Create argv before fork

src/crystal/system/process.cr

@@ -77,7 +77,7 @@ struct Crystal::System::Process
   # def self.spawn(command_args : Args, 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_args : Args, env : Env?, clear_env : Bool, input : Stdio, output : Stdio, error : Stdio, chdir : Path | String?) : NoReturn
+  # def self.replace(command : String, command_args : Args, env : Env?, clear_env : Bool, input : Stdio, output : Stdio, error : Stdio, chdir : Path | String?) : NoReturn
 
   # Converts a command and array of arguments to the system-specific representation.
   # def self.prepare_args(command : String, args : Enumerable(String)?, shell : Bool) : Args

src/crystal/system/unix/process.cr

@@ -307,25 +307,27 @@ struct Crystal::System::Process
     pid
   end
 
-  def self.prepare_args(command : String, args : Enumerable(String)?, shell : Bool) : Array(String)
+  def self.prepare_args(command : String, args : Enumerable(String)?, shell : Bool) : {String, UInt8**}
     if shell
       command = %(#{command} "${@}") unless command.includes?(' ')
-      shell_args = ["/bin/sh", "-c", command, "sh"]
+      argv_ary = ["/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
-
-        shell_args.concat(args)
       end
 
-      shell_args
+      pathname = "/bin/sh"
     else
-      command_args = [command]
-      command_args.concat(args) if args
-      command_args
+      argv_ary = [command]
+      pathname = command
     end
+
+    argv_ary.concat(args) if args
+
+    argv = argv_ary.map(&.check_no_null_byte.to_unsafe)
+    {pathname, argv.to_unsafe}
   end
 
   private def self.try_replace(command_args, env, clear_env, input, output, error, chdir)
@@ -344,16 +346,14 @@ struct Crystal::System::Process
 
     ::Dir.cd(chdir) if chdir
 
-    command = command_args[0]
-    argv = command_args.map &.check_no_null_byte.to_unsafe
-    argv << Pointer(UInt8).null
+    pathname, argv = command_args
 
-    lock_write { LibC.execvp(command, argv) }
+    lock_write { LibC.execvp(pathname, argv) }
   end
 
-  def self.replace(command_args, env, clear_env, input, output, error, chdir)
+  def self.replace(command, command_args, env, clear_env, input, output, error, chdir)
     try_replace(command_args, env, clear_env, input, output, error, chdir)
-    raise_exception_from_errno(command_args[0])
+    raise_exception_from_errno(command)
   end
 
   private def self.raise_exception_from_errno(command, errno = Errno.value)

src/crystal/system/wasi/process.cr

@@ -96,7 +96,7 @@ struct Crystal::System::Process
     raise NotImplementedError.new("Process.prepare_args")
   end
 
-  def self.replace(command_args, env, clear_env, input, output, error, chdir)
+  def self.replace(command, command_args, env, clear_env, input, output, error, chdir)
     raise NotImplementedError.new("Process.replace")
   end
 

src/crystal/system/win32/process.cr

@@ -343,7 +343,7 @@ struct Crystal::System::Process
     end
   end
 
-  private def self.try_replace(command_args, env, clear_env, input, output, error, chdir)
+  private def self.try_replace(command, command_args, env, clear_env, input, output, error, chdir)
     old_input_fd = reopen_io(input, ORIGINAL_STDIN)
     old_output_fd = reopen_io(output, ORIGINAL_STDOUT)
     old_error_fd = reopen_io(error, ORIGINAL_STDERR)
@@ -378,8 +378,8 @@ struct Crystal::System::Process
     errno
   end
 
-  def self.replace(command_args, env, clear_env, input, output, error, chdir) : NoReturn
-    errno = try_replace(command_args, env, clear_env, input, output, error, chdir)
+  def self.replace(command, command_args, env, clear_env, input, output, error, chdir) : NoReturn
+    errno = try_replace(command, command_args, env, clear_env, input, output, error, chdir)
     raise_exception_from_errno(command_args.is_a?(String) ? command_args : command_args[0], errno)
   end
 

src/process.cr

@@ -221,7 +221,7 @@ class Process
     output = exec_stdio_to_fd(output, for: STDOUT)
     error = exec_stdio_to_fd(error, for: STDERR)
 
-    Crystal::System::Process.replace(command_args, env, clear_env, input, output, error, chdir)
+    Crystal::System::Process.replace(command, command_args, env, clear_env, input, output, error, chdir)
   end
 
   private def self.exec_stdio_to_fd(stdio : ExecStdio, for dst_io : IO::FileDescriptor) : IO::FileDescriptor