Add basic symlink support.

- sys$readlink + readlink()
- Add a /proc/PID/exe symlink to the process's executable.
- Print symlink contents in ls output.
- Some work on plumbing options into VFS::open().

20 files changed, 140 insertions, 46 deletions

diff --git a/Kernel/ProcFileSystem.cpp b/Kernel/ProcFileSystem.cpp
index 225f55278f..6f8f6ebc8e 100644
--- a/Kernel/ProcFileSystem.cpp
+++ b/Kernel/ProcFileSystem.cpp
@@ -96,6 +96,16 @@ ByteBuffer procfs$pid_stack(Task& task)
     return buffer;
 }
 
+ByteBuffer procfs$pid_exe(Task& task)
+{
+    InodeIdentifier inode;
+    {
+        InterruptDisabler disabler;
+        inode = task.executableInode();
+    }
+    return VirtualFileSystem::the().absolutePath(inode).toByteBuffer();
+}
+
 void ProcFileSystem::addProcess(Task& task)
 {
     ASSERT_INTERRUPTS_DISABLED();
@@ -105,6 +115,8 @@ void ProcFileSystem::addProcess(Task& task)
     m_pid2inode.set(task.pid(), dir.index());
     addFile(createGeneratedFile("vm", [&task] { return procfs$pid_vm(task); }), dir.index());
     addFile(createGeneratedFile("stack", [&task] { return procfs$pid_stack(task); }), dir.index());
+    if (task.executableInode().isValid())
+        addFile(createGeneratedFile("exe", [&task] { return procfs$pid_exe(task); }, 00120777), dir.index());
 }
 
 void ProcFileSystem::removeProcess(Task& task)
diff --git a/Kernel/Syscall.cpp b/Kernel/Syscall.cpp
index e80bed6601..ba9884e0d5 100644
--- a/Kernel/Syscall.cpp
+++ b/Kernel/Syscall.cpp
@@ -116,6 +116,8 @@ DWORD handle(DWORD function, DWORD arg1, DWORD arg2, DWORD arg3)
         return current->sys$uname((utsname*)arg1);
     case Syscall::SetMmapName:
         return current->sys$set_mmap_name((void*)arg1, (size_t)arg2, (const char*)arg3);
+    case Syscall::PosixReadlink:
+        return current->sys$readlink((const char*)arg1, (char*)arg2, (size_t)arg3);
     default:
         kprintf("int0x80: Unknown function %x requested {%x, %x, %x}\n", function, arg1, arg2, arg3);
         break;
diff --git a/Kernel/Syscall.h b/Kernel/Syscall.h
index 1d55e4bd2e..b35c95b233 100644
--- a/Kernel/Syscall.h
+++ b/Kernel/Syscall.h
@@ -35,6 +35,7 @@ enum Function {
     PosixChdir = 0x2003,
     PosixUname = 0x2004,
     SetMmapName = 0x2005,
+    PosixReadlink = 0x2006,
 };
 
 void initialize();
diff --git a/Kernel/Task.cpp b/Kernel/Task.cpp
index f5bc6160fc..0eb92e2458 100644
--- a/Kernel/Task.cpp
+++ b/Kernel/Task.cpp
@@ -234,7 +234,7 @@ Task* Task::createUserTask(const String& path, uid_t uid, gid_t gid, pid_t paren
             cwd = parentTask->m_cwd.copyRef();
     }
 
-    auto handle = VirtualFileSystem::the().open(path, cwd ? cwd->inode : InodeIdentifier());
+    auto handle = VirtualFileSystem::the().open(path, 0, cwd ? cwd->inode : InodeIdentifier());
     if (!handle) {
         error = -ENOENT; // FIXME: Get a more detailed error from VFS.
         return nullptr;
@@ -261,7 +261,7 @@ Task* Task::createUserTask(const String& path, uid_t uid, gid_t gid, pid_t paren
     }
 
     InterruptDisabler disabler; // FIXME: Get rid of this, jesus christ. This "critical" section is HUGE.
-    Task* t = new Task(parts.takeLast(), uid, gid, parentPID, Ring3);
+    Task* t = new Task(parts.takeLast(), uid, gid, parentPID, Ring3, handle->vnode());
 
     t->m_arguments = move(taskArguments);
 
@@ -362,13 +362,14 @@ Task* Task::createKernelTask(void (*e)(), String&& name)
     return task;
 }
 
-Task::Task(String&& name, uid_t uid, gid_t gid, pid_t parentPID, RingLevel ring)
+Task::Task(String&& name, uid_t uid, gid_t gid, pid_t parentPID, RingLevel ring, RetainPtr<VirtualFileSystem::Node>&& executable)
     : m_name(move(name))
     , m_pid(next_pid++)
     , m_uid(uid)
     , m_gid(gid)
     , m_state(Runnable)
     , m_ring(ring)
+    , m_executable(move(executable))
     , m_parentPID(parentPID)
 {
     m_fileHandles.append(nullptr); // stdin
@@ -785,17 +786,39 @@ int Task::sys$close(int fd)
 int Task::sys$lstat(const char* path, Unix::stat* statbuf)
 {
     VALIDATE_USER_BUFFER(statbuf, sizeof(Unix::stat));
-    auto handle = VirtualFileSystem::the().open(move(path), cwdInode());
+    auto handle = VirtualFileSystem::the().open(move(path), O_NOFOLLOW_NOERROR, cwdInode());
     if (!handle)
         return -1;
     handle->stat(statbuf);
     return 0;
 }
 
+int Task::sys$readlink(const char* path, char* buffer, size_t size)
+{
+    VALIDATE_USER_BUFFER(path, strlen(path));
+    VALIDATE_USER_BUFFER(buffer, size);
+
+    auto handle = VirtualFileSystem::the().open(path, O_RDONLY | O_NOFOLLOW_NOERROR, cwdInode());
+    if (!handle)
+        return -ENOENT; // FIXME: Get a more detailed error from VFS.
+
+    if (!handle->metadata().isSymbolicLink())
+        return -EINVAL;
+
+    auto contents = handle->readEntireFile();
+    if (!contents)
+        return -EIO; // FIXME: Get a more detailed error from VFS.
+
+    memcpy(buffer, contents.pointer(), min(size, contents.size()));
+    if (contents.size() + 1 < size)
+        buffer[contents.size()] = '\0';
+    return 0;
+}
+
 int Task::sys$chdir(const char* path)
 {
     VALIDATE_USER_BUFFER(path, strlen(path));
-    auto handle = VirtualFileSystem::the().open(path, cwdInode());
+    auto handle = VirtualFileSystem::the().open(path, 0, cwdInode());
     if (!handle)
         return -ENOENT; // FIXME: More detailed error.
     if (!handle->isDirectory())
@@ -811,17 +834,20 @@ int Task::sys$getcwd(char* buffer, size_t size)
     return -ENOTIMPL;
 }
 
-int Task::sys$open(const char* path, size_t pathLength)
+int Task::sys$open(const char* path, int options)
 {
 #ifdef DEBUG_IO
     kprintf("Task::sys$open(): PID=%u, path=%s {%u}\n", m_pid, path, pathLength);
 #endif
-    VALIDATE_USER_BUFFER(path, pathLength);
+    VALIDATE_USER_BUFFER(path, strlen(path));
     if (m_fileHandles.size() >= m_maxFileHandles)
         return -EMFILE;
-    auto handle = VirtualFileSystem::the().open(String(path, pathLength), cwdInode());
+    auto handle = VirtualFileSystem::the().open(path, 0, cwdInode());
     if (!handle)
         return -ENOENT; // FIXME: Detailed error.
+    if (options & O_DIRECTORY && !handle->isDirectory())
+        return -ENOTDIR; // FIXME: This should be handled by VFS::open.
+
     int fd = m_fileHandles.size();
     handle->setFD(fd);
     m_fileHandles.append(move(handle));
diff --git a/Kernel/Task.h b/Kernel/Task.h
index 10ea3a2dd3..c1ec246e58 100644
--- a/Kernel/Task.h
+++ b/Kernel/Task.h
@@ -87,7 +87,7 @@ public:
     uid_t sys$getuid();
     gid_t sys$getgid();
     pid_t sys$getpid();
-    int sys$open(const char* path, size_t pathLength);
+    int sys$open(const char* path, int options);
     int sys$close(int fd);
     int sys$read(int fd, void* outbuf, size_t nread);
     int sys$lstat(const char*, Unix::stat*);
@@ -108,6 +108,7 @@ public:
     int sys$gethostname(char* name, size_t length);
     int sys$get_arguments(int* argc, char*** argv);
     int sys$uname(utsname*);
+    int sys$readlink(const char*, char*, size_t);
 
     static void initialize();
 
@@ -134,12 +135,13 @@ public:
     bool isValidAddressForUser(LinearAddress) const;
 
     InodeIdentifier cwdInode() const { return m_cwd ? m_cwd->inode : InodeIdentifier(); }
+    InodeIdentifier executableInode() const { return m_executable ? m_executable->inode : InodeIdentifier(); }
 
 private:
     friend class MemoryManager;
     friend bool scheduleNewTask();
 
-    Task(String&& name, uid_t, gid_t, pid_t parentPID, RingLevel);
+    Task(String&& name, uid_t, gid_t, pid_t parentPID, RingLevel, RetainPtr<VirtualFileSystem::Node>&& = nullptr);
 
     void allocateLDT();
 
@@ -171,6 +173,7 @@ private:
     size_t m_maxFileHandles { 16 };
 
     RetainPtr<VirtualFileSystem::Node> m_cwd;
+    RetainPtr<VirtualFileSystem::Node> m_executable;
 
     struct Region : public Retainable<Region> {
         Region(LinearAddress, size_t, RetainPtr<Zone>&&, String&&);
diff --git a/Kernel/errno.h b/Kernel/errno.h
index d487ec94a2..71a874b5a4 100644
--- a/Kernel/errno.h
+++ b/Kernel/errno.h
@@ -35,7 +35,6 @@
 #define EDOM      33    // Math argument out of domain of func
 #define ERANGE    34    // Math result not representable
 #define ENAMETOOLONG 36 // Name too long
-
+#define ELOOP     40    // Too many symbolic links
 #define EOVERFLOW 75    // Value too large for defined data type
-
 #define ENOTIMPL 999    // Not implemented
diff --git a/LibC/dirent.cpp b/LibC/dirent.cpp
index bda115d456..e1e914b1f0 100644
--- a/LibC/dirent.cpp
+++ b/LibC/dirent.cpp
@@ -8,8 +8,7 @@ extern "C" {
 
 DIR* opendir(const char* name)
 {
-    // FIXME: Should fail if it's not a directory!
-    int fd = open(name);
+    int fd = open(name, O_RDONLY | O_DIRECTORY);
     if (fd == -1)
         return nullptr;
     DIR* dirp = (DIR*)malloc(sizeof(dirp));
diff --git a/LibC/unistd.cpp b/LibC/unistd.cpp
index 1640ab0357..b554fcb549 100644
--- a/LibC/unistd.cpp
+++ b/LibC/unistd.cpp
@@ -20,10 +20,9 @@ pid_t getpid()
     return Syscall::invoke(Syscall::PosixGetpid);
 }
 
-int open(const char* path)
+int open(const char* path, int options)
 {
-    size_t length = strlen(path);
-    int rc = Syscall::invoke(Syscall::PosixOpen, (dword)path, (dword)length);
+    int rc = Syscall::invoke(Syscall::PosixOpen, (dword)path, (dword)options);
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
@@ -74,5 +73,11 @@ int gethostname(char* buffer, size_t size)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
+ssize_t readlink(const char* path, char* buffer, size_t size)
+{
+    int rc = Syscall::invoke(Syscall::PosixReadlink, (dword)path, (dword)buffer, (dword)size);
+    __RETURN_WITH_ERRNO(rc, rc, -1);
+}
+
 }
 
diff --git a/LibC/unistd.h b/LibC/unistd.h
index 74ee98ebda..e4dcfd4ca3 100644
--- a/LibC/unistd.h
+++ b/LibC/unistd.h
@@ -7,7 +7,7 @@ extern "C" {
 uid_t getuid();
 gid_t getgid();
 pid_t getpid();
-int open(const char* path);
+int open(const char* path, int options);
 ssize_t read(int fd, void* buf, size_t count);
 int close(int fd);
 pid_t waitpid(pid_t, int* wstatus, int options);
@@ -16,6 +16,7 @@ char* getcwd(char* buffer, size_t size);
 int lstat(const char* path, stat* statbuf);
 int sleep(unsigned seconds);
 int gethostname(char*, size_t);
+ssize_t readlink(const char* path, char* buffer, size_t);
 
 #define WEXITSTATUS(status) (((status) & 0xff00) >> 8)
 #define WTERMSIG(status) ((status) & 0x7f)
@@ -52,4 +53,10 @@ int gethostname(char*, size_t);
 #define S_ISFIFO(m) (((m) & S_IFMT) == S_IFIFO)
 #define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK)
 
+#define O_RDONLY 0
+#define O_WRONLY 1
+#define O_RDWR 2
+#define O_DIRECTORY 00200000
+#define O_NOFOLLOW 00400000
+
 }
diff --git a/Userland/cat.cpp b/Userland/cat.cpp
index fd0044a7fe..b127bf2cc9 100644
--- a/Userland/cat.cpp
+++ b/Userland/cat.cpp
@@ -9,7 +9,7 @@ int main(int argc, char** argv)
         printf("usage: cat <file>\n");
         return 1;
     }
-    int fd = open(argv[1]);
+    int fd = open(argv[1], O_RDONLY);
     if (fd == -1) {
         printf("failed to open %s: %s\n", argv[1], strerror(errno));
         return 1;
diff --git a/Userland/ls.cpp b/Userland/ls.cpp
index 30983147d9..ad26e020ad 100644
--- a/Userland/ls.cpp
+++ b/Userland/ls.cpp
@@ -65,7 +65,9 @@ int main(int c, char** v)
         const char* endColor = "";
 
         if (colorize) {
-            if (S_ISDIR(st.st_mode))
+            if (S_ISLNK(st.st_mode))
+                beginColor = "\033[36;1m";
+            else if (S_ISDIR(st.st_mode))
                 beginColor = "\033[34;1m";
             else if (st.st_mode & 0111)
                 beginColor = "\033[32;1m";
@@ -76,10 +78,19 @@ int main(int c, char** v)
 
         printf("%s%s%s", beginColor, de->d_name, endColor);
 
-        if (S_ISDIR(st.st_mode))
+        if (S_ISLNK(st.st_mode)) {
+            char linkbuf[256];
+            ssize_t nread = readlink(pathbuf, linkbuf, sizeof(linkbuf));
+            if (nread < 0) {
+                perror("readlink failed");
+            } else {
+                printf(" -> %s", linkbuf);
+            }
+        } else if (S_ISDIR(st.st_mode)) {
             printf("/");
-        else if (st.st_mode & 0111)
+        } else if (st.st_mode & 0111) {
             printf("*");
+        }
         printf("\n");
     }
     return 0;
diff --git a/Userland/mm.cpp b/Userland/mm.cpp
index ee03598867..8cd674f255 100644
--- a/Userland/mm.cpp
+++ b/Userland/mm.cpp
@@ -3,7 +3,7 @@
 
 int main(int c, char** v)
 {
-    int fd = open("/proc/mm");
+    int fd = open("/proc/mm", O_RDONLY);
     if (fd == -1) {
         perror("failed to open /proc/mm");
         return 1;
diff --git a/Userland/ps.cpp b/Userland/ps.cpp
index ec49c480d0..89f16a06a8 100644
--- a/Userland/ps.cpp
+++ b/Userland/ps.cpp
@@ -3,7 +3,7 @@
 
 int main(int c, char** v)
 {
-    int fd = open("/proc/summary");
+    int fd = open("/proc/summary", O_RDONLY);
     if (fd == -1) {
         perror("failed to open /proc/summary");
         return 1;
diff --git a/Userland/sh.cpp b/Userland/sh.cpp
index 3f503419a6..a0e3d1f976 100644
--- a/Userland/sh.cpp
+++ b/Userland/sh.cpp
@@ -147,7 +147,7 @@ int main(int, char**)
     int linedx = 0;
     linebuf[0] = '\0';
 
-    int fd = open("/dev/keyboard");
+    int fd = open("/dev/keyboard", O_RDONLY);
     if (fd == -1) {
         printf("failed to open /dev/keyboard :(\n");
         return 1;
diff --git a/VirtualFileSystem/FileSystem.cpp b/VirtualFileSystem/FileSystem.cpp
index b718fe5c35..6bb738245d 100644
--- a/VirtualFileSystem/FileSystem.cpp
+++ b/VirtualFileSystem/FileSystem.cpp
@@ -74,7 +74,8 @@ ByteBuffer FileSystem::readEntireInode(InodeIdentifier inode, FileHandle* handle
         return nullptr;
     }
 
-    auto contents = ByteBuffer::createUninitialized(metadata.size);
+    size_t initialSize = metadata.size ? metadata.size : 4096;
+    auto contents = ByteBuffer::createUninitialized(initialSize);
 
     Unix::ssize_t nread;
     byte buffer[512];
@@ -87,6 +88,7 @@ ByteBuffer FileSystem::readEntireInode(InodeIdentifier inode, FileHandle* handle
         memcpy(out, buffer, nread);
         out += nread;
         offset += nread;
+        ASSERT(offset <= initialSize); // FIXME: Support dynamically growing the buffer.
     }
     if (nread < 0) {
         kprintf("[fs] readInode: ERROR: %d\n", nread);
diff --git a/VirtualFileSystem/SyntheticFileSystem.cpp b/VirtualFileSystem/SyntheticFileSystem.cpp
index 314e43c52d..db8b34e8d5 100644
--- a/VirtualFileSystem/SyntheticFileSystem.cpp
+++ b/VirtualFileSystem/SyntheticFileSystem.cpp
@@ -60,12 +60,12 @@ auto SyntheticFileSystem::createTextFile(String&& name, String&& text) -> OwnPtr
     file->metadata.size = file->data.size();
     file->metadata.uid = 100;
     file->metadata.gid = 200;
-    file->metadata.mode = 04;
+    file->metadata.mode = 0040644;
     file->metadata.mtime = mepoch;
     return file;
 }
 
-auto SyntheticFileSystem::createGeneratedFile(String&& name, Function<ByteBuffer()>&& generator) -> OwnPtr<File>
+auto SyntheticFileSystem::createGeneratedFile(String&& name, Function<ByteBuffer()>&& generator, Unix::mode_t mode) -> OwnPtr<File>
 {
     auto file = make<File>();
     file->generator = move(generator);
@@ -73,7 +73,7 @@ auto SyntheticFileSystem::createGeneratedFile(String&& name, Function<ByteBuffer
     file->metadata.size = 0;
     file->metadata.uid = 0;
     file->metadata.gid = 0;
-    file->metadata.mode = 0100644;
+    file->metadata.mode = mode;
     file->metadata.mtime = mepoch;
     return file;
 }
@@ -146,9 +146,8 @@ bool SyntheticFileSystem::enumerateDirectoryInode(InodeIdentifier inode, Functio
     callback({ ".", synInode.metadata.inode });
     callback({ "..", synInode.parent });
 
-    for (auto& child : synInode.children) {
+    for (auto& child : synInode.children)
         callback({ child->name, child->metadata.inode });
-    }
     return true;
 }
 
@@ -214,8 +213,8 @@ Unix::ssize_t SyntheticFileSystem::readInodeBytes(InodeIdentifier inode, Unix::o
             generatedData = handle->generatorCache();
         }
     }
-    auto* data = generatedData ? &generatedData : &file.data;
 
+    auto* data = generatedData ? &generatedData : &file.data;
     Unix::ssize_t nread = min(static_cast<Unix::off_t>(data->size() - offset), static_cast<Unix::off_t>(count));
     memcpy(buffer, data->pointer() + offset, nread);
     if (nread == 0 && handle && handle->generatorCache())
diff --git a/VirtualFileSystem/SyntheticFileSystem.h b/VirtualFileSystem/SyntheticFileSystem.h
index d9d84c962a..ed7a9d900e 100644
--- a/VirtualFileSystem/SyntheticFileSystem.h
+++ b/VirtualFileSystem/SyntheticFileSystem.h
@@ -40,7 +40,7 @@ protected:
 
     OwnPtr<File> createDirectory(String&& name);
     OwnPtr<File> createTextFile(String&& name, String&& text);
-    OwnPtr<File> createGeneratedFile(String&& name, Function<ByteBuffer()>&&);
+    OwnPtr<File> createGeneratedFile(String&& name, Function<ByteBuffer()>&&, Unix::mode_t = 0100644);
 
     InodeIdentifier addFile(OwnPtr<File>&&, InodeIndex parent = RootInodeIndex);
     bool removeFile(InodeIndex);
diff --git a/VirtualFileSystem/VirtualFileSystem.cpp b/VirtualFileSystem/VirtualFileSystem.cpp
index f8ead5960a..5145d9a1d1 100644
--- a/VirtualFileSystem/VirtualFileSystem.cpp
+++ b/VirtualFileSystem/VirtualFileSystem.cpp
@@ -5,6 +5,7 @@
 #include <AK/kmalloc.h>
 #include <AK/kstdio.h>
 #include <AK/ktime.h>
+#include "sys-errno.h"
 
 //#define VFS_DEBUG
 
@@ -104,7 +105,8 @@ bool VirtualFileSystem::mount(RetainPtr<FileSystem>&& fileSystem, const String&
 {
     ASSERT(fileSystem);
 
-    auto inode = resolvePath(path);
+    int error;
+    auto inode = resolvePath(path, error);
     if (!inode.isValid()) {
         kprintf("[VFS] mount can't resolve mount point '%s'\n", path.characters());
         return false;
@@ -172,7 +174,8 @@ void VirtualFileSystem::freeNode(Node* node)
 
 bool VirtualFileSystem::isDirectory(const String& path, InodeIdentifier base)
 {
-    auto inode = resolvePath(path, base);
+    int error;
+    auto inode = resolvePath(path, error, base);
     if (!inode.isValid())
         return false;
 
@@ -226,7 +229,8 @@ void VirtualFileSystem::enumerateDirectoryInode(InodeIdentifier directoryInode,
 
 void VirtualFileSystem::listDirectory(const String& path)
 {
-    auto directoryInode = resolvePath(path);
+    int error;
+    auto directoryInode = resolvePath(path, error);
     if (!directoryInode.isValid())
         return;
 
@@ -326,7 +330,8 @@ void VirtualFileSystem::listDirectory(const String& path)
 
 void VirtualFileSystem::listDirectoryRecursively(const String& path)
 {
-    auto directory = resolvePath(path);
+    int error;
+    auto directory = resolvePath(path, error);
     if (!directory.isValid())
         return;
 
@@ -351,17 +356,19 @@ bool VirtualFileSystem::touch(const String& path)
 {
     Locker locker(VirtualFileSystem::lock());
 
-    auto inode = resolvePath(path);
+    int error;
+    auto inode = resolvePath(path, error);
     if (!inode.isValid())
         return false;
     return inode.fileSystem()->setModificationTime(inode, ktime(nullptr));
 }
 
-OwnPtr<FileHandle> VirtualFileSystem::open(const String& path, InodeIdentifier base)
+OwnPtr<FileHandle> VirtualFileSystem::open(const String& path, int options, InodeIdentifier base)
 {
     Locker locker(VirtualFileSystem::lock());
 
-    auto inode = resolvePath(path, base);
+    int error;
+    auto inode = resolvePath(path, error, base, options);
     if (!inode.isValid())
         return nullptr;
     auto vnode = getOrCreateNode(inode);
@@ -397,7 +404,8 @@ InodeIdentifier VirtualFileSystem::resolveSymbolicLink(const String& basePath, I
         return { };
     char buf[4096];
     ksprintf(buf, "/%s/%s", basePath.characters(), String((const char*)symlinkContents.pointer(), symlinkContents.size()).characters());
-    return resolvePath(buf);
+    int error;
+    return resolvePath(buf, error);
 }
 
 String VirtualFileSystem::absolutePath(InodeIdentifier inode)
@@ -407,6 +415,7 @@ String VirtualFileSystem::absolutePath(InodeIdentifier inode)
     if (!inode.isValid())
         return String();
 
+    int error;
     Vector<InodeIdentifier> lineage;
     while (inode != m_rootNode->inode) {
         if (auto* mount = findMountForGuest(inode))
@@ -414,7 +423,7 @@ String VirtualFileSystem::absolutePath(InodeIdentifier inode)
         else
             lineage.append(inode);
         if (inode.metadata().isDirectory()) {
-            inode = resolvePath("..", inode);
+            inode = resolvePath("..", error, inode);
         } else
             inode = inode.fileSystem()->findParentOfInode(inode);
         ASSERT(inode.isValid());
@@ -434,7 +443,7 @@ String VirtualFileSystem::absolutePath(InodeIdentifier inode)
     return builder.build();
 }
 
-InodeIdentifier VirtualFileSystem::resolvePath(const String& path, InodeIdentifier base)
+InodeIdentifier VirtualFileSystem::resolvePath(const String& path, int& error, InodeIdentifier base, int options)
 {
     if (path.isEmpty())
         return { };
@@ -455,12 +464,14 @@ InodeIdentifier VirtualFileSystem::resolvePath(const String& path, InodeIdentifi
 #ifdef VFS_DEBUG
             kprintf("invalid metadata\n");
 #endif
+            error = -EIO;
             return { };
         }
         if (!metadata.isDirectory()) {
 #ifdef VFS_DEBUG
             kprintf("not directory\n");
 #endif
+            error = -EIO;
             return { };
         }
         inode = inode.fileSystem()->childOfDirectoryInodeWithName(inode, part);
@@ -468,6 +479,7 @@ InodeIdentifier VirtualFileSystem::resolvePath(const String& path, InodeIdentifi
 #ifdef VFS_DEBUG
             kprintf("bad child\n");
 #endif
+            error = -EIO;
             return { };
         }
 #ifdef VFS_DEBUG
@@ -489,6 +501,14 @@ InodeIdentifier VirtualFileSystem::resolvePath(const String& path, InodeIdentifi
         }
         metadata = inode.metadata();
         if (metadata.isSymbolicLink()) {
+            if (i == parts.size() - 1) {
+                if (options & O_NOFOLLOW) {
+                    error = -ELOOP;
+                    return { };
+                }
+                if (options & O_NOFOLLOW_NOERROR)
+                    return inode;
+            }
             char buf[4096] = "";
             char* p = buf;
             for (unsigned j = 0; j < i; ++j) {
@@ -497,6 +517,7 @@ InodeIdentifier VirtualFileSystem::resolvePath(const String& path, InodeIdentifi
             inode = resolveSymbolicLink(buf, inode);
             if (!inode.isValid()) {
                 kprintf("Symbolic link resolution failed :(\n");
+                error = -ENOENT;
                 return { };
             }
         }
diff --git a/VirtualFileSystem/VirtualFileSystem.h b/VirtualFileSystem/VirtualFileSystem.h
index 099cf2c853..c697b0df4c 100644
--- a/VirtualFileSystem/VirtualFileSystem.h
+++ b/VirtualFileSystem/VirtualFileSystem.h
@@ -12,6 +12,13 @@
 #include "Limits.h"
 #include "FileSystem.h"
 
+#define O_RDONLY 0
+#define O_WRONLY 1
+#define O_RDWR 2
+#define O_DIRECTORY 00200000
+#define O_NOFOLLOW 00400000
+#define O_NOFOLLOW_NOERROR 0x4000000
+
 class CharacterDevice;
 class FileHandle;
 
@@ -79,7 +86,7 @@ public:
     bool mountRoot(RetainPtr<FileSystem>&&);
     bool mount(RetainPtr<FileSystem>&&, const String& path);
 
-    OwnPtr<FileHandle> open(const String& path, InodeIdentifier base = InodeIdentifier());
+    OwnPtr<FileHandle> open(const String& path, int options = 0, InodeIdentifier base = InodeIdentifier());
     OwnPtr<FileHandle> create(const String& path, InodeIdentifier base = InodeIdentifier());
     OwnPtr<FileHandle> mkdir(const String& path, InodeIdentifier base = InodeIdentifier());
 
@@ -98,7 +105,7 @@ private:
     friend class FileHandle;
 
     void enumerateDirectoryInode(InodeIdentifier, Function<bool(const FileSystem::DirectoryEntry&)>);
-    InodeIdentifier resolvePath(const String& path, InodeIdentifier base = InodeIdentifier());
+    InodeIdentifier resolvePath(const String& path, int& error, InodeIdentifier base = InodeIdentifier(), int options = 0);
     InodeIdentifier resolveSymbolicLink(const String& basePath, InodeIdentifier symlinkInode);
 
     RetainPtr<Node> allocateNode();
diff --git a/VirtualFileSystem/sys-errno.h b/VirtualFileSystem/sys-errno.h
index e01e73798a..7549c562b5 100644
--- a/VirtualFileSystem/sys-errno.h
+++ b/VirtualFileSystem/sys-errno.h
@@ -34,5 +34,5 @@
 #define EPIPE     32    // Broken pipe
 #define EDOM      33    // Math argument out of domain of func
 #define ERANGE    34    // Math result not representable
-
+#define ELOOP     40    // Too many symbolic links
 #define EOVERFLOW 75    // Value too large for defined data type