Lots of hacking to make a very simple "ls" utility.

I added a dead-simple malloc that only allows allocations < 4096 bytes.
It just forwards the request to mmap() every time.

I also added simplified versions of opendir() and readdir().

Kernel/ProcFileSystem.cpp

@@ -21,17 +21,18 @@ bool ProcFileSystem::initialize()
         InterruptDisabler disabler;
         auto tasks = Task::allTasks();
         char* buffer;
-        auto stringImpl = StringImpl::createUninitialized(tasks.size() * 128, buffer);
+        auto stringImpl = StringImpl::createUninitialized(tasks.size() * 256, buffer);
         memset(buffer, 0, stringImpl->length());
         char* ptr = buffer;
-        ptr += ksprintf(ptr, "PID    OWNER      STATE  NSCHED  NAME\n");
+        ptr += ksprintf(ptr, "PID    OWNER      STATE  NSCHED  FDS    NAME\n");
         for (auto* task : tasks) {
-            ptr += ksprintf(ptr, "%w   %w:%w  %b     %w    %s\n",
+            ptr += ksprintf(ptr, "%w   %w:%w  %b     %w    %w   %s\n",
                 task->pid(),
                 task->uid(),
                 task->gid(),
                 task->state(),
                 task->timesScheduled(),
+                task->fileHandleCount(),
                 task->name().characters());
         }
         ptr += ksprintf(ptr, "kmalloc: alloc: %u / free: %u\n", sum_alloc, sum_free);

Kernel/Syscall.cpp

@@ -66,6 +66,8 @@ DWORD handle(DWORD function, DWORD arg1, DWORD arg2, DWORD arg3)
         break;
     case Syscall::Spawn:
         return current->sys$spawn((const char*)arg1);
+    case Syscall::GetDirEntries:
+        return current->sys$get_dir_entries((int)arg1, (void*)arg2, (size_t)arg3);
     case Syscall::PosixOpen:
         //kprintf("syscall: open('%s', %u)\n", arg1, arg2);
         return current->sys$open((const char*)arg1, (size_t)arg2);

Kernel/Syscall.h

@@ -26,6 +26,7 @@ enum Function {
     PosixWaitpid = 0x1994,
     PosixMmap = 0x1995,
     PosixMunmap = 0x1996,
+    GetDirEntries = 0x1997,
 };
 
 void initialize();

Kernel/Task.cpp

@@ -230,6 +230,10 @@ Task::Task(String&& name, uid_t uid, gid_t gid)
     , m_state(Runnable)
     , m_ring(Ring3)
 {
+    m_fileHandles.append(nullptr);
+    m_fileHandles.append(nullptr);
+    m_fileHandles.append(nullptr);
+
     m_nextRegion = LinearAddress(0x600000);
 
     memset(&m_tss, 0, sizeof(m_tss));
@@ -280,6 +284,10 @@ Task::Task(void (*e)(), const char* n, IPC::Handle h, RingLevel ring)
     , m_state(Runnable)
     , m_ring(ring)
 {
+    m_fileHandles.append(nullptr);
+    m_fileHandles.append(nullptr);
+    m_fileHandles.append(nullptr);
+
     m_nextRegion = LinearAddress(0x600000);
 
     Region* codeRegion = nullptr;
@@ -643,6 +651,14 @@ FileHandle* Task::fileHandleIfExists(int fd)
     return nullptr;
 }
 
+ssize_t Task::sys$get_dir_entries(int fd, void* buffer, size_t size)
+{
+    auto* handle = fileHandleIfExists(fd);
+    if (!handle)
+        return -1;
+    return handle->get_dir_entries((byte*)buffer, size);
+}
+
 int Task::sys$seek(int fd, int offset)
 {
     auto* handle = fileHandleIfExists(fd);

Kernel/Task.h

@@ -101,6 +101,7 @@ public:
     pid_t sys$waitpid(pid_t);
     void* sys$mmap(void*, size_t size);
     int sys$munmap(void*, size_t size);
+    int sys$get_dir_entries(int fd, void*, size_t);
 
     struct
     {
@@ -122,6 +123,8 @@ public:
 
     pid_t waitee() const { return m_waitee; }
 
+    size_t fileHandleCount() const { return m_fileHandles.size(); }
+
 private:
     friend class MemoryManager;