Generate a basic /proc/summary file with some info about all tasks.

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/63e253bac91

Kernel/InlineLinkedList.h

@@ -45,7 +45,7 @@ public:
     InlineLinkedList() { }
     
     bool isEmpty() const { return !m_head; }
-    size_t size() const;
+    size_t sizeSlow() const;
     void clear();
 
     T* head() const { return m_head; }
@@ -72,7 +72,7 @@ private:
     T* m_tail { nullptr };
 };
 
-template<typename T> inline size_t InlineLinkedList<T>::size() const
+template<typename T> inline size_t InlineLinkedList<T>::sizeSlow() const
 {
     size_t size = 0;
     for (T* node = m_head; node; node = node->next())

Kernel/ProcFileSystem.cpp

@@ -1,5 +1,5 @@
 #include "ProcFileSystem.h"
-#include <AK/StdLib.h>
+#include "Task.h"
 
 RetainPtr<ProcFileSystem> ProcFileSystem::create()
 {
@@ -18,7 +18,24 @@ bool ProcFileSystem::initialize()
 {
     SyntheticFileSystem::initialize();
     addFile(createGeneratedFile("summary", [] {
-        return String("Process summary!").toByteBuffer();
+        cli();
+        auto tasks = Task::allTasks();
+        char* buffer;
+        auto stringImpl = StringImpl::createUninitialized(tasks.size() * 64, buffer);
+        memset(buffer, 0, stringImpl->length());
+        char* ptr = buffer;
+        ptr += ksprintf(ptr, "PID    OWNER      STATE  NAME\n");
+        for (auto* task : tasks) {
+            ptr += ksprintf(ptr, "%w   %w:%w  %b     %s\n",
+                task->pid(),
+                task->uid(),
+                task->gid(),
+                task->state(),
+                task->name().characters());
+        }
+        *ptr = '\0';
+        sti();
+        return ByteBuffer::copy((byte*)buffer, ptr - buffer);
     }));
     return true;
 }

Kernel/Task.cpp

@@ -95,6 +95,15 @@ void Task::allocateLDT()
     m_tss.ldt = newLDTSelector;
 }
 
+Vector<Task*> Task::allTasks()
+{
+    Vector<Task*> tasks;
+    tasks.ensureCapacity(s_tasks->sizeSlow());
+    for (auto* task = s_tasks->head(); task; task = task->next())
+        tasks.append(task);
+    return tasks;
+}
+
 Task::Region* Task::allocateRegion(size_t size, String&& name)
 {
     // FIXME: This needs sanity checks. What if this overlaps existing regions?

Kernel/Task.h

@@ -19,6 +19,8 @@ public:
     static Task* create(const String& path, uid_t, gid_t);
     Task(String&& name, uid_t, gid_t);
 
+    static Vector<Task*> allTasks();
+
 #ifdef TASK_SANITY_CHECKS
     static void checkSanity(const char* msg = nullptr);
 #else
@@ -58,6 +60,8 @@ public:
     TSS32& tss() { return m_tss; }
     State state() const { return m_state; }
     IPC::Handle handle() const { return m_handle; }
+    uid_t uid() const { return m_uid; }
+    uid_t gid() const { return m_gid; }
 
     const FarPtr& farPtr() const { return m_farPtr; }
 

Kernel/init.cpp

@@ -138,7 +138,7 @@ static void init_stage2()
     vfs->mount(procfs.copyRef(), "/proc");
 
     {
-        auto motdFile = vfs->open("/motd.txt");
+        auto motdFile = vfs->open("/proc/summary");
         ASSERT(motdFile);
         auto motdData = motdFile->readEntireFile();