kernel+libc: Implement isatty()

kernel/src/fs/VFS.h

@@ -81,6 +81,11 @@ namespace VFS
             return err(ENOTTY);
         }
 
+        virtual Result<u64> isatty() const
+        {
+            return err(ENOTTY);
+        }
+
         // Directory-specific methods
         virtual Result<SharedPtr<Inode>> find(const char* name) const = 0;
 

kernel/src/fs/devices/ConsoleDevice.cpp

@@ -5,6 +5,7 @@
 #include "memory/MemoryManager.h"
 #include "thread/Scheduler.h"
 #include "video/TextConsole.h"
+#include <bits/ioctl-defs.h>
 #include <bits/termios.h>
 #include <luna/Buffer.h>
 #include <luna/CString.h>

kernel/src/fs/devices/ConsoleDevice.h

@@ -22,5 +22,10 @@ class ConsoleDevice : public Device
         return "console";
     }
 
+    Result<u64> isatty() const override
+    {
+        return 1;
+    }
+
     virtual ~ConsoleDevice() = default;
 };

kernel/src/fs/devices/Device.h

@@ -14,6 +14,11 @@ class Device
         return err(ENOTTY);
     }
 
+    virtual Result<u64> isatty() const
+    {
+        return err(ENOTTY);
+    }
+
     virtual usize size() const
     {
         return 0;

kernel/src/fs/tmpfs/Inode.h

@@ -276,6 +276,11 @@ namespace TmpFS
             return m_device->ioctl(request, arg);
         }
 
+        Result<u64> isatty() const override
+        {
+            return m_device->isatty();
+        }
+
         bool blocking() const override
         {
             return m_device->blocking();

kernel/src/sys/file.cpp

@@ -157,6 +157,16 @@ Result<u64> sys_ioctl(Registers*, SyscallArgs args)
     return descriptor.inode->ioctl(request, arg);
 }
 
+Result<u64> sys_isatty(Registers*, SyscallArgs args)
+{
+    int fd = (int)args[0];
+
+    Thread* current = Scheduler::current();
+    auto& descriptor = *TRY(current->resolve_fd(fd));
+
+    return descriptor.inode->isatty();
+}
+
 Result<u64> sys_dup2(Registers*, SyscallArgs args)
 {
     int oldfd = (int)args[0];

libc/include/unistd.h

@@ -168,6 +168,9 @@ extern "C"
     /* Check for a file's accessibility relative to a file descriptor. */
     int faccessat(int dirfd, const char* path, int amode, int flags);
 
+    /* Check whether a file descriptor refers to a terminal device. */
+    int isatty(int fd);
+
 #ifdef __cplusplus
 }
 #endif

libc/src/unistd.cpp

@@ -467,4 +467,15 @@ extern "C"
         long rc = syscall(SYS_faccessat, dirfd, path, amode, flags);
         __errno_return(rc, int);
     }
+
+    int isatty(int fd)
+    {
+        long rc = syscall(SYS_isatty, fd);
+        if (rc < 0)
+        {
+            errno = -rc;
+            return 0;
+        }
+        return rc;
+    }
 }

libluna/include/luna/Syscall.h

@@ -6,7 +6,7 @@
             _e(getgid) _e(getegid) _e(setuid) _e(setgid) _e(seteuid) _e(setegid) _e(fchmodat) _e(fchownat) _e(ioctl)   \
                 _e(fstatat) _e(chdir) _e(getcwd) _e(unlinkat) _e(uname) _e(sethostname) _e(dup2) _e(pipe) _e(mount)    \
                     _e(umount) _e(pstat) _e(getrusage) _e(symlinkat) _e(readlinkat) _e(umask) _e(linkat) _e(faccessat) \
-                        _e(pivot_root) _e(sigreturn) _e(sigaction) _e(kill) _e(sigprocmask) _e(setpgid)
+                        _e(pivot_root) _e(sigreturn) _e(sigaction) _e(kill) _e(sigprocmask) _e(setpgid) _e(isatty)
 
 enum Syscalls
 {