UnixLabels(3o) OCaml library UnixLabels(3o)
NAME
UnixLabels - Interface to the Unix system.
Module
Module UnixLabels
Documentation
Module UnixLabels
: sig end
Interface to the Unix system.
To use the labeled version of this module, add module Unix = UnixLabels
in your implementation.
Note: all the functions of this module (except UnixLabels.error_message
and UnixLabels.handle_unix_error ) are liable to raise the UnixLa-
bels.Unix_error exception whenever the underlying system call signals
an error.
Error report
type error = Unix.error =
| E2BIG (* Argument list too long
*)
| EACCES (* Permission denied
*)
| EAGAIN (* Resource temporarily unavailable; try again
*)
| EBADF (* Bad file descriptor
*)
| EBUSY (* Resource unavailable
*)
| ECHILD (* No child process
*)
| EDEADLK (* Resource deadlock would occur
*)
| EDOM (* Domain error for math functions, etc.
*)
| EEXIST (* File exists
*)
| EFAULT (* Bad address
*)
| EFBIG (* File too large
*)
| EINTR (* Function interrupted by signal
*)
| EINVAL (* Invalid argument
*)
| EIO (* Hardware I/O error
*)
| EISDIR (* Is a directory
*)
| EMFILE (* Too many open files by the process
*)
| EMLINK (* Too many links
*)
| ENAMETOOLONG (* Filename too long
*)
| ENFILE (* Too many open files in the system
*)
| ENODEV (* No such device
*)
| ENOENT (* No such file or directory
*)
| ENOEXEC (* Not an executable file
*)
| ENOLCK (* No locks available
*)
| ENOMEM (* Not enough memory
*)
| ENOSPC (* No space left on device
*)
| ENOSYS (* Function not supported
*)
| ENOTDIR (* Not a directory
*)
| ENOTEMPTY (* Directory not empty
*)
| ENOTTY (* Inappropriate I/O control operation
*)
| ENXIO (* No such device or address
*)
| EPERM (* Operation not permitted
*)
| EPIPE (* Broken pipe
*)
| ERANGE (* Result too large
*)
| EROFS (* Read-only file system
*)
| ESPIPE (* Invalid seek e.g. on a pipe
*)
| ESRCH (* No such process
*)
| EXDEV (* Invalid link
*)
| EWOULDBLOCK (* Operation would block
*)
| EINPROGRESS (* Operation now in progress
*)
| EALREADY (* Operation already in progress
*)
| ENOTSOCK (* Socket operation on non-socket
*)
| EDESTADDRREQ (* Destination address required
*)
| EMSGSIZE (* Message too long
*)
| EPROTOTYPE (* Protocol wrong type for socket
*)
| ENOPROTOOPT (* Protocol not available
*)
| EPROTONOSUPPORT (* Protocol not supported
*)
| ESOCKTNOSUPPORT (* Socket type not supported
*)
| EOPNOTSUPP (* Operation not supported on socket
*)
| EPFNOSUPPORT (* Protocol family not supported
*)
| EAFNOSUPPORT (* Address family not supported by protocol family
*)
| EADDRINUSE (* Address already in use
*)
| EADDRNOTAVAIL (* Can't assign requested address
*)
| ENETDOWN (* Network is down
*)
| ENETUNREACH (* Network is unreachable
*)
| ENETRESET (* Network dropped connection on reset
*)
| ECONNABORTED (* Software caused connection abort
*)
| ECONNRESET (* Connection reset by peer
*)
| ENOBUFS (* No buffer space available
*)
| EISCONN (* Socket is already connected
*)
| ENOTCONN (* Socket is not connected
*)
| ESHUTDOWN (* Can't send after socket shutdown
*)
| ETOOMANYREFS (* Too many references: can't splice
*)
| ETIMEDOUT (* Connection timed out
*)
| ECONNREFUSED (* Connection refused
*)
| EHOSTDOWN (* Host is down
*)
| EHOSTUNREACH (* No route to host
*)
| ELOOP (* Too many levels of symbolic links
*)
| EOVERFLOW (* File size or position not representable
*)
| EUNKNOWNERR of int
(* Unknown error
*)
The type of error codes. Errors defined in the POSIX standard and ad-
ditional errors from UNIX98 and BSD. All other errors are mapped to
EUNKNOWNERR.
exception Unix_error of error * string * string
Raised by the system calls below when an error is encountered. The
first component is the error code; the second component is the function
name; the third component is the string parameter to the function, if
it has one, or the empty string otherwise.
UnixLabels.Unix_error and Unix.Unix_error are the same, and catching
one will catch the other.
val error_message : error -> string
Return a string describing the given error code.
val handle_unix_error : ('a -> 'b) -> 'a -> 'b
handle_unix_error f x applies f to x and returns the result. If the
exception UnixLabels.Unix_error is raised, it prints a message describ-
ing the error and exits with code 2.
Access to the process environment
val environment : unit -> string array
Return the process environment, as an array of strings with the format
``variable=value''. The returned array is empty if the process has
special privileges.
val unsafe_environment : unit -> string array
Return the process environment, as an array of strings with the format
``variable=value''. Unlike UnixLabels.environment , this function re-
turns a populated array even if the process has special privileges.
See the documentation for UnixLabels.unsafe_getenv for more details.
Since 4.12.0
val getenv : string -> string
Return the value associated to a variable in the process environment,
unless the process has special privileges.
Raises Not_found if the variable is unbound or the process has special
privileges.
This function is identical to Sys.getenv .
val unsafe_getenv : string -> string
Return the value associated to a variable in the process environment.
Unlike UnixLabels.getenv , this function returns the value even if the
process has special privileges. It is considered unsafe because the
programmer of a setuid or setgid program must be careful to avoid using
maliciously crafted environment variables in the search path for exe-
cutables, the locations for temporary files or logs, and the like.
Since 4.06.0
Raises Not_found if the variable is unbound.
val putenv : string -> string -> unit
putenv name value sets the value associated to a variable in the
process environment. name is the name of the environment variable, and
value its new associated value.
Process handling
type process_status = Unix.process_status =
| WEXITED of int
(* The process terminated normally by exit ; the argument is the re-
turn code.
*)
| WSIGNALED of int
(* The process was killed by a signal; the argument is the signal
number.
*)
| WSTOPPED of int
(* The process was stopped by a signal; the argument is the signal
number.
*)
The termination status of a process. See module Sys for the defini-
tions of the standard signal numbers. Note that they are not the num-
bers used by the OS.
type wait_flag = Unix.wait_flag =
| WNOHANG (* Do not block if no child has died yet, but immediately
return with a pid equal to 0.
*)
| WUNTRACED (* Report also the children that receive stop signals.
*)
Flags for UnixLabels.waitpid .
val execv : prog:string -> args:string array -> 'a
execv ~prog ~args execute the program in file prog , with the arguments
args , and the current process environment. These execv* functions
never return: on success, the current program is replaced by the new
one.
Raises Unix_error on failure
val execve : prog:string -> args:string array -> env:string array -> 'a
Same as UnixLabels.execv , except that the third argument provides the
environment to the program executed.
val execvp : prog:string -> args:string array -> 'a
Same as UnixLabels.execv , except that the program is searched in the
path.
val execvpe : prog:string -> args:string array -> env:string array ->
'a
Same as UnixLabels.execve , except that the program is searched in the
path.
val fork : unit -> int
Fork a new process. The returned integer is 0 for the child process,
the pid of the child process for the parent process.
On Windows: not implemented, use UnixLabels.create_process or threads.
val wait : unit -> int * process_status
Wait until one of the children processes die, and return its pid and
termination status.
On Windows: not implemented, use UnixLabels.waitpid .
val waitpid : mode:wait_flag list -> int -> int * process_status
Same as UnixLabels.wait , but waits for the child process whose pid is
given. A pid of -1 means wait for any child. A pid of 0 means wait
for any child in the same process group as the current process. Nega-
tive pid arguments represent process groups. The list of options indi-
cates whether waitpid should return immediately without waiting, and
whether it should report stopped children.
On Windows: can only wait for a given PID, not any child process.
val system : string -> process_status
Execute the given command, wait until it terminates, and return its
termination status. The string is interpreted by the shell /bin/sh (or
the command interpreter cmd.exe on Windows) and therefore can contain
redirections, quotes, variables, etc. To properly quote whitespace and
shell special characters occurring in file names or command arguments,
the use of Filename.quote_command is recommended. The result WEXITED
127 indicates that the shell couldn't be executed.
val _exit : int -> 'a
Terminate the calling process immediately, returning the given status
code to the operating system: usually 0 to indicate no errors, and a
small positive integer to indicate failure. Unlike exit , Unix._exit
performs no finalization whatsoever: functions registered with at_exit
are not called, input/output channels are not flushed, and the C
run-time system is not finalized either.
The typical use of Unix._exit is after a Unix.fork operation, when the
child process runs into a fatal error and must exit. In this case, it
is preferable to not perform any finalization action in the child
process, as these actions could interfere with similar actions per-
formed by the parent process. For example, output channels should not
be flushed by the child process, as the parent process may flush them
again later, resulting in duplicate output.
Since 4.12.0
val getpid : unit -> int
Return the pid of the process.
val getppid : unit -> int
Return the pid of the parent process.
On Windows: not implemented (because it is meaningless).
val nice : int -> int
Change the process priority. The integer argument is added to the
``nice'' value. (Higher values of the ``nice'' value mean lower priori-
ties.) Return the new nice value.
On Windows: not implemented.
Basic file input/output
type file_descr = Unix.file_descr
The abstract type of file descriptors.
val stdin : file_descr
File descriptor for standard input.
val stdout : file_descr
File descriptor for standard output.
val stderr : file_descr
File descriptor for standard error.
type open_flag = Unix.open_flag =
| O_RDONLY (* Open for reading
*)
| O_WRONLY (* Open for writing
*)
| O_RDWR (* Open for reading and writing
*)
| O_NONBLOCK (* Open in non-blocking mode
*)
| O_APPEND (* Open for append
*)
| O_CREAT (* Create if nonexistent
*)
| O_TRUNC (* Truncate to 0 length if existing
*)
| O_EXCL (* Fail if existing
*)
| O_NOCTTY (* Don't make this dev a controlling tty
*)
| O_DSYNC (* Writes complete as `Synchronised I/O data integrity com-
pletion'
*)
| O_SYNC (* Writes complete as `Synchronised I/O file integrity com-
pletion'
*)
| O_RSYNC (* Reads complete as writes (depending on O_SYNC/O_DSYNC)
*)
| O_SHARE_DELETE (* Windows only: allow the file to be deleted while
still open
*)
| O_CLOEXEC (* Set the close-on-exec flag on the descriptor returned
by UnixLabels.openfile . See UnixLabels.set_close_on_exec for more in-
formation.
*)
| O_KEEPEXEC (* Clear the close-on-exec flag. This is currently the
default.
*)
The flags to UnixLabels.openfile .
type file_perm = int
The type of file access rights, e.g. 0o640 is read and write for user,
read for group, none for others
val openfile : string -> mode:open_flag list -> perm:file_perm ->
file_descr
Open the named file with the given flags. Third argument is the permis-
sions to give to the file if it is created (see UnixLabels.umask ). Re-
turn a file descriptor on the named file.
val close : file_descr -> unit
Close a file descriptor.
val fsync : file_descr -> unit
Flush file buffers to disk.
Since 4.12.0
val read : file_descr -> buf:bytes -> pos:int -> len:int -> int
read fd ~buf ~pos ~len reads len bytes from descriptor fd , storing
them in byte sequence buf , starting at position pos in buf . Return
the number of bytes actually read.
val write : file_descr -> buf:bytes -> pos:int -> len:int -> int
write fd ~buf ~pos ~len writes len bytes to descriptor fd , taking them
from byte sequence buf , starting at position pos in buff . Return the
number of bytes actually written. write repeats the writing operation
until all bytes have been written or an error occurs.
val single_write : file_descr -> buf:bytes -> pos:int -> len:int -> int
Same as UnixLabels.write , but attempts to write only once. Thus, if
an error occurs, single_write guarantees that no data has been written.
val write_substring : file_descr -> buf:string -> pos:int -> len:int ->
int
Same as UnixLabels.write , but take the data from a string instead of a
byte sequence.
Since 4.02.0
val single_write_substring : file_descr -> buf:string -> pos:int ->
len:int -> int
Same as UnixLabels.single_write , but take the data from a string in-
stead of a byte sequence.
Since 4.02.0
Interfacing with the standard input/output library
val in_channel_of_descr : file_descr -> in_channel
Create an input channel reading from the given descriptor. The channel
is initially in binary mode; use set_binary_mode_in ic false if text
mode is desired. Text mode is supported only if the descriptor refers
to a file or pipe, but is not supported if it refers to a socket.
On Windows: set_binary_mode_in always fails on channels created with
this function.
Beware that input channels are buffered, so more characters may have
been read from the descriptor than those accessed using channel func-
tions. Channels also keep a copy of the current position in the file.
Closing the channel ic returned by in_channel_of_descr fd using
close_in ic also closes the underlying descriptor fd . It is incorrect
to close both the channel ic and the descriptor fd .
If several channels are created on the same descriptor, one of the
channels must be closed, but not the others. Consider for example a
descriptor s connected to a socket and two channels ic = in_chan-
nel_of_descr s and oc = out_channel_of_descr s . The recommended clos-
ing protocol is to perform close_out oc , which flushes buffered output
to the socket then closes the socket. The ic channel must not be
closed and will be collected by the GC eventually.
val out_channel_of_descr : file_descr -> out_channel
Create an output channel writing on the given descriptor. The channel
is initially in binary mode; use set_binary_mode_out oc false if text
mode is desired. Text mode is supported only if the descriptor refers
to a file or pipe, but is not supported if it refers to a socket.
On Windows: set_binary_mode_out always fails on channels created with
this function.
Beware that output channels are buffered, so you may have to call flush
to ensure that all data has been sent to the descriptor. Channels also
keep a copy of the current position in the file.
Closing the channel oc returned by out_channel_of_descr fd using
close_out oc also closes the underlying descriptor fd . It is incor-
rect to close both the channel ic and the descriptor fd .
See Unix.in_channel_of_descr for a discussion of the closing protocol
when several channels are created on the same descriptor.
val descr_of_in_channel : in_channel -> file_descr
Return the descriptor corresponding to an input channel.
val descr_of_out_channel : out_channel -> file_descr
Return the descriptor corresponding to an output channel.
Seeking and truncating
type seek_command = Unix.seek_command =
| SEEK_SET (* indicates positions relative to the beginning of the
file
*)
| SEEK_CUR (* indicates positions relative to the current position
*)
| SEEK_END (* indicates positions relative to the end of the file
*)
Positioning modes for UnixLabels.lseek .
val lseek : file_descr -> int -> mode:seek_command -> int
Set the current position for a file descriptor, and return the result-
ing offset (from the beginning of the file).
val truncate : string -> len:int -> unit
Truncates the named file to the given size.
val ftruncate : file_descr -> len:int -> unit
Truncates the file corresponding to the given descriptor to the given
size.
File status
type file_kind = Unix.file_kind =
| S_REG (* Regular file
*)
| S_DIR (* Directory
*)
| S_CHR (* Character device
*)
| S_BLK (* Block device
*)
| S_LNK (* Symbolic link
*)
| S_FIFO (* Named pipe
*)
| S_SOCK (* Socket
*)
type stats = Unix.stats = {
st_dev : int ; (* Device number
*)
st_ino : int ; (* Inode number
*)
st_kind : file_kind ; (* Kind of the file
*)
st_perm : file_perm ; (* Access rights
*)
st_nlink : int ; (* Number of links
*)
st_uid : int ; (* User id of the owner
*)
st_gid : int ; (* Group ID of the file's group
*)
st_rdev : int ; (* Device ID (if special file)
*)
st_size : int ; (* Size in bytes
*)
st_atime : float ; (* Last access time
*)
st_mtime : float ; (* Last modification time
*)
st_ctime : float ; (* Last status change time
*)
}
The information returned by the UnixLabels.stat calls.
val stat : string -> stats
Return the information for the named file.
val lstat : string -> stats
Same as UnixLabels.stat , but in case the file is a symbolic link, re-
turn the information for the link itself.
val fstat : file_descr -> stats
Return the information for the file associated with the given descrip-
tor.
val isatty : file_descr -> bool
Return true if the given file descriptor refers to a terminal or con-
sole window, false otherwise.
File operations on large files
module LargeFile : sig end
File operations on large files. This sub-module provides 64-bit vari-
ants of the functions UnixLabels.LargeFile.lseek (for positioning a
file descriptor), UnixLabels.LargeFile.truncate and UnixLabels.Large-
File.ftruncate (for changing the size of a file), and UnixLabels.Large-
File.stat , UnixLabels.LargeFile.lstat and UnixLabels.LargeFile.fstat
(for obtaining information on files). These alternate functions repre-
sent positions and sizes by 64-bit integers (type int64 ) instead of
regular integers (type int ), thus allowing operating on files whose
sizes are greater than max_int .
Mapping files into memory
val map_file : file_descr -> ?pos:int64 -> kind:('a, 'b) Bigarray.kind
-> layout:'c Bigarray.layout -> shared:bool -> dims:int array -> ('a,
'b, 'c) Bigarray.Genarray.t
Memory mapping of a file as a Bigarray. map_file fd ~kind ~layout
~shared ~dims returns a Bigarray of kind kind , layout layout , and di-
mensions as specified in dims . The data contained in this Bigarray
are the contents of the file referred to by the file descriptor fd (as
opened previously with UnixLabels.openfile , for example). The op-
tional pos parameter is the byte offset in the file of the data being
mapped; it defaults to 0 (map from the beginning of the file).
If shared is true , all modifications performed on the array are re-
flected in the file. This requires that fd be opened with write per-
missions. If shared is false , modifications performed on the array
are done in memory only, using copy-on-write of the modified pages; the
underlying file is not affected.
Genarray.map_file is much more efficient than reading the whole file in
a Bigarray, modifying that Bigarray, and writing it afterwards.
To adjust automatically the dimensions of the Bigarray to the actual
size of the file, the major dimension (that is, the first dimension for
an array with C layout, and the last dimension for an array with For-
tran layout) can be given as -1 . Genarray.map_file then determines
the major dimension from the size of the file. The file must contain
an integral number of sub-arrays as determined by the non-major dimen-
sions, otherwise Failure is raised.
If all dimensions of the Bigarray are given, the file size is matched
against the size of the Bigarray. If the file is larger than the Bi-
garray, only the initial portion of the file is mapped to the Bigarray.
If the file is smaller than the big array, the file is automatically
grown to the size of the Bigarray. This requires write permissions on
fd .
Array accesses are bounds-checked, but the bounds are determined by the
initial call to map_file . Therefore, you should make sure no other
process modifies the mapped file while you're accessing it, or a SIGBUS
signal may be raised. This happens, for instance, if the file is
shrunk.
Invalid_argument or Failure may be raised in cases where argument vali-
dation fails.
Since 4.06.0
Operations on file names
val unlink : string -> unit
Removes the named file.
If the named file is a directory, raises:
- EPERM on POSIX compliant system
- EISDIR on Linux >= 2.1.132
- EACCESS on Windows
val rename : src:string -> dst:string -> unit
rename ~src ~dst changes the name of a file from src to dst , moving it
between directories if needed. If dst already exists, its contents
will be replaced with those of src . Depending on the operating sys-
tem, the metadata (permissions, owner, etc) of dst can either be pre-
served or be replaced by those of src .
val link : ?follow:bool -> src:string -> dst:string -> unit
link ?follow ~src ~dst creates a hard link named dst to the file named
src .
Raises ENOSYS On Unix if ~follow:_ is requested, but linkat is unavail-
able.
Raises ENOSYS On Windows if ~follow:false is requested.
val realpath : string -> string
realpath p is an absolute pathname for p obtained by resolving all ex-
tra / characters, relative path segments and symbolic links.
Since 4.13.0
File permissions and ownership
type access_permission = Unix.access_permission =
| R_OK (* Read permission
*)
| W_OK (* Write permission
*)
| X_OK (* Execution permission
*)
| F_OK (* File exists
*)
Flags for the UnixLabels.access call.
val chmod : string -> perm:file_perm -> unit
Change the permissions of the named file.
val fchmod : file_descr -> perm:file_perm -> unit
Change the permissions of an opened file.
On Windows: not implemented.
val chown : string -> uid:int -> gid:int -> unit
Change the owner uid and owner gid of the named file.
On Windows: not implemented.
val fchown : file_descr -> uid:int -> gid:int -> unit
Change the owner uid and owner gid of an opened file.
On Windows: not implemented.
val umask : int -> int
Set the process's file mode creation mask, and return the previous
mask.
On Windows: not implemented.
val access : string -> perm:access_permission list -> unit
Check that the process has the given permissions over the named file.
On Windows: execute permission X_OK cannot be tested, just tests for
read permission instead.
Raises Unix_error otherwise.
Operations on file descriptors
val dup : ?cloexec:bool -> file_descr -> file_descr
Return a new file descriptor referencing the same file as the given de-
scriptor. See UnixLabels.set_close_on_exec for documentation on the
cloexec optional argument.
val dup2 : ?cloexec:bool -> src:file_descr -> dst:file_descr -> unit
dup2 ~src ~dst duplicates src to dst , closing dst if already opened.
See UnixLabels.set_close_on_exec for documentation on the cloexec op-
tional argument.
val set_nonblock : file_descr -> unit
Set the ``non-blocking'' flag on the given descriptor. When the
non-blocking flag is set, reading on a descriptor on which there is
temporarily no data available raises the EAGAIN or EWOULDBLOCK error
instead of blocking; writing on a descriptor on which there is tempo-
rarily no room for writing also raises EAGAIN or EWOULDBLOCK .
val clear_nonblock : file_descr -> unit
Clear the ``non-blocking'' flag on the given descriptor. See UnixLa-
bels.set_nonblock .
val set_close_on_exec : file_descr -> unit
Set the ``close-on-exec'' flag on the given descriptor. A descriptor
with the close-on-exec flag is automatically closed when the current
process starts another program with one of the exec , create_process
and open_process functions.
It is often a security hole to leak file descriptors opened on, say, a
private file to an external program: the program, then, gets access to
the private file and can do bad things with it. Hence, it is highly
recommended to set all file descriptors ``close-on-exec'', except in
the very few cases where a file descriptor actually needs to be trans-
mitted to another program.
The best way to set a file descriptor ``close-on-exec'' is to create it
in this state. To this end, the openfile function has O_CLOEXEC and
O_KEEPEXEC flags to enforce ``close-on-exec'' mode or ``keep-on-exec''
mode, respectively. All other operations in the Unix module that cre-
ate file descriptors have an optional argument ?cloexec:bool to indi-
cate whether the file descriptor should be created in ``close-on-exec''
mode (by writing ~cloexec:true ) or in ``keep-on-exec'' mode (by writ-
ing ~cloexec:false ). For historical reasons, the default file de-
scriptor creation mode is ``keep-on-exec'', if no cloexec optional ar-
gument is given. This is not a safe default, hence it is highly recom-
mended to pass explicit cloexec arguments to operations that create
file descriptors.
The cloexec optional arguments and the O_KEEPEXEC flag were introduced
in OCaml 4.05. Earlier, the common practice was to create file de-
scriptors in the default, ``keep-on-exec'' mode, then call
set_close_on_exec on those freshly-created file descriptors. This is
not as safe as creating the file descriptor in ``close-on-exec'' mode
because, in multithreaded programs, a window of vulnerability exists
between the time when the file descriptor is created and the time
set_close_on_exec completes. If another thread spawns another program
during this window, the descriptor will leak, as it is still in the
``keep-on-exec'' mode.
Regarding the atomicity guarantees given by ~cloexec:true or by the use
of the O_CLOEXEC flag: on all platforms it is guaranteed that a concur-
rently-executing Caml thread cannot leak the descriptor by starting a
new process. On Linux, this guarantee extends to concurrently-execut-
ing C threads. As of Feb 2017, other operating systems lack the neces-
sary system calls and still expose a window of vulnerability during
which a C thread can see the newly-created file descriptor in
``keep-on-exec'' mode.
val clear_close_on_exec : file_descr -> unit
Clear the ``close-on-exec'' flag on the given descriptor. See UnixLa-
bels.set_close_on_exec .
Directories
val mkdir : string -> perm:file_perm -> unit
Create a directory with the given permissions (see UnixLabels.umask ).
val rmdir : string -> unit
Remove an empty directory.
val chdir : string -> unit
Change the process working directory.
val getcwd : unit -> string
Return the name of the current working directory.
val chroot : string -> unit
Change the process root directory.
On Windows: not implemented.
type dir_handle = Unix.dir_handle
The type of descriptors over opened directories.
val opendir : string -> dir_handle
Open a descriptor on a directory
val readdir : dir_handle -> string
Return the next entry in a directory.
Raises End_of_file when the end of the directory has been reached.
val rewinddir : dir_handle -> unit
Reposition the descriptor to the beginning of the directory
val closedir : dir_handle -> unit
Close a directory descriptor.
Pipes and redirections
val pipe : ?cloexec:bool -> unit -> file_descr * file_descr
Create a pipe. The first component of the result is opened for reading,
that's the exit to the pipe. The second component is opened for writ-
ing, that's the entrance to the pipe. See UnixLabels.set_close_on_exec
for documentation on the cloexec optional argument.
val mkfifo : string -> perm:file_perm -> unit
Create a named pipe with the given permissions (see UnixLabels.umask ).
On Windows: not implemented.
High-level process and redirection management
val create_process : prog:string -> args:string array -> stdin:file_de-
scr -> stdout:file_descr -> stderr:file_descr -> int
create_process ~prog ~args ~stdin ~stdout ~stderr forks a new process
that executes the program in file prog , with arguments args . The pid
of the new process is returned immediately; the new process executes
concurrently with the current process. The standard input and outputs
of the new process are connected to the descriptors stdin , stdout and
stderr . Passing e.g. Stdlib.stdout for stdout prevents the redirect-
ion and causes the new process to have the same standard output as the
current process. The executable file prog is searched in the path.
The new process has the same environment as the current process.
val create_process_env : prog:string -> args:string array -> env:string
array -> stdin:file_descr -> stdout:file_descr -> stderr:file_descr ->
int
create_process_env ~prog ~args ~env ~stdin ~stdout ~stderr works as
UnixLabels.create_process , except that the extra argument env speci-
fies the environment passed to the program.
val open_process_in : string -> in_channel
High-level pipe and process management. This function runs the given
command in parallel with the program. The standard output of the com-
mand is redirected to a pipe, which can be read via the returned input
channel. The command is interpreted by the shell /bin/sh (or cmd.exe
on Windows), cf. UnixLabels.system . The Filename.quote_command func-
tion can be used to quote the command and its arguments as appropriate
for the shell being used. If the command does not need to be run
through the shell, UnixLabels.open_process_args_in can be used as a
more robust and more efficient alternative to UnixLa-
bels.open_process_in .
val open_process_out : string -> out_channel
Same as UnixLabels.open_process_in , but redirect the standard input of
the command to a pipe. Data written to the returned output channel is
sent to the standard input of the command. Warning: writes on output
channels are buffered, hence be careful to call flush at the right
times to ensure correct synchronization. If the command does not need
to be run through the shell, UnixLabels.open_process_args_out can be
used instead of UnixLabels.open_process_out .
val open_process : string -> in_channel * out_channel
Same as UnixLabels.open_process_out , but redirects both the standard
input and standard output of the command to pipes connected to the two
returned channels. The input channel is connected to the output of the
command, and the output channel to the input of the command. If the
command does not need to be run through the shell, UnixLa-
bels.open_process_args can be used instead of UnixLabels.open_process .
val open_process_full : string -> env:string array -> in_channel *
out_channel * in_channel
Similar to UnixLabels.open_process , but the second argument specifies
the environment passed to the command. The result is a triple of chan-
nels connected respectively to the standard output, standard input, and
standard error of the command. If the command does not need to be run
through the shell, UnixLabels.open_process_args_full can be used in-
stead of UnixLabels.open_process_full .
val open_process_args_in : string -> string array -> in_channel
open_process_args_in prog args runs the program prog with arguments
args . The new process executes concurrently with the current process.
The standard output of the new process is redirected to a pipe, which
can be read via the returned input channel.
The executable file prog is searched in the path. This behaviour
changed in 4.12; previously prog was looked up only in the current di-
rectory.
The new process has the same environment as the current process.
Since 4.08.0
val open_process_args_out : string -> string array -> out_channel
Same as UnixLabels.open_process_args_in , but redirect the standard in-
put of the new process to a pipe. Data written to the returned output
channel is sent to the standard input of the program. Warning: writes
on output channels are buffered, hence be careful to call flush at the
right times to ensure correct synchronization.
Since 4.08.0
val open_process_args : string -> string array -> in_channel *
out_channel
Same as UnixLabels.open_process_args_out , but redirects both the stan-
dard input and standard output of the new process to pipes connected to
the two returned channels. The input channel is connected to the out-
put of the program, and the output channel to the input of the program.
Since 4.08.0
val open_process_args_full : string -> string array -> string array ->
in_channel * out_channel * in_channel
Similar to UnixLabels.open_process_args , but the third argument speci-
fies the environment passed to the new process. The result is a triple
of channels connected respectively to the standard output, standard in-
put, and standard error of the program.
Since 4.08.0
val process_in_pid : in_channel -> int
Return the pid of a process opened via UnixLabels.open_process_in or
UnixLabels.open_process_args_in .
Since 4.12.0
val process_out_pid : out_channel -> int
Return the pid of a process opened via UnixLabels.open_process_out or
UnixLabels.open_process_args_out .
Since 4.12.0
val process_pid : in_channel * out_channel -> int
Return the pid of a process opened via UnixLabels.open_process or
UnixLabels.open_process_args .
Since 4.12.0
val process_full_pid : in_channel * out_channel * in_channel -> int
Return the pid of a process opened via UnixLabels.open_process_full or
UnixLabels.open_process_args_full .
Since 4.12.0
val close_process_in : in_channel -> process_status
Close channels opened by UnixLabels.open_process_in , wait for the as-
sociated command to terminate, and return its termination status.
val close_process_out : out_channel -> process_status
Close channels opened by UnixLabels.open_process_out , wait for the as-
sociated command to terminate, and return its termination status.
val close_process : in_channel * out_channel -> process_status
Close channels opened by UnixLabels.open_process , wait for the associ-
ated command to terminate, and return its termination status.
val close_process_full : in_channel * out_channel * in_channel ->
process_status
Close channels opened by UnixLabels.open_process_full , wait for the
associated command to terminate, and return its termination status.
Symbolic links
val symlink : ?to_dir:bool -> src:string -> dst:string -> unit
symlink ?to_dir ~src ~dst creates the file dst as a symbolic link to
the file src . On Windows, ~to_dir indicates if the symbolic link
points to a directory or a file; if omitted, symlink examines src using
stat and picks appropriately, if src does not exist then false is as-
sumed (for this reason, it is recommended that the ~to_dir parameter be
specified in new code). On Unix, ~to_dir is ignored.
Windows symbolic links are available in Windows Vista onwards. There
are some important differences between Windows symlinks and their POSIX
counterparts.
Windows symbolic links come in two flavours: directory and regular,
which designate whether the symbolic link points to a directory or a
file. The type must be correct - a directory symlink which actually
points to a file cannot be selected with chdir and a file symlink which
actually points to a directory cannot be read or written (note that
Cygwin's emulation layer ignores this distinction).
When symbolic links are created to existing targets, this distinction
doesn't matter and symlink will automatically create the correct kind
of symbolic link. The distinction matters when a symbolic link is cre-
ated to a non-existent target.
The other caveat is that by default symbolic links are a privileged op-
eration. Administrators will always need to be running elevated (or
with UAC disabled) and by default normal user accounts need to be
granted the SeCreateSymbolicLinkPrivilege via Local Security Policy
(secpol.msc) or via Active Directory.
UnixLabels.has_symlink can be used to check that a process is able to
create symbolic links.
val has_symlink : unit -> bool
Returns true if the user is able to create symbolic links. On Windows,
this indicates that the user not only has the SeCreateSymbolicLinkPriv-
ilege but is also running elevated, if necessary. On other platforms,
this is simply indicates that the symlink system call is available.
Since 4.03.0
val readlink : string -> string
Read the contents of a symbolic link.
Polling
val select : read:file_descr list -> write:file_descr list -> ex-
cept:file_descr list -> timeout:float -> file_descr list * file_descr
list * file_descr list
Wait until some input/output operations become possible on some chan-
nels. The three list arguments are, respectively, a set of descriptors
to check for reading (first argument), for writing (second argument),
or for exceptional conditions (third argument). The fourth argument is
the maximal timeout, in seconds; a negative fourth argument means no
timeout (unbounded wait). The result is composed of three sets of de-
scriptors: those ready for reading (first component), ready for writing
(second component), and over which an exceptional condition is pending
(third component).
Locking
type lock_command = Unix.lock_command =
| F_ULOCK (* Unlock a region
*)
| F_LOCK (* Lock a region for writing, and block if already locked
*)
| F_TLOCK (* Lock a region for writing, or fail if already locked
*)
| F_TEST (* Test a region for other process locks
*)
| F_RLOCK (* Lock a region for reading, and block if already locked
*)
| F_TRLOCK (* Lock a region for reading, or fail if already locked
*)
Commands for UnixLabels.lockf .
val lockf : file_descr -> mode:lock_command -> len:int -> unit
lockf fd ~mode ~len puts a lock on a region of the file opened as fd .
The region starts at the current read/write position for fd (as set by
UnixLabels.lseek ), and extends len bytes forward if len is positive,
len bytes backwards if len is negative, or to the end of the file if
len is zero. A write lock prevents any other process from acquiring a
read or write lock on the region. A read lock prevents any other
process from acquiring a write lock on the region, but lets other pro-
cesses acquire read locks on it.
The F_LOCK and F_TLOCK commands attempts to put a write lock on the
specified region. The F_RLOCK and F_TRLOCK commands attempts to put a
read lock on the specified region. If one or several locks put by an-
other process prevent the current process from acquiring the lock,
F_LOCK and F_RLOCK block until these locks are removed, while F_TLOCK
and F_TRLOCK fail immediately with an exception. The F_ULOCK removes
whatever locks the current process has on the specified region. Fi-
nally, the F_TEST command tests whether a write lock can be acquired on
the specified region, without actually putting a lock. It returns im-
mediately if successful, or fails otherwise.
What happens when a process tries to lock a region of a file that is
already locked by the same process depends on the OS. On POSIX-compli-
ant systems, the second lock operation succeeds and may "promote" the
older lock from read lock to write lock. On Windows, the second lock
operation will block or fail.
Signals
Note: installation of signal handlers is performed via the functions
Sys.signal and Sys.set_signal .
val kill : pid:int -> signal:int -> unit
kill ~pid ~signal sends signal number signal to the process with id pid
.
On Windows: only the Sys.sigkill signal is emulated.
type sigprocmask_command = Unix.sigprocmask_command =
| SIG_SETMASK
| SIG_BLOCK
| SIG_UNBLOCK
val sigprocmask : mode:sigprocmask_command -> int list -> int list
sigprocmask ~mode sigs changes the set of blocked signals. If mode is
SIG_SETMASK , blocked signals are set to those in the list sigs . If
mode is SIG_BLOCK , the signals in sigs are added to the set of blocked
signals. If mode is SIG_UNBLOCK , the signals in sigs are removed from
the set of blocked signals. sigprocmask returns the set of previously
blocked signals.
When the systhreads version of the Thread module is loaded, this func-
tion redirects to Thread.sigmask . I.e., sigprocmask only changes the
mask of the current thread.
On Windows: not implemented (no inter-process signals on Windows).
val sigpending : unit -> int list
Return the set of blocked signals that are currently pending.
On Windows: not implemented (no inter-process signals on Windows).
val sigsuspend : int list -> unit
sigsuspend sigs atomically sets the blocked signals to sigs and waits
for a non-ignored, non-blocked signal to be delivered. On return, the
blocked signals are reset to their initial value.
On Windows: not implemented (no inter-process signals on Windows).
val pause : unit -> unit
Wait until a non-ignored, non-blocked signal is delivered.
On Windows: not implemented (no inter-process signals on Windows).
Time functions
type process_times = Unix.process_times = {
tms_utime : float ; (* User time for the process
*)
tms_stime : float ; (* System time for the process
*)
tms_cutime : float ; (* User time for the children processes
*)
tms_cstime : float ; (* System time for the children processes
*)
}
The execution times (CPU times) of a process.
type tm = Unix.tm = {
tm_sec : int ; (* Seconds 0..60
*)
tm_min : int ; (* Minutes 0..59
*)
tm_hour : int ; (* Hours 0..23
*)
tm_mday : int ; (* Day of month 1..31
*)
tm_mon : int ; (* Month of year 0..11
*)
tm_year : int ; (* Year - 1900
*)
tm_wday : int ; (* Day of week (Sunday is 0)
*)
tm_yday : int ; (* Day of year 0..365
*)
tm_isdst : bool ; (* Daylight time savings in effect
*)
}
The type representing wallclock time and calendar date.
val time : unit -> float
Return the current time since 00:00:00 GMT, Jan. 1, 1970, in seconds.
val gettimeofday : unit -> float
Same as UnixLabels.time , but with resolution better than 1 second.
val gmtime : float -> tm
Convert a time in seconds, as returned by UnixLabels.time , into a date
and a time. Assumes UTC (Coordinated Universal Time), also known as
GMT. To perform the inverse conversion, set the TZ environment vari-
able to "UTC", use UnixLabels.mktime , and then restore the original
value of TZ.
val localtime : float -> tm
Convert a time in seconds, as returned by UnixLabels.time , into a date
and a time. Assumes the local time zone. The function performing the
inverse conversion is UnixLabels.mktime .
val mktime : tm -> float * tm
Convert a date and time, specified by the tm argument, into a time in
seconds, as returned by UnixLabels.time . The tm_isdst , tm_wday and
tm_yday fields of tm are ignored. Also return a normalized copy of the
given tm record, with the tm_wday , tm_yday , and tm_isdst fields re-
computed from the other fields, and the other fields normalized (so
that, e.g., 40 October is changed into 9 November). The tm argument is
interpreted in the local time zone.
val alarm : int -> int
Schedule a SIGALRM signal after the given number of seconds.
On Windows: not implemented.
val sleep : int -> unit
Stop execution for the given number of seconds.
val sleepf : float -> unit
Stop execution for the given number of seconds. Like sleep , but frac-
tions of seconds are supported.
Since 4.12.0
val times : unit -> process_times
Return the execution times of the process.
On Windows: partially implemented, will not report timings for child
processes.
val utimes : string -> access:float -> modif:float -> unit
Set the last access time (second arg) and last modification time (third
arg) for a file. Times are expressed in seconds from 00:00:00 GMT, Jan.
1, 1970. If both times are 0.0 , the access and last modification
times are both set to the current time.
type interval_timer = Unix.interval_timer =
| ITIMER_REAL (* decrements in real time, and sends the signal
SIGALRM when expired.
*)
| ITIMER_VIRTUAL (* decrements in process virtual time, and sends
SIGVTALRM when expired.
*)
| ITIMER_PROF (* (for profiling) decrements both when the process is
running and when the system is running on behalf of the process; it
sends SIGPROF when expired.
*)
The three kinds of interval timers.
type interval_timer_status = Unix.interval_timer_status = {
it_interval : float ; (* Period
*)
it_value : float ; (* Current value of the timer
*)
}
The type describing the status of an interval timer
val getitimer : interval_timer -> interval_timer_status
Return the current status of the given interval timer.
On Windows: not implemented.
val setitimer : interval_timer -> interval_timer_status -> inter-
val_timer_status
setitimer t s sets the interval timer t and returns its previous sta-
tus. The s argument is interpreted as follows: s.it_value , if nonzero,
is the time to the next timer expiration; s.it_interval , if nonzero,
specifies a value to be used in reloading it_value when the timer ex-
pires. Setting s.it_value to zero disables the timer. Setting
s.it_interval to zero causes the timer to be disabled after its next
expiration.
On Windows: not implemented.
User id, group id
val getuid : unit -> int
Return the user id of the user executing the process.
On Windows: always returns 1 .
val geteuid : unit -> int
Return the effective user id under which the process runs.
On Windows: always returns 1 .
val setuid : int -> unit
Set the real user id and effective user id for the process.
On Windows: not implemented.
val getgid : unit -> int
Return the group id of the user executing the process.
On Windows: always returns 1 .
val getegid : unit -> int
Return the effective group id under which the process runs.
On Windows: always returns 1 .
val setgid : int -> unit
Set the real group id and effective group id for the process.
On Windows: not implemented.
val getgroups : unit -> int array
Return the list of groups to which the user executing the process be-
longs.
On Windows: always returns [|1|] .
val setgroups : int array -> unit
setgroups groups sets the supplementary group IDs for the calling
process. Appropriate privileges are required.
On Windows: not implemented.
val initgroups : string -> int -> unit
initgroups user group initializes the group access list by reading the
group database /etc/group and using all groups of which user is a mem-
ber. The additional group group is also added to the list.
On Windows: not implemented.
type passwd_entry = Unix.passwd_entry = {
pw_name : string ;
pw_passwd : string ;
pw_uid : int ;
pw_gid : int ;
pw_gecos : string ;
pw_dir : string ;
pw_shell : string ;
}
Structure of entries in the passwd database.
type group_entry = Unix.group_entry = {
gr_name : string ;
gr_passwd : string ;
gr_gid : int ;
gr_mem : string array ;
}
Structure of entries in the groups database.
val getlogin : unit -> string
Return the login name of the user executing the process.
val getpwnam : string -> passwd_entry
Find an entry in passwd with the given name.
Raises Not_found if no such entry exists, or always on Windows.
val getgrnam : string -> group_entry
Find an entry in group with the given name.
Raises Not_found if no such entry exists, or always on Windows.
val getpwuid : int -> passwd_entry
Find an entry in passwd with the given user id.
Raises Not_found if no such entry exists, or always on Windows.
val getgrgid : int -> group_entry
Find an entry in group with the given group id.
Raises Not_found if no such entry exists, or always on Windows.
Internet addresses
type inet_addr = Unix.inet_addr
The abstract type of Internet addresses.
val inet_addr_of_string : string -> inet_addr
Conversion from the printable representation of an Internet address to
its internal representation. The argument string consists of 4 numbers
separated by periods ( XXX.YYY.ZZZ.TTT ) for IPv4 addresses, and up to
8 numbers separated by colons for IPv6 addresses.
Raises Failure when given a string that does not match these formats.
val string_of_inet_addr : inet_addr -> string
Return the printable representation of the given Internet address. See
UnixLabels.inet_addr_of_string for a description of the printable rep-
resentation.
val inet_addr_any : inet_addr
A special IPv4 address, for use only with bind , representing all the
Internet addresses that the host machine possesses.
val inet_addr_loopback : inet_addr
A special IPv4 address representing the host machine ( 127.0.0.1 ).
val inet6_addr_any : inet_addr
A special IPv6 address, for use only with bind , representing all the
Internet addresses that the host machine possesses.
val inet6_addr_loopback : inet_addr
A special IPv6 address representing the host machine ( ::1 ).
val is_inet6_addr : inet_addr -> bool
Whether the given inet_addr is an IPv6 address.
Since 4.12.0
Sockets
type socket_domain = Unix.socket_domain =
| PF_UNIX (* Unix domain
*)
| PF_INET (* Internet domain (IPv4)
*)
| PF_INET6 (* Internet domain (IPv6)
*)
The type of socket domains. Not all platforms support IPv6 sockets
(type PF_INET6 ).
On Windows: PF_UNIX not implemented.
type socket_type = Unix.socket_type =
| SOCK_STREAM (* Stream socket
*)
| SOCK_DGRAM (* Datagram socket
*)
| SOCK_RAW (* Raw socket
*)
| SOCK_SEQPACKET (* Sequenced packets socket
*)
The type of socket kinds, specifying the semantics of communications.
SOCK_SEQPACKET is included for completeness, but is rarely supported by
the OS, and needs system calls that are not available in this library.
type sockaddr = Unix.sockaddr =
| ADDR_UNIX of string
| ADDR_INET of inet_addr * int
The type of socket addresses. ADDR_UNIX name is a socket address in
the Unix domain; name is a file name in the file system.
ADDR_INET(addr,port) is a socket address in the Internet domain; addr
is the Internet address of the machine, and port is the port number.
val socket : ?cloexec:bool -> domain:socket_domain -> kind:socket_type
-> protocol:int -> file_descr
Create a new socket in the given domain, and with the given kind. The
third argument is the protocol type; 0 selects the default protocol for
that kind of sockets. See UnixLabels.set_close_on_exec for documenta-
tion on the cloexec optional argument.
val domain_of_sockaddr : sockaddr -> socket_domain
Return the socket domain adequate for the given socket address.
val socketpair : ?cloexec:bool -> domain:socket_domain ->
kind:socket_type -> protocol:int -> file_descr * file_descr
Create a pair of unnamed sockets, connected together. See UnixLa-
bels.set_close_on_exec for documentation on the cloexec optional argu-
ment.
val accept : ?cloexec:bool -> file_descr -> file_descr * sockaddr
Accept connections on the given socket. The returned descriptor is a
socket connected to the client; the returned address is the address of
the connecting client. See UnixLabels.set_close_on_exec for documenta-
tion on the cloexec optional argument.
val bind : file_descr -> addr:sockaddr -> unit
Bind a socket to an address.
val connect : file_descr -> addr:sockaddr -> unit
Connect a socket to an address.
val listen : file_descr -> max:int -> unit
Set up a socket for receiving connection requests. The integer argument
is the maximal number of pending requests.
type shutdown_command = Unix.shutdown_command =
| SHUTDOWN_RECEIVE (* Close for receiving
*)
| SHUTDOWN_SEND (* Close for sending
*)
| SHUTDOWN_ALL (* Close both
*)
The type of commands for shutdown .
val shutdown : file_descr -> mode:shutdown_command -> unit
Shutdown a socket connection. SHUTDOWN_SEND as second argument causes
reads on the other end of the connection to return an end-of-file con-
dition. SHUTDOWN_RECEIVE causes writes on the other end of the connec-
tion to return a closed pipe condition ( SIGPIPE signal).
val getsockname : file_descr -> sockaddr
Return the address of the given socket.
val getpeername : file_descr -> sockaddr
Return the address of the host connected to the given socket.
type msg_flag = Unix.msg_flag =
| MSG_OOB
| MSG_DONTROUTE
| MSG_PEEK
The flags for UnixLabels.recv , UnixLabels.recvfrom , UnixLabels.send
and UnixLabels.sendto .
val recv : file_descr -> buf:bytes -> pos:int -> len:int ->
mode:msg_flag list -> int
Receive data from a connected socket.
val recvfrom : file_descr -> buf:bytes -> pos:int -> len:int ->
mode:msg_flag list -> int * sockaddr
Receive data from an unconnected socket.
val send : file_descr -> buf:bytes -> pos:int -> len:int ->
mode:msg_flag list -> int
Send data over a connected socket.
val send_substring : file_descr -> buf:string -> pos:int -> len:int ->
mode:msg_flag list -> int
Same as send , but take the data from a string instead of a byte se-
quence.
Since 4.02.0
val sendto : file_descr -> buf:bytes -> pos:int -> len:int ->
mode:msg_flag list -> addr:sockaddr -> int
Send data over an unconnected socket.
val sendto_substring : file_descr -> buf:string -> pos:int -> len:int
-> mode:msg_flag list -> sockaddr -> int
Same as sendto , but take the data from a string instead of a byte se-
quence.
Since 4.02.0
Socket options
type socket_bool_option = Unix.socket_bool_option =
| SO_DEBUG (* Record debugging information
*)
| SO_BROADCAST (* Permit sending of broadcast messages
*)
| SO_REUSEADDR (* Allow reuse of local addresses for bind
*)
| SO_KEEPALIVE (* Keep connection active
*)
| SO_DONTROUTE (* Bypass the standard routing algorithms
*)
| SO_OOBINLINE (* Leave out-of-band data in line
*)
| SO_ACCEPTCONN (* Report whether socket listening is enabled
*)
| TCP_NODELAY (* Control the Nagle algorithm for TCP sockets
*)
| IPV6_ONLY (* Forbid binding an IPv6 socket to an IPv4 address
*)
| SO_REUSEPORT (* Allow reuse of address and port bindings
*)
The socket options that can be consulted with UnixLabels.getsockopt and
modified with UnixLabels.setsockopt . These options have a boolean (
true / false ) value.
type socket_int_option = Unix.socket_int_option =
| SO_SNDBUF (* Size of send buffer
*)
| SO_RCVBUF (* Size of received buffer
*)
| SO_ERROR (* Deprecated. Use UnixLabels.getsockopt_error instead.
*)
| SO_TYPE (* Report the socket type
*)
| SO_RCVLOWAT (* Minimum number of bytes to process for input opera-
tions
*)
| SO_SNDLOWAT (* Minimum number of bytes to process for output opera-
tions
*)
The socket options that can be consulted with UnixLabels.getsockopt_int
and modified with UnixLabels.setsockopt_int . These options have an
integer value.
type socket_optint_option = Unix.socket_optint_option =
| SO_LINGER (* Whether to linger on closed connections that have data
present, and for how long (in seconds)
*)
The socket options that can be consulted with UnixLabels.getsock-
opt_optint and modified with UnixLabels.setsockopt_optint . These op-
tions have a value of type int option , with None meaning ``disabled''.
type socket_float_option = Unix.socket_float_option =
| SO_RCVTIMEO (* Timeout for input operations
*)
| SO_SNDTIMEO (* Timeout for output operations
*)
The socket options that can be consulted with UnixLabels.getsock-
opt_float and modified with UnixLabels.setsockopt_float . These op-
tions have a floating-point value representing a time in seconds. The
value 0 means infinite timeout.
val getsockopt : file_descr -> socket_bool_option -> bool
Return the current status of a boolean-valued option in the given
socket.
val setsockopt : file_descr -> socket_bool_option -> bool -> unit
Set or clear a boolean-valued option in the given socket.
val getsockopt_int : file_descr -> socket_int_option -> int
Same as UnixLabels.getsockopt for an integer-valued socket option.
val setsockopt_int : file_descr -> socket_int_option -> int -> unit
Same as UnixLabels.setsockopt for an integer-valued socket option.
val getsockopt_optint : file_descr -> socket_optint_option -> int op-
tion
Same as UnixLabels.getsockopt for a socket option whose value is an int
option .
val setsockopt_optint : file_descr -> socket_optint_option -> int op-
tion -> unit
Same as UnixLabels.setsockopt for a socket option whose value is an int
option .
val getsockopt_float : file_descr -> socket_float_option -> float
Same as UnixLabels.getsockopt for a socket option whose value is a
floating-point number.
val setsockopt_float : file_descr -> socket_float_option -> float ->
unit
Same as UnixLabels.setsockopt for a socket option whose value is a
floating-point number.
val getsockopt_error : file_descr -> error option
Return the error condition associated with the given socket, and clear
it.
High-level network connection functions
val open_connection : sockaddr -> in_channel * out_channel
Connect to a server at the given address. Return a pair of buffered
channels connected to the server. Remember to call flush on the output
channel at the right times to ensure correct synchronization.
The two channels returned by open_connection share a descriptor to a
socket. Therefore, when the connection is over, you should call
close_out on the output channel, which will also close the underlying
socket. Do not call close_in on the input channel; it will be col-
lected by the GC eventually.
val shutdown_connection : in_channel -> unit
``Shut down'' a connection established with UnixLabels.open_connection
; that is, transmit an end-of-file condition to the server reading on
the other side of the connection. This does not close the socket and
the channels used by the connection. See Unix.open_connection for how
to close them once the connection is over.
val establish_server : (in_channel -> out_channel -> unit) ->
addr:sockaddr -> unit
Establish a server on the given address. The function given as first
argument is called for each connection with two buffered channels con-
nected to the client. A new process is created for each connection. The
function UnixLabels.establish_server never returns normally.
The two channels given to the function share a descriptor to a socket.
The function does not need to close the channels, since this occurs au-
tomatically when the function returns. If the function prefers ex-
plicit closing, it should close the output channel using close_out and
leave the input channel unclosed, for reasons explained in
Unix.in_channel_of_descr .
On Windows: not implemented (use threads).
Host and protocol databases
type host_entry = Unix.host_entry = {
h_name : string ;
h_aliases : string array ;
h_addrtype : socket_domain ;
h_addr_list : inet_addr array ;
}
Structure of entries in the hosts database.
type protocol_entry = Unix.protocol_entry = {
p_name : string ;
p_aliases : string array ;
p_proto : int ;
}
Structure of entries in the protocols database.
type service_entry = Unix.service_entry = {
s_name : string ;
s_aliases : string array ;
s_port : int ;
s_proto : string ;
}
Structure of entries in the services database.
val gethostname : unit -> string
Return the name of the local host.
val gethostbyname : string -> host_entry
Find an entry in hosts with the given name.
Raises Not_found if no such entry exists.
val gethostbyaddr : inet_addr -> host_entry
Find an entry in hosts with the given address.
Raises Not_found if no such entry exists.
val getprotobyname : string -> protocol_entry
Find an entry in protocols with the given name.
Raises Not_found if no such entry exists.
val getprotobynumber : int -> protocol_entry
Find an entry in protocols with the given protocol number.
Raises Not_found if no such entry exists.
val getservbyname : string -> protocol:string -> service_entry
Find an entry in services with the given name.
Raises Not_found if no such entry exists.
val getservbyport : int -> protocol:string -> service_entry
Find an entry in services with the given service number.
Raises Not_found if no such entry exists.
type addr_info = Unix.addr_info = {
ai_family : socket_domain ; (* Socket domain
*)
ai_socktype : socket_type ; (* Socket type
*)
ai_protocol : int ; (* Socket protocol number
*)
ai_addr : sockaddr ; (* Address
*)
ai_canonname : string ; (* Canonical host name
*)
}
Address information returned by UnixLabels.getaddrinfo .
type getaddrinfo_option = Unix.getaddrinfo_option =
| AI_FAMILY of socket_domain
(* Impose the given socket domain
*)
| AI_SOCKTYPE of socket_type
(* Impose the given socket type
*)
| AI_PROTOCOL of int
(* Impose the given protocol
*)
| AI_NUMERICHOST (* Do not call name resolver, expect numeric IP ad-
dress
*)
| AI_CANONNAME (* Fill the ai_canonname field of the result
*)
| AI_PASSIVE (* Set address to ``any'' address for use with UnixLa-
bels.bind
*)
Options to UnixLabels.getaddrinfo .
val getaddrinfo : string -> string -> getaddrinfo_option list ->
addr_info list
getaddrinfo host service opts returns a list of UnixLabels.addr_info
records describing socket parameters and addresses suitable for commu-
nicating with the given host and service. The empty list is returned
if the host or service names are unknown, or the constraints expressed
in opts cannot be satisfied.
host is either a host name or the string representation of an IP ad-
dress. host can be given as the empty string; in this case, the
``any'' address or the ``loopback'' address are used, depending whether
opts contains AI_PASSIVE . service is either a service name or the
string representation of a port number. service can be given as the
empty string; in this case, the port field of the returned addresses is
set to 0. opts is a possibly empty list of options that allows the
caller to force a particular socket domain (e.g. IPv6 only or IPv4
only) or a particular socket type (e.g. TCP only or UDP only).
type name_info = Unix.name_info = {
ni_hostname : string ; (* Name or IP address of host
*)
ni_service : string ; (* Name of service or port number
*)
}
Host and service information returned by UnixLabels.getnameinfo .
type getnameinfo_option = Unix.getnameinfo_option =
| NI_NOFQDN (* Do not qualify local host names
*)
| NI_NUMERICHOST (* Always return host as IP address
*)
| NI_NAMEREQD (* Fail if host name cannot be determined
*)
| NI_NUMERICSERV (* Always return service as port number
*)
| NI_DGRAM (* Consider the service as UDP-based instead of the de-
fault TCP
*)
Options to UnixLabels.getnameinfo .
val getnameinfo : sockaddr -> getnameinfo_option list -> name_info
getnameinfo addr opts returns the host name and service name corre-
sponding to the socket address addr . opts is a possibly empty list of
options that governs how these names are obtained.
Raises Not_found if an error occurs.
Terminal interface
The following functions implement the POSIX standard terminal inter-
face. They provide control over asynchronous communication ports and
pseudo-terminals. Refer to the termios man page for a complete descrip-
tion.
type terminal_io = Unix.terminal_io = {
mutable c_ignbrk : bool ; (* Ignore the break condition.
*)
mutable c_brkint : bool ; (* Signal interrupt on break condition.
*)
mutable c_ignpar : bool ; (* Ignore characters with parity errors.
*)
mutable c_parmrk : bool ; (* Mark parity errors.
*)
mutable c_inpck : bool ; (* Enable parity check on input.
*)
mutable c_istrip : bool ; (* Strip 8th bit on input characters.
*)
mutable c_inlcr : bool ; (* Map NL to CR on input.
*)
mutable c_igncr : bool ; (* Ignore CR on input.
*)
mutable c_icrnl : bool ; (* Map CR to NL on input.
*)
mutable c_ixon : bool ; (* Recognize XON/XOFF characters on input.
*)
mutable c_ixoff : bool ; (* Emit XON/XOFF chars to control input flow.
*)
mutable c_opost : bool ; (* Enable output processing.
*)
mutable c_obaud : int ; (* Output baud rate (0 means close connec-
tion).
*)
mutable c_ibaud : int ; (* Input baud rate.
*)
mutable c_csize : int ; (* Number of bits per character (5-8).
*)
mutable c_cstopb : int ; (* Number of stop bits (1-2).
*)
mutable c_cread : bool ; (* Reception is enabled.
*)
mutable c_parenb : bool ; (* Enable parity generation and detection.
*)
mutable c_parodd : bool ; (* Specify odd parity instead of even.
*)
mutable c_hupcl : bool ; (* Hang up on last close.
*)
mutable c_clocal : bool ; (* Ignore modem status lines.
*)
mutable c_isig : bool ; (* Generate signal on INTR, QUIT, SUSP.
*)
mutable c_icanon : bool ; (* Enable canonical processing (line buffer-
ing and editing)
*)
mutable c_noflsh : bool ; (* Disable flush after INTR, QUIT, SUSP.
*)
mutable c_echo : bool ; (* Echo input characters.
*)
mutable c_echoe : bool ; (* Echo ERASE (to erase previous character).
*)
mutable c_echok : bool ; (* Echo KILL (to erase the current line).
*)
mutable c_echonl : bool ; (* Echo NL even if c_echo is not set.
*)
mutable c_vintr : char ; (* Interrupt character (usually ctrl-C).
*)
mutable c_vquit : char ; (* Quit character (usually ctrl-\).
*)
mutable c_verase : char ; (* Erase character (usually DEL or ctrl-H).
*)
mutable c_vkill : char ; (* Kill line character (usually ctrl-U).
*)
mutable c_veof : char ; (* End-of-file character (usually ctrl-D).
*)
mutable c_veol : char ; (* Alternate end-of-line char. (usually none).
*)
mutable c_vmin : int ; (* Minimum number of characters to read before
the read request is satisfied.
*)
mutable c_vtime : int ; (* Maximum read wait (in 0.1s units).
*)
mutable c_vstart : char ; (* Start character (usually ctrl-Q).
*)
mutable c_vstop : char ; (* Stop character (usually ctrl-S).
*)
}
val tcgetattr : file_descr -> terminal_io
Return the status of the terminal referred to by the given file de-
scriptor.
On Windows: not implemented.
type setattr_when = Unix.setattr_when =
| TCSANOW
| TCSADRAIN
| TCSAFLUSH
val tcsetattr : file_descr -> mode:setattr_when -> terminal_io -> unit
Set the status of the terminal referred to by the given file descrip-
tor. The second argument indicates when the status change takes place:
immediately ( TCSANOW ), when all pending output has been transmitted (
TCSADRAIN ), or after flushing all input that has been received but not
read ( TCSAFLUSH ). TCSADRAIN is recommended when changing the output
parameters; TCSAFLUSH , when changing the input parameters.
On Windows: not implemented.
val tcsendbreak : file_descr -> duration:int -> unit
Send a break condition on the given file descriptor. The second argu-
ment is the duration of the break, in 0.1s units; 0 means standard du-
ration (0.25s).
On Windows: not implemented.
val tcdrain : file_descr -> unit
Waits until all output written on the given file descriptor has been
transmitted.
On Windows: not implemented.
type flush_queue = Unix.flush_queue =
| TCIFLUSH
| TCOFLUSH
| TCIOFLUSH
val tcflush : file_descr -> mode:flush_queue -> unit
Discard data written on the given file descriptor but not yet transmit-
ted, or data received but not yet read, depending on the second argu-
ment: TCIFLUSH flushes data received but not read, TCOFLUSH flushes
data written but not transmitted, and TCIOFLUSH flushes both.
On Windows: not implemented.
type flow_action = Unix.flow_action =
| TCOOFF
| TCOON
| TCIOFF
| TCION
val tcflow : file_descr -> mode:flow_action -> unit
Suspend or restart reception or transmission of data on the given file
descriptor, depending on the second argument: TCOOFF suspends output,
TCOON restarts output, TCIOFF transmits a STOP character to suspend in-
put, and TCION transmits a START character to restart input.
On Windows: not implemented.
val setsid : unit -> int
Put the calling process in a new session and detach it from its con-
trolling terminal.
On Windows: not implemented.
OCamldoc 2023-02-12 UnixLabels(3o)
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