From 81627cf7d539b3aa15773967f6c3d7c6e7ca86be Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Fri, 26 Oct 2018 18:43:25 +0200
Subject: [PATCH] Add a simple /proc/mounts that enumerates the current VFS
 mounts.

---
 Kernel/Console.h                        |  2 +-
 Kernel/MemoryManager.h                  |  2 +-
 Kernel/ProcFileSystem.cpp               | 17 +++++++++++++
 Kernel/ProcFileSystem.h                 |  2 +-
 VirtualFileSystem/VirtualFileSystem.cpp |  7 ++++++
 VirtualFileSystem/VirtualFileSystem.h   | 33 ++++++++++++++-----------
 6 files changed, 46 insertions(+), 17 deletions(-)

diff --git a/Kernel/Console.h b/Kernel/Console.h
index 18f3882924..3d82cb126e 100644
--- a/Kernel/Console.h
+++ b/Kernel/Console.h
@@ -4,7 +4,7 @@
 
 class Console final : public CharacterDevice {
 public:
-    static Console& the();
+    static Console& the() PURE;
 
     Console();
     virtual ~Console() override;
diff --git a/Kernel/MemoryManager.h b/Kernel/MemoryManager.h
index 7b1a607914..d2873c0d79 100644
--- a/Kernel/MemoryManager.h
+++ b/Kernel/MemoryManager.h
@@ -37,7 +37,7 @@ bool copyToZone(Zone&, const void* data, size_t);
 
 class MemoryManager {
 public:
-    static MemoryManager& the();
+    static MemoryManager& the() PURE;
 
     PhysicalAddress pageDirectoryBase() const { return PhysicalAddress(reinterpret_cast<dword>(m_pageDirectory)); }
 
diff --git a/Kernel/ProcFileSystem.cpp b/Kernel/ProcFileSystem.cpp
index 5f79b448c1..8c594eecf1 100644
--- a/Kernel/ProcFileSystem.cpp
+++ b/Kernel/ProcFileSystem.cpp
@@ -1,5 +1,6 @@
 #include "ProcFileSystem.h"
 #include "Task.h"
+#include <VirtualFileSystem/VirtualFileSystem.h>
 
 static ProcFileSystem* s_the;
 
@@ -64,6 +65,22 @@ bool ProcFileSystem::initialize()
 {
     SyntheticFileSystem::initialize();
 
+    addFile(createGeneratedFile("mounts", [] {
+        InterruptDisabler disabler;
+        auto buffer = ByteBuffer::createUninitialized(VirtualFileSystem::the().mountCount() * 80);
+        char* ptr = (char*)buffer.pointer();
+        VirtualFileSystem::the().forEachMount([&ptr] (auto& mount) {
+            auto& fs = mount.fileSystem();
+            ptr += ksprintf(ptr, "%s @ ", fs.className());
+            if (!mount.host().isValid())
+                ptr += ksprintf(ptr, "/\n", fs.className());
+            else
+                ptr += ksprintf(ptr, "%u:%u\n", mount.host().fileSystemID(), mount.host().index());
+        });
+        buffer.trim(ptr - (char*)buffer.pointer());
+        return buffer;
+    }));
+
     addFile(createGeneratedFile("kmalloc", [] {
         InterruptDisabler disabler;
         auto buffer = ByteBuffer::createUninitialized(128);
diff --git a/Kernel/ProcFileSystem.h b/Kernel/ProcFileSystem.h
index f7602cc20f..954c4e4dea 100644
--- a/Kernel/ProcFileSystem.h
+++ b/Kernel/ProcFileSystem.h
@@ -7,7 +7,7 @@ class Task;
 
 class ProcFileSystem final : public SyntheticFileSystem {
 public:
-    static ProcFileSystem& the();
+    static ProcFileSystem& the() PURE;
 
     virtual ~ProcFileSystem() override;
     static RetainPtr<ProcFileSystem> create();
diff --git a/VirtualFileSystem/VirtualFileSystem.cpp b/VirtualFileSystem/VirtualFileSystem.cpp
index 3b5a2ccd7f..f7c91d38d7 100644
--- a/VirtualFileSystem/VirtualFileSystem.cpp
+++ b/VirtualFileSystem/VirtualFileSystem.cpp
@@ -501,3 +501,10 @@ void VirtualFileSystem::registerCharacterDevice(unsigned major, unsigned minor,
 {
     m_characterDevices.set(encodedDevice(major, minor), &device);
 }
+
+void VirtualFileSystem::forEachMount(Function<void(const Mount&)> callback) const
+{
+    for (auto& mount : m_mounts) {
+        callback(*mount);
+    }
+}
diff --git a/VirtualFileSystem/VirtualFileSystem.h b/VirtualFileSystem/VirtualFileSystem.h
index 6c20bc6ad1..f23da02f6a 100644
--- a/VirtualFileSystem/VirtualFileSystem.h
+++ b/VirtualFileSystem/VirtualFileSystem.h
@@ -20,6 +20,21 @@ public:
     static void initializeGlobals();
     static SpinLock& lock();
 
+    class Mount {
+    public:
+        Mount(InodeIdentifier host, RetainPtr<FileSystem>&&);
+
+        InodeIdentifier host() const { return m_host; }
+        InodeIdentifier guest() const { return m_guest; }
+
+        const FileSystem& fileSystem() const { return *m_fileSystem; }
+
+    private:
+        InodeIdentifier m_host;
+        InodeIdentifier m_guest;
+        RetainPtr<FileSystem> m_fileSystem;
+    };
+
     struct Node {
         InodeIdentifier inode;
         const InodeMetadata& metadata() const;
@@ -46,7 +61,7 @@ public:
         mutable InodeMetadata m_cachedMetadata;
     };
 
-    static VirtualFileSystem& the();
+    static VirtualFileSystem& the() PURE;
 
     VirtualFileSystem();
     ~VirtualFileSystem();
@@ -74,6 +89,9 @@ public:
 
     void registerCharacterDevice(unsigned major, unsigned minor, CharacterDevice&);
 
+    size_t mountCount() const { return m_mounts.size(); }
+    void forEachMount(Function<void(const Mount&)>) const;
+
 private:
     friend class FileHandle;
 
@@ -88,19 +106,6 @@ private:
     RetainPtr<Node> makeNode(InodeIdentifier);
     RetainPtr<Node> getOrCreateNode(InodeIdentifier);
 
-    class Mount {
-    public:
-        Mount(InodeIdentifier host, RetainPtr<FileSystem>&&);
-
-        InodeIdentifier host() const { return m_host; }
-        InodeIdentifier guest() const { return m_guest; }
-
-    private:
-        InodeIdentifier m_host;
-        InodeIdentifier m_guest;
-        RetainPtr<FileSystem> m_fileSystem;
-    };
-
     Mount* findMountForHost(InodeIdentifier);
     Mount* findMountForGuest(InodeIdentifier);