Module Netsys

module Netsys: sig .. end

Some POSIX system calls missing in the Unix module

Helper functions

val restart : ('a -> 'b) -> 'a -> 'b

restart f arg calls f arg, and restarts this call if the exception Unix_error(EINTR,_,_) is caught.

Note that there are some cases where this handling of EINTR is not sufficient:

Functions that have a timeout argument like Unix.select: When EINTR is caught the timeout should be adjusted.
Unix.connect with a blocking descriptor because this is not well-enough specified by POSIX

val restarting_select : Unix.file_descr list ->
       Unix.file_descr list ->
       Unix.file_descr list ->
       float -> Unix.file_descr list * Unix.file_descr list * Unix.file_descr list

A wrapper around Unix.select that handles the EINTR condition

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

really_write fd s pos len: Writes exactly the len bytes from s to fd starting at pos. The conditions EINTR, EAGAIN and EWOULDBLOCK are handled.

val blocking_read : Unix.file_descr -> string -> int -> int -> int

let p = blocking_read fd s pos len: Reads exactly p bytes from fd and stores them in s starting at pos where p is the minimum of len and the number of bytes that are available on fd until the end of the file. If the function is called with len>0 but returns less than len this indicates end of file. The conditions EINTR, EAGAIN and EWOULDBLOCK are handled.

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

really_read fd s pos len: Reads exactly len bytes from fd and stores them in s starting at pos. If the end of file condition is seen before len bytes are read, the exception End_of_file is raised, and it is unspecified how many bytes have been stored in s. The conditions EINTR, EAGAIN and EWOULDBLOCK are handled.

val domain_of_inet_addr : Unix.inet_addr -> Unix.socket_domain

Returns the socket domain of Internet addresses, i.e. whether the address is IPv4 or IPv6

Standard POSIX functions

val int_of_file_descr : Unix.file_descr -> int

Return the file descriptor as integer

val file_descr_of_int : int -> Unix.file_descr

Make a file descriptor from an integer

val _exit : int -> unit

Exit the program immediately without running the atexit handlers. The argument is the exit code, just as for exit.

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 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 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.

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 (in O'Caml use one of the map_file functions in the Bigarray module). 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

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