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().

LibC/dirent.cpp

@@ -0,0 +1,67 @@
+#include "dirent.h"
+#include "unistd.h"
+#include "stdlib.h"
+#include <Kernel/Syscall.h>
+#include "stdio.h"
+
+extern "C" {
+
+DIR* opendir(const char* name)
+{
+    // FIXME: Should fail if it's not a directory!
+    int fd = open(name);
+    if (fd == -1)
+        return nullptr;
+    DIR* dirp = (DIR*)malloc(sizeof(dirp));
+    dirp->fd = fd;
+    dirp->buffer = nullptr;
+    dirp->buffer_size = 0;
+    dirp->nextptr = nullptr;
+    return dirp;
+}
+
+struct sys_dirent {
+    ino_t ino;
+    byte file_type;
+    size_t namelen;
+    char name[];
+    size_t total_size()
+    {
+        return sizeof(ino_t) + sizeof(byte) + sizeof(size_t) + sizeof(char) * namelen;
+    }
+} __attribute__ ((packed));
+
+dirent* readdir(DIR* dirp)
+{
+    if (!dirp)
+        return nullptr;
+    if (dirp->fd == -1)
+        return nullptr;
+
+    if (!dirp->buffer) {
+        // FIXME: Figure out how much to actually allocate.
+        dirp->buffer = (char*)malloc(4096);
+        ssize_t nread = Syscall::invoke(Syscall::GetDirEntries, (dword)dirp->fd, (dword)dirp->buffer, 4096);
+        dirp->buffer_size = nread;
+        dirp->nextptr = dirp->buffer;
+    }
+
+    if (dirp->nextptr > (dirp->buffer + dirp->buffer_size))
+        return nullptr;
+
+    auto* sys_ent = (sys_dirent*)dirp->nextptr;
+    dirp->cur_ent.d_ino = sys_ent->ino;
+    dirp->cur_ent.d_type = sys_ent->file_type;
+    dirp->cur_ent.d_off = 0;
+    dirp->cur_ent.d_reclen = sys_ent->total_size();
+    for (size_t i = 0; i < sys_ent->namelen; ++i)
+        dirp->cur_ent.d_name[i] = sys_ent->name[i];
+    // FIXME: I think this null termination behavior is not supposed to be here.
+    dirp->cur_ent.d_name[sys_ent->namelen] = '\0';
+
+    dirp->nextptr += sys_ent->total_size();
+    return &dirp->cur_ent;
+}
+
+}
+