From d3cf3f08d1343d6b265516d5a79ce2d197b59d26 Mon Sep 17 00:00:00 2001
From: Richard Qin <richard.qin.x@gmail.com>
Date: Sun, 4 Jan 2026 14:05:49 +0800
Subject: feat(file-system): implement read and write FAT32 File System and
 basic shell

---
 src/fs/file.cc | 137 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 135 insertions(+), 2 deletions(-)

(limited to 'src/fs/file.cc')

diff --git a/src/fs/file.cc b/src/fs/file.cc
index 99bb65d..623b535 100644
--- a/src/fs/file.cc
+++ b/src/fs/file.cc
@@ -3,12 +3,135 @@
 #include "kernel/mm.h"
 #include "drivers/uart.h"
 #include "kernel/proc.h"
+#include "kernel/slab.h"
 
 #define NFILE 100
 #define SEEK_SET 0
 #define SEEK_CUR 1
 #define SEEK_END 2
 
+extern void *operator new(unsigned long, void *p);
+
+int Pipe::create_pair(file** f0, file** f1)
+{
+    void *mem = Slab::kmalloc(sizeof(Pipe));
+    if (!mem)
+        return -1;
+    Pipe *pi = new (mem) Pipe();
+
+    *f0 = FileTable::alloc();
+    *f1 = FileTable::alloc();
+
+    if (*f0 == nullptr || *f1 == nullptr)
+    {
+        if (*f0)
+            FileTable::close(*f0);
+        if (*f1)
+            FileTable::close(*f1);
+        pi->~Pipe();
+        Slab::kfree(pi);
+        return -1;
+    }
+
+    (*f0)->type = FD_PIPE;
+    (*f0)->readable = 1;
+    (*f0)->writable = 0;
+    (*f0)->pipe = pi;
+
+    (*f1)->type = FD_PIPE;
+    (*f1)->readable = 0;
+    (*f1)->writable = 1;
+    (*f1)->pipe = pi;
+
+    return 0;
+}
+
+void Pipe::close(bool is_writer)
+{
+    lock.acquire();
+    if (is_writer)
+    {
+        write_open = false;
+        ProcManager::wakeup(&nread); // Wake up the process that is currently reading
+    }
+    else
+    {
+        read_open = false;
+        ProcManager::wakeup(&nwrite); // Wake up the process that is writing
+    }
+
+    bool empty = !read_open && !write_open;
+    lock.release();
+
+    if (empty)
+    {
+        this->~Pipe();
+        Slab::kfree(this);
+    }
+}
+
+int Pipe::write(uint64_t addr, int n)
+{
+    int i = 0;
+    struct Proc *p = myproc();
+
+    lock.acquire();
+    while (i < n)
+    {
+        if (!read_open || p->xstate) // The read end is closed or the process is abnormal
+        {
+            lock.release();
+            return -1;
+        }
+
+        if (nwrite == nread + SIZE) // buffer is full
+        {
+            ProcManager::wakeup(&nread);
+            ProcManager::sleep(&nwrite, &lock);
+        }
+        else
+        {
+            char ch;
+            if (VM::copyin(p->pagetable, &ch, addr + i, 1) < 0)
+                break;
+            data[nwrite++ % SIZE] = ch;
+            i++;
+        }
+    }
+    ProcManager::wakeup(&nread);
+    lock.release();
+    return i;
+}
+
+int Pipe::read(uint64_t addr, int n)
+{
+    int i = 0;
+    struct Proc *p = myproc();
+
+    lock.acquire();
+    while (nread == nwrite && write_open) // The buffer is empty and the write end is not closed
+    {
+        if (p->xstate)
+        {
+            lock.release();
+            return -1;
+        }
+        ProcManager::sleep(&nread, &lock);
+    }
+
+    for (i = 0; i < n; ++i)
+    {
+        if (nread == nwrite)
+            break;
+        char ch = data[nread++ % SIZE];
+        if (VM::copyout(p->pagetable, addr + i, &ch, 1) < 0)
+            break;
+    }
+    ProcManager::wakeup(&nwrite);
+    lock.release();
+    return i;
+}
+
 namespace FileTable
 {
     struct
@@ -82,7 +205,8 @@ namespace FileTable
         }
         else if (ff.type == FD_PIPE)
         {
-            // pipeclose(ff.pipe, ff.writable);
+            if (ff.pipe)
+                ff.pipe->close(ff.writable);
         }
     }
 
@@ -101,6 +225,11 @@ namespace FileTable
             VFS::iunlock(f->ip);
             return r;
         }
+        else if (f->type == FD_PIPE)
+        {
+            if (f->pipe)
+                return f->pipe->read(addr, n);
+        }
         return -1;
     }
     
@@ -119,7 +248,11 @@ namespace FileTable
             VFS::iunlock(f->ip);
             return r;
         }
-        // else if (f->type == FD_PIPE) ...
+        else if (f->type == FD_PIPE)
+        {
+            if (f->pipe)
+                return f->pipe->write(addr, n);
+        }
 
         return -1;
     }
-- 
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