mmap all the font files!

Font now uses the same in-memory format as the font files we have on disk.
This allows us to simply mmap() the font files and not use any additional
memory for them. Very cool! :^)

Hacking on this exposed a bug in file-backed VMObjects where the first client
to instantiate a VMObject for a specific inode also got to decide its size.
Since file-backed VMObjects always have the same size as the underlying file,
this made no sense, so I removed the ability to even set a size in that case.

Kernel/MemoryManager.cpp

@@ -304,15 +304,12 @@ bool MemoryManager::page_in_from_inode(Region& region, unsigned page_index_in_re
 
     auto& vmo_page = vmo.physical_pages()[region.first_page_index() + page_index_in_region];
 
-    bool interrupts_were_enabled = are_interrupts_enabled();
-
-    if (!interrupts_were_enabled)
-        sti();
+    // FIXME: Maybe this should have a separate class like InterruptFlagSaver?
+    InterruptDisabler disabler;
 
+    disabler.temporarily_sti();
     LOCKER(vmo.m_paging_lock);
-
-    if (!interrupts_were_enabled)
-        cli();
+    disabler.temporarily_cli();
 
     if (!vmo_page.is_null()) {
         kprintf("MM: page_in_from_inode() but page already present. Fine with me!\n");
@@ -321,9 +318,9 @@ bool MemoryManager::page_in_from_inode(Region& region, unsigned page_index_in_re
     }
 
 #ifdef MM_DEBUG
-    dbgprintf("MM: page_in_from_inode ready to read from inode, will write to L%x!\n", dest_ptr);
+    dbgprintf("MM: page_in_from_inode ready to read from inode\n");
 #endif
-    sti(); // Oh god here we go...
+    disabler.temporarily_sti();
     byte page_buffer[PAGE_SIZE];
     auto& inode = *vmo.inode();
     auto nread = inode.read_bytes(vmo.inode_offset() + ((region.first_page_index() + page_index_in_region) * PAGE_SIZE), PAGE_SIZE, page_buffer, nullptr);
@@ -335,7 +332,7 @@ bool MemoryManager::page_in_from_inode(Region& region, unsigned page_index_in_re
         // If we read less than a page, zero out the rest to avoid leaking uninitialized data.
         memset(page_buffer + nread, 0, PAGE_SIZE - nread);
     }
-    cli();
+    disabler.temporarily_cli();
     vmo_page = allocate_physical_page(ShouldZeroFill::No);
     if (vmo_page.is_null()) {
         kprintf("MM: page_in_from_inode was unable to allocate a physical page\n");
@@ -610,7 +607,7 @@ Region::Region(LinearAddress a, size_t s, String&& n, bool r, bool w, bool cow)
 Region::Region(LinearAddress a, size_t s, RetainPtr<Inode>&& inode, String&& n, bool r, bool w)
     : m_laddr(a)
     , m_size(s)
-    , m_vmo(VMObject::create_file_backed(move(inode), s))
+    , m_vmo(VMObject::create_file_backed(move(inode)))
     , m_name(move(n))
     , m_readable(r)
     , m_writable(w)
@@ -661,13 +658,12 @@ void PhysicalPage::return_to_freelist()
 #endif
 }
 
-RetainPtr<VMObject> VMObject::create_file_backed(RetainPtr<Inode>&& inode, size_t size)
+RetainPtr<VMObject> VMObject::create_file_backed(RetainPtr<Inode>&& inode)
 {
     InterruptDisabler disabler;
     if (inode->vmo())
         return static_cast<VMObject*>(inode->vmo());
-    size = ceil_div(size, PAGE_SIZE) * PAGE_SIZE;
-    auto vmo = adopt(*new VMObject(move(inode), size));
+    auto vmo = adopt(*new VMObject(move(inode)));
     vmo->inode()->set_vmo(vmo.ptr());
     return vmo;
 }
@@ -720,10 +716,11 @@ VMObject::VMObject(PhysicalAddress paddr, size_t size)
 }
 
 
-VMObject::VMObject(RetainPtr<Inode>&& inode, size_t size)
-    : m_size(size)
-    , m_inode(move(inode))
+VMObject::VMObject(RetainPtr<Inode>&& inode)
+    : m_inode(move(inode))
 {
+    ASSERT(m_inode);
+    m_size = ceil_div(m_inode->size(), PAGE_SIZE) * PAGE_SIZE;
     m_physical_pages.resize(page_count());
     MM.register_vmo(*this);
 }

Kernel/MemoryManager.h

@@ -79,7 +79,7 @@ private:
 class VMObject : public Retainable<VMObject> {
     friend class MemoryManager;
 public:
-    static RetainPtr<VMObject> create_file_backed(RetainPtr<Inode>&&, size_t);
+    static RetainPtr<VMObject> create_file_backed(RetainPtr<Inode>&&);
     static RetainPtr<VMObject> create_anonymous(size_t);
     static RetainPtr<VMObject> create_framebuffer_wrapper(PhysicalAddress, size_t);
     RetainPtr<VMObject> clone();
@@ -99,7 +99,7 @@ public:
     Vector<RetainPtr<PhysicalPage>>& physical_pages() { return m_physical_pages; }
 
 private:
-    VMObject(RetainPtr<Inode>&&, size_t);
+    VMObject(RetainPtr<Inode>&&);
     explicit VMObject(VMObject&);
     explicit VMObject(size_t);
     VMObject(PhysicalAddress, size_t);

Kernel/Process.cpp

@@ -325,7 +325,7 @@ int Process::do_exec(const String& path, Vector<String>&& arguments, Vector<Stri
 #endif
     ProcessPagingScope paging_scope(*this);
 
-    auto vmo = VMObject::create_file_backed(descriptor->inode(), descriptor->metadata().size);
+    auto vmo = VMObject::create_file_backed(descriptor->inode());
     vmo->set_name(descriptor->absolute_path());
     RetainPtr<Region> region = allocate_region_with_vmo(LinearAddress(), descriptor->metadata().size, vmo.copy_ref(), 0, "helper", true, false);
 

Kernel/Process.h

@@ -52,6 +52,7 @@ class Process : public InlineLinkedListNode<Process>, public Weakable<Process> {
     friend class InlineLinkedListNode<Process>;
     friend class WSWindowManager; // FIXME: Make a better API for allocate_region().
     friend class GraphicsBitmap; // FIXME: Make a better API for allocate_region().
+    friend class Font; //FIXME: This is beyond gross.
 public:
     static Process* create_kernel_process(String&& name, void (*entry)());
     static Process* create_user_process(const String& path, uid_t, gid_t, pid_t ppid, int& error, Vector<String>&& arguments = Vector<String>(), Vector<String>&& environment = Vector<String>(), TTY* = nullptr);

Kernel/i386.h

@@ -120,6 +120,16 @@ public:
             sti();
     }
 
+    void temporarily_cli()
+    {
+        cli();
+    }
+
+    void temporarily_sti()
+    {
+        sti();
+    }
+
 private:
     dword m_flags;
 };