Kernel: Remove broken implementation of Unix SHM

This code never worked, as was never used for anything. We can build
a much better SHM implementation on top of TmpFS or similar when we
get to the point when we need one.

Kernel/FileSystem/File.h

@@ -63,7 +63,6 @@ public:
     virtual bool is_seekable() const { return false; }
 
     virtual bool is_inode() const { return false; }
-    virtual bool is_shared_memory() const { return false; }
     virtual bool is_fifo() const { return false; }
     virtual bool is_device() const { return false; }
     virtual bool is_tty() const { return false; }

Kernel/FileSystem/FileDescription.cpp

@@ -6,7 +6,6 @@
 #include <Kernel/FileSystem/FileDescription.h>
 #include <Kernel/FileSystem/FileSystem.h>
 #include <Kernel/FileSystem/InodeFile.h>
-#include <Kernel/FileSystem/SharedMemory.h>
 #include <Kernel/Net/Socket.h>
 #include <Kernel/Process.h>
 #include <Kernel/TTY/MasterPTY.h>
@@ -244,25 +243,6 @@ KResult FileDescription::truncate(off_t length)
     return m_file->truncate(length);
 }
 
-bool FileDescription::is_shared_memory() const
-{
-    return m_file->is_shared_memory();
-}
-
-SharedMemory* FileDescription::shared_memory()
-{
-    if (!is_shared_memory())
-        return nullptr;
-    return static_cast<SharedMemory*>(m_file.ptr());
-}
-
-const SharedMemory* FileDescription::shared_memory() const
-{
-    if (!is_shared_memory())
-        return nullptr;
-    return static_cast<const SharedMemory*>(m_file.ptr());
-}
-
 bool FileDescription::is_fifo() const
 {
     return m_file->is_fifo();

Kernel/FileSystem/FileDescription.h

@@ -18,7 +18,6 @@ class MasterPTY;
 class Process;
 class Region;
 class CharacterDevice;
-class SharedMemory;
 
 class FileDescription : public RefCounted<FileDescription> {
 public:
@@ -87,10 +86,6 @@ public:
     FIFO::Direction fifo_direction() { return m_fifo_direction; }
     void set_fifo_direction(Badge<FIFO>, FIFO::Direction direction) { m_fifo_direction = direction; }
 
-    bool is_shared_memory() const;
-    SharedMemory* shared_memory();
-    const SharedMemory* shared_memory() const;
-
     Optional<KBuffer>& generator_cache() { return m_generator_cache; }
 
     void set_original_inode(Badge<VFS>, NonnullRefPtr<Inode>&& inode) { m_inode = move(inode); }

Kernel/FileSystem/SharedMemory.cpp

@@ -1,97 +0,0 @@
-#include <AK/HashMap.h>
-#include <Kernel/FileSystem/SharedMemory.h>
-#include <Kernel/Lock.h>
-#include <Kernel/Process.h>
-#include <Kernel/VM/AnonymousVMObject.h>
-
-Lockable<HashMap<String, RefPtr<SharedMemory>>>& shared_memories()
-{
-    static Lockable<HashMap<String, RefPtr<SharedMemory>>>* map;
-    if (!map)
-        map = new Lockable<HashMap<String, RefPtr<SharedMemory>>>;
-    return *map;
-}
-
-KResultOr<NonnullRefPtr<SharedMemory>> SharedMemory::open(const String& name, int flags, mode_t mode)
-{
-    UNUSED_PARAM(flags);
-    LOCKER(shared_memories().lock());
-    auto it = shared_memories().resource().find(name);
-    if (it != shared_memories().resource().end()) {
-        auto shared_memory = it->value;
-        // FIXME: Improved access checking.
-        if (shared_memory->uid() != current->process().uid())
-            return KResult(-EACCES);
-        return *shared_memory;
-    }
-    auto shared_memory = adopt(*new SharedMemory(name, current->process().uid(), current->process().gid(), mode));
-    shared_memories().resource().set(name, shared_memory.ptr());
-    return shared_memory;
-}
-
-KResult SharedMemory::unlink(const String& name)
-{
-    LOCKER(shared_memories().lock());
-    auto it = shared_memories().resource().find(name);
-    if (it == shared_memories().resource().end())
-        return KResult(-ENOENT);
-    shared_memories().resource().remove(it);
-    return KSuccess;
-}
-
-SharedMemory::SharedMemory(const String& name, uid_t uid, gid_t gid, mode_t mode)
-    : m_name(name)
-    , m_uid(uid)
-    , m_gid(gid)
-    , m_mode(mode)
-{
-}
-
-SharedMemory::~SharedMemory()
-{
-}
-
-KResult SharedMemory::truncate(int length)
-{
-    if (!length) {
-        m_vmobject = nullptr;
-        return KSuccess;
-    }
-
-    if (!m_vmobject) {
-        m_vmobject = AnonymousVMObject::create_with_size(length);
-        return KSuccess;
-    }
-
-    // FIXME: Support truncation.
-    ASSERT_NOT_REACHED();
-    return KResult(-ENOTIMPL);
-}
-
-String SharedMemory::absolute_path(const FileDescription&) const
-{
-    return String::format("shm:%u", this);
-}
-
-int SharedMemory::read(FileDescription&, u8* buffer, int buffer_size)
-{
-    UNUSED_PARAM(buffer);
-    UNUSED_PARAM(buffer_size);
-    // FIXME: Implement.
-    ASSERT_NOT_REACHED();
-}
-
-int SharedMemory::write(FileDescription&, const u8* data, int data_size)
-{
-    UNUSED_PARAM(data);
-    UNUSED_PARAM(data_size);
-    // FIXME: Implement.
-    ASSERT_NOT_REACHED();
-}
-
-KResultOr<Region*> SharedMemory::mmap(Process& process, FileDescription&, VirtualAddress vaddr, size_t offset, size_t size, int prot)
-{
-    if (!vmobject())
-        return KResult(-ENODEV);
-    return process.allocate_region_with_vmobject(vaddr, size, *vmobject(), offset, name(), prot);
-}

Kernel/FileSystem/SharedMemory.h

@@ -1,43 +0,0 @@
-#pragma once
-
-#include <AK/String.h>
-#include <AK/RefPtr.h>
-#include <AK/RefCounted.h>
-#include <Kernel/FileSystem/File.h>
-#include <Kernel/KResult.h>
-#include <Kernel/UnixTypes.h>
-
-class AnonymousVMObject;
-
-class SharedMemory : public File {
-public:
-    static KResultOr<NonnullRefPtr<SharedMemory>> open(const String& name, int flags, mode_t);
-    static KResult unlink(const String& name);
-    virtual ~SharedMemory() override;
-
-    const String& name() const { return m_name; }
-    virtual KResult truncate(off_t) override;
-    AnonymousVMObject* vmobject() { return m_vmobject.ptr(); }
-    const AnonymousVMObject* vmobject() const { return m_vmobject.ptr(); }
-    uid_t uid() const { return m_uid; }
-    gid_t gid() const { return m_gid; }
-
-private:
-    // ^File
-    virtual bool can_read(const FileDescription&) const override { return true; }
-    virtual bool can_write(const FileDescription&) const override { return true; }
-    virtual int read(FileDescription&, u8*, int) override;
-    virtual int write(FileDescription&, const u8*, int) override;
-    virtual String absolute_path(const FileDescription&) const override;
-    virtual const char* class_name() const override { return "SharedMemory"; }
-    virtual bool is_shared_memory() const override { return true; }
-    virtual KResultOr<Region*> mmap(Process&, FileDescription&, VirtualAddress, size_t offset, size_t size, int prot) override;
-
-    SharedMemory(const String& name, uid_t, gid_t, mode_t);
-
-    String m_name;
-    uid_t m_uid { 0 };
-    gid_t m_gid { 0 };
-    mode_t m_mode { 0 };
-    RefPtr<AnonymousVMObject> m_vmobject;
-};

Kernel/Makefile

@@ -50,7 +50,6 @@ OBJS = \
     FileSystem/InodeFile.o \
     FileSystem/InodeWatcher.o \
     FileSystem/ProcFS.o \
-    FileSystem/SharedMemory.o \
     FileSystem/TmpFS.o \
     FileSystem/VirtualFileSystem.o \
     Heap/SlabAllocator.o \

Kernel/Process.cpp

@@ -17,7 +17,6 @@
 #include <Kernel/FileSystem/FileDescription.h>
 #include <Kernel/FileSystem/InodeWatcher.h>
 #include <Kernel/FileSystem/ProcFS.h>
-#include <Kernel/FileSystem/SharedMemory.h>
 #include <Kernel/FileSystem/TmpFS.h>
 #include <Kernel/FileSystem/VirtualFileSystem.h>
 #include <Kernel/Heap/kmalloc.h>
@@ -3320,28 +3319,6 @@ int Process::sys$rename(const char* oldpath, const char* newpath)
     return VFS::the().rename(StringView(oldpath), StringView(newpath), current_directory());
 }
 
-int Process::sys$shm_open(const char* name, int flags, mode_t mode)
-{
-    if (!validate_read_str(name))
-        return -EFAULT;
-    int fd = alloc_fd();
-    if (fd < 0)
-        return fd;
-    auto shm_or_error = SharedMemory::open(String(name), flags, mode);
-    if (shm_or_error.is_error())
-        return shm_or_error.error();
-    auto description = FileDescription::create(shm_or_error.value());
-    m_fds[fd].set(move(description), FD_CLOEXEC);
-    return fd;
-}
-
-int Process::sys$shm_unlink(const char* name)
-{
-    if (!validate_read_str(name))
-        return -EFAULT;
-    return SharedMemory::unlink(String(name));
-}
-
 int Process::sys$ftruncate(int fd, off_t length)
 {
     auto* description = file_description(fd);

Kernel/Process.h

@@ -108,8 +108,6 @@ public:
     int sys$dump_backtrace();
     int sys$gettid();
     int sys$donate(int tid);
-    int sys$shm_open(const char* name, int flags, mode_t);
-    int sys$shm_unlink(const char* name);
     int sys$ftruncate(int fd, off_t);
     pid_t sys$setsid();
     pid_t sys$getsid(pid_t);

Kernel/Syscall.h

@@ -107,8 +107,8 @@ typedef u32 socklen_t;
     __ENUMERATE_SYSCALL(gettid)                     \
     __ENUMERATE_SYSCALL(donate)                     \
     __ENUMERATE_SYSCALL(rename)                     \
-    __ENUMERATE_SYSCALL(shm_open)                   \
+    __ENUMERATE_REMOVED_SYSCALL(shm_open)           \
-    __ENUMERATE_SYSCALL(shm_unlink)                 \
+    __ENUMERATE_REMOVED_SYSCALL(shm_unlink)         \
     __ENUMERATE_SYSCALL(ftruncate)                  \
     __ENUMERATE_SYSCALL(systrace)                   \
     __ENUMERATE_SYSCALL(exit_thread)                \

Libraries/LibC/mman.cpp

@@ -45,18 +45,6 @@ int set_mmap_name(void* addr, size_t size, const char* name)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
-int shm_open(const char* name, int flags, mode_t mode)
-{
-    int rc = syscall(SC_shm_open, name, flags, mode);
-    __RETURN_WITH_ERRNO(rc, rc, -1);
-}
-
-int shm_unlink(const char* name)
-{
-    int rc = syscall(SC_shm_unlink, name);
-    __RETURN_WITH_ERRNO(rc, rc, -1);
-}
-
 int madvise(void* address, size_t size, int advice)
 {
     int rc = syscall(SC_madvise, address, size, advice);

Libraries/LibC/mman.h

@@ -29,8 +29,6 @@ void* mmap_with_name(void* addr, size_t, int prot, int flags, int fd, off_t, con
 int munmap(void*, size_t);
 int mprotect(void*, size_t, int prot);
 int set_mmap_name(void*, size_t, const char*);
-int shm_open(const char* name, int flags, mode_t);
-int shm_unlink(const char* name);
 int madvise(void*, size_t, int advice);
 
 __END_DECLS