feat: implement ProcessExecuter.run_command

Run a command and return the status including stdout and stderr output

See the YARD doc for ProcessExecuter::run_command for full details.

lib/process_executer.rb

@@ -2,8 +2,10 @@
 
 require 'process_executer/monitored_pipe'
 require 'process_executer/options'
+require 'process_executer/command'
 require 'process_executer/status'
 
+require 'logger'
 require 'timeout'
 
 # Execute a command in a subprocess and optionally capture its output
@@ -55,6 +57,162 @@ def self.spawn(*command, **options_hash)
     wait_for_process(pid, options)
   end
 
+  # Run a command and return the status including stdout and stderr output
+  #
+  # @example Run a command given as a single string (uses shell)
+  #   # command must be shell escaped and can have shell expansions and redirections
+  #   command = 'echo "stdout: `pwd`"" && echo "stderr: $HOME" 1>&2'
+  #   result = ProcessExecuter.run_command(command)
+  #   result.success? #=> true
+  #   result.stdout.string #=> "stdout: /Users/james/projects/main-branch/process_executer\n"
+  #   result.stderr.string #=> "stderr: /Users/james\n"
+  #
+  # @example Run a command given as an array of strings (does not use shell)
+  #   # command args must be separate strings in the array
+  #   # shell expansions and redirections are not supported
+  #   command = ['git', 'clone', 'https://github.com/main-branch/process_executer']
+  #   result = ProcessExecuter.run_command(*command)
+  #   result.success? #=> true
+  #   result.stdout.string #=> ""
+  #   result.stderr.string #=> "Cloning into 'process_executer'...\n"
+  #
+  # @example Run a command with a timeout
+  #   command = ['sleep', '1']
+  #   result = ProcessExecuter.run_command(*command, timeout: 0.01)
+  #   #=> raises ProcessExecuter::Command::TimeoutError which contains the command result
+  #
+  # @example Run a command which fails
+  #   command = ['exit 1']
+  #   result = ProcessExecuter.run_command(*command)
+  #   #=> raises ProcessExecuter::Command::FailedError which contains the command result
+  #
+  # @example Run a command which exits due to an unhandled signal
+  #   command = ['kill -9 $$']
+  #   result = ProcessExecuter.run_command(*command)
+  #   #=> raises ProcessExecuter::Command::SignaledError which contains the command result
+  #
+  # @example Do not raise errors
+  #   command = ['echo "Some error" 1>&2 && exit 1']
+  #   result = ProcessExecuter.run_command(*command, raise_errors: false)
+  #   # An error is not raised
+  #   result.success? #=> false
+  #   result.exitstatus #=> 1
+  #   result.stdout.string #=> ""
+  #   result.stderr.string #=> "Some error\n"
+  #
+  # @example Set environment variables
+  #   env = { 'FOO' => 'foo', 'BAR' => 'bar' }
+  #   command = 'echo "$FOO$BAR"'
+  #   result = ProcessExecuter.run_command(env, *command)
+  #   result.stdout.string #=> "foobar\n"
+  #
+  # @example Set environment variables when using a command array
+  #   env = { 'GIT_DIR' => '/path/to/.git' }
+  #   command = ['git', 'status']
+  #   result = ProcessExecuter.run_command(env, *command)
+  #   result.stdout.string #=> "On branch main\nYour branch is ..."
+  #
+  # @example Unset environment variables
+  #   env = { 'GIT_DIR' => nil } # setting to nil unsets the variable in the environment
+  #   command = ['git', 'status']
+  #   result = ProcessExecuter.run_command(env, *command)
+  #   result.stdout.string #=> "On branch main\nYour branch is ..."
+  #
+  # @example Reset existing environment variables will adding new ones
+  #   env = { 'PATH' => '/bin' }
+  #   result = ProcessExecuter.run_command(env, 'echo "Home: $HOME" && echo "Path: $PATH"', unsetenv_others: true)
+  #   result.stdout.string #=> "Home: \n/Path: bin\n"
+  #
+  # @example Run command in a different directory
+  #   command = ['pwd']
+  #   result = ProcessExecuter.run_command(*command, chdir: '/tmp')
+  #   result.stdout.string #=> "/tmp\n"
+  #
+  # @example Capture stdout and stderr into a single buffer
+  #   command = ['echo "stdout" && echo "stderr" 1>&2']
+  #   result = ProcessExecuter.run_command(*command, merge: true)
+  #   result.stdout.string #=> "stdout\nstderr\n"
+  #   result.stdout.object_id == result.stderr.object_id #=> true
+  #
+  # @example Capture to an explicit buffer
+  #   out = StringIO.new
+  #   err = StringIO.new
+  #   command = ['echo "stdout" && echo "stderr" 1>&2']
+  #   result = ProcessExecuter.run_command(*command, out: out, err: err)
+  #   out.string #=> "stdout\n"
+  #   err.string #=> "stderr\n"
+  #   result.stdout.object_id == out.object_id #=> true
+  #   result.stderr.object_id == err.object_id #=> true
+  #
+  # @example Capture to a file
+  #   # Same technique can be used for stderr
+  #   out = File.open('stdout.txt', 'w')
+  #   command = ['echo "stdout" && echo "stderr" 1>&2']
+  #   result = ProcessExecuter.run_command(*command, out: out, err: err)
+  #   out.close
+  #   File.read('stdout.txt') #=> "stdout\n"
+  #   # stderr is still captured to a StringIO buffer internally
+  #   result.stderr.string #=> "stderr\n"
+  #
+  # @example Capture to multiple writers (e.g. files, buffers, STDOUT, etc.)
+  #   # Same technique can be used for stderr
+  #   out_buffer = StringIO.new
+  #   out_file = File.open('stdout.txt', 'w')
+  #   command = ['echo "stdout" && echo "stderr" 1>&2']
+  #   result = ProcessExecuter.run_command(*command, out: [out_buffer, out_file])
+  #   out_file.close
+  #   out_buffer.string #=> "stdout\n"
+  #   File.read('stdout.txt') #=> "stdout\n"
+  #
+  # @param command [Array<String>] The command to run
+  #
+  #   If the first element of command is a Hash, it is added to the ENV of
+  #   the new process. See [Execution Environment](https://ruby-doc.org/3.3.6/Process.html#module-Process-label-Execution+Environment)
+  #   for more details. The env hash is then removed from the command array.
+  #
+  #   If the first and only (remaining) command element is a string, it is (possibly) passsed
+  #   to a subshell to run. The command is passed to a subshell run if it begins with a shell
+  #   reserved word or special built-in, or if it contains one or more meta characters.
+  #
+  #   Care must be taken to properly escape shell metacharacters in the command string.
+  #
+  #   Otherwise, the command is run bypassing the shell. When bypassing the shell, shell expansions
+  #   and redirections are not supported.
+  #
+  # @param logger [Logger] The logger to use
+  # @param options_hash [Hash] Additional options
+  # @option options_hash [Numeric] :timeout The maximum seconds to wait for the command to complete
+  #
+  #     If timeout is zero of nil, the command will not time out. If the command
+  #     times out, it is killed via a SIGKILL signal and {ProcessExecuter::Command::TimeoutError} is raised.
+  #
+  #     If the command does not respond to SIGKILL, it will hang this method.
+  #
+  # @option options_hash [#write] :out (nil) The object to write stdout to
+  # @option options_hash [#write] :err (nil) The object to write stdout to
+  # @option options_hash [Boolean] :merge (false) Write both stdout and stderr into the buffer for stdout
+  # @option options_hash [Boolean] :raise_errors (true) Raise an exception if the command fails
+  # @option options_hash [Boolean] :unsetenv_others (false) If true, unset all environment variables before
+  #   applying the new ones
+  # @option options_hash [true, Integer, nil] :pgroup (nil) true or 0: new process group; non-zero: join
+  #   the group, nil: existing group
+  # @option options_hash [Boolean] :new_pgroup (nil) Create a new process group (Windows only)
+  # @option options_hash [Integer] :rlimit_resource_name (nil) Set resource limits (see Process.setrlimit)
+  # @option options_hash [Integer] :umask (nil) Set the umask (see File.umask)
+  # @option options_hash [Boolean] :close_others (false) If true, close non-standard file descriptors
+  # @option options_hash [String] :chdir (nil) The directory to run the command in
+  #
+  # @raise [ProcessExecuter::Command::FailedError] if the command returned a non-zero exit status
+  # @raise [ProcessExecuter::Command::SignaledError] if the command exited because of an unhandled signal
+  # @raise [ProcessExecuter::Command::TimeoutError] if the command timed out
+  # @raise [ProcessExecuter::Command::ProcessIOError] if an exception was raised while collecting subprocess output
+  #
+  # @return [ProcessExecuter::Command::Result] The result of running the command
+  #
+  def self.run_command(*command, logger: Logger.new(nil), **options_hash)
+    ProcessExecuter::Command::Runner.new(logger).call(*command, **options_hash)
+  end
+
   # Wait for process to terminate
   #
   # If a timeout is speecified in options, kill the process after options.timeout seconds.
@@ -68,10 +226,10 @@ def self.spawn(*command, **options_hash)
   #
   private_class_method def self.wait_for_process(pid, options)
     Timeout.timeout(options.timeout) do
-      ProcessExecuter::Status.new(Process.wait2(pid).last, false)
+      ProcessExecuter::Status.new(Process.wait2(pid).last, false, options.timeout)
     end
   rescue Timeout::Error
     Process.kill('KILL', pid)
-    ProcessExecuter::Status.new(Process.wait2(pid).last, true)
+    ProcessExecuter::Status.new(Process.wait2(pid).last, true, options.timeout)
   end
 end

lib/process_executer/command.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+module ProcessExecuter
+  # This module contains classes for implementing ProcessExecuter.run_command
+  module Command; end
+end
+
+require_relative 'command/errors'
+require_relative 'command/result'
+require_relative 'command/runner'
+
+# Runs a command and returns the result

lib/process_executer/command/errors.rb

@@ -0,0 +1,170 @@
+# frozen_string_literal: true
+
+# rubocop:disable Layout/LineLength:
+
+module ProcessExecuter
+  module Command
+    # Base class for all ProcessExecuter::Command errors
+    #
+    # It is recommended to rescue `ProcessExecuter::Command::Error` to catch any
+    # runtime error raised by this gem unless you need more specific error handling.
+    #
+    # Custom errors are arranged in the following class heirarchy:
+    #
+    # ```text
+    # ::StandardError
+    #   └─> Error
+    #       ├─> CommandError
+    #       │   ├─> FailedError
+    #       │   └─> SignaledError
+    #       │       └─> TimeoutError
+    #       └─> ProcessIOError
+    # ```
+    #
+    # | Error Class | Description |
+    # | --- | --- |
+    # | `Error` | This catch-all error serves as the base class for other custom errors. |
+    # | `CommandError` | A subclass of this error is raised when there is a problem executing a command. |
+    # | `FailedError` | This error is raised when the command exits with a non-zero status code. |
+    # | `SignaledError` | This error is raised when the command is terminated as a result of receiving a signal. This could happen if the process is forcibly terminated or if there is a serious system error. |
+    # | `TimeoutError` | This is a specific type of `SignaledError` that is raised when the command times out and is killed via the SIGKILL signal. This happens if the operation takes longer than the timeout duration (if given). |
+    # | `ProcessIOError` | An error was encountered reading or writing to the command's subprocess. |
+    #
+    # @example Rescuing any error
+    #   begin
+    #     ProcessExecuter.run_command('git', 'status')
+    #   rescue ProcessExecuter::Command::Error => e
+    #     puts "An error occurred: #{e.message}"
+    #   end
+    #
+    # @example Rescuing a timeout error
+    #   begin
+    #     timeout_duration = 0.1 # seconds
+    #     ProcessExecuter.run_command('sleep', '1', timeout: timeout_duration)
+    #   rescue ProcessExecuter::TimeoutError => e # Catch the more specific error first!
+    #     puts "Command took too long and timed out: #{e}"
+    #   rescue ProcessExecuter::Error => e
+    #     puts "Some other error occured: #{e}"
+    #   end
+    #
+    # @api public
+    #
+    class Error < ::StandardError; end
+
+    # Raised when a command fails or exits because of an uncaught signal
+    #
+    # The command executed, status, stdout, and stderr are available from this
+    # object.
+    #
+    # The Gem will raise a more specific error for each type of failure:
+    #
+    # * {FailedError}: when the command exits with a non-zero status
+    # * {SignaledError}: when the command exits because of an uncaught signal
+    # * {TimeoutError}: when the command times out
+    #
+    # @api public
+    #
+    class CommandError < ProcessExecuter::Command::Error
+      # Create a CommandError object
+      #
+      # @example
+      #   `exit 1` # set $? appropriately for this example
+      #   result = ProcessExecuter::Command::Result.new(%w[git status], $?, 'stdout', 'stderr')
+      #   error = ProcessExecuter::Command::CommandError.new(result)
+      #   error.to_s #=> '["git", "status"], status: pid 89784 exit 1, stderr: "stderr"'
+      #
+      # @param result [Result] the result of the command including the command,
+      #   status, stdout, and stderr
+      #
+      def initialize(result)
+        @result = result
+        super(error_message)
+      end
+
+      # The human readable representation of this error
+      #
+      # @example
+      #   error.error_message #=> '["git", "status"], status: pid 89784 exit 1, stderr: "stderr"'
+      #
+      # @return [String]
+      #
+      def error_message
+        "#{result.command}, status: #{result}, stderr: #{result.stderr_to_s.inspect}"
+      end
+
+      # @attribute [r] result
+      #
+      # The result of the command including the command, its status and its output
+      #
+      # @example
+      #   error.result #=> #<ProcessExecuter::Command::Result:0x00007f9b1b8b3d20>
+      #
+      # @return [Result]
+      #
+      attr_reader :result
+    end
+
+    # This error is raised when the command returns a non-zero exitstatus
+    #
+    # @api public
+    #
+    class FailedError < ProcessExecuter::Command::CommandError; end
+
+    # This error is raised when the command exits because of an uncaught signal
+    #
+    # @api public
+    #
+    class SignaledError < ProcessExecuter::Command::CommandError; end
+
+    # This error is raised when the command takes longer than the configured timeout
+    #
+    # @example
+    #   result.status.timeout? #=> true
+    #
+    # @api public
+    #
+    class TimeoutError < ProcessExecuter::Command::SignaledError
+      # Create a TimeoutError object
+      #
+      # @example
+      #   command = %w[sleep 10]
+      #   timeout_duration = 1
+      #   status = ProcessExecuter.spawn(*command, timeout: timeout_duration)
+      #   result = Result.new(command, status, 'stdout', 'err output')
+      #   error = TimeoutError.new(result, timeout_duration)
+      #   error.error_message
+      #     #=> '["sleep", "10"], status: pid 70144 SIGKILL (signal 9), stderr: "err output", timed out after 1s'
+      #
+      # @param result [Result] the result of the command including the git command,
+      #   status, stdout, and stderr
+      #
+      # @param timeout_duration [Numeric] the amount of time the subprocess was allowed
+      #   to run before being killed
+      #
+      def initialize(result, timeout_duration)
+        @timeout_duration = timeout_duration
+        super(result)
+      end
+
+      # The amount of time the subprocess was allowed to run before being killed
+      #
+      # @example
+      #   `kill -9 $$` # set $? appropriately for this example
+      #   result = Result.new(%w[git status], $?, '', "killed")
+      #   error = TimeoutError.new(result, 10)
+      #   error.timeout_duration #=> 10
+      #
+      # @return [Numeric]
+      #
+      attr_reader :timeout_duration
+    end
+
+    # Raised when the output of a git command can not be read
+    #
+    # @api public
+    #
+    class ProcessIOError < ProcessExecuter::Command::Error; end
+  end
+end
+
+# rubocop:enable Layout/LineLength: