Add Process.new with args instead of command, args

spec/std/process_spec.cr

@@ -63,14 +63,89 @@ private def newline
   {% end %}
 end
 
+private def to_ary(tuple)
+  [tuple[0]].concat(tuple[1])
+end
+
 # interpreted code doesn't receive SIGCHLD for `#wait` to work (#12241)
 {% if flag?(:interpreted) && !flag?(:win32) %}
   pending Process
   {% skip_file %}
 {% end %}
 
 describe Process do
-  describe ".new" do
+  describe ".new (args)" do
+    it "raises if args is empty" do
+      expect_raises(File::NotFoundError, "Error executing process: No command") do
+        Process.new([] of String)
+      end
+    end
+
+    it "raises if args[0] is empty" do
+      expect_raises(IO::Error, /Error executing process: '("")?'/) do
+        Process.new([""] of String)
+      end
+    end
+
+    it "raises if command doesn't exist" do
+      expect_raises(File::NotFoundError, "Error executing process: 'foobarbaz'") do
+        Process.new(["foobarbaz"])
+      end
+    end
+
+    it "raises for long path" do
+      expect_raises(File::NotFoundError, "Error executing process: 'aaaaaaa") do
+        Process.new(["a" * 1000])
+      end
+    end
+
+    it "accepts nilable string for `chdir` (#13767)" do
+      expect_raises(File::NotFoundError, "Error executing process: 'foobarbaz'") do
+        Process.new(["foobarbaz"], chdir: nil.as(String?))
+      end
+    end
+
+    it "raises if command is not executable" do
+      with_tempfile("crystal-spec-run") do |path|
+        File.touch path
+        expect_raises({% if flag?(:win32) %} File::BadExecutableError {% else %} File::AccessDeniedError {% end %}, "Error executing process: '#{path.inspect_unquoted}'") do
+          Process.new([path])
+        end
+      end
+    end
+
+    it "raises if command is not executable" do
+      with_tempfile("crystal-spec-run") do |path|
+        Dir.mkdir path
+        expect_raises(File::AccessDeniedError, "Error executing process: '#{path.inspect_unquoted}'") do
+          Process.new([path])
+        end
+      end
+    end
+
+    it "raises if command could not be executed" do
+      with_tempfile("crystal-spec-run") do |path|
+        File.touch path
+        command = File.join(path, "foo")
+        expect_raises(IO::Error, "Error executing process: '#{command.inspect_unquoted}'") do
+          Process.new([command])
+        end
+      end
+    end
+
+    it "doesn't break if process is collected before completion", tags: %w[slow] do
+      200.times { Process.new(to_ary(exit_code_command(0))) }
+
+      # run the GC multiple times to unmap as much memory as possible
+      10.times { GC.collect }
+
+      # the processes above have now been queued after completion; if this last
+      # one finishes at all, nothing was broken by the GC
+      Process.run(*exit_code_command(0))
+    end
+  end
+
+  describe ".new (command + args)" do
     it "raises if command doesn't exist" do
       expect_raises(File::NotFoundError, "Error executing process: 'foobarbaz'") do
         Process.new("foobarbaz")

src/crystal/system/process.cr

@@ -73,8 +73,11 @@ struct Crystal::System::Process
   # def self.fork : ProcessInformation
   # def self.fork(&)
 
+  # def prepare_args(command : String, args : Enumerable(String)?, shell : Bool) : Args
+  # def prepare_args(args : Enumerable(String)) : Args
+
   # Launches a child process with the command + args.
-  # def self.spawn(command : String, args : Enumerable(String)?, shell : Bool, env : Env?, clear_env : Bool, input : Stdio, output : Stdio, error : Stdio, chdir : Path | String?) : ProcessInformation
+  # def self.spawn(prepared_args : Args, shell : Bool, env : Env?, clear_env : Bool, input : Stdio, output : Stdio, error : Stdio, chdir : Path | String?) : ProcessInformation
 
   # Replaces the current process with a new one.
   # def self.replace(command : String, args : Enumerable(String)?, shell : Bool, env : Env?, clear_env : Bool, input : Stdio, output : Stdio, error : Stdio, chdir : Path | String?) : NoReturn

src/crystal/system/unix/process.cr

@@ -292,23 +292,25 @@ struct Crystal::System::Process
   def self.prepare_args(command : String, args : Enumerable(String)?, shell : Bool) : {String, LibC::Char**}
     if shell
       command = %(#{command} "${@}") unless command.includes?(' ')
-      argv_ary = ["/bin/sh", "-c", command, "sh"]
+      command_args = ["/bin/sh", "-c", command, "sh"]
 
       if args
         unless command.includes?(%("${@}"))
           raise ArgumentError.new(%(Can't specify arguments in both command and args without including "${@}" into your command))
         end
       end
-
-      pathname = "/bin/sh"
     else
-      argv_ary = [command]
-      pathname = command
+      command_args = [command]
     end
 
-    argv_ary.concat(args) if args
+    command_args.concat(args) if args
+
+    prepare_args(command_args)
+  end
 
-    argv = argv_ary.map(&.check_no_null_byte.to_unsafe)
+  def self.prepare_args(args : Enumerable(String)) : {String, LibC::Char**}
+    pathname = args.first
+    argv = args.map(&.check_no_null_byte.to_unsafe)
     {pathname, argv.to_unsafe}
   end
 

src/crystal/system/unix/spawn.cr

@@ -2,9 +2,7 @@ require "c/signal"
 require "c/unistd"
 
 struct Crystal::System::Process
-  def self.spawn(command, args, shell, env, clear_env, input, output, error, chdir)
-    prepared_args = prepare_args(command, args, shell)
-
+  def self.spawn(prepared_args, shell, env, clear_env, input, output, error, chdir)
     r, w = FileDescriptor.system_pipe
 
     envp = Env.make_envp(env, clear_env)

src/crystal/system/win32/process.cr

@@ -286,7 +286,7 @@ struct Crystal::System::Process
     {new_handle, dup_handle}
   end
 
-  def self.spawn(command, args, shell, env, clear_env, input, output, error, chdir)
+  def self.spawn(prepared_args, shell, env, clear_env, input, output, error, chdir)
     startup_info = LibC::STARTUPINFOW.new
     startup_info.cb = sizeof(LibC::STARTUPINFOW)
     startup_info.dwFlags = LibC::STARTF_USESTDHANDLES
@@ -297,7 +297,6 @@ struct Crystal::System::Process
 
     process_info = LibC::PROCESS_INFORMATION.new
 
-    prepared_args = prepare_args(command, args, shell)
     prepared_args = ::Process.quote_windows(prepared_args) unless prepared_args.is_a?(String)
 
     if LibC.CreateProcessW(
@@ -331,20 +330,25 @@ struct Crystal::System::Process
       end
       command
     else
-      # Disable implicit execution of batch files (https://github.com/crystal-lang/crystal/issues/14536)
-      #
-      # > `CreateProcessW()` implicitly spawns `cmd.exe` when executing batch files (`.bat`, `.cmd`, etc.), even if the application didn’t specify them in the command line.
-      # > The problem is that the `cmd.exe` has complicated parsing rules for the command arguments, and programming language runtimes fail to escape the command arguments properly.
-      # > Because of this, it’s possible to inject commands if someone can control the part of command arguments of the batch file.
-      # https://flatt.tech/research/posts/batbadbut-you-cant-securely-execute-commands-on-windows/
-      if command.rstrip(". ").byte_slice?(-4, 4).try(&.downcase).in?(".bat", ".cmd")
-        raise ::File::Error.from_os_error("Error executing process", WinError::ERROR_BAD_EXE_FORMAT, file: command)
-      end
+      command_args = [command]
+      command_args.concat(args) if args
+      prepare_args(command_args)
+    end
+  end
 
-      prepared_args = [command]
-      prepared_args.concat(args) if args
-      prepared_args
+  def self.prepare_args(args : Enumerable(String))
+    # Disable implicit execution of batch files (https://github.com/crystal-lang/crystal/issues/14536)
+    #
+    # > `CreateProcessW()` implicitly spawns `cmd.exe` when executing batch files (`.bat`, `.cmd`, etc.), even if the application didn’t specify them in the command line.
+    # > The problem is that the `cmd.exe` has complicated parsing rules for the command arguments, and programming language runtimes fail to escape the command arguments properly.
+    # > Because of this, it’s possible to inject commands if someone can control the part of command arguments of the batch file.
+    # https://flatt.tech/research/posts/batbadbut-you-cant-securely-execute-commands-on-windows/
+    command = args.first
+    if command.rstrip(". ").byte_slice?(-4, 4).try(&.downcase).in?(".bat", ".cmd")
+      raise ::File::Error.from_os_error("Error executing process", WinError::ERROR_BAD_EXE_FORMAT, file: command)
     end
+
+    args
   end
 
   private def self.try_replace(command, prepared_args, env, clear_env, input, output, error, chdir)

src/process.cr

@@ -286,6 +286,67 @@ class Process
   @process_info : Crystal::System::Process
   @wait_count = 0
 
+  # Creates and executes a child process.
+  #
+  # This starts a new process for the command given in *args[0]*.
+  #
+  # The command is either a path to the executable to run, or the name of an
+  # executable which is then looked up by the operating system.
+  # The lookup uses the `PATH` variable of the current process environment
+  # (i.e. `ENV["PATH"]).
+  # In order to resolve to a specific executable, provide a path instead of
+  # only a command name. `Process.find_executable` can help with looking up a
+  # command in a custom `PATH`.
+  #
+  # The following arguments in *args* are passed as arguments to the child process.
+  #
+  # Raises `IO::Error` if executing *args[0]* fails, for example because the
+  # executable doesn't exist or is not executable.
+  #
+  # *env* provides a mapping of environment variables for the child process.
+  # If *clear_env* is `true`, only these explicit variables are used; if `false`,
+  # the child inherits the parent's environment with *env*  merged.
+  #
+  # *input*, *output*, *error* configure the child process's standard streams.
+  # * `Redirect::Close` passes the null device
+  # * `Redirect::Pipe` creates a pipe that's accessible via `#input`, `#output`
+  #    or `#error`.
+  # * `Redirect::Inherit` to share the parent's streams (`STDIN`, `STDOUT`, `STDERR`).
+  # * An `IO` instance creates a pipe that reads/writes into the given IO.
+  #
+  # *chdir* changes the working directory of the child process. If `nil`, uses
+  # the current working directory of the parent process.
+  #
+  # Example:
+  #
+  # ```
+  # process = Process.new(["echo", "Hello"], output: Process::Redirect::Pipe)
+  # process.output.gets_to_end # => "Hello\n"
+  # process.wait               # => Process::Status[0]
+  # ```
+  #
+  # Similar methods:
+  #
+  # * `Process.run` is a convenient short cut if you just want to run a command
+  #    and wait for it to finish.
+  # * `Process.exec` replaces the current process.
+  def initialize(args : Enumerable(String), *, env : Env = nil, clear_env : Bool = false,
+                 input : Stdio = Redirect::Close, output : Stdio = Redirect::Close, error : Stdio = Redirect::Close, chdir : Path | String? = nil)
+    raise File::NotFoundError.new("Error executing process: No command", file: "") if args.empty?
+
+    fork_input = stdio_to_fd(input, for: STDIN)
+    fork_output = stdio_to_fd(output, for: STDOUT)
+    fork_error = stdio_to_fd(error, for: STDERR)
+
+    prepared_args = Crystal::System::Process.prepare_args(args)
+    pid = Crystal::System::Process.spawn(prepared_args, false, env, clear_env, fork_input, fork_output, fork_error, chdir.try &.to_s)
+    @process_info = Crystal::System::Process.new(pid)
+
+    fork_input.close unless fork_input.in?(input, STDIN)
+    fork_output.close unless fork_output.in?(output, STDOUT)
+    fork_error.close unless fork_error.in?(error, STDERR)
+  end
+
   # Creates and executes a child process.
   #
   # This starts a new process for `command`.
@@ -359,7 +420,8 @@ class Process
     fork_output = stdio_to_fd(output, for: STDOUT)
     fork_error = stdio_to_fd(error, for: STDERR)
 
-    pid = Crystal::System::Process.spawn(command, args, shell, env, clear_env, fork_input, fork_output, fork_error, chdir.try &.to_s)
+    prepared_args = Crystal::System::Process.prepare_args(command, args, shell)
+    pid = Crystal::System::Process.spawn(prepared_args, shell, env, clear_env, fork_input, fork_output, fork_error, chdir.try &.to_s)
     @process_info = Crystal::System::Process.new(pid)
 
     fork_input.close unless fork_input.in?(input, STDIN)
@@ -436,10 +498,12 @@ class Process
     fork_io
   end
 
-  # :nodoc:
-  def initialize(pid : LibC::PidT)
-    @process_info = Crystal::System::Process.new(pid)
-  end
+  {% unless flag?(:interpreted) %}
+    # :nodoc:
+    def initialize(pid : LibC::PidT)
+      @process_info = Crystal::System::Process.new(pid)
+    end
+  {% end %}
 
   # Sends *signal* to this process.
   #