Add support for starting processes, getting file timestamps

g++-4.9 -std=c++11 -I.. -o bd bd.cxx process.cxx timestamp.cxx

6 files changed, 690 insertions, 13 deletions

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;
+  }
 }
diff --git a/build/process b/build/process
new file mode 100644
index 0000000..0b45846
--- /dev/null
+++ b/build/process
@@ -0,0 +1,67 @@
+// file      : build/process -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef BUILD_PROCESS
+#define BUILD_PROCESS
+
+#ifndef _WIN32
+#  include <sys/types.h> // pid_t
+#endif
+
+#include <cassert>
+#include <system_error>
+
+namespace build
+{
+
+  struct process_error: std::system_error
+  {
+    process_error (int e, bool child)
+        : system_error (e, std::system_category ()), child_ (child) {}
+
+    bool
+    child () const {return child_;}
+
+  private:
+    bool child_;
+  };
+
+  struct process
+  {
+    // Start another process using the specified command line. Connect the
+    // newly created process' stdin to out_fd. Also if connect_* are true,
+    // connect the created process' stdout and stderr to in_*fd. Throw
+    // process_error if anything goes wrong.
+    //
+    // Note that some of the exceptions (e.g., if exec() failed) can be
+    // thrown in the child version of us.
+    //
+    process (char const* args[],
+             bool connect_stdin = false,
+             bool connect_stderr = false,
+             bool connect_stdout = false);
+
+    // Wait for the process to terminate. Return true if the process
+    // terminated normally and with the zero exit status. Throw
+    // process_error if anything goes wrong.
+    //
+    bool
+    wait ();
+
+    ~process () {assert (id == 0);}
+
+#ifndef _WIN32
+    typedef pid_t id_type;
+#else
+    typedef void* id_type; // Win32 HANDLE.
+#endif
+
+    id_type id;
+    int out_fd; // Write to this fd to send to the new process' stdin.
+    int in_efd; // Read from this fd to receive from the new process' stderr.
+    int in_ofd; // Read from this fd to receive from the new process' stdout.
+  };
+}
+
+#endif // BUILD_PROCESS
diff --git a/build/process.cxx b/build/process.cxx
new file mode 100644
index 0000000..09b8d36
--- /dev/null
+++ b/build/process.cxx
@@ -0,0 +1,326 @@
+// file      : build/process.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
+// license   : MIT; see accompanying LICENSE file
+
+#include <build/process>
+
+#ifndef _WIN32
+#  include <unistd.h>    // execvp, fork, dup2, pipe, {STDIN,STDERR}_FILENO
+#  include <sys/wait.h>  // waitpid
+#else
+#  ifndef WIN32_LEAN_AND_MEAN
+#    define WIN32_LEAN_AND_MEAN
+#  endif
+#  include <windows.h>   // CreatePipe, CreateProcess
+#  include <io.h>        // _open_osfhandle
+#  include <fcntl.h>     // _O_TEXT
+#endif
+
+using namespace std;
+
+namespace build
+{
+#ifndef _WIN32
+
+  process::
+  process (char const* args[], bool in, bool err, bool out)
+  {
+    int out_fd[2];
+    int in_efd[2];
+    int in_ofd[2];
+
+    if ((in && pipe (out_fd) == -1)  ||
+        (err && pipe (in_efd) == -1) ||
+        (out && pipe (in_ofd) == -1))
+      throw process_error (errno, false);
+
+    id = fork ();
+
+    if (id == -1)
+      throw process_error (errno, false);
+
+    if (id == 0)
+    {
+      // Child. If requested, close the write end of the pipe and duplicate
+      // the read end to stdin. Then close the original read end descriptor.
+      //
+      if (in)
+      {
+        if (close (out_fd[1]) == -1 ||
+            dup2 (out_fd[0], STDIN_FILENO) == -1 ||
+            close (out_fd[0]) == -1)
+          throw process_error (errno, true);
+      }
+
+      // Do the same for the stderr if requested.
+      //
+      if (err)
+      {
+        if (close (in_efd[0]) == -1 ||
+            dup2 (in_efd[1], STDERR_FILENO) == -1 ||
+            close (in_efd[1]) == -1)
+          throw process_error (errno, true);
+      }
+
+      // Do the same for the stdout if requested.
+      //
+      if (out)
+      {
+        if (close (in_ofd[0]) == -1 ||
+            dup2 (in_ofd[1], STDOUT_FILENO) == -1 ||
+            close (in_ofd[1]) == -1)
+          throw process_error (errno, true);
+      }
+
+      if (execvp (args[0], const_cast<char**> (&args[0])) == -1)
+        throw process_error (errno, true);
+    }
+    else
+    {
+      // Parent. Close the other ends of the pipes.
+      //
+      if ((in && close (out_fd[0])) == -1  ||
+          (err && close (in_efd[1]) == -1) ||
+          (out && close (in_ofd[1]) == -1))
+        throw process_error (errno, false);
+    }
+
+    this->out_fd = in ? out_fd[1] : 0;
+    this->in_efd = err ? in_efd[0] : 0;
+    this->in_ofd = out ? in_ofd[0] : 0;
+  }
+
+  bool process::
+  wait ()
+  {
+    int status;
+    int r (waitpid (id, &status, 0));
+    id = 0; // We have tried.
+
+    if (r == -1)
+      throw process_error (errno, false);
+
+    return WIFEXITED (status) && WEXITSTATUS (status) == 0;
+  }
+
+#else // _WIN32
+
+  static void
+  print_error (char const* name)
+  {
+    LPTSTR msg;
+    DWORD e (GetLastError());
+
+    if (!FormatMessage(
+          FORMAT_MESSAGE_ALLOCATE_BUFFER |
+          FORMAT_MESSAGE_FROM_SYSTEM |
+          FORMAT_MESSAGE_IGNORE_INSERTS,
+          0,
+          e,
+          MAKELANGID (LANG_NEUTRAL, SUBLANG_DEFAULT),
+          (LPTSTR) &msg,
+          0,
+          0))
+    {
+      cerr << name << ": error: unknown error code " << e << endl;
+      return;
+    }
+
+    cerr << name << ": error: " << msg << endl;
+    LocalFree (msg);
+  }
+
+  static process_info
+  start_process (char const* args[], char const* name, bool err, bool out)
+  {
+    HANDLE out_h[2];
+    HANDLE in_eh[2];
+    HANDLE in_oh[2];
+    SECURITY_ATTRIBUTES sa;
+
+    sa.nLength = sizeof (SECURITY_ATTRIBUTES);
+    sa.bInheritHandle = true;
+    sa.lpSecurityDescriptor = 0;
+
+    if (!CreatePipe (&out_h[0], &out_h[1], &sa, 0) ||
+        !SetHandleInformation (out_h[1], HANDLE_FLAG_INHERIT, 0))
+    {
+      print_error (name);
+      throw process_failure ();
+    }
+
+    if (err)
+    {
+      if (!CreatePipe (&in_eh[0], &in_eh[1], &sa, 0) ||
+          !SetHandleInformation (in_eh[0], HANDLE_FLAG_INHERIT, 0))
+      {
+        print_error (name);
+        throw process_failure ();
+      }
+    }
+
+    if (out)
+    {
+      if (!CreatePipe (&in_oh[0], &in_oh[1], &sa, 0) ||
+          !SetHandleInformation (in_oh[0], HANDLE_FLAG_INHERIT, 0))
+      {
+        print_error (name);
+        throw process_failure ();
+      }
+    }
+
+    // Create the process.
+    //
+    path file (args[0]);
+
+    // Do PATH search.
+    //
+    if (file.directory ().empty ())
+      file = path_search (file);
+
+    if (file.empty ())
+    {
+      cerr << args[0] << ": error: file not found" << endl;
+      throw process_failure ();
+    }
+
+    // Serialize the arguments to string.
+    //
+    string cmd_line;
+
+    for (char const** p (args); *p != 0; ++p)
+    {
+      if (p != args)
+        cmd_line += ' ';
+
+      // On Windows we need to protect values with spaces using quotes.
+      // Since there could be actual quotes in the value, we need to
+      // escape them.
+      //
+      string a (*p);
+      bool quote (a.find (' ') != string::npos);
+
+      if (quote)
+        cmd_line += '"';
+
+      for (size_t i (0); i < a.size (); ++i)
+      {
+        if (a[i] == '"')
+          cmd_line += "\\\"";
+        else
+          cmd_line += a[i];
+      }
+
+      if (quote)
+        cmd_line += '"';
+    }
+
+    // Prepare other info.
+    //
+    STARTUPINFO si;
+    PROCESS_INFORMATION pi;
+
+    memset (&si, 0, sizeof (STARTUPINFO));
+    memset (&pi, 0, sizeof (PROCESS_INFORMATION));
+
+    si.cb = sizeof(STARTUPINFO);
+
+    if (err)
+      si.hStdError = in_eh[1];
+    else
+      si.hStdError = GetStdHandle (STD_ERROR_HANDLE);
+
+    if (out)
+      si.hStdOutput = in_oh[1];
+    else
+      si.hStdOutput = GetStdHandle (STD_OUTPUT_HANDLE);
+
+    si.hStdInput = out_h[0];
+    si.dwFlags |= STARTF_USESTDHANDLES;
+
+    if (!CreateProcess (
+          file.string ().c_str (),
+          const_cast<char*> (cmd_line.c_str ()),
+          0,    // Process security attributes.
+          0,    // Primary thread security attributes.
+          true, // Inherit handles.
+          0,    // Creation flags.
+          0,    // Use our environment.
+          0,    // Use our current directory.
+          &si,
+          &pi))
+    {
+      print_error (name);
+      throw process_failure ();
+    }
+
+    CloseHandle (pi.hThread);
+    CloseHandle (out_h[0]);
+
+    if (err)
+      CloseHandle (in_eh[1]);
+
+    if (out)
+      CloseHandle (in_oh[1]);
+
+    process_info r;
+    r.id = pi.hProcess;
+    r.out_fd = _open_osfhandle ((intptr_t) (out_h[1]), 0);
+
+    if (r.out_fd == -1)
+    {
+      cerr << name << ": error: unable to obtain C file handle" << endl;
+      throw process_failure ();
+    }
+
+    if (err)
+    {
+      // Pass _O_TEXT to get newline translation.
+      //
+      r.in_efd = _open_osfhandle ((intptr_t) (in_eh[0]), _O_TEXT);
+
+      if (r.in_efd == -1)
+      {
+        cerr << name << ": error: unable to obtain C file handle" << endl;
+        throw process_failure ();
+      }
+    }
+    else
+      r.in_efd = 0;
+
+    if (out)
+    {
+      // Pass _O_TEXT to get newline translation.
+      //
+      r.in_ofd = _open_osfhandle ((intptr_t) (in_oh[0]), _O_TEXT);
+
+      if (r.in_ofd == -1)
+      {
+        cerr << name << ": error: unable to obtain C file handle" << endl;
+        throw process_failure ();
+      }
+    }
+    else
+      r.in_ofd = 0;
+
+    return r;
+  }
+
+  static bool
+  wait_process (process_info pi, char const* name)
+  {
+    DWORD status;
+
+    if (WaitForSingleObject (pi.id, INFINITE) != WAIT_OBJECT_0 ||
+        !GetExitCodeProcess (pi.id, &status))
+    {
+      print_error (name);
+      throw process_failure ();
+    }
+
+    CloseHandle (pi.id);
+    return status == 0;
+  }
+
+#endif // _WIN32
+}
diff --git a/build/target b/build/target
index e6f05a5..4319ccb 100644
--- a/build/target
+++ b/build/target
@@ -2,9 +2,12 @@
 // copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
 // license   : MIT; see accompanying LICENSE file
 
+#ifndef BUILD_TARGET
+#define BUILD_TARGET
+
 #include <string>
 #include <vector>
-#include <functional>
+#include <functional> // std::reference_wrapper
 
 namespace build
 {
@@ -29,7 +32,7 @@ namespace build
     prerequisite (target& t) {prerequisites_.push_back (t);}
 
   public:
-    typedef bool (*rule_type) (target&, const targets&);
+    typedef bool (*rule_type) (target&);
 
     rule_type
     rule () const {return rule_;}
@@ -67,3 +70,5 @@ namespace build
     using target::target;
   };
 }
+
+#endif // BUILD_TARGET
diff --git a/build/timestamp b/build/timestamp
new file mode 100644
index 0000000..6ed2f2c
--- /dev/null
+++ b/build/timestamp
@@ -0,0 +1,52 @@
+// file      : build/timestamp -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef BUILD_TIMESTAMP
+#define BUILD_TIMESTAMP
+
+#include <chrono>
+#include <string>
+#include <iosfwd>
+
+namespace build
+{
+  // On all three main platforms that we target (GNU/Linux, Windows (both
+  // VC++ and GCC/MinGW64), and MacOS X) with recent C++ runtimes,
+  // system_clock has nanoseconds resolution and counts from the UNIX
+  // epoch. The latter is important since struct stat also returns times
+  // based on UNIX epoch.
+  //
+  // The underlying type for nanoseconds duration is signed integer type
+  // of at least 64 bits (currently int64_t). Because it is signed, we
+  // will overflow in year 2262 but by then the underlying type will
+  // most likely have changed to something larger than 64-bit.
+  //
+  // So to support other platforms that could possibly use a different
+  // system_clock resolutions (e.g., microseconds), we actually not going
+  // to assume anywhere (except perhaps timestamp.cxx) that we are dealing
+  // with nanoseconds or the 64-bit underlying type.
+  //
+  using std::chrono::system_clock;
+
+  using timestamp = system_clock::time_point;
+  using duration = system_clock::duration;
+
+  const timestamp timestamp_unknown {duration {-1}};
+  const timestamp timestamp_nonexistent {duration {0}};
+
+  std::ostream&
+  operator<< (std::ostream&, timestamp);
+
+  std::ostream&
+  operator<< (std::ostream&, duration);
+
+  // Returns timestamp_nonexistent if the entry at the specified path
+  // does not exist. All other errors are reported by throwing
+  // std::system_error.
+  //
+  timestamp
+  path_timestamp (const std::string&);
+};
+
+#endif // BUILD_TIMESTAMP
diff --git a/build/timestamp.cxx b/build/timestamp.cxx
new file mode 100644
index 0000000..db8efb2
--- /dev/null
+++ b/build/timestamp.cxx
@@ -0,0 +1,154 @@
+// file      : build/timestamp.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
+// license   : MIT; see accompanying LICENSE file
+
+#include <build/timestamp>
+
+#include <unistd.h>    // stat
+#include <sys/types.h> // stat
+#include <sys/stat.h>  // stat
+
+#include <time.h> // localtime, gmtime, strftime
+
+#include <ostream>
+#include <system_error>
+
+using namespace std;
+
+namespace build
+{
+  // Figuring out whether we have the nanoseconds in some form.
+  //
+  template <typename S>
+  constexpr auto nsec (const S* s) -> decltype(s->st_mtim.tv_nsec)
+  {
+    return s->st_mtim.tv_nsec; // POSIX (GNU/Linux, Solaris).
+  }
+
+  template <typename S>
+  constexpr auto nsec (const S* s) -> decltype(s->st_mtimespec.tv_nsec)
+  {
+    return s->st_mtimespec.tv_nsec; // MacOS X.
+  }
+
+  template <typename S>
+  constexpr auto nsec (const S* s) -> decltype(s->st_mtime_n)
+  {
+    return s->st_mtime_n; // AIX 5.2 and later.
+  }
+
+  template <typename S>
+  constexpr int nsec (...) {return 0;}
+
+  timestamp
+  path_timestamp (const std::string& p)
+  {
+    struct stat s;
+    if (stat (p.c_str (), &s) != 0)
+    {
+      if (errno == ENOENT || errno == ENOTDIR)
+        return timestamp_nonexistent;
+      else
+        throw system_error (errno, system_category ());
+    }
+
+    return system_clock::from_time_t (s.st_mtime) +
+      chrono::duration_cast<duration> (
+        chrono::nanoseconds (nsec<struct stat> (&s)));
+  }
+
+  ostream&
+  operator<< (ostream& os, timestamp ts)
+  {
+    // @@ replace with put_time()
+    //
+
+    time_t t (system_clock::to_time_t (ts));
+
+    if (t == 0)
+      return os << "<nonexistent>";
+
+    std::tm tm;
+    if (localtime_r (&t, &tm) == nullptr)
+      throw system_error (errno, system_category ());
+
+    // If year is greater than 9999, we will overflow.
+    //
+    char buf[20]; // YYYY-MM-DD HH:MM:SS\0
+    if (strftime (buf, sizeof (buf), "%Y-%m-%d %H:%M:%S", &tm) == 0)
+      return os << "<beyond year 9999>";
+
+    os << buf;
+
+    using namespace chrono;
+
+    timestamp sec (system_clock::from_time_t (t));
+    nanoseconds ns (duration_cast<nanoseconds> (ts - sec));
+
+    if (ns != nanoseconds::zero ())
+    {
+      os << '.';
+      os.width (9);
+      os.fill ('0');
+      os << ns.count ();
+    }
+
+    return os;
+  }
+
+  ostream&
+  operator<< (ostream& os, duration d)
+  {
+    // @@ replace with put_time()
+    //
+
+    timestamp ts; // Epoch.
+    ts += d;
+
+    time_t t (system_clock::to_time_t (ts));
+
+    const char* fmt (nullptr);
+    if (t >= 365 * 12 * 24 * 60 * 60)
+      fmt = "%Y-%m-%d %H:%M:%S";
+    else if (t >= 12 * 24 * 60* 60)
+      fmt = "%m-%d %H:%M:%S";
+    else if (t >= 24 * 60* 60)
+      fmt = "%d %H:%M:%S";
+    else if (t >= 60 * 60)
+      fmt = "%H:%M:%S";
+    else if (t >= 60)
+      fmt = "%M:%S";
+    else if (t >= 1)
+      fmt = "%S";
+
+    if (fmt != nullptr)
+    {
+      std::tm tm;
+      if (gmtime_r (&t, &tm) == nullptr)
+        throw system_error (errno, system_category ());
+
+      char buf[20]; // YYYY-MM-DD HH:MM:SS\0
+      if (strftime (buf, sizeof (buf), fmt, &tm) == 0)
+        return os << "<beyond 9999 years>";
+
+      os << buf;
+    }
+
+    using namespace chrono;
+
+    timestamp sec (system_clock::from_time_t (t));
+    nanoseconds ns (duration_cast<nanoseconds> (ts - sec));
+
+    if (ns != nanoseconds::zero ())
+    {
+      os << '.';
+      os.width (9);
+      os.fill ('0');
+      os << ns.count ();
+    }
+    else if (fmt == 0)
+      os << '0';
+
+    return os;
+  }
+}