Implement /proc/PID/vm.

Refactored SyntheticFileSystem to maintain an arbitrary directory structure.
ProcFileSystem creates a directory entry in /proc for each new process.

Kernel/ProcFileSystem.cpp

@@ -1,6 +1,14 @@
 #include "ProcFileSystem.h"
 #include "Task.h"
 
+static ProcFileSystem* s_the;
+
+ProcFileSystem& ProcFileSystem::the()
+{
+    ASSERT(s_the);
+    return *s_the;
+}
+
 RetainPtr<ProcFileSystem> ProcFileSystem::create()
 {
     return adopt(*new ProcFileSystem);
@@ -8,15 +16,56 @@ RetainPtr<ProcFileSystem> ProcFileSystem::create()
 
 ProcFileSystem::ProcFileSystem()
 {
+    s_the = this;
 }
 
 ProcFileSystem::~ProcFileSystem()
 {
 }
 
+void ProcFileSystem::addProcess(Task& task)
+{
+    ASSERT_INTERRUPTS_DISABLED();
+    char buf[16];
+    ksprintf(buf, "%d", task.pid());
+    auto dir = addFile(createDirectory(buf));
+    m_pid2inode.set(task.pid(), dir.index());
+    addFile(createGeneratedFile("vm", [&task] {
+        InterruptDisabler disabler;
+        char* buffer;
+        auto stringImpl = StringImpl::createUninitialized(80 + task.regionCount() * 80, buffer);
+        memset(buffer, 0, stringImpl->length());
+        char* ptr = buffer;
+        ptr += ksprintf(ptr, "BEGIN       END         SIZE        NAME\n");
+        for (auto& region : task.regions()) {
+            ptr += ksprintf(ptr, "%x -- %x    %x    %s\n",
+                region->linearAddress.get(),
+                region->linearAddress.offset(region->size - 1).get(),
+                region->size,
+                region->name.characters());
+        }
+        *ptr = '\0';
+        return ByteBuffer::copy((byte*)buffer, ptr - buffer);
+    }), dir.index());
+}
+
+void ProcFileSystem::removeProcess(Task& task)
+{
+    ASSERT_INTERRUPTS_DISABLED();
+    auto pid = task.pid();
+    auto it = m_pid2inode.find(pid);
+    ASSERT(it != m_pid2inode.end());
+    bool success = removeFile((*it).value);
+    ASSERT(success);
+    m_pid2inode.remove(pid);
+}
+
 bool ProcFileSystem::initialize()
 {
     SyntheticFileSystem::initialize();
+
+    auto d = addFile(createDirectory("sys"));
+
     addFile(createGeneratedFile("summary", [] {
         InterruptDisabler disabler;
         auto tasks = Task::allTasks();

Kernel/ProcFileSystem.h

@@ -3,15 +3,24 @@
 #include <AK/Types.h>
 #include <VirtualFileSystem/SyntheticFileSystem.h>
 
+class Task;
+
 class ProcFileSystem final : public SyntheticFileSystem {
 public:
+    static ProcFileSystem& the();
+
     virtual ~ProcFileSystem() override;
     static RetainPtr<ProcFileSystem> create();
 
     virtual bool initialize() override;
     virtual const char* className() const override;
 
+    void addProcess(Task&);
+    void removeProcess(Task&);
+
 private:
     ProcFileSystem();
+
+    HashMap<pid_t, InodeIndex> m_pid2inode;
 };
 

Kernel/Task.cpp

@@ -12,6 +12,7 @@
 #include "errno.h"
 #include "i8253.h"
 #include "RTC.h"
+#include "ProcFileSystem.h"
 
 //#define DEBUG_IO
 //#define TASK_DEBUG
@@ -397,11 +398,14 @@ Task::Task(String&& name, uid_t uid, gid_t gid, pid_t parentPID, RingLevel ring)
     // HACK: Ring2 SS in the TSS is the current PID.
     m_tss.ss2 = m_pid;
     m_farPtr.offset = 0x98765432;
+
+    ProcFileSystem::the().addProcess(*this);
 }
 
 Task::~Task()
 {
     InterruptDisabler disabler;
+    ProcFileSystem::the().removeProcess(*this);
     system.nprocess--;
     delete [] m_ldtEntries;
     m_ldtEntries = nullptr;

Kernel/Task.h

@@ -15,6 +15,7 @@ class Zone;
 
 class Task : public InlineLinkedListNode<Task> {
     friend class InlineLinkedListNode<Task>;
+    class Region;
 public:
     static Task* createKernelTask(void (*entry)(), String&& name);
     static Task* createUserTask(const String& path, uid_t, gid_t, pid_t parentPID, int& error, const char** args = nullptr);
@@ -110,6 +111,8 @@ public:
 
     static void taskDidCrash(Task*);
 
+    size_t regionCount() const { return m_regions.size(); }
+    const Vector<OwnPtr<Region>>& regions() const { return m_regions; }
     void dumpRegions();
 
     void didSchedule() { ++m_timesScheduled; }

Kernel/init.cpp

@@ -108,9 +108,7 @@ static void init_stage2()
 
     vfs->mountRoot(e2fs.copyRef());
 
-    auto procfs = ProcFileSystem::create();
-    procfs->initialize();
-    vfs->mount(procfs.copyRef(), "/proc");
+    vfs->mount(ProcFileSystem::the(), "/proc");
 
 #endif
 
@@ -200,6 +198,9 @@ void init()
     kprintf("%u kB base memory\n", base_memory);
     kprintf("%u kB extended memory\n", ext_memory);
 
+    auto procfs = ProcFileSystem::create();
+    procfs->initialize();
+
     Task::initialize();
 
     Task::createKernelTask(undertaker_main, "undertaker");