POSIX and Linux System Calls in Idris2

This project has been split into two libraries, both providing bindings to the most important system calls and utilities available on Unix-like operating systems.

The libraries are the result of working through the Linux Programming Interface and writing bindings for the most important system calls (usually via the corresponding C functions) in Idris. As I crawl through the chapters, the todo-list below will continuously grow.

In the examples subproject you can find many of the example applications and exercises from the book implemented as a single command-line application.

Chapter Overview

Chapter 4

• [x] implement open plus flags and mode
• [x] implement read for raw buffers and ByteString
• [x] implement write for raw buffers and ByteString
• [x] implement close
• [x] implement lseek including different whence constants
• [x] solve exercises in Idris

Chapter 5

• [x] get and set file flags using fcntl
• [x] implement file duplication: dup, dup2, and via fcntl
• [x] implement pread and pwrite
• [x] implement truncate and ftruncate
• [x] implement mkstemp
• [x] solve (most) exercises in Idris

The following will probably not be implemented:

• scatter and gather versions of read and write
• tmpfile as it operates on FILE *
• dup3 as it is not part of POSIX

Chapter 6

• [x] implement getpid and getppid.

The following will probably not be implemented:

• setjmp and longjmp as they belong strictly to C land
• exercises, as they deal either with non-implementable stuff or with the environment, and we already have that from base

Chapter 7

• [ ] implement realloc

The following will probably not be implemented:

• alloca because it is mostly useful in C land
• memalign and posix_memalign because they are non-standard

Chapter 8

Note: Calls to crypt are available from idris2-crypt.

The following will probably not be implemented:

• getpwnam, getpwuid, getgrnam, getgruid, getpwent, setpwent endpwent, getspnam, getspent, setspent, endspent: All of these can be implemented by reading or streaming the corresponding files in /etc into proper Idris records.

Chapter 9

• [x] implement getuid, geteuid, setuid, and seteuid
• [x] implement getgid, getegid, setgid, and setegid
• [ ] implement setreuid and setregid
• [ ] implement getgroups
• [ ] implement setgroups
• [ ] implement initgroups

The following will probably not be implemented:

• getresuid, getresgid, setfsuid, and setfsgid (all are non-standard)

Chapter 10

• [ ] implement gmtime_r
• [ ] implement localtime_r
• [ ] implement mktime
• [ ] implement strftime_l

The following will probably not be implemented:

• settimeofday and adjtime because these are typically handled by a system daemon

Note: Different types of clocks are implemented in System.Clock in base.

Chapter 11

• [x] implement sysconf, pathconf, and fpathconf

Chapter 12

• [ ] implement uname
• [x] solve process tree exercise

Chapter 13

• [ ] implement fileno
• [ ] implement fdopen
• [ ] do the exercises

Notes: Currently, I am more interested in the raw system calls. Buffered file I/O is available from System.File in base.

Chapter 14

• [ ] implement mount
• [ ] implement umount and umount2
• [x] implement statvfs and fstatvfs
• [ ] do the exercise

Chapter 15

• [x] implement stat, lstat, and fstat
• [ ] implement utimes, futimes, and lutimes
• [ ] implement chown, lchown, and fchown
• [ ] implement umask
• [ ] implement chmod and fchmod
• [ ] do the exercises

The following will probably not be implemented:

• access as its use is discouraged
• setting of i-node flags as these are non-standard

Chapter 16

Extended attributes are non-standard and will not be supported for the time being.

Chapter 17

Access control lists are non-standard and will not be supported for the time being.

Chapter 18

• [x] implement link and unlink
• [x] implement rename
• [x] implement symlink and readlink
• [x] implement mkidr, rmdir, and something similar to mkdir -p
• [x] implement remove
• [x] implement opendir and fopendir
• [x] implement rewinddir and closedir
• [x] implement readdir
• [x] implement getcwd
• [x] implement chdir
• [x] implement chroot
• [ ] do the exercises

The following will probably not be implemented:

• nfwt: We should probably write our tree-walking routines in Idris proper instead of messing around with C callbacks.
• realpath because it's even more broken than getcwd

Chapter 19

• [x] implement inotify utilities for monitoring files
• [ ] do the exercise

Chapter 20

• [x] implement kill and raise
• [x] implement utilities for working with sigset_t
• [x] implement different versions of sigprocmask
• [x] implement sigpending

Notes: As per the Chez Scheme documentation, it is not safe to call from C to Scheme from C interrupt handlers. We can therefore not make use of signal and sigaction when on one of the Scheme backends. ~~Instead, a Scheme specific utility called onsignal is added for registering signal handlers~~ (this is no longer available, as it caused spurious core dumps). An alternative would be to use epoll with a signal file descriptor (under Linux) or synchronous signal handling. See chapter 22.

Chapter 21

• [x] implement abort

The following will probably not be implemented:

• sigsetjmp siglongjmp, and sigaltstack as I can't see their use on the default backends.

Chapter 22

• [x] implement sigsuspend
• [x] implement sigwaitinfo and sigtimedwait
• [x] implement raising and handling of realtime signals
• [x] implement signal fetching via a file descriptor

Chapter 23

• [x] implement setitimerval and getitimerval
• [x] implement nanosleep and clock_nanosleep.
• [x] implement clock_gettime and clock_settime
• [ ] add support for process and thread clock IDs
• [ ] implement POSIX clocks timers
• [x] implement timer handling via file descriptors

Chapter 24

• [x] implement fork
• [x] add example applications with some IPC via signals

Chapter 25

exit is already available in base.

The following will probably not be implemented:

• Installing exit handlers via atexit and onexit, as these might suffer from the same limitations as other callbacks when used from Schemes.

Chapter 26

• [x] implement wait
• [x] implement waitpid
• [x] implement waitid
• [ ] do the exercises

The following will probably not be implemented:

• wait3 and wait4 as they are (according to the book) not often used and lack standardization.

Chapter 27

• [x] implement execve and related functions
• [x] implement system
• [ ] do the exercises

Chapter 28

The following will probably not be implemented:

• clone as it takes a callback function and is probably not very useful in this generality when using Idris.

Chapter 29

• [x] implement pthreadSelf
• [x] implement pthreadJoin

The following will probably not be implemented:

• pthread_create, pthread_exit, pthread_detach, and thread attributes as the lifetime of threads is controlled by the Scheme runtime.

Chapter 30

• [x] implement MutexT and utilities for working with mutexes
• [x] implement CondT and utilities for working with condition variables

The following will probably not be implemented:

• Fine grained details about mutex and condition attributes.

Chapter 31

The following will probably not be implemented:

• pthread_once as it involves callbacks and is not clear how it interacts with Scheme's thread management.
• thread specific data, because we have other mechanisms in Idris to achieve this
• thread-local storage, because this makes use of a C language keyword.

Chapter 32

• [x] implement pthread_cancel
• [x] implement pthread_setcanceltype and pthread_setcancelstate
• [x] implement pthread_testcancel

The following will probably not be implemented:

• registering and handling of thread cleanup handlers. I might come back to this and check interop with the Scheme backends

Chapter 33

• [x] implement pthread_sigmask in various forms
• [x] implement pthread_kill
• [x] implement pthread_sigqueue
• [x] implement sigwait
• [ ] do the exercises

Chapters 34 - 43

To be added...

Chapter 44

• [x] implement pipe
• [x] implement pipe2
• [ ] implement popen and pclose
• [x] implement mkfifo
• [ ] do the exercises

Chapter 45

• [ ] do the exercises