Module Netsys_posix

module Netsys_posix: sig .. end

POSIX-specific system calls missing in the Unix module

File descriptor polling

type poll_array

The array of poll_cell entries

type poll_req_events

type poll_act_events

Poll events. poll_req_events is used to request that certain event types are observed. poll_act_event shows which event types are actually possible

type poll_cell = {

	`mutable poll_fd : Unix.file_descr;`
	`mutable poll_req_events : poll_req_events;`
	`mutable poll_act_events : poll_act_events;`

}

The poll cell refers to the descriptor poll_fd. The poll_req_events are the events the descriptor is polled for. The poll_act_events are the actually reported events.

val have_poll : unit -> bool

Whether there is a native poll implementation on this OS

val poll_req_events : bool -> bool -> bool -> poll_req_events

poll_req_events rd wr pri: Create a set of in events consisting of the bits rd, wr, and pri. rd means to poll for input data, wr to poll for output data, and pri to poll for urgent input data.

val poll_req_triple : poll_req_events -> bool * bool * bool

Looks into a poll_req_events value, and returns the triple (rd,wr,pri).

val poll_null_events : unit -> poll_act_events

Create an empty set of poll_act_events, for initilization of poll cells.

val poll_result : poll_act_events -> bool

Look whether there is any event in poll_out_events

val poll_rd_result : poll_act_events -> bool

val poll_wr_result : poll_act_events -> bool

val poll_pri_result : poll_act_events -> bool

val poll_err_result : poll_act_events -> bool

val poll_hup_result : poll_act_events -> bool

val poll_nval_result : poll_act_events -> bool

Look for the bit in poll_act_events and return the status

val create_poll_array : int -> poll_array

Create a poll array with the given size. The poll_fd member is initialized with Unix.stdin, and the two event members are empty.

val set_poll_cell : poll_array -> int -> poll_cell -> unit

set_poll_cell a k c: Sets the poll cell k to c. The index k must be in the range from 0 to N-1 when N is the length of the poll array.

val get_poll_cell : poll_array -> int -> poll_cell

get_poll_cell a k: Returns the poll cell k. The index k must be in the range from 0 to N-1 when N is the length of the poll array.

val blit_poll_array : poll_array ->
       int -> poll_array -> int -> int -> unit

blit_poll_array a1 p1 a2 p2 len: Copies the len cells at index p1 from a1 to a2 at index p2.

val poll_array_length : poll_array -> int

Return the number of cells in the poll array

val poll : poll_array -> int -> float -> int

poll a n tmo: Poll for the events of the cells 0 to n-1 of poll array a, and set the poll_revents member of all cells. Wait for at most tmo seconds (a negative value means there is no timeout). Returns the number of ready file descriptors.

On platforms without native support for poll the function is emulated using Unix.select. Note, however, that there is a performance penalty for the emulation, and that the output flags poll_error_result, poll_hangup_result, and poll_invalid_result are not emulated.

val restarting_poll : poll_array -> int -> float -> int

A wrapper around poll that handles the EINTR condition

val poll_single : Unix.file_descr -> bool -> bool -> bool -> float -> bool

poll_single fd rd wr pri tmo: Polls a single descriptor for the events given by rd, wr, and pri. In tmo the timeout can be passed. Returns true if one of the requested events is indicated for the descriptor. The EINTR case is not handled.

Actually, poll_req_events and poll_act_events are integers that are bitmasks of some constants. The following functions allow access to this detail.

val int_of_req_events : poll_req_events -> int

val int_of_act_events : poll_act_events -> int

val req_events_of_int : int -> poll_req_events

val act_events_of_int : int -> poll_act_events

val const_rd_event : int

val const_wr_event : int

val const_pri_event : int

val const_err_event : int

val const_hup_event : int

val const_nval_event : int

Fork helpers

Ocamlnet invokes Unix.fork at some places to create child processes for doing real work. The following functions allow it to register a handler that is run in the forked child process. Note that this is done by the O'caml code calling fork, and not via the POSIX atfork() facility.

The handler should release OS resources like file descriptors that are by default shared with the parent process.

The handler are not invoked when the only purpose of the fork is to exec a different process.

class type post_fork_handler = object .. end

A post_fork_handler is a named function unit -> unit

val register_post_fork_handler : post_fork_handler -> unit

Registers a new post fork handler (MT-Safe)

val remove_post_fork_handler : post_fork_handler -> unit

Removes a post fork handler from the registry (MT-Safe)

val run_post_fork_handlers : unit -> unit

Runs all post fork handlers. Exceptions are caught and printed to stderr.

The "at" variants of system calls

Note that a few "at" calls have been omitted because the same functionality can be achieved by first opening the file with openat and then by using a function that references the file by descriptor. An example for this is fstatat: After the openat call one can use fstat to get the stat record of the file.

val have_at : unit -> bool

Whether the *at functions are available (they were only recently standardized and cannot be expected on all OS yet)

val at_fdcwd : Unix.file_descr

Pseudo descriptor value to be used as first argument of *at functions

type at_flag =

`\|`	`AT_EACCESS`
`\|`	`AT_SYMLINK_NOFOLLOW`
`\|`	`AT_REMOVEDIR`	`(*`	Flags one can pass to "at" functions. Not all functions support all flags	`*)`

val openat : Unix.file_descr ->
       string -> Unix.open_flag list -> Unix.file_perm -> Unix.file_descr

Same as Unix.openfile but open relative to the directory given by first argument

val faccessat : Unix.file_descr ->
       string -> Unix.access_permission list -> at_flag list -> unit

Same as Unix.access but the file is taken relative to the directory given by first argument

val mkdirat : Unix.file_descr -> string -> int -> unit

Same as Unix.mkdir but the file is taken relative to the directory given by first argument

val renameat : Unix.file_descr -> string -> Unix.file_descr -> string -> unit

renameat olddirfd oldpath newdirfd newpath

val linkat : Unix.file_descr ->
       string -> Unix.file_descr -> string -> at_flag list -> unit

linkat olddirfd oldpath newdirfd newpath flags

val unlinkat : Unix.file_descr -> string -> at_flag list -> unit

Same as Unix.unlink but unlink the file relative to the directory given by first argument

val symlinkat : string -> Unix.file_descr -> string -> unit

symlinkat oldpath newdirfd newpath flags

val mkfifoat : Unix.file_descr -> string -> int -> unit

mkfifoat dirfd path mode

val readlinkat : Unix.file_descr -> string -> string

readlinkat dirfd path

Misc

val int_of_file_descr : Unix.file_descr -> int

Return the file descriptor as integer. See also Netsys.int64_of_file_descr which works for all OS.

val file_descr_of_int : int -> Unix.file_descr

Make a file descriptor from an integer

val sysconf_open_max : unit -> int

Return the maximum number of open file descriptor per process. It is also ensured that for every file descriptor fd: fd < sysconf_open_max()

val fchdir : Unix.file_descr -> unit

Set the current directory to the directory referenced by the file descriptor

val fdopendir : Unix.file_descr -> Unix.dir_handle

Make a directory handle from a file descriptor. The descriptor is then "owned" by the directory handle, and will be closed by Unix.closedir.

This function is useful in conjunction with Netsys_posix.openat to read directories relative to a parent directory.

This is a recent addition to the POSIX standard; be prepared to get Invalid_argument because it is unavailable.

val getpgid : int -> int

Return the process group ID of the process with the passed PID. For the number 0, the process group ID of the current process is returned.

val getpgrp : unit -> int

Same as getpgid 0, i.e. returns the process group ID of the current process.

val setpgid : int -> int -> unit

setpgid pid pgid: Set the process group ID of the process pid to pgid. If pid = 0, the process group ID of the current process is changed. If pgid = 0, as process group ID the process ID of the process referenced by pid is used.

It is only possible for a process to join a process group if both belong to the same session.

val setpgrp : unit -> unit

Same as setpgid 0 0: A new process group ID is created, and the current process becomes its sole member.

val tcgetpgrp : Unix.file_descr -> int

Return the process group ID of the foreground process group of the session associated with the file descriptor, which must be a tty.

val tcsetpgrp : Unix.file_descr -> int -> unit

Sets the foreground process group ID of the session associated with the file descriptor, which must be a tty.

val ctermid : unit -> string

Returns the name of the controlling tty of the current process as pathname to a device file

val ttyname : Unix.file_descr -> string

Returns the name of the controlling tty referred to by the file descriptor.

val getsid : int -> int

Returns the session ID of the process with the passed PID. For the PID 0, the session ID of the current process is returned.

val with_tty : (Unix.file_descr -> unit) -> unit

with_tty f: Runs f fd where fd is the terminal of the process. If the process does not have a terminal (because it is a daemon) with_tty will fail.

val tty_read_password : ?tty:Unix.file_descr -> string -> string

tty_read_password prompt: If tty is a terminal, the prompt is output, and a password is read from the terminal (echo off). If tty is not a terminal, no prompt is printed, and just a line is read from the tty descriptor (non-interactive case).

tty defaults to Unix.stdin. If this function is used in a program where stdin is not redirected, and the program is started in a terminal, it will read the password with prompt and echo disabled. If stdin is redirected, it is assumed that the program is used in a script, and the password is piped into it.

Use in conjunction with with_tty to ensure that tty is the terminal even if a redirection is in effect, e.g.

 with_tty (fun tty -> tty_read_password ~tty prompt)

Raises Sys.Break if the user triggers SIGINT (i.e. presses CTRL-C) to abort the input of a password.

val setreuid : int -> int -> unit

Changes both the real and the effective user ID of the current process.

val setregid : int -> int -> unit

Changes both the real and the effective group ID of the current process.

Fork+exec

The following function has some similarity with posix_spawn, but is changed to our needs, Only special (although frequent) cases can be implemented with posix_spawn.

type wd_spec =

`\|`	`Wd_keep`
`\|`	`Wd_chdir of string`
`\|`	`Wd_fchdir of Unix.file_descr`

type pg_spec =

`\|`	`Pg_keep`
`\|`	`Pg_new_bg_group`
`\|`	`Pg_new_fg_group`
`\|`	`Pg_join_group of int`

type fd_action =

`\|`	`Fda_close of Unix.file_descr`	`(*`	Close the descriptor	`*)`
`\|`	`Fda_close_ignore of Unix.file_descr`	`(*`	Close the descriptor but ignore `EBADF` errors	`*)`
`\|`	`Fda_close_except of bool array`	`(*`	Closes all descriptors except those for which `except.(k)` is true where `k = int_of_file_descr fd`. Descriptors outside the array index range are closed.	`*)`
`\|`	`Fda_dup2 of Unix.file_descr * Unix.file_descr`	`(*`	Duplicate the first descriptor to the second as `dup2` does	`*)`

type sig_action =

`\|`	`Sig_default of int`
`\|`	`Sig_ignore of int`

val spawn : ?chdir:wd_spec ->
       ?pg:pg_spec ->
       ?fd_actions:fd_action list ->
       ?sig_actions:sig_action list ->
       ?env:string array -> string -> string array -> int

spawn cmd args: Fork the process and exec cmd which gets the arguments args. On success, the PID of the new process is returned.

chdir: If set, the new process starts with this working directory (this is done before anything else)
pg: If set, the new process will be a member of this process group
fd_actions: If set, these descriptor actions are executed sequentially
sig_actions: If set, these signal actions are executed sequentially
env: If set, the process gets this environment instead of the current one

Any exceptions in the subprocess are detected, and reported. However, if Fda_close leads to EBADF for a descriptor, this error is ignored.

If pg=Pg_new_fg_group, one should include Sig_ignore Sys.sigttou in sig_actions.

Subprocesses and signals

Watching subprocesses requires that the right signal handler is installed: install_subprocess_handler

type watched_subprocess

val watch_subprocess : int -> int -> bool -> Unix.file_descr * watched_subprocess

let fd, ws = watch_subprocess pid pgid kill_flag: Enters the subprocess pid into the watch list. If pgid > 0, the process group ID is pgid (for killpg_subprocess and killpg_all_subprocesses). The kill_flag controls the process selection of kill_all_subprocesses and killpg_all_subprocesses.

The returned descriptor fd is open for reading and will indicate EOF when the subprocess is terminated. Via ws it is possible to query information about the subprocess. The installed signal handler will wait for the subprocess and put the process status into ws.

The caller has to close fd after the termination is signaled.

val ignore_subprocess : watched_subprocess -> unit

Changes the arrangement so that the termination of the subprocess is no longer reported by the file descriptor. The file descriptor indicates EOF immediately (and can be closed by the caller). Nevertheless, the signal handler still waits for the subprocess to avoid zombies.

Any further access to ws will fail.

val forget_subprocess : watched_subprocess -> unit

Frees OS resources. Any further access to the ws will fail.

val get_subprocess_status : watched_subprocess -> Unix.process_status option

If the subprocess is terminated, this function returns the status. Otherwise None is returned

val kill_subprocess : int -> watched_subprocess -> unit

Sends this signal to the subprocess if this process still exists. Never throws an exception.

val killpg_subprocess : int -> watched_subprocess -> unit

Sends this signal to the process group of the subprocess if there is still a watched subprocess belonging to this group. Never throws an exception.

val kill_all_subprocesses : int -> bool -> bool -> unit

kill_all_subprocess signal override nogroup: Sends a signal to potentially all subprocesses. The signal is sent to a watched process if the process still exists, and these two conditions hold both:

not nogroup || pgid = 0: Processes with pgid > 0 are excluded if nogroup is set
kill_flag || override: A process needs to have kill_flag set, or override is specified

Never throws an exception if the signal handler is installed.

val killpg_all_subprocesses : int -> bool -> unit

killpg_all_subprocess signal override: Sends a signal to potentially all subprocesses belonging to a process group (i.e. pgid>0). . The signal is sent to a process group if there are still watched subprocesses belonging to the group, and if either the kill_flag of any of the subprocesses process was set to true, or override is true.

Never throws an exception if the signal handler is installed.

val install_subprocess_handler : unit -> unit

Installs a SIGCHLD handler for watching subprocesses. Note that only processes are waited for that are registered with watch_subprocess.

The handler works both in the single-threaded and the multi-threaded case. install_subprocess_handler can safely called several times. The handler is installed every time the function is called, but the required data structures are only initialized at the first call.

val register_subprocess_handler : unit -> unit

Uses the Netsys_signal framework to manage the installation of the SIGCHLD handler.

This is the preferred method of installing the SIGCHLD handler.

Further notes.

The subprocess handler and fork(): The subprocess handler uses pipes for notification, and because of this it is sensitive to unpredicted duplicates of the pipe descriptors. fork() duplicates these pipe descriptors. If nothing is done about this issue, it can happen that the notification does not work anymore as it relies on detecting closed pipes.

If fork() is immediately followed by exec() (as it is done to run subcommands), the problem does not occur, because the relevant descriptors are closed at exec() time.

If fork() is used to start worker processes, however, we have to be careful. The descriptors need to be closed, so that the parent can continue to monitor subprocesses, and to allow the worker processes to use this mechanism. This module defines post fork handlers (see above), and a handler is automatically added that cleans the descriptors up. All user code has to do is to call run_post_fork_handlers immediately after fork() has spawned the new child, from the new child. This completely resets everything.

The subprocess handler and multi-threading: The handler has been carefully designed, and works even in multi-threaded programs. However, one should know that multi-threading and fork() do not interact well with each other. Again, the problems do not occur if fork() is followed by exec(). There is no solution for the case that worker processes are started with fork(), though. The (very generic) problem is that the state of mutexes and other multi-threading primitives is not well-defined after a fork().

Syslog

type level = Netlog.level

The log levels

type syslog_facility = [ `Authpriv
       | `Cron
       | `Daemon
       | `Default
       | `Ftp
       | `Kern
       | `Local0
       | `Local1
       | `Local2
       | `Local3
       | `Local4
       | `Local5
       | `Local6
       | `Local7
       | `Lpr
       | `Mail
       | `News
       | `Syslog
       | `User
       | `Uucp ]

The facilities. Only `User and `Local0 to `Local7 are standard POSIX. If a facility is unavailable it is silently substituted by `Local0. The value `Default leaves this unspecified.

type syslog_option = [ `Cons | `Ndelay | `Nowait | `Odelay | `Pid ]

The syslog options:

`Cons: Fall back to console logging if syslog is unavailable
`Ndelay: Open the connection immediately
`Odelay: Open the connection at the first call syslog (default)
`Nowait: Do not wait until it is ensured that the message is sent
`Pid: Log the PID with every message

val openlog : string option ->
       syslog_option list -> syslog_facility -> unit

openlog ident options facility: Opens a log stream. ident is prepended to every message if given (usually the program name). The facility is the default facility for syslog calls.

val syslog : syslog_facility -> level -> string -> unit

syslog facility level message: Logs message at level for facility

val closelog : unit -> unit

Closes the log stream

Usually, the log stream is redirected to syslog by either:

setting Netlog.current_logger to syslog facility, e.g.

 Netlog.current_logger := Netsys_posix.syslog `User

using the Netplex class for sending message to syslog (XXX)

Sync

val fsync : Unix.file_descr -> unit

Sync data and metadata to disk

val fdatasync : Unix.file_descr -> unit

Syncs only data to disk. If this is not implemented, same effect as fsync

Optional POSIX functions

val have_fadvise : unit -> bool

Returns whether the OS supports the fadvise POSIX option

type advice =

`\|`	`POSIX_FADV_NORMAL`
`\|`	`POSIX_FADV_SEQUENTIAL`
`\|`	`POSIX_FADV_RANDOM`
`\|`	`POSIX_FADV_NOREUSE`
`\|`	`POSIX_FADV_WILLNEED`
`\|`	`POSIX_FADV_DONTNEED`
`\|`	`FADV_NORMAL`
`\|`	`FADV_SEQUENTIAL`
`\|`	`FADV_RANDOM`
`\|`	`FADV_NOREUSE`
`\|`	`FADV_WILLNEED`
`\|`	`FADV_DONTNEED`	`(*`	Possible advices for fadvise. The names starting with "POSIX_" and the ones lacking the prefix have the same meaning. In new code, the names starting with "POSIX_" should be preferred (for better compaibility with other libraries).	`*)`

val fadvise : Unix.file_descr -> int64 -> int64 -> advice -> unit

Advises to load pages into the page table from the file, or to remove such pages.

val have_fallocate : unit -> bool

Returns whether the OS supports the fallocate POSIX option

val fallocate : Unix.file_descr -> int64 -> int64 -> unit

Allocate space for the file and the specified file region

POSIX Shared Memory

val have_posix_shm : unit -> bool

Returns whether the OS supports POSIX shared memory

type shm_open_flag =

`\|`	`SHM_O_RDONLY`
`\|`	`SHM_O_RDWR`
`\|`	`SHM_O_CREAT`
`\|`	`SHM_O_EXCL`
`\|`	`SHM_O_TRUNC`

val shm_open : string -> shm_open_flag list -> int -> Unix.file_descr

Opens a shared memory object. The first arg is the name of the object. The name must begin with a slash, but there must be no further slash in it (e.g. "/sample"). The second arg are the open flags. The third arg are the permission bits.

The open flags are interpreted as follows:

SHM_O_RDONLY: Open the object for read access
SHM_O_RDWR: Open the object for read-write access
SHM_O_CREAT: Create the object if it does not exist
SHM_O_EXCL: If SHM_O_CREAT was also specified, and a an object with the given name already exists, return an error (Unix.EEXIST).
SHM_O_TRUNC: If the object already exists, truncate it to zero bytes

One of SHM_O_RDONLY or SHM_O_RDWR must be given.

On success, the function returns a file descriptor representing the object. To access the object, one has to memory-map this file use one of the map_file functions in the Bigarray module, or in Netsys_mem). Use Unix.ftruncate to resize the object.

Note that it is unspecified whether this file pops up somewhere in the file system, and if so, where.

If a system error occurs, the function raises a Unix.Unix_error exception.

val shm_unlink : string -> unit

Unlinks the name for a shared memory object

val shm_create : string -> int -> Unix.file_descr * string

let (fd,name) = shm_create prefix size: Creates an shm object with a unique name. The name has the passed prefix. The prefix must start with "/" but must not contain any further "/". The object has a length of size bytes. The object has a permissions 0o600 (independent of umask).

POSIX semaphores

val have_posix_semaphores : unit -> bool

Returns true if POSIX semaphores are supported on this system

Constants.

val sem_value_max : int

The maximum value of a semaphore, but at most max_int

val sem_size : int

The size of an anonymous semaphore in bytes (sizeof(sem_t))

Types.

type sem_kind = [ `Anonymous | `Named ]

type 'a semaphore

type named_semaphore = [ `Named ] semaphore

type anon_sempahore = [ `Anonymous ] semaphore

type sem_open_flag =

`\|`	`SEM_O_CREAT`
`\|`	`SEM_O_EXCL`

Named semaphores.

val sem_open : string ->
       sem_open_flag list -> int -> int -> named_semaphore

sem_open name flags mode init_value: Opens a named semaphore which is optionally created. Sempahore names usually begin with a slash followed by a single name component (not containing a further slash).

Interpretation of flags:

SEM_O_CREAT: The semaphore is created if not yet existing. The mode and init_value are interpreted if the creation actually occurs. mode is the permission of the semaphore. init_value is the (non-negative) initial value, up to sem_value_max.
SEM_O_EXCL: The semaphore is only opened if the semaphore does not exist yet. Othwerwise an EEXIST error is returned

val sem_close : named_semaphore -> unit

Closes a named semaphore. Semaphores are also automatically closed when the GC finds that the semaphore is unreachable.

val sem_unlink : string -> unit

Unlinks the semaphore name

val sem_create : string -> int -> named_semaphore * string

let (sem,name) = sem_create prefix init_value: Creates a new semaphore with a unique name. The name has the passed prefix. The prefix must start with "/" but must not contain any further "/". The semaphore is initialized with init_value. The object has permissions 0o600 (modulo umask).

Anonymous semaphores.

val sem_init : Netsys_types.memory -> int -> bool -> int -> anon_sempahore

sem_init mem pos pshared init_value: Initializes the memory at position pos to pos + sem_size() - 1 as anonymous semaphore. If pshared the semaphore is shared between processes. init_value is the initial non-negative value (max is sem_value_max.

val sem_destroy : anon_sempahore -> unit

Destroys the anonymous semaphore

val as_sem : Netsys_types.memory -> int -> anon_sempahore

as_sem mem pos: Interprets the memory at position pos to pos + sem_size() - 1 as anonymous semaphore. The memory region must already have been initialized.

Operations.

val sem_getvalue : 'a semaphore -> int

Returns the value of the semaphore. If the value is bigger than what can be represented as int, an EINVAL error is returned.

The returned value is non-negative - if the underlying POSIX function reports a negative value zero is returned instead.

val sem_post : 'a semaphore -> unit

Unlocks the semaphore (increases the value by 1)

type sem_wait_behavior =

`\|`	`SEM_WAIT_BLOCK`
`\|`	`SEM_WAIT_NONBLOCK`

val sem_wait : 'a semaphore -> sem_wait_behavior -> unit

Locks the semaphore (decreases the value by 1). If the semaphore value is already zero, and SEM_WAIT_BLOCK is given, the function waits until another process or thread posts. If SEM_WAIT_NONBLOCK the error EAGAIN is returned.

sem_wait may be interrupted by signals.

Locales

type langinfo = {

`nl_CODESET : string;`	`(*`	from `LC_CTYPE`: codeset name	`*)`
`nl_D_T_FMT : string;`	`(*`	from `LC_TIME`: string for formatting date and time	`*)`
`nl_D_FMT : string;`	`(*`	from `LC_TIME`: date format string	`*)`
`nl_T_FMT : string;`	`(*`	from `LC_TIME`: time format string	`*)`
`nl_T_FMT_AMPM : string;`	`(*`	from `LC_TIME`: a.m. or p.m. time format string	`*)`
`nl_AM_STR : string;`	`(*`	from `LC_TIME`: Ante Meridian affix	`*)`
`nl_PM_STR : string;`	`(*`	from `LC_TIME`: Post Meridian affix	`*)`
`nl_DAY_1 : string;`	`(*`	from `LC_TIME`: name of the first day of the week (for example, Sunday)	`*)`
`nl_DAY_2 : string;`	`(*`	from `LC_TIME`: name of the second day of the week (for example, Monday)	`*)`
`nl_DAY_3 : string;`	`(*`	from `LC_TIME`: name of the third day of the week (for example, Tuesday)	`*)`
`nl_DAY_4 : string;`	`(*`	from `LC_TIME`: name of the fourth day of the week (for example, Wednesday)	`*)`
`nl_DAY_5 : string;`	`(*`	from `LC_TIME`: name of the fifth day of the week (for example, Thursday)	`*)`
`nl_DAY_6 : string;`	`(*`	from `LC_TIME`: name of the sixth day of the week (for example, Friday)	`*)`
`nl_DAY_7 : string;`	`(*`	from `LC_TIME`: name of the seventh day of the week (for example, Saturday)	`*)`
`nl_ABDAY_1 : string;`	`(*`	from `LC_TIME`: abbreviated name of the first day of the week	`*)`
`nl_ABDAY_2 : string;`	`(*`	from `LC_TIME`: abbreviated name of the second day of the week	`*)`
`nl_ABDAY_3 : string;`	`(*`	from `LC_TIME`: abbreviated name of the third day of the week	`*)`
`nl_ABDAY_4 : string;`	`(*`	from `LC_TIME`: abbreviated name of the fourth day of the week	`*)`
`nl_ABDAY_5 : string;`	`(*`	from `LC_TIME`: abbreviated name of the fifth day of the week	`*)`
`nl_ABDAY_6 : string;`	`(*`	from `LC_TIME`: abbreviated name of the sixth day of the week	`*)`
`nl_ABDAY_7 : string;`	`(*`	from `LC_TIME`: abbreviated name of the seventh day of the week	`*)`
`nl_MON_1 : string;`	`(*`	from `LC_TIME`: name of the first month of the year	`*)`
`nl_MON_2 : string;`	`(*`	from `LC_TIME`: name of the second month	`*)`
`nl_MON_3 : string;`	`(*`	from `LC_TIME`: name of the third month	`*)`
`nl_MON_4 : string;`	`(*`	from `LC_TIME`: name of the fourth month	`*)`
`nl_MON_5 : string;`	`(*`	from `LC_TIME`: name of the fifth month	`*)`
`nl_MON_6 : string;`	`(*`	from `LC_TIME`: name of the sixth month	`*)`
`nl_MON_7 : string;`	`(*`	from `LC_TIME`: name of the seventh month	`*)`
`nl_MON_8 : string;`	`(*`	from `LC_TIME`: name of the eighth month	`*)`
`nl_MON_9 : string;`	`(*`	from `LC_TIME`: name of the ninth month	`*)`
`nl_MON_10 : string;`	`(*`	from `LC_TIME`: name of the tenth month	`*)`
`nl_MON_11 : string;`	`(*`	from `LC_TIME`: name of the eleventh month	`*)`
`nl_MON_12 : string;`	`(*`	from `LC_TIME`: name of the twelfth month	`*)`
`nl_ABMON_1 : string;`	`(*`	from `LC_TIME`: abbreviated name of the first month	`*)`
`nl_ABMON_2 : string;`	`(*`	from `LC_TIME`: abbreviated name of the second month	`*)`
`nl_ABMON_3 : string;`	`(*`	from `LC_TIME`: abbreviated name of the third month	`*)`
`nl_ABMON_4 : string;`	`(*`	from `LC_TIME`: abbreviated name of the fourth month	`*)`
`nl_ABMON_5 : string;`	`(*`	from `LC_TIME`: abbreviated name of the fifth month	`*)`
`nl_ABMON_6 : string;`	`(*`	from `LC_TIME`: abbreviated name of the sixth month	`*)`
`nl_ABMON_7 : string;`	`(*`	from `LC_TIME`: abbreviated name of the seventh month	`*)`
`nl_ABMON_8 : string;`	`(*`	from `LC_TIME`: abbreviated name of the eighth month	`*)`
`nl_ABMON_9 : string;`	`(*`	from `LC_TIME`: abbreviated name of the ninth month	`*)`
`nl_ABMON_10 : string;`	`(*`	from `LC_TIME`: abbreviated name of the tenth month	`*)`
`nl_ABMON_11 : string;`	`(*`	from `LC_TIME`: abbreviated name of the eleventh month	`*)`
`nl_ABMON_12 : string;`	`(*`	from `LC_TIME`: abbreviated name of the twelfth month	`*)`
`nl_ERA : string;`	`(*`	from `LC_TIME`: era description segments	`*)`
`nl_ERA_D_FMT : string;`	`(*`	from `LC_TIME`: era date format string	`*)`
`nl_ERA_D_T_FMT : string;`	`(*`	from `LC_TIME`: era date and time format string	`*)`
`nl_ERA_T_FMT : string;`	`(*`	from `LC_TIME`: era time format string	`*)`
`nl_ALT_DIGITS : string;`	`(*`	from `LC_TIME`: alternative symbols for digits	`*)`
`nl_RADIXCHAR : string;`	`(*`	from `LC_NUMERIC`: radix character	`*)`
`nl_THOUSEP : string;`	`(*`	from `LC_NUMERIC`: separator for thousands	`*)`
`nl_YESEXPR : string;`	`(*`	from `LC_MESSAGES`: affirmative response expression	`*)`
`nl_NOEXPR : string;`	`(*`	from `LC_MESSAGES`: negative response expression	`*)`
`nl_CRNCYSTR : string;`	`(*`	from `LC_MONETARY`: currency	`*)`

}

val query_langinfo : string -> langinfo

query_langinfo locale: Temporarily sets the passed locale and determines the language attributes. After that the orignal locale is restored. Pass "" as locale to get the locale requested in the environment.

The value for "" is cached.

Linux I/O Priorities

These system calls are only available on Linux since kernel 2.6.13, and not even on every architecture. i386, x86_64, ia64, and PPC are known to work.

Per-process I/O priorities are currently only supported by the CFQ I/O scheduler.

val have_ioprio : unit -> bool

Returns true if the system call ioprio_get is supported

type ioprio_target =

`\|`	`Ioprio_process of int`	`(*`	A single process	`*)`
`\|`	`Ioprio_pgrp of int`	`(*`	A process group	`*)`
`\|`	`Ioprio_user of int`	`(*`	All processes owned by this user	`*)`

type ioprio =

`\|`	`Noprio`	`(*`	I/O prioritization is unsupported by block layer	`*)`
`\|`	`Real_time of int`	`(*`	0..7 (higest..lowest prio)	`*)`
`\|`	`Best_effort of int`	`(*`	0..7 (higest..lowest prio)	`*)`
`\|`	`Idle`

val ioprio_get : ioprio_target -> ioprio

Retrieve the priority of the target. If several processes match the target, the highest priority is returned. If no process matches, the unix error ESRCH will be raised.

val ioprio_set : ioprio_target -> ioprio -> unit

Sets the priority of the target processes.

Debugging

module Debug: sig .. end

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