[nit.git] / lib / standard / exec.nit

# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Copyright 2004-2008 Jean Privat <jean@pryen.org>
# Copyright 2008 Floréal Morandat <morandat@lirmm.fr>
#
# This file is free software, which comes along with NIT.  This software is
# distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
# without  even  the implied warranty of  MERCHANTABILITY or  FITNESS FOR A
# PARTICULAR PURPOSE.  You can modify it is you want,  provided this header
# is kept unaltered, and a notification of the changes is added.
# You  are  allowed  to  redistribute it and sell it, alone or is a part of
# another product.

# Invocation and management of operating system sub-processes.
# Standard input and output can be handled through streams.
module exec

import file

# Simple sub-process
class Process
        # The pid of the process
        fun id: Int do return data.id

        # Is the process finished?
        fun is_finished: Bool do return data.is_finished

        # Wait the termination of the process
        fun wait
        do
                data.wait
                assert is_finished
        end

        # The status once finished
        fun status: Int
        do
                assert is_finished
                return data.status
        end

        # The executable run
        # Is a filepath, or a executable found in PATH
        var command: String

        # The arguments of the command
        # Starts with the first real arguments---ie. does not include the progname (`argv[0]`, in C)
        var arguments: nullable Array[String]

        # Launch a command with some arguments
        init(command: String, arguments: String...) is old_style_init do
                self.command = command
                self.arguments = arguments
                execute
        end

        # Launch a simple command with arguments passed as an array
        init from_a(command: String, arguments: nullable Array[String])
        do
                self.command = command
                self.arguments = arguments
                execute
        end

        # flags used internally to know whith pipe to open
        private fun pipeflags: Int do return 0

        # Internal code to handle execution
        protected fun execute
        do
                # The pass the arguments as a big C string where elements are separated with '\0'
                var args = new FlatBuffer
                var l = 1 # Number of elements in args
                args.append(command)
                if arguments != null then
                        for a in arguments do
                                args.add('\0')
                                #a.output_class_name
                                args.append(a)
                        end
                        l += arguments.length
                end
                data = basic_exec_execute(command.to_cstring, args.to_s.to_cstring, l, pipeflags)
        end

        private var data: NativeProcess
        private fun basic_exec_execute(p: NativeString, av: NativeString, ac: Int, pf: Int): NativeProcess is extern "exec_Process_Process_basic_exec_execute_4"
end

# stdout of the process is readable
class IProcess
        super Process
        super IStream

        # File Descriptor used for the input.
        var stream_in: IFStream is noinit

        redef fun close do stream_in.close

        redef fun read_char do return stream_in.read_char

        redef fun eof do return stream_in.eof

        redef fun pipeflags do return 2

        redef fun execute
        do
                super
                stream_in = new IFStream.from_fd(data.out_fd)
        end
end

# stdin of the process is writable
class OProcess
        super Process
        super OStream

        # File Descriptor used for the output.
        var stream_out: OStream is noinit

        redef fun close do stream_out.close

        redef fun is_writable do return stream_out.is_writable

        redef fun write(s) do stream_out.write(s)

        redef fun pipeflags do return 1

        redef fun execute
        do
                super
                stream_out = new OFStream.from_fd(data.in_fd)
        end
end

# stdin and stdout are both accessible
class IOProcess
        super IProcess
        super OProcess
        super IOStream

        redef fun close
        do
                stream_in.close
                stream_out.close
        end

        redef fun pipeflags do return 3

        redef fun execute
        do
                super
        end
end

redef class Sys
        # Execute a shell command and return its error code
        fun system(command: String): Int
        do
                return command.to_cstring.system
        end
end

redef class NativeString
        # Execute self as a shell command.
        #
        # See the posix function system(3).
        fun system: Int is extern "string_NativeString_NativeString_system_0"
end

private extern class NativeProcess
        fun id: Int is extern "exec_NativeProcess_NativeProcess_id_0"
        fun is_finished: Bool is extern "exec_NativeProcess_NativeProcess_is_finished_0"
        fun status: Int is extern "exec_NativeProcess_NativeProcess_status_0"
        fun wait is extern "exec_NativeProcess_NativeProcess_wait_0"

        fun in_fd: Int is extern "exec_NativeProcess_NativeProcess_in_fd_0"
        fun out_fd: Int is extern "exec_NativeProcess_NativeProcess_out_fd_0"
        fun err_fd: Int is extern "exec_NativeProcess_NativeProcess_err_fd_0"
end