[FIXUP] Implement some of Peter's changes.

Author: NlightNFotis

src/util/piped_process.cpp

@@ -19,6 +19,7 @@
 #  include <iostream>
 #  include <vector>
 
+#  include "exception_utils.h"
 #  include "invariant.h"
 #  include "narrow.h"
 #  include "optional.h"
@@ -35,20 +36,20 @@ piped_processt::piped_processt(const std::vector<std::string> commandvec)
 
   if(pipe(pipe_input) == -1)
   {
-    throw std::runtime_error("Input pipe creation failed");
+    throw system_exceptiont("Input pipe creation failed");
   }
 
   if(pipe(pipe_output) == -1)
   {
-    throw std::runtime_error("Output pipe creation failed");
+    throw system_exceptiont("Output pipe creation failed");
   }
 
   // Default state
   process_state = statet::NOT_CREATED;
 
   if(fcntl(pipe_output[0], F_SETFL, O_NONBLOCK) < 0)
   {
-    throw std::runtime_error("Setting pipe non-blocking failed");
+    throw system_exceptiont("Setting pipe non-blocking failed");
   }
 
   // Create a new process for the child that will execute the
@@ -114,7 +115,7 @@ piped_processt::~piped_processt()
 #  ifdef _WIN32
   UNIMPLEMENTED_FEATURE("Pipe IPC on windows: piped_processt constructor")
 #  else
-  // Close the parent side of the remaning pipes
+  // Close the parent side of the remaining pipes
   fclose(command_stream);
   // Note that the above will call close(pipe_input[1]);
   close(pipe_output[0]);

src/util/piped_process.h

@@ -84,6 +84,10 @@ class piped_processt
   // Child process ID.
   pid_t pid;
   FILE *command_stream;
+  // The member fields below are so named from the perspective of the
+  // parent -> child process. So `pipe_input` is where we are feeding
+  // commands to the child process, and `pipe_output` is where we read
+  // the results of execution from.
   int pipe_input[2];
   int pipe_output[2];
   statet process_state;