# Implemented System Calls
The following is a list of system calls that are currently implemented. We will update the list when there is a major release.

## System calls that are fully implemented

### System calls that require multi-process coordination

* Process creation (fork/vfork)
* execve
* Process/thread termination (exit/exit_group)
* Waiting for process/thread (wait4/waitid)
* Signaling (kill/tkill/tgkill)
* System V IPC semaphore (semget/semop/semtimedop/semctl)
* System V IPC message queue (msgget/msgsnd/msgrcv)

### System calls that require no multi-process coordination

* File open/close (open/openat/creat/close)
* File descriptor access (read/write/readv/writev/pread64/pwrite64)
* File/file descriptor attributes (stat/fstat/lstat)
* File permission (access/faccessat)
* File descriptor polling (poll/ppoll)
* File descriptor selecting (select/pselect)
* Create/change/remove memory mapping (mmap/mprotect/munmap)
* Signal handling (rt_sigaction/rt_sigprocmask/rt_sigreturn)
* Duplicating file descriptors (dup/dup2/dup3)
* Pipe/socket pair creation (pipe/pipe2/socketpair)
* Scheduler yielding (sched_yield)
* Pausing/sleeping (pause/nanosleep)
* Timer/alarm (alarm/setitimer/getitimer)
* Creation/connection of TCP/UDP socket (socket/connect/accept/accept4/listen)
* Sending/receiving network packets (sendto/recvfrom/sendmsg/recvmsg)
* Tear down socket (shutdown)
* Getting socket address (getsockname/getpeername)
* Socket options (getsockopt/setsockopt)
* System information (uname)
* Process credentials (getpid/gettid/getpgid/getpgrp)
* User credentials (getuid/setuid/getgid/setgid)
* Effective user credentials (geteuid/seteuid/getegid/setegid)
* Program break (brk)
* File flushing (fsync)
* File offset (lseek)
* File truncating (truncate/ftruncate)
* File copy (sendfile)
* Current directory (getcwd/chdir/fchdir)
* Listing directory (getdents/getdents64)
* Creating/deleting directory (mkdir/rmdir/mkdirat)
* Changing file metadata (rename/renameat/unlink/unlinkat/chmod/fchmod/fchmodat)
* Query system time (gettimeofday/time/clock_gettime)
* Asynchronous file descriptor polling (epoll_create/epoll_create1/epoll_wait/epoll_ctl/epoll_pwait)
* Changing thread metadata (chroot/umask)
* Futex and related system calls (futex/set_tid_address/set_robust_list/get_robust_list)
* Thread-state (arch_prctl)


## System calls that are partially implemented

* ioctl

   Currently only FIONREAD is supported for the ioctl system call.

* fcntl
   + Supported: Duplicate FDs (F_DUPFD/F_DUPFD_CLOEXEC), Set FD flags (F_GETFD/F_SETFD), Set file flags (F_GETFL/F_SETFL)
   + Unsupported: File locking (F_SETLK/F_SETLKW/F_GETLK)
* clone

   The Linux clone system call is ubiquitously used for creation of processes and threads. However, in Graphene, we only use the clone system call for thread creation. Process creation are implemented as the fork system call. In practice, it is quite rare for applications to use methods that are not forking to create processes.

   The namespace options for the clone system calls (CLONE_FS, CLONE_NEWIPC, CLONE_NEWNET, etc) are currently not supported.

* msgctl

   Only IPC_RMID is supported

* setpgid/setsid

   These two system calls will set the process credential, but do not coordinate any cross-process state.

* bind

   Binding on path (UNIX socket) is only supported locally in the process.

* readlink

   Symbolic links are not supported. Readlink will simply resolve absolute paths.

* getrlimit

   getrlimit() returns the static values of RLIMIT_NOFILE, RLIMIT_RSS, RLIMIT_AS, RLIMIT_STACK.

## System calls that are added in Graphene as _Hypercalls_