Improve process execution diagnostics by reusing run_*() API

17 files changed, 250 insertions, 315 deletions

diff --git a/build2/bin/guess.cxx b/build2/bin/guess.cxx
index 780ccf8..795477e 100644
--- a/build2/bin/guess.cxx
+++ b/build2/bin/guess.cxx
@@ -78,7 +78,7 @@ namespace build2
         // (yes, it goes to stdout) but that seems harmless.
         //
         sha256 cs;
-        arr = run<guess_result> (arp, "--version", f, false, false, &cs);
+        arr = run<guess_result> (3, arp, "--version", f, false, false, &cs);
 
         if (!arr.empty ())
           arr.checksum = cs.string ();
@@ -101,7 +101,7 @@ namespace build2
         // Redirect STDERR to STDOUT and ignore exit status.
         //
         sha256 cs;
-        arr = run<guess_result> (arp, f, false, true, &cs);
+        arr = run<guess_result> (3, arp, f, false, true, &cs);
 
         if (!arr.empty ())
         {
@@ -142,7 +142,7 @@ namespace build2
           };
 
           sha256 cs;
-          rlr = run<guess_result> (rlp, "--version", f, false, false, &cs);
+          rlr = run<guess_result> (3, rlp, "--version", f, false, false, &cs);
 
           if (!rlr.empty ())
             rlr.checksum = cs.string ();
@@ -162,7 +162,7 @@ namespace build2
           // Redirect STDERR to STDOUT and ignore exit status.
           //
           sha256 cs;
-          rlr = run<guess_result> (rlp, f, false, true, &cs);
+          rlr = run<guess_result> (3, rlp, f, false, true, &cs);
 
           if (!rlr.empty ())
           {
@@ -224,7 +224,7 @@ namespace build2
         // but that seems harmless.
         //
         sha256 cs;
-        r = run<guess_result> (pp, "--version", f, false, true, &cs);
+        r = run<guess_result> (3, pp, "--version", f, false, true, &cs);
 
         if (!r.empty ())
           r.checksum = cs.string ();
@@ -255,7 +255,7 @@ namespace build2
         };
 
         sha256 cs;
-        r = run<guess_result> (pp, "-v", f, false, false, &cs);
+        r = run<guess_result> (3, pp, "-v", f, false, false, &cs);
 
         if (!r.empty ())
           r.checksum = cs.string ();
@@ -282,7 +282,7 @@ namespace build2
         // option.
         //
         sha256 cs;
-        r = run<guess_result> (pp, "-version", f, false, false, &cs);
+        r = run<guess_result> (3, pp, "-version", f, false, false, &cs);
 
         if (!r.empty ())
           r.checksum = cs.string ();
@@ -322,7 +322,7 @@ namespace build2
         // option.
         //
         sha256 cs;
-        r = run<guess_result> (pp, "--version", f, false, false, &cs);
+        r = run<guess_result> (3, pp, "--version", f, false, false, &cs);
 
         if (!r.empty ())
           r.checksum = cs.string ();
@@ -342,7 +342,7 @@ namespace build2
         };
 
         sha256 cs;
-        r = run<guess_result> (pp, "/?", f, false, false, &cs);
+        r = run<guess_result> (3, pp, "/?", f, false, false, &cs);
 
         if (!r.empty ())
           r.checksum = cs.string ();
diff --git a/build2/bin/init.cxx b/build2/bin/init.cxx
index ef4b3df..d9f3c0e 100644
--- a/build2/bin/init.cxx
+++ b/build2/bin/init.cxx
@@ -250,7 +250,8 @@ namespace build2
           //
           if (!hint && ops.config_sub_specified ())
           {
-            s = run<string> (ops.config_sub (),
+            s = run<string> (3,
+                             ops.config_sub (),
                              s.c_str (),
                              [] (string& l) {return move (l);});
             l5 ([&]{trace << "config.sub target: '" << s << "'";});
diff --git a/build2/cc/compile.cxx b/build2/cc/compile.cxx
index d73e67c..3b60a5b 100644
--- a/build2/cc/compile.cxx
+++ b/build2/cc/compile.cxx
@@ -2723,7 +2723,7 @@ namespace build2
               continue;
             }
             else
-              fail << args[0] << " terminated abnormally: " << e.description ();
+              run_finish (args, pr); // Throws.
           }
           catch (const process_error& e)
           {
@@ -3012,7 +3012,7 @@ namespace build2
             info << "then run failing command to display compiler diagnostics";
         }
         else
-          fail << args[0] << " terminated abnormally: " << e.description ();
+          run_finish (args, pr); // Throws.
       }
       catch (const process_error& e)
       {
@@ -4489,17 +4489,12 @@ namespace build2
           catch (const io_error&) {} // Assume exits with error.
         }
 
-        if (!pr.wait ())
-          throw failed ();
+        run_finish (args, pr);
       }
       catch (const process_error& e)
       {
         error << "unable to execute " << args[0] << ": " << e;
 
-        // 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).
-        //
         if (e.child)
           exit (1);
 
@@ -4541,8 +4536,7 @@ namespace build2
                       nullptr, // CWD
                       env.empty () ? nullptr : env.data ());
 
-          if (!pr.wait ())
-            throw failed ();
+          run_finish (args, pr);
         }
         catch (const process_error& e)
         {
diff --git a/build2/cc/gcc.cxx b/build2/cc/gcc.cxx
index ce1450e..0ce4c4f 100644
--- a/build2/cc/gcc.cxx
+++ b/build2/cc/gcc.cxx
@@ -180,57 +180,43 @@ namespace build2
       if (verb >= 3)
         print_process (args);
 
+      process pr (run_start (xc, args.data (), -1)); // Open pipe to stdout.
+
       string l;
       try
       {
-        process pr (xc, args.data (), 0, -1); // Open pipe to stdout.
-
-        try
+        ifdstream is (
+          move (pr.in_ofd), fdstream_mode::skip, ifdstream::badbit);
+
+        // The output of -print-search-dirs are a bunch of lines that start
+        // with "<name>: =" where name can be "install", "programs", or
+        // "libraries". If you have English locale, that is. If you set your
+        // LC_ALL="tr_TR", then it becomes "kurulum", "programlar", and
+        // "kitapl?klar". Also, Clang omits "install" while GCC and Intel icc
+        // print all three. The "libraries" seem to be alwasy last, however.
+        //
+        string s;
+        for (bool found (false); !found && getline (is, s); )
         {
-          ifdstream is (
-            move (pr.in_ofd), fdstream_mode::skip, ifdstream::badbit);
-
-          // The output of -print-search-dirs are a bunch of lines that start
-          // with "<name>: =" where name can be "install", "programs", or
-          // "libraries". If you have English locale, that is. If you set your
-          // LC_ALL="tr_TR", then it becomes "kurulum", "programlar", and
-          // "kitapl?klar". Also, Clang omits "install" while GCC and Intel
-          // icc print all three. The "libraries" seem to be alwasy last,
-          // however.
-          //
-          string s;
-          for (bool found (false); !found && getline (is, s); )
-          {
-            found = (s.compare (0, 12, "libraries: =") == 0);
-
-            size_t p (found ? 9 : s.find (": ="));
-
-            if (p != string::npos)
-              l.assign (s, p + 3, string::npos);
-          }
+          found = (s.compare (0, 12, "libraries: =") == 0);
 
-          is.close (); // Don't block.
+          size_t p (found ? 9 : s.find (": ="));
 
-          if (!pr.wait ())
-            throw failed (); // Assume issued diagnostics to stderr.
-        }
-        catch (const io_error&)
-        {
-          pr.wait ();
-          fail << "error reading " << x_lang << " compiler -print-search-dirs "
-               << "output";
+          if (p != string::npos)
+            l.assign (s, p + 3, string::npos);
         }
+
+        is.close (); // Don't block.
       }
-      catch (const process_error& e)
+      catch (const io_error&)
       {
-        error << "unable to execute " << args[0] << ": " << e;
-
-        if (e.child)
-          exit (1);
-
-        throw failed ();
+        pr.wait ();
+        fail << "error reading " << x_lang << " compiler -print-search-dirs "
+             << "output";
       }
 
+      run_finish (args, pr);
+
       if (l.empty ())
         fail << "unable to extract " << x_lang << " compiler system library "
              << "search paths";
diff --git a/build2/cc/guess.cxx b/build2/cc/guess.cxx
index 6dea97d..c39c02e 100644
--- a/build2/cc/guess.cxx
+++ b/build2/cc/guess.cxx
@@ -248,7 +248,7 @@ namespace build2
         // Suppress all the compiler errors because we may be trying an
         // unsupported option.
         //
-        r = run<guess_result> (pp, "-v", f, false, false, &cs);
+        r = run<guess_result> (3, pp, "-v", f, false, false, &cs);
 
         if (!r.empty ())
         {
@@ -284,7 +284,7 @@ namespace build2
           return guess_result ();
         };
 
-        r = run<guess_result> (pp, "--version", f, false);
+        r = run<guess_result> (3, pp, "--version", f, false);
       }
 
       // Finally try to run it without any options to detect msvc.
@@ -317,7 +317,7 @@ namespace build2
           return guess_result ();
         };
 
-        r = run<guess_result> (pp, f, false);
+        r = run<guess_result> (3, pp, f, false);
       }
 
       if (!r.empty ())
@@ -487,7 +487,7 @@ namespace build2
       //
       auto f = [] (string& l) {return move (l);};
 
-      string t (run<string> (args.data (), f, false));
+      string t (run<string> (3, args.data (), f, false));
 
       if (t.empty ())
       {
@@ -495,7 +495,7 @@ namespace build2
                       << "falling back to -dumpmachine";});
 
         args[1] = "-dumpmachine";
-        t = run<string> (args.data (), f);
+        t = run<string> (3, args.data (), f);
       }
 
       if (t.empty ())
@@ -609,7 +609,7 @@ namespace build2
       // The output of -dumpmachine is a single line containing just the
       // target triplet.
       //
-      string t (run<string> (args.data (), [] (string& l) {return move (l);}));
+      string t (run<string> (3, args.data (), [](string& l) {return move (l);}));
 
       if (t.empty ())
         fail << "unable to extract target architecture from " << xc
@@ -682,7 +682,7 @@ namespace build2
 
       // The -V output is sent to STDERR.
       //
-      s = run<string> (xc, "-V", f, false);
+      s = run<string> (3, xc, "-V", f, false);
 
       if (s.empty ())
         fail << "unable to extract signature from " << xc << " -V output";
@@ -781,7 +781,7 @@ namespace build2
 
       // The -V output is sent to STDERR.
       //
-      string t (run<string> (args.data (), f, false));
+      string t (run<string> (3, args.data (), f, false));
 
       if (t.empty ())
         fail << "unable to extract target architecture from " << xc
@@ -823,7 +823,7 @@ namespace build2
       // on which we are running), who knows what will happen in the future.
       // So instead we are going to use -dumpmachine and substitute the CPU.
       //
-      t = run<string> (xc, "-dumpmachine", [] (string& l) {return move (l);});
+      t = run<string> (3, xc, "-dumpmachine", [](string& l) {return move (l);});
 
       if (t.empty ())
         fail << "unable to extract target architecture from " << xc
diff --git a/build2/cc/link.cxx b/build2/cc/link.cxx
index c0ff10c..f69d549 100644
--- a/build2/cc/link.cxx
+++ b/build2/cc/link.cxx
@@ -1297,9 +1297,6 @@ namespace build2
                 os << "\"" << endl;
 
                 os.close ();
-
-                if (!pr.wait ())
-                  throw failed (); // Assume diagnostics issued.
               }
               catch (const io_error& e)
               {
@@ -1307,6 +1304,8 @@ namespace build2
                   fail << "unable to pipe resource file to " << args[0]
                        << ": " << e;
               }
+
+              run_finish (args, pr);
             }
             catch (const process_error& e)
             {
@@ -1963,8 +1962,7 @@ namespace build2
           catch (const io_error&) {} // Assume exits with error.
         }
 
-        if (!pr.wait ())
-          throw failed ();
+        run_finish (args, pr);
       }
       catch (const process_error& e)
       {
@@ -1997,22 +1995,7 @@ namespace build2
         if (verb >= 2)
           print_process (args);
 
-        try
-        {
-          process pr (rl, args);
-
-          if (!pr.wait ())
-            throw failed ();
-        }
-        catch (const process_error& e)
-        {
-          error << "unable to execute " << args[0] << ": " << e;
-
-          if (e.child)
-            exit (1);
-
-          throw failed ();
-        }
+        run (rl, args);
       }
 
       if (tclass == "windows")
diff --git a/build2/cc/module.cxx b/build2/cc/module.cxx
index 9fbae4b..d4962a4 100644
--- a/build2/cc/module.cxx
+++ b/build2/cc/module.cxx
@@ -119,7 +119,8 @@ namespace build2
 
         if (ops.config_sub_specified ())
         {
-          ct = run<string> (ops.config_sub (),
+          ct = run<string> (3,
+                            ops.config_sub (),
                             ci.target.c_str (),
                             [] (string& l) {return move (l);});
           l5 ([&]{trace << "config.sub target: '" << ct << "'";});
diff --git a/build2/cc/msvc.cxx b/build2/cc/msvc.cxx
index a4c4317..59bb55c 100644
--- a/build2/cc/msvc.cxx
+++ b/build2/cc/msvc.cxx
@@ -151,10 +151,13 @@ namespace build2
                             l.string ().c_str (),
                             nullptr};
 
+      if (verb >= 3)
+        print_process (args);
+
       // Link.exe seem to always dump everything to stdout but just in case
       // redirect stderr to stdout.
       //
-      process pr (run_start (ld, args, false));
+      process pr (run_start (ld, args, -1 /* stdout */, false /* error */));
 
       bool obj (false), dll (false);
       string s;
diff --git a/build2/cli/init.cxx b/build2/cli/init.cxx
index d257efa..c698fd2 100644
--- a/build2/cli/init.cxx
+++ b/build2/cli/init.cxx
@@ -107,6 +107,8 @@ namespace build2
         {
           const char* args[] = {cli.string ().c_str (), "--version", nullptr};
 
+          // @@ TODO: redo using run_start()/run_finish().
+
           try
           {
             pp = process::path_search (cli, true); // Can throw.
diff --git a/build2/cli/rule.cxx b/build2/cli/rule.cxx
index 83774a3..d05b190 100644
--- a/build2/cli/rule.cxx
+++ b/build2/cli/rule.cxx
@@ -283,25 +283,9 @@ namespace build2
       else if (verb)
         text << "cli " << s;
 
-      try
-      {
-        process pr (cli, args.data ());
-
-        if (!pr.wait ())
-          throw failed ();
-
-        t.mtime (system_clock::now ());
-      }
-      catch (const process_error& e)
-      {
-        error << "unable to execute " << args[0] << ": " << e;
-
-        if (e.child)
-          exit (1);
-
-        throw failed ();
-      }
+      run (cli, args);
 
+      t.mtime (system_clock::now ());
       return target_state::changed;
     }
   }
diff --git a/build2/context.cxx b/build2/context.cxx
index cfd925b..73717be 100644
--- a/build2/context.cxx
+++ b/build2/context.cxx
@@ -477,7 +477,7 @@ namespace build2
       //
       string orig (
         ops.config_guess_specified ()
-        ? run<string> (ops.config_guess (), [] (string& l) {return move (l);})
+        ? run<string> (3, ops.config_guess (), [](string& l) {return move (l);})
         : BUILD2_HOST_TRIPLET);
 
       l5 ([&]{trace << "original host: '" << orig << "'";});
diff --git a/build2/dist/operation.cxx b/build2/dist/operation.cxx
index 7539fc1..7644ba9 100644
--- a/build2/dist/operation.cxx
+++ b/build2/dist/operation.cxx
@@ -395,22 +395,7 @@ namespace build2
       else if (verb)
         text << "dist -d " << d;
 
-      try
-      {
-        process pr (cmd, args.data ());
-
-        if (!pr.wait ())
-          throw failed ();
-      }
-      catch (const process_error& e)
-      {
-        error << "unable to execute " << args[0] << ": " << e;
-
-        if (e.child)
-          exit (1);
-
-        throw failed ();
-      }
+      run (cmd, args);
     }
 
     // install <file> <dir>
@@ -449,22 +434,7 @@ namespace build2
       else if (verb)
         text << "dist " << t;
 
-      try
-      {
-        process pr (cmd, args.data ());
-
-        if (!pr.wait ())
-          throw failed ();
-      }
-      catch (const process_error& e)
-      {
-        error << "unable to execute " << args[0] << ": " << e;
-
-        if (e.child)
-          exit (1);
-
-        throw failed ();
-      }
+      run (cmd, args);
 
       return d / relf.leaf ();
     }
@@ -494,31 +464,16 @@ namespace build2
         args = {"tar", "-a", "-cf",
                 ap.string ().c_str (), pkg.c_str (), nullptr};
 
-      try
-      {
-        process_path pp (process::path_search (args[0]));
-
-        if (verb >= 2)
-          print_process (args);
-        else if (verb)
-          text << args[0] << " " << ap;
+      process_path pp (run_search (args[0]));
 
-        // Change child's working directory to dist_root.
-        //
-        process pr (pp, args.data (), 0, 1, 2, root.string ().c_str ());
-
-        if (!pr.wait ())
-          throw failed ();
-      }
-      catch (const process_error& e)
-      {
-        error << "unable to execute " << args[0] << ": " << e;
-
-        if (e.child)
-          exit (1);
+      if (verb >= 2)
+        print_process (args);
+      else if (verb)
+        text << args[0] << " " << ap;
 
-        throw failed ();
-      }
+      // Change child's working directory to dist_root.
+      //
+      run (pp, args, root);
     }
 
     const meta_operation_info mo_dist {
diff --git a/build2/install/rule.cxx b/build2/install/rule.cxx
index 75de96f..79287f8 100644
--- a/build2/install/rule.cxx
+++ b/build2/install/rule.cxx
@@ -553,29 +553,14 @@ namespace build2
       args.push_back (reld.c_str ());
       args.push_back (nullptr);
 
-      try
-      {
-        process_path pp (process::path_search (args[0]));
-
-        if (verb >= 2)
-          print_process (args);
-        else if (verb && verbose)
-          text << "install " << chd;
-
-        process pr (pp, args.data ());
-
-        if (!pr.wait ())
-          throw failed ();
-      }
-      catch (const process_error& e)
-      {
-        error << "unable to execute " << args[0] << ": " << e;
+      process_path pp (run_search (args[0]));
 
-        if (e.child)
-          exit (1);
+      if (verb >= 2)
+        print_process (args);
+      else if (verb && verbose)
+        text << "install " << chd;
 
-        throw failed ();
-      }
+      run (pp, args);
     }
 
     // install <file> <dir>/
@@ -622,29 +607,14 @@ namespace build2
       args.push_back (reld.c_str ());
       args.push_back (nullptr);
 
-      try
-      {
-        process_path pp (process::path_search (args[0]));
+      process_path pp (run_search (args[0]));
 
-        if (verb >= 2)
-          print_process (args);
-        else if (verb && verbose)
-          text << "install " << t;
+      if (verb >= 2)
+        print_process (args);
+      else if (verb && verbose)
+        text << "install " << t;
 
-        process pr (pp, args.data ());
-
-        if (!pr.wait ())
-          throw failed ();
-      }
-      catch (const process_error& e)
-      {
-        error << "unable to execute " << args[0] << ": " << e;
-
-        if (e.child)
-          exit (1);
-
-        throw failed ();
-      }
+      run (pp, args);
     }
 
     void file_rule::
@@ -672,29 +642,14 @@ namespace build2
 
       const char** args (&args_a[base.sudo == nullptr ? 1 : 0]);
 
-      try
-      {
-        process_path pp (process::path_search (args[0]));
-
-        if (verb >= 2)
-          print_process (args);
-        else if (verb && verbose)
-          text << "install " << rell << " -> " << target;
-
-        process pr (pp, args);
-
-        if (!pr.wait ())
-          throw failed ();
-      }
-      catch (const process_error& e)
-      {
-        error << "unable to execute " << args[0] << ": " << e;
+      process_path pp (run_search (args[0]));
 
-        if (e.child)
-          exit (1);
+      if (verb >= 2)
+        print_process (args);
+      else if (verb && verbose)
+        text << "install " << rell << " -> " << target;
 
-        throw failed ();
-      }
+      run (pp, args);
     }
 
     target_state file_rule::
@@ -839,29 +794,14 @@ namespace build2
 
           const char** args (&args_a[base.sudo == nullptr ? 1 : 0]);
 
-          try
-          {
-            process_path pp (process::path_search (args[0]));
-
-            if (verb >= 2)
-              print_process (args);
-            else if (verb && verbose)
-              text << "uninstall " << reld;
-
-            process pr (pp, args);
+          process_path pp (run_search (args[0]));
 
-            if (!pr.wait ())
-              throw failed ();
-          }
-          catch (const process_error& e)
-          {
-            error << "unable to execute " << args[0] << ": " << e;
-
-            if (e.child)
-              exit (1);
+          if (verb >= 2)
+            print_process (args);
+          else if (verb && verbose)
+            text << "uninstall " << reld;
 
-            throw failed ();
-          }
+          run (pp, args);
         }
       }
 
@@ -942,27 +882,12 @@ namespace build2
 
         const char** args (&args_a[base.sudo == nullptr ? 1 : 0]);
 
-        try
-        {
-          process_path pp (process::path_search (args[0]));
-
-          if (verb >= 2)
-            print_process (args);
-
-          process pr (pp, args);
+        process_path pp (run_search (args[0]));
 
-          if (!pr.wait ())
-            throw failed ();
-        }
-        catch (const process_error& e)
-        {
-          error << "unable to execute " << args[0] << ": " << e;
-
-          if (e.child)
-            exit (1);
+        if (verb >= 2)
+          print_process (args);
 
-          throw failed ();
-        }
+        run (pp, args);
       }
 
       return true;
diff --git a/build2/utility.cxx b/build2/utility.cxx
index df19b92..e8e5fe9 100644
--- a/build2/utility.cxx
+++ b/build2/utility.cxx
@@ -208,29 +208,32 @@ namespace build2
   }
 
   process
-  run_start (const process_path& pp, const char* args[], bool err)
+  run_start (const process_path& pp,
+             const char* args[],
+             int out,
+             bool err,
+             const dir_path& cwd)
+  try
   {
     assert (args[0] == pp.recall_string ());
-
-    if (verb >= 3)
-      print_process (args);
-
-    try
-    {
-      return process (pp, args, 0, -1, (err ? 2 : 1));
-    }
-    catch (const process_error& e)
+    return process (pp, args, 0, out, (err ? 2 : 1), cwd.string ().c_str ());
+  }
+  catch (const process_error& e)
+  {
+    if (e.child)
     {
-      if (e.child)
-      {
-        // Note: run_finish() expects this exact message.
-        //
-        cerr << "unable to execute " << args[0] << ": " << e << endl;
-        exit (1);
-      }
-      else
-        fail << "unable to execute " << args[0] << ": " << e << endf;
+      // Note: run_finish() expects this exact message.
+      //
+      cerr << "unable to execute " << args[0] << ": " << e << endl;
+
+      // 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).
+      //
+      exit (1);
     }
+    else
+      fail << "unable to execute " << args[0] << ": " << e << endf;
   }
 
   bool
@@ -240,6 +243,14 @@ namespace build2
     if (pr.wait ())
       return true;
 
+    const process_exit& e (*pr.exit);
+
+    if (!e.normal ())
+      fail << "process " << args[0] << " terminated abnormally: "
+           << e.description () << (e.core () ? " (core dumped)" : "");
+
+    // Normall but non-zero exit status.
+    //
     if (err)
       // Assuming diagnostics has already been issued (to STDERR).
       //
diff --git a/build2/utility.hxx b/build2/utility.hxx
index 77c46a8..db6460c 100644
--- a/build2/utility.hxx
+++ b/build2/utility.hxx
@@ -166,12 +166,16 @@ namespace build2
 
   // Basic process utilities.
   //
+  // The run*() functions with process_path assume that you are printing
+  // the process command line yourself.
 
-  // Start a process with the specified arguments printing the command at
-  // verbosity level 3 and higher. Redirect STDOUT to a pipe. If error is
-  // false, then redirecting STDERR to STDOUT (this can be used to suppress
-  // diagnostics from the child process). Issue diagnostics and throw failed
-  // in case of an error.
+  extern uint16_t verb; // diagnostics.hxx
+
+  void
+  print_process (const char* const*, size_t); // diagnostics.hxx
+
+  // Search for a process executable. Issue diagnostics and throw failed in
+  // case of an error.
   //
   process_path
   run_search (const char*& args0);
@@ -179,20 +183,88 @@ namespace build2
   process_path
   run_search (const path&, bool init, const dir_path& fallback = dir_path ());
 
+  // Wait for process termination. Issue diagnostics and throw failed in case
+  // of abnormal termination. If the process has terminated normally but with
+  // a non-zero exit status, then, if error is true, assume the diagnostics
+  // has already been issued and throw failed as well. Otherwise (error is
+  // false), return false. The last argument is used in cooperation with
+  // run_start() in case STDERR is redirected to STDOUT.
+  //
+  bool
+  run_finish (const char* args[],
+              process&,
+              bool error = true,
+              const string& = string ());
+
+  inline void
+  run_finish (cstrings& args, process& pr)
+  {
+    run_finish (args.data (), pr);
+  }
+
+  // Start a process with the specified arguments. If out is -1, redirect
+  // STDOUT to a pipe. If error is false, then redirecting STDERR to STDOUT
+  // (this can be used to suppress diagnostics from the child process). Issue
+  // diagnostics and throw failed in case of an error.
+  //
   process
-  run_start (const process_path&, const char* args[], bool error = true);
+  run_start (const process_path&,
+             const char* args[],
+             int out,
+             bool error = true,
+             const dir_path& cwd = dir_path ());
+
+  inline void
+  run (const process_path& p,
+       const char* args[],
+       const dir_path& cwd = dir_path ())
+  {
+    process pr (run_start (p, args, 1 /* stdout */, true, cwd));
+    run_finish (args, pr);
+  }
 
+  inline void
+  run (const process_path& p,
+       cstrings& args,
+       const dir_path& cwd = dir_path ())
+  {
+    run (p, args.data (), cwd);
+  }
+
+  // As above, but search for the process (including updating args[0]) and
+  // print the process commands line at the specified verbosity level.
+  //
   inline process
-  run_start (const char* args[], bool error = true)
+  run_start (uint16_t verbosity,
+             const char* args[],
+             int out,
+             bool error = true,
+             const dir_path& cwd = dir_path ())
   {
-    return run_start (run_search (args[0]), args, error);
+    process_path pp (run_search (args[0]));
+
+    if (verb >= verbosity)
+      print_process (args, 0);
+
+    return run_start (pp, args, out, error, cwd);
   }
 
-  bool
-  run_finish (const char* args[],
-              process&,
-              bool error = true,
-              const string& = string ());
+  inline void
+  run (uint16_t verbosity,
+       const char* args[],
+       const dir_path& cwd = dir_path ())
+  {
+    process pr (run_start (verbosity, args, 1 /* stdout */, true, cwd));
+    run_finish (args, pr);
+  }
+
+  inline void
+  run (uint16_t verbosity,
+       cstrings& args,
+       const dir_path& cwd = dir_path ())
+  {
+    run (verbosity, args.data (), cwd);
+  }
 
   // Start the process as above and then call the specified function on each
   // trimmed line of the output until it returns a non-empty object T (tested
@@ -220,40 +292,50 @@ namespace build2
 
   template <typename T, typename F>
   inline T
-  run (const char* args[],
+  run (uint16_t verbosity,
+       const char* args[],
        F&& f,
        bool error = true,
        bool ignore_exit = false,
        sha256* checksum = nullptr)
   {
-    return run<T> (
-      run_search (
-        args[0]), args, forward<F> (f), error, ignore_exit, checksum);
+    process_path pp (run_search (args[0]));
+
+    if (verb >= verbosity)
+      print_process (args, 0);
+
+    return run<T> (pp, args, forward<F> (f), error, ignore_exit, checksum);
   }
 
   // run <prog>
   //
   template <typename T, typename F>
   inline T
-  run (const path& prog,
+  run (uint16_t verb,
+       const path& prog,
        F&& f,
        bool error = true,
        bool ignore_exit = false,
        sha256* checksum = nullptr)
   {
     const char* args[] = {prog.string ().c_str (), nullptr};
-    return run<T> (args, forward<F> (f), error, ignore_exit, checksum);
+    return run<T> (verb, args, forward<F> (f), error, ignore_exit, checksum);
   }
 
   template <typename T, typename F>
   inline T
-  run (const process_path& pp,
+  run (uint16_t verbosity,
+       const process_path& pp,
        F&& f,
        bool error = true,
        bool ignore_exit = false,
        sha256* checksum = nullptr)
   {
     const char* args[] = {pp.recall_string (), nullptr};
+
+    if (verb >= verbosity)
+      print_process (args, 0);
+
     return run<T> (pp, args, forward<F> (f), error, ignore_exit, checksum);
   }
 
@@ -261,7 +343,8 @@ namespace build2
   //
   template <typename T, typename F>
   inline T
-  run (const path& prog,
+  run (uint16_t verb,
+       const path& prog,
        const char* arg,
        F&& f,
        bool error = true,
@@ -269,12 +352,13 @@ namespace build2
        sha256* checksum = nullptr)
   {
     const char* args[] = {prog.string ().c_str (), arg, nullptr};
-    return run<T> (args, forward<F> (f), error, ignore_exit, checksum);
+    return run<T> (verb, args, forward<F> (f), error, ignore_exit, checksum);
   }
 
   template <typename T, typename F>
   inline T
-  run (const process_path& pp,
+  run (uint16_t verbosity,
+       const process_path& pp,
        const char* arg,
        F&& f,
        bool error = true,
@@ -282,6 +366,10 @@ namespace build2
        sha256* checksum = nullptr)
   {
     const char* args[] = {pp.recall_string (), arg, nullptr};
+
+    if (verb >= verbosity)
+      print_process (args, 0);
+
     return run<T> (pp, args, forward<F> (f), error, ignore_exit, checksum);
   }
 
diff --git a/build2/utility.txx b/build2/utility.txx
index d195ea6..6ca245f 100644
--- a/build2/utility.txx
+++ b/build2/utility.txx
@@ -65,7 +65,7 @@ namespace build2
        bool ignore_exit,
        sha256* checksum)
   {
-    process pr (run_start (pp, args, err));
+    process pr (run_start (pp, args, -1 /* stdout */, err));
 
     T r;
     string l; // Last line of output.
diff --git a/build2/version/snapshot-git.cxx b/build2/version/snapshot-git.cxx
index 9ff1cc9..bf863ce 100644
--- a/build2/version/snapshot-git.cxx
+++ b/build2/version/snapshot-git.cxx
@@ -30,7 +30,7 @@ namespace build2
       {
         const char* args[] {"git", "-C", d, "status", "--porcelain", nullptr};
 
-        if (!run<string> (args, [] (string& s) {return move (s);}).empty ())
+        if (!run<string> (3, args, [](string& s) {return move (s);}).empty ())
           return r;
       }
 
@@ -49,7 +49,7 @@ namespace build2
 
       const char* args[] {
         "git", "-C", d, "cat-file", "commit", "HEAD", nullptr};
-      process pr (run_start (args));
+      process pr (run_start (3 /* verbosity */, args, -1 /* stdout */));
 
       try
       {
@@ -116,7 +116,9 @@ namespace build2
         // that.
       }
 
-      if (!run_finish (args, pr) || r.sn == 0)
+      run_finish (args, pr);
+
+      if (r.sn == 0)
         fail << "unable to extract git commit id/date for " << src_root;
 
       sha1 cs;