ b/include/fs/fs.h
@@ -57,6 +57,8 @@ public:
     virtual void getattr(struct kstat *st);
     // Truncate file (set size to 0, release all data blocks)
     virtual void truncate() = 0;
+    // Delete the file named 'name' from the directory (Unlink)
+    virtual int unlink(const char *name) = 0;
 };
 
 // File System Abstraction (SuperBlock)
@@ -90,4 +92,6 @@ namespace VFS
     Inode *get_root();
     // Path Analysis
     Inode *namei(const char *path);
+    // Find the parent directory inode of the path, and copy the last part of the path (the file name) into the name buffer
+    Inode *nameiparent(const char *path, char *name);
 } // namespace VFS