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------------------------------------------------------------------------------
-- --
-- GNAT LIBRARY COMPONENTS --
-- --
-- G N A T . E X P E C T --
-- --
-- S p e c --
-- --
-- Copyright (C) 2000-2022, AdaCore --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- Currently this package is implemented on all native GNAT ports. It is not
-- yet implemented for any of the cross-ports (e.g. it is not available for
-- VxWorks or LynxOS).
-- -----------
-- -- Usage --
-- -----------
-- This package provides a set of subprograms similar to what is available
-- with the standard Tcl Expect tool.
-- It allows you to easily spawn and communicate with an external process.
-- You can send commands or inputs to the process, and compare the output
-- with some expected regular expression.
-- Usage example:
-- Non_Blocking_Spawn
-- (Fd, "ftp",
-- (1 => new String' ("machine@domain")));
-- Timeout := 10_000; -- 10 seconds
-- Expect (Fd, Result, Regexp_Array'(+"\(user\)", +"\(passwd\)"),
-- Timeout);
-- case Result is
-- when 1 => Send (Fd, "my_name"); -- matched "user"
-- when 2 => Send (Fd, "my_passwd"); -- matched "passwd"
-- when Expect_Timeout => null; -- timeout
-- when others => null;
-- end case;
-- Close (Fd);
-- You can also combine multiple regular expressions together, and get the
-- specific string matching a parenthesis pair by doing something like this:
-- If you expect either "lang=optional ada" or "lang=ada" from the external
-- process, you can group the two together, which is more efficient, and
-- simply get the name of the language by doing:
-- declare
-- Matched : Match_Array (0 .. 2);
-- begin
-- Expect (Fd, Result, "lang=(optional)? ([a-z]+)", Matched);
-- Put_Line ("Seen: " &
-- Expect_Out (Fd) (Matched (2).First .. Matched (2).Last));
-- end;
-- Alternatively, you might choose to use a lower-level interface to the
-- processes, where you can give your own input and output filters every
-- time characters are read from or written to the process.
-- procedure My_Filter
-- (Descriptor : Process_Descriptor'Class;
-- Str : String;
-- User_Data : System.Address)
-- is
-- begin
-- Put_Line (Str);
-- end;
-- Non_Blocking_Spawn
-- (Fd, "tail",
-- (new String' ("-f"), new String' ("a_file")));
-- Add_Filter (Fd, My_Filter'Access, Output);
-- Expect (Fd, Result, "", 0); -- wait forever
-- The above example should probably be run in a separate task, since it is
-- blocking on the call to Expect.
-- Both examples can be combined, for instance to systematically print the
-- output seen by expect, even though you still want to let Expect do the
-- filtering. You can use the Trace_Filter subprogram for such a filter.
-- If you want to get the output of a simple command, and ignore any previous
-- existing output, it is recommended to do something like:
-- Expect (Fd, Result, ".*", Timeout => 0);
-- -- Empty the buffer, by matching everything (after checking
-- -- if there was any input).
-- Send (Fd, "command");
-- Expect (Fd, Result, ".."); -- match only on the output of command
-- -----------------
-- -- Task Safety --
-- -----------------
-- This package is not task-safe: there should not be concurrent calls to the
-- functions defined in this package. In other words, separate tasks must not
-- access the facilities of this package without synchronization that
-- serializes access.
with System;
with GNAT.OS_Lib;
with GNAT.Regpat;
package GNAT.Expect is
type Process_Id is new Integer;
Invalid_Pid : constant Process_Id := -1;
Null_Pid : constant Process_Id := 0;
type Filter_Type is (Output, Input, Died);
-- The signals that are emitted by the Process_Descriptor upon state change
-- in the child. One can connect to any of these signals through the
-- Add_Filter subprograms.
--
-- Output => Every time new characters are read from the process
-- associated with Descriptor, the filter is called with
-- these new characters in the argument.
--
-- Note that output is generated only when the program is
-- blocked in a call to Expect.
--
-- Input => Every time new characters are written to the process
-- associated with Descriptor, the filter is called with
-- these new characters in the argument.
-- Note that input is generated only by calls to Send.
--
-- Died => The child process has died, or was explicitly killed
type Process_Descriptor is tagged private;
-- Contains all the components needed to describe a process handled
-- in this package, including a process identifier, file descriptors
-- associated with the standard input, output and error, and the buffer
-- needed to handle the expect calls.
type Process_Descriptor_Access is access Process_Descriptor'Class;
------------------------
-- Spawning a process --
------------------------
procedure Non_Blocking_Spawn
(Descriptor : out Process_Descriptor'Class;
Command : String;
Args : GNAT.OS_Lib.Argument_List;
Buffer_Size : Natural := 4096;
Err_To_Out : Boolean := False);
-- This call spawns a new process and allows sending commands to
-- the process and/or automatic parsing of the output.
--
-- The expect buffer associated with that process can contain at most
-- Buffer_Size characters. Older characters are simply discarded when this
-- buffer is full. Beware that if the buffer is too big, this could slow
-- down the Expect calls if the output not is matched, since Expect has to
-- match all the regexp against all the characters in the buffer. If
-- Buffer_Size is 0, there is no limit (i.e. all the characters are kept
-- till Expect matches), but this is slower.
--
-- If Err_To_Out is True, then the standard error of the spawned process is
-- connected to the standard output. This is the only way to get the Expect
-- subprograms to also match on output on standard error.
--
-- Invalid_Process is raised if the process could not be spawned.
--
-- For information about spawning processes from tasking programs, see the
-- "NOTE: Spawn in tasking programs" in System.OS_Lib (s-os_lib.ads).
procedure Close (Descriptor : in out Process_Descriptor);
-- Terminate the process and close the pipes to it. It implicitly does the
-- 'wait' command required to clean up the process table. This also frees
-- the buffer associated with the process id. Raise Invalid_Process if the
-- process id is invalid.
procedure Close
(Descriptor : in out Process_Descriptor;
Status : out Integer);
-- Same as above, but also returns the exit status of the process, as set
-- for example by the procedure GNAT.OS_Lib.OS_Exit.
procedure Send_Signal
(Descriptor : Process_Descriptor;
Signal : Integer);
-- Send a given signal to the process. Raise Invalid_Process if the process
-- id is invalid.
procedure Interrupt (Descriptor : in out Process_Descriptor);
-- Interrupt the process (the equivalent of Ctrl-C on unix and windows)
-- and call close if the process dies.
function Get_Input_Fd
(Descriptor : Process_Descriptor) return GNAT.OS_Lib.File_Descriptor;
-- Return the input file descriptor associated with Descriptor
function Get_Output_Fd
(Descriptor : Process_Descriptor) return GNAT.OS_Lib.File_Descriptor;
-- Return the output file descriptor associated with Descriptor
function Get_Error_Fd
(Descriptor : Process_Descriptor) return GNAT.OS_Lib.File_Descriptor;
-- Return the error output file descriptor associated with Descriptor
function Get_Pid
(Descriptor : Process_Descriptor) return Process_Id;
-- Return the process id associated with a given process descriptor
function Get_Command_Output
(Command : String;
Arguments : GNAT.OS_Lib.Argument_List;
Input : String;
Status : not null access Integer;
Err_To_Out : Boolean := False) return String;
-- Execute Command with the specified Arguments and Input, and return the
-- generated standard output data as a single string. If Err_To_Out is
-- True, generated standard error output is included as well. On return,
-- Status is set to the command's exit status.
--------------------
-- Adding filters --
--------------------
-- This is a rather low-level interface to subprocesses, since basically
-- the filtering is left entirely to the user. See the Expect subprograms
-- below for higher level functions.
type Filter_Function is access
procedure
(Descriptor : Process_Descriptor'Class;
Str : String;
User_Data : System.Address := System.Null_Address);
-- Function called every time new characters are read from or written to
-- the process.
--
-- Str is a string of all these characters.
--
-- User_Data, if specified, is user specific data that will be passed to
-- the filter. Note that no checks are done on this parameter, so it should
-- be used with caution.
procedure Add_Filter
(Descriptor : in out Process_Descriptor;
Filter : Filter_Function;
Filter_On : Filter_Type := Output;
User_Data : System.Address := System.Null_Address;
After : Boolean := False);
-- Add a new filter for one of the filter types. This filter will be run
-- before all the existing filters, unless After is set True, in which case
-- it will be run after existing filters. User_Data is passed as is to the
-- filter procedure.
procedure Remove_Filter
(Descriptor : in out Process_Descriptor;
Filter : Filter_Function);
-- Remove a filter from the list of filters (whatever the type of the
-- filter).
procedure Trace_Filter
(Descriptor : Process_Descriptor'Class;
Str : String;
User_Data : System.Address := System.Null_Address);
-- Function that can be used as a filter and that simply outputs Str on
-- Standard_Output. This is mainly used for debugging purposes.
-- User_Data is ignored.
procedure Lock_Filters (Descriptor : in out Process_Descriptor);
-- Temporarily disables all output and input filters. They will be
-- reactivated only when Unlock_Filters has been called as many times as
-- Lock_Filters.
procedure Unlock_Filters (Descriptor : in out Process_Descriptor);
-- Unlocks the filters. They are reactivated only if Unlock_Filters
-- has been called as many times as Lock_Filters.
------------------
-- Sending data --
------------------
procedure Send
(Descriptor : in out Process_Descriptor;
Str : String;
Add_LF : Boolean := True;
Empty_Buffer : Boolean := False);
-- Send a string to the file descriptor.
--
-- The string is not formatted in any way, except if Add_LF is True, in
-- which case an ASCII.LF is added at the end, so that Str is recognized
-- as a command by the external process.
--
-- If Empty_Buffer is True, any input waiting from the process (or in the
-- buffer) is first discarded before the command is sent. The output
-- filters are of course called as usual.
-----------------------------------------------------------
-- Working on the output (single process, simple regexp) --
-----------------------------------------------------------
type Expect_Match is new Integer;
Expect_Full_Buffer : constant Expect_Match := -1;
-- If the buffer was full and some characters were discarded
Expect_Timeout : constant Expect_Match := -2;
-- If no output matching the regexps was found before the timeout
function "+" (S : String) return GNAT.OS_Lib.String_Access;
-- Allocate some memory for the string. This is merely a convenience
-- function to help create the array of regexps in the call to Expect.
procedure Expect
(Descriptor : in out Process_Descriptor;
Result : out Expect_Match;
Regexp : String;
Timeout : Integer := 10_000;
Full_Buffer : Boolean := False);
-- Wait till a string matching Fd can be read from Fd, and return 1 if a
-- match was found.
--
-- It consumes all the characters read from Fd until a match found, and
-- then sets the return values for the subprograms Expect_Out and
-- Expect_Out_Match.
--
-- The empty string "" will never match, and can be used if you only want
-- to match after a specific timeout. Beware that if Timeout is -1 at the
-- time, the current task will be blocked forever.
--
-- This command times out after Timeout milliseconds (or never if Timeout
-- is -1). In that case, Expect_Timeout is returned. The value returned by
-- Expect_Out and Expect_Out_Match are meaningless in that case.
--
-- Note that using a timeout of 0ms leads to unpredictable behavior, since
-- the result depends on whether the process has already sent some output
-- the first time Expect checks, and this depends on the operating system.
--
-- The regular expression must obey the syntax described in GNAT.Regpat.
--
-- If Full_Buffer is True, then Expect will match if the buffer was too
-- small and some characters were about to be discarded. In that case,
-- Expect_Full_Buffer is returned.
procedure Expect
(Descriptor : in out Process_Descriptor;
Result : out Expect_Match;
Regexp : GNAT.Regpat.Pattern_Matcher;
Timeout : Integer := 10_000;
Full_Buffer : Boolean := False);
-- Same as the previous one, but with a precompiled regular expression.
-- This is more efficient however, especially if you are using this
-- expression multiple times, since this package won't need to recompile
-- the regexp every time.
procedure Expect
(Descriptor : in out Process_Descriptor;
Result : out Expect_Match;
Regexp : String;
Matched : out GNAT.Regpat.Match_Array;
Timeout : Integer := 10_000;
Full_Buffer : Boolean := False);
-- Same as above, but it is now possible to get the indexes of the
-- substrings for the parentheses in the regexp (see the example at the
-- top of this package, as well as the documentation in the package
-- GNAT.Regpat).
--
-- Matched'First should be 0, and this index will contain the indexes for
-- the whole string that was matched. The index 1 will contain the indexes
-- for the first parentheses-pair, and so on.
------------
-- Expect --
------------
procedure Expect
(Descriptor : in out Process_Descriptor;
Result : out Expect_Match;
Regexp : GNAT.Regpat.Pattern_Matcher;
Matched : out GNAT.Regpat.Match_Array;
Timeout : Integer := 10_000;
Full_Buffer : Boolean := False);
-- Same as above, but with a precompiled regular expression
-------------------------------------------------------------
-- Working on the output (single process, multiple regexp) --
-------------------------------------------------------------
type Regexp_Array is array (Positive range <>) of GNAT.OS_Lib.String_Access;
type Pattern_Matcher_Access is access all GNAT.Regpat.Pattern_Matcher;
type Compiled_Regexp_Array is
array (Positive range <>) of Pattern_Matcher_Access;
function "+"
(P : GNAT.Regpat.Pattern_Matcher) return Pattern_Matcher_Access;
-- Allocate some memory for the pattern matcher. This is only a convenience
-- function to help create the array of compiled regular expressions.
procedure Expect
(Descriptor : in out Process_Descriptor;
Result : out Expect_Match;
Regexps : Regexp_Array;
Timeout : Integer := 10_000;
Full_Buffer : Boolean := False);
-- Wait till a string matching one of the regular expressions in Regexps
-- is found. This function returns the index of the regexp that matched.
-- This command is blocking, but will timeout after Timeout milliseconds.
-- In that case, Timeout is returned.
procedure Expect
(Descriptor : in out Process_Descriptor;
Result : out Expect_Match;
Regexps : Compiled_Regexp_Array;
Timeout : Integer := 10_000;
Full_Buffer : Boolean := False);
-- Same as the previous one, but with precompiled regular expressions.
-- This can be much faster if you are using them multiple times.
procedure Expect
(Descriptor : in out Process_Descriptor;
Result : out Expect_Match;
Regexps : Regexp_Array;
Matched : out GNAT.Regpat.Match_Array;
Timeout : Integer := 10_000;
Full_Buffer : Boolean := False);
-- Same as above, except that you can also access the parenthesis
-- groups inside the matching regular expression.
--
-- The first index in Matched must be 0, or Constraint_Error will be
-- raised. The index 0 contains the indexes for the whole string that was
-- matched, the index 1 contains the indexes for the first parentheses
-- pair, and so on.
procedure Expect
(Descriptor : in out Process_Descriptor;
Result : out Expect_Match;
Regexps : Compiled_Regexp_Array;
Matched : out GNAT.Regpat.Match_Array;
Timeout : Integer := 10_000;
Full_Buffer : Boolean := False);
-- Same as above, but with precompiled regular expressions. The first index
-- in Matched must be 0, or Constraint_Error will be raised.
-------------------------------------------
-- Working on the output (multi-process) --
-------------------------------------------
type Multiprocess_Regexp is record
Descriptor : Process_Descriptor_Access;
Regexp : Pattern_Matcher_Access;
end record;
type Multiprocess_Regexp_Array is
array (Positive range <>) of Multiprocess_Regexp;
procedure Free (Regexp : in out Multiprocess_Regexp);
-- Free the memory occupied by Regexp
function Has_Process (Regexp : Multiprocess_Regexp_Array) return Boolean;
-- Return True if at least one entry in Regexp is non-null, ie there is
-- still at least one process to monitor
function First_Dead_Process
(Regexp : Multiprocess_Regexp_Array) return Natural;
-- Find the first entry in Regexp that corresponds to a dead process that
-- wasn't Free-d yet. This function is called in general when Expect
-- (below) raises the exception Process_Died. This returns 0 if no process
-- has died yet.
procedure Expect
(Result : out Expect_Match;
Regexps : Multiprocess_Regexp_Array;
Matched : out GNAT.Regpat.Match_Array;
Timeout : Integer := 10_000;
Full_Buffer : Boolean := False);
-- Same as above, but for multi processes. Any of the entries in
-- Regexps can have a null Descriptor or Regexp. Such entries will
-- simply be ignored. Therefore when a process terminates, you can
-- simply reset its entry.
--
-- The expect loop would therefore look like:
--
-- Processes : Multiprocess_Regexp_Array (...) := ...;
-- R : Natural;
--
-- while Has_Process (Processes) loop
-- begin
-- Expect (Result, Processes, Timeout => -1);
-- ... process output of process Result (output, full buffer,...)
--
-- exception
-- when Process_Died =>
-- -- Free memory
-- R := First_Dead_Process (Processes);
-- Close (Processes (R).Descriptor.all, Status);
-- Free (Processes (R));
-- end;
-- end loop;
procedure Expect
(Result : out Expect_Match;
Regexps : Multiprocess_Regexp_Array;
Timeout : Integer := 10_000;
Full_Buffer : Boolean := False);
-- Same as the previous one, but for multiple processes. This procedure
-- finds the first regexp that match the associated process.
------------------------
-- Getting the output --
------------------------
procedure Flush
(Descriptor : in out Process_Descriptor;
Timeout : Integer := 0);
-- Discard all output waiting from the process.
--
-- This output is simply discarded, and no filter is called. This output
-- will also not be visible by the next call to Expect, nor will any output
-- currently buffered.
--
-- Timeout is the delay for which we wait for output to be available from
-- the process. If 0, we only get what is immediately available.
function Expect_Out (Descriptor : Process_Descriptor) return String;
-- Return the string matched by the last Expect call.
--
-- The returned string is in fact the concatenation of all the strings read
-- from the file descriptor up to, and including, the characters that
-- matched the regular expression.
--
-- For instance, with an input "philosophic", and a regular expression "hi"
-- in the call to expect, the strings returned the first and second time
-- would be respectively "phi" and "losophi".
function Expect_Out_Match (Descriptor : Process_Descriptor) return String;
-- Return the string matched by the last Expect call.
--
-- The returned string includes only the character that matched the
-- specific regular expression. All the characters that came before are
-- simply discarded.
--
-- For instance, with an input "philosophic", and a regular expression
-- "hi" in the call to expect, the strings returned the first and second
-- time would both be "hi".
----------------
-- Exceptions --
----------------
Invalid_Process : exception;
-- Raised by most subprograms above when the parameter Descriptor is not a
-- valid process or is a closed process.
Process_Died : exception;
-- Raised by all the expect subprograms if Descriptor was originally a
-- valid process that died while Expect was executing. It is also raised
-- when Expect receives an end-of-file.
private
type Filter_List_Elem;
type Filter_List is access Filter_List_Elem;
type Filter_List_Elem is record
Filter : Filter_Function;
User_Data : System.Address;
Filter_On : Filter_Type;
Next : Filter_List;
end record;
type Pipe_Type is record
Input, Output : GNAT.OS_Lib.File_Descriptor;
end record;
-- This type represents a pipe, used to communicate between two processes
procedure Set_Up_Communications
(Pid : in out Process_Descriptor;
Err_To_Out : Boolean;
Pipe1 : not null access Pipe_Type;
Pipe2 : not null access Pipe_Type;
Pipe3 : not null access Pipe_Type);
-- Set up all the communication pipes and file descriptors prior to
-- spawning the child process.
procedure Set_Up_Parent_Communications
(Pid : in out Process_Descriptor;
Pipe1 : in out Pipe_Type;
Pipe2 : in out Pipe_Type;
Pipe3 : in out Pipe_Type);
-- Finish the set up of the pipes while in the parent process
procedure Set_Up_Child_Communications
(Pid : in out Process_Descriptor;
Pipe1 : in out Pipe_Type;
Pipe2 : in out Pipe_Type;
Pipe3 : in out Pipe_Type;
Cmd : String;
Args : System.Address);
-- Finish the set up of the pipes while in the child process This also
-- spawns the child process (based on Cmd). On systems that support fork,
-- this procedure is executed inside the newly created process.
procedure Close_Input (Pid : in out Process_Descriptor);
-- Closes input file descriptor. Set Input_Fd to Invalid_Fd as well as
-- Output_Fd and Error_Fd when they share same file descriptor.
type Process_Descriptor is tagged record
Pid : aliased Process_Id := Invalid_Pid;
Input_Fd : GNAT.OS_Lib.File_Descriptor := GNAT.OS_Lib.Invalid_FD;
Output_Fd : GNAT.OS_Lib.File_Descriptor := GNAT.OS_Lib.Invalid_FD;
Error_Fd : GNAT.OS_Lib.File_Descriptor := GNAT.OS_Lib.Invalid_FD;
Filters_Lock : Integer := 0;
Filters : Filter_List := null;
Buffer : GNAT.OS_Lib.String_Access := null;
Buffer_Size : Natural := 0;
Buffer_Index : Natural := 0;
Last_Match_Start : Natural := 0;
Last_Match_End : Natural := 0;
end record;
-- The following subprogram is provided for use in the body, and also
-- possibly in future child units providing extensions to this package.
procedure Portable_Execvp
(Pid : not null access Process_Id;
Cmd : String;
Args : System.Address);
pragma Import (C, Portable_Execvp, "__gnat_expect_portable_execvp");
-- Executes, in a portable way, the command Cmd (full path must be
-- specified), with the given Args, which must be an array of string
-- pointers. Note that the first element in Args must be the executable
-- name, and the last element must be a null pointer. The returned value
-- in Pid is the process ID, or zero if not supported on the platform.
end GNAT.Expect;