Add sys$ttyname_r and ttyname_r() + ttyname().

And print a greeting when sh starts up so we know which TTY we're on.

Kernel/Syscall.cpp

@@ -114,6 +114,8 @@ DWORD handle(DWORD function, DWORD arg1, DWORD arg2, DWORD arg3)
         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);
+    case Syscall::PosixTtynameR:
+        return current->sys$ttyname_r((int)arg1, (char*)arg2, (size_t)arg3);
     default:
         kprintf("int0x80: Unknown function %x requested {%x, %x, %x}\n", function, arg1, arg2, arg3);
         break;

Kernel/Syscall.h

@@ -37,6 +37,7 @@ enum Function {
     SetMmapName = 0x2005,
     PosixReadlink = 0x2006,
     PosixWrite = 0x2007,
+    PosixTtynameR = 0x2008,
 };
 
 void initialize();

Kernel/TTY.h

@@ -13,6 +13,8 @@ public:
     virtual String ttyName() const = 0;
 
 protected:
+    virtual bool isTTY() const final { return true; }
+
     TTY(unsigned major, unsigned minor);
     void emit(byte);
 

Kernel/Task.cpp

@@ -741,7 +741,7 @@ ssize_t Task::sys$get_dir_entries(int fd, void* buffer, size_t size)
     VALIDATE_USER_BUFFER(buffer, size);
     auto* handle = fileHandleIfExists(fd);
     if (!handle)
-        return -1;
+        return -EBADF;
     return handle->get_dir_entries((byte*)buffer, size);
 }
 
@@ -749,10 +749,25 @@ int Task::sys$seek(int fd, int offset)
 {
     auto* handle = fileHandleIfExists(fd);
     if (!handle)
-        return -1;
+        return -EBADF;
     return handle->seek(offset, SEEK_SET);
 }
 
+int Task::sys$ttyname_r(int fd, char* buffer, size_t size)
+{
+    VALIDATE_USER_BUFFER(buffer, size);
+    auto* handle = fileHandleIfExists(fd);
+    if (!handle)
+        return -EBADF;
+    if (!handle->isTTY())
+        return -ENOTTY;
+    auto ttyName = handle->tty()->ttyName();
+    if (size < ttyName.length() + 1)
+        return -ERANGE;
+    strcpy(buffer, ttyName.characters());
+    return 0;
+}
+
 ssize_t Task::sys$write(int fd, const void* data, size_t size)
 {
     VALIDATE_USER_BUFFER(data, size);
@@ -802,7 +817,7 @@ int Task::sys$close(int fd)
 {
     auto* handle = fileHandleIfExists(fd);
     if (!handle)
-        return -1;
+        return -EBADF;
     // FIXME: Implement.
     return 0;
 }

Kernel/Task.h

@@ -111,6 +111,7 @@ public:
     int sys$get_arguments(int* argc, char*** argv);
     int sys$uname(utsname*);
     int sys$readlink(const char*, char*, size_t);
+    int sys$ttyname_r(int fd, char*, size_t);
 
     static void initialize();
 

LibC/unistd.cpp

@@ -38,6 +38,20 @@ ssize_t write(int fd, const void* buf, size_t count)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
+int ttyname_r(int fd, char* buffer, size_t size)
+{
+    int rc = Syscall::invoke(Syscall::PosixTtynameR, (dword)fd, (dword)buffer, (dword)size);
+    __RETURN_WITH_ERRNO(rc, rc, -1);
+}
+
+static char ttyname_buf[32];
+char* ttyname(int fd)
+{
+    if (ttyname_r(fd, ttyname_buf, sizeof(ttyname_buf)) < 0)
+        return nullptr;
+    return ttyname_buf;
+}
+
 int close(int fd)
 {
     int rc = Syscall::invoke(Syscall::PosixClose, fd);

LibC/unistd.h

@@ -18,6 +18,8 @@ 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);
+char* ttyname(int fd);
+int ttyname_r(int fd, char* buffer, size_t);
 
 #define WEXITSTATUS(status) (((status) & 0xff00) >> 8)
 #define WTERMSIG(status) ((status) & 0x7f)

Userland/sh.cpp

@@ -4,6 +4,7 @@
 #include <LibC/errno.h>
 #include <LibC/string.h>
 #include <LibC/stdlib.h>
+#include <LibC/utsname.h>
 #include <AK/FileSystemPath.h>
 
 struct GlobalState {
@@ -148,6 +149,17 @@ static int runcmd(char* cmd)
     return retval;
 }
 
+static void greeting()
+{
+    utsname uts;
+    int rc = uname(&uts);
+    if (rc < 0) {
+        perror("uname");
+        return;
+    }
+    printf("\n%s/%s on %s\n\n", uts.sysname, uts.machine, ttyname(0));
+}
+
 int main(int, char**)
 {
     g = new GlobalState;
@@ -155,6 +167,8 @@ int main(int, char**)
     if (rc < 0)
         perror("gethostname");
 
+    greeting();
+
     char linebuf[128];
     int linedx = 0;
     linebuf[0] = '\0';

VirtualFileSystem/CharacterDevice.h

@@ -18,6 +18,8 @@ public:
     unsigned major() const { return m_major; }
     unsigned minor() const { return m_minor; }
 
+    virtual bool isTTY() const { return false; }
+
 protected:
     CharacterDevice(unsigned major, unsigned minor) : m_major(major), m_minor(minor) { }
 

VirtualFileSystem/FileHandle.cpp

@@ -3,6 +3,7 @@
 #include "CharacterDevice.h"
 #include "sys-errno.h"
 #include "UnixTypes.h"
+#include "TTY.h"
 #include <AK/BufferStream.h>
 
 FileHandle::FileHandle(RetainPtr<VirtualFileSystem::Node>&& vnode)
@@ -109,6 +110,7 @@ Unix::ssize_t FileHandle::write(const byte* data, Unix::size_t size)
     }
     // FIXME: Implement non-device writes.
     ASSERT_NOT_REACHED();
+    return -1;
 }
 
 bool FileHandle::hasDataAvailableForRead()
@@ -160,3 +162,17 @@ ssize_t FileHandle::get_dir_entries(byte* buffer, Unix::size_t size)
     memcpy(buffer, tempBuffer.pointer(), stream.offset());
     return stream.offset();
 }
+
+bool FileHandle::isTTY() const
+{
+    if (auto* device = m_vnode->characterDevice())
+        return device->isTTY();
+    return false;
+}
+
+const TTY* FileHandle::tty() const
+{
+    if (auto* device = m_vnode->characterDevice())
+        return static_cast<const TTY*>(device);
+    return nullptr;
+}

VirtualFileSystem/FileHandle.h

@@ -4,6 +4,8 @@
 #include "InodeMetadata.h"
 #include <AK/ByteBuffer.h>
 
+class TTY;
+
 class FileHandle {
 public:
     explicit FileHandle(RetainPtr<VirtualFileSystem::Node>&&);
@@ -24,6 +26,9 @@ public:
 
     bool isDirectory() const;
 
+    bool isTTY() const;
+    const TTY* tty() const;
+
     InodeMetadata metadata() const { return m_vnode->metadata(); }
 
     VirtualFileSystem::Node* vnode() { return m_vnode.ptr(); }

VirtualFileSystem/VirtualFileSystem.h

@@ -55,6 +55,7 @@ public:
 
         bool isCharacterDevice() const { return m_characterDevice; }
         CharacterDevice* characterDevice() { return m_characterDevice; }
+        const CharacterDevice* characterDevice() const { return m_characterDevice; }
 
         void retain();
         void release();