From 985e8f5f28da87be779b80942577f088321024af Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 5 Dec 2014 13:26:29 +0200
Subject: Add support for starting processes, getting file timestamps

g++-4.9 -std=c++11 -I.. -o bd bd.cxx process.cxx timestamp.cxx
---
 build/bd.cxx | 95 +++++++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 84 insertions(+), 11 deletions(-)

(limited to 'build/bd.cxx')

diff --git a/build/bd.cxx b/build/bd.cxx
index 918434a..03d0aa4 100644
--- a/build/bd.cxx
+++ b/build/bd.cxx
@@ -1,10 +1,17 @@
-// file      : build/bd.cxx
+// file      : build/bd.cxx -*- C++ -*-
 // copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
 // license   : MIT; see accompanying LICENSE file
 
+#include <time.h> // tzset()
+
 #include <vector>
+#include <cstdlib>      // exit
+#include <cassert>
 #include <iostream>
+#include <system_error>
 
+#include <build/process>
+#include <build/timestamp>
 #include <build/target>
 
 using namespace std;
@@ -14,33 +21,91 @@ namespace build
   bool
   update (target& t)
   {
-    const targets& ps (t.prerequisites ());
+    auto tts (path_timestamp (t.name ()));
+    cout << t.name () << ": " << tts << endl;
 
-    for (target& p: ps)
+    bool u (tts == timestamp_nonexistent);
+    for (target& p: t.prerequisites ())
+    {
       if (!update (p))
         return false;
 
-    //@@ TODO: check for existance, compare timestamps.
+      if (!u)
+      {
+        auto tps (path_timestamp (p.name ()));
+
+        if (tts <= tps) // Note: not just less.
+        {
+          cout << t.name () << " vs " << p.name () << ": " << (tps - tts)
+               << " ahead" << endl;
+          u = true;
+        }
+      }
+    }
 
-    auto r (t.rule ());
-    return r != 0 ? r (t, t.prerequisites ()) : true;
+    if (!u) // Nothing to do.
+      return true;
+
+    try
+    {
+      auto r (t.rule ());
+      return r != 0 ? r (t) : true;
+    }
+    catch (const process_error& e)
+    {
+      // Take care of failed children. In a multi-threaded program that
+      // fork()'ed but did not exec(), it is unwise to try to do any kind
+      // of cleanup (like unwinding the stack and running destructors).
+      //
+      assert (e.child ());
+      exit (1);
+    }
   }
 }
 
 using namespace build;
 
 bool
-cxx_compile_rule (target& t, const targets& p)
+cxx_compile_rule (target& t)
 {
-  //@@ TODO: actually execute
+  const targets& ps (t.prerequisites ());
+
+  //@@ TODO: assuming .cxx is first.
+  //
+  const target& p0 (ps[0]);
+  const char* args[] {
+    "g++-4.9",
+      "-std=c++11",
+      "-I..",
+      "-c",
+      "-o", t.name ().c_str (),
+      p0.name ().c_str (),
+      nullptr};
 
   cerr << "c++ " << t.name () << endl;
-  return true;
+
+  try
+  {
+    process pr (args);
+    return pr.wait ();
+  }
+  catch (const process_error& e)
+  {
+    cerr << "error: unable to execute '" << args[0] << "': " <<
+      e.what () << endl;
+
+    if (e.child ())
+      throw; // Let our caller terminate us quickly without causing a scene.
+
+    return false;
+  }
 }
 
 bool
-cxx_link_rule (target& t, const targets& p)
+cxx_link_rule (target& t)
 {
+  const targets& ps (t.prerequisites ());
+
   cerr << "ld " << t.name () << endl;
   return true;
 }
@@ -48,6 +113,10 @@ cxx_link_rule (target& t, const targets& p)
 int
 main (int argc, char* argv[])
 {
+  // Initialize time conversion data that is used by localtime_r().
+  //
+  tzset ();
+
   exe bd ("bd");
   obj bd_o ("bd.o");
   bd.prerequisite (bd_o);
@@ -59,5 +128,9 @@ main (int argc, char* argv[])
   bd_o.prerequisite (target);
   bd_o.rule (&cxx_compile_rule);
 
-  update (bd);
+  if (!update (bd))
+  {
+    cerr << "unable to update '" << bd.name () << "'" << endl;
+    return 1;
+  }
 }
-- 
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