Adapt to fdstream extension

13 files changed, 311 insertions, 299 deletions

diff --git a/build2/b.cxx b/build2/b.cxx
index d16c0c6..748eda7 100644
--- a/build2/b.cxx
+++ b/build2/b.cxx
@@ -168,6 +168,9 @@ main (int argc, char* argv[])
         //
         return p.wait () ? 0 : 1;
       }
+      // Catch ios_base::failure as std::system_error together with the
+      // pager-specific exceptions.
+      //
       catch (const system_error& e)
       {
         error << "pager failed: " << e.what ();
diff --git a/build2/cli/module.cxx b/build2/cli/module.cxx
index e604bcf..a9bed86 100644
--- a/build2/cli/module.cxx
+++ b/build2/cli/module.cxx
@@ -102,34 +102,42 @@ namespace build2
           if (verb >= 3)
             print_process (args);
 
-          string ver;
           try
           {
             process pr (args, 0, -1); // Open pipe to stdout.
-            ifdstream is (pr.in_ofd);
 
-            // The version should be the last word on the first line.
-            //
-            getline (is, ver);
-            auto p (ver.rfind (' '));
-            if (p != string::npos)
-              ver = string (ver, p + 1);
+            try
+            {
+              ifdstream is (pr.in_ofd, fdstream_mode::skip);
 
-            // Skip until the end as cli doesn't handle writing to the closed
-            // pipe very well (SIGPIPE).
-            //
-            if (is.good ())
-              is.ignore (numeric_limits<streamsize>::max ());
+              // The version should be the last word on the first line.
+              //
+              string ver;
+              getline (is, ver);
+              auto p (ver.rfind (' '));
+              if (p != string::npos)
+                ver = string (ver, p + 1);
 
-            is.close (); // Don't block the other end.
+              is.close (); // Don't block the other end.
 
-            if (!pr.wait ())    // Presumably issued diagnostics.
-              return string (); // Not found.
+              if (pr.wait ())
+              {
+                if (ver.empty ())
+                  fail << "unexpected output from " << cli;
 
-            if (ver.empty ())
-              fail << "unexpected output from " << cli;
+                return ver;
+              }
 
-            return ver;
+              // Presumably issued diagnostics. Fall through.
+            }
+            catch (const ifdstream::failure&)
+            {
+              pr.wait ();
+
+              // Fall through.
+            }
+
+            // Fall through.
           }
           catch (const process_error& e)
           {
@@ -143,8 +151,10 @@ namespace build2
             if (e.child ())
               exit (1);
 
-            return string (); // Not found.
+            // Fall through.
           }
+
+          return string (); // Not found.
         };
 
         string ver;       // Empty means unconfigured.
diff --git a/build2/config/operation.cxx b/build2/config/operation.cxx
index 1b40832..617e74c 100644
--- a/build2/config/operation.cxx
+++ b/build2/config/operation.cxx
@@ -5,7 +5,6 @@
 #include <build2/config/operation>
 
 #include <set>
-#include <fstream>
 
 #include <build2/file>
 #include <build2/scope>
@@ -48,21 +47,19 @@ namespace build2
 
       try
       {
-        ofstream ofs (f.string ());
-        if (!ofs.is_open ())
-          fail << "unable to open " << f;
-
-        ofs.exceptions (ofstream::failbit | ofstream::badbit);
+        ofdstream ofs (f);
 
         ofs << "# Created automatically by the config module." << endl
             << "#" << endl
             << "src_root = ";
         to_stream (ofs, name (src_root), true, '@'); // Quote.
         ofs << endl;
+
+        ofs.close ();
       }
-      catch (const ofstream::failure&)
+      catch (const ofdstream::failure& e)
       {
-        fail << "unable to write " << f;
+        fail << "unable to write " << f << ": " << e.what ();
       }
     }
 
@@ -79,11 +76,7 @@ namespace build2
 
       try
       {
-        ofstream ofs (f.string ());
-        if (!ofs.is_open ())
-          fail << "unable to open " << f;
-
-        ofs.exceptions (ofstream::failbit | ofstream::badbit);
+        ofdstream ofs (f);
 
         ofs << "# Created automatically by the config module, but feel " <<
           "free to edit." << endl
@@ -248,10 +241,12 @@ namespace build2
               ofs << n << " = [null]" << endl;
           }
         }
+
+        ofs.close ();
       }
-      catch (const ofstream::failure&)
+      catch (const ofdstream::failure& e)
       {
-        fail << "unable to write " << f;
+        fail << "unable to write " << f << ": " << e.what ();
       }
     }
 
diff --git a/build2/cxx/common.cxx b/build2/cxx/common.cxx
index 0b66eb5..ec724a5 100644
--- a/build2/cxx/common.cxx
+++ b/build2/cxx/common.cxx
@@ -18,7 +18,10 @@ namespace build2
     lorder
     link_order (scope& bs, otype ot)
     {
-      const char* var;
+      // Initialize to suppress 'may be used uninitialized' warning produced by
+      // MinGW GCC 5.4.0.
+      //
+      const char* var (nullptr);
 
       switch (ot)
       {
diff --git a/build2/cxx/compile.cxx b/build2/cxx/compile.cxx
index 5205fdf..730ab5a 100644
--- a/build2/cxx/compile.cxx
+++ b/build2/cxx/compile.cxx
@@ -1042,180 +1042,184 @@ namespace build2
                         cid == "msvc" ? -2 : -1,
                         cid == "msvc" ? -1 : 2);
 
-            ifdstream is (cid == "msvc" ? pr.in_efd : pr.in_ofd,
-                          fdtranslate::text);
-
-            // In some cases we may need to ignore the error return
-            // status. The good_error flag keeps track of that. Similarly
-            // we sometimes expect the error return status based on the
-            // output we see. The bad_error flag is for that.
-            //
-            bool good_error (false), bad_error (false);
-
-            size_t skip (skip_count);
-            for (bool first (true), second (false); !(restart || is.eof ()); )
+            try
             {
-              string l;
-              getline (is, l);
+              // We may not read all the output (e.g., due to a restart).
+              // Before we used to just close the file descriptor to signal to
+              // the other end that we are not interested in the rest. This
+              // works fine with GCC but Clang (3.7.0) finds this impolite and
+              // complains, loudly (broken pipe). So now we are going to skip
+              // until the end.
+              //
+              ifdstream is (cid == "msvc" ? pr.in_efd : pr.in_ofd,
+                            fdstream_mode::text | fdstream_mode::skip,
+                            ifdstream::badbit);
+
+              // In some cases we may need to ignore the error return
+              // status. The good_error flag keeps track of that. Similarly
+              // we sometimes expect the error return status based on the
+              // output we see. The bad_error flag is for that.
+              //
+              bool good_error (false), bad_error (false);
 
-              if (is.fail ())
+              size_t skip (skip_count);
+              for (bool first (true), second (false);
+                   !(restart || is.eof ()); )
               {
-                if (is.eof ()) // Trailing newline.
-                  break;
+                string l;
+                getline (is, l);
 
-                fail << "unable to read C++ compiler header dependency output";
-              }
-
-              l6 ([&]{trace << "header dependency line '" << l << "'";});
-
-              // Parse different dependency output formats.
-              //
-              if (cid == "msvc")
-              {
-                if (first)
+                if (is.fail ())
                 {
-                  // The first line should be the file we are compiling. If it
-                  // is not, then something went wrong even before we could
-                  // compile anything (e.g., file does not exist). In this
-                  // case the first line (and everything after it) is
-                  // presumably diagnostics.
-                  //
-                  if (l != s.path ().leaf ().string ())
-                  {
-                    text << l;
-                    bad_error = true;
+                  if (is.eof ()) // Trailing newline.
                     break;
-                  }
 
-                  first = false;
-                  continue;
+                  throw ifdstream::failure ("");
                 }
 
-                string f (next_show (l, good_error));
-
-                if (f.empty ()) // Some other diagnostics.
-                {
-                  text << l;
-                  bad_error = true;
-                  break;
-                }
+                l6 ([&]{trace << "header dependency line '" << l << "'";});
 
-                // Skip until where we left off.
+                // Parse different dependency output formats.
                 //
-                if (skip != 0)
+                if (cid == "msvc")
                 {
-                  // We can't be skipping over a non-existent header.
-                  //
-                  assert (!good_error);
-                  skip--;
-                }
-                else
-                {
-                  restart = add (path (move (f)), false);
-                  skip_count++;
+                  if (first)
+                  {
+                    // The first line should be the file we are compiling. If
+                    // it is not, then something went wrong even before we
+                    // could compile anything (e.g., file does not exist). In
+                    // this case the first line (and everything after it) is
+                    // presumably diagnostics.
+                    //
+                    if (l != s.path ().leaf ().string ())
+                    {
+                      text << l;
+                      bad_error = true;
+                      break;
+                    }
+
+                    first = false;
+                    continue;
+                  }
 
-                  // If the header does not exist, we better restart.
-                  //
-                  assert (!good_error || restart);
+                  string f (next_show (l, good_error));
 
-                  if (restart)
-                    l6 ([&]{trace << "restarting";});
-                }
-              }
-              else
-              {
-                // Make dependency declaration.
-                //
-                size_t pos (0);
-
-                if (first)
-                {
-                  // Empty output should mean the wait() call below will
-                  // return false.
-                  //
-                  if (l.empty ())
+                  if (f.empty ()) // Some other diagnostics.
                   {
+                    text << l;
                     bad_error = true;
                     break;
                   }
 
-                  assert (l[0] == '^' && l[1] == ':' && l[2] == ' ');
-
-                  first = false;
-                  second = true;
-
-                  // While normally we would have the source file on the first
-                  // line, if too long, it will be moved to the next line and
-                  // all we will have on this line is "^: \".
+                  // Skip until where we left off.
                   //
-                  if (l.size () == 4 && l[3] == '\\')
-                    continue;
+                  if (skip != 0)
+                  {
+                    // We can't be skipping over a non-existent header.
+                    //
+                    assert (!good_error);
+                    skip--;
+                  }
                   else
-                    pos = 3; // Skip "^: ".
+                  {
+                    restart = add (path (move (f)), false);
+                    skip_count++;
 
-                  // Fall through to the 'second' block.
-                }
+                    // If the header does not exist, we better restart.
+                    //
+                    assert (!good_error || restart);
 
-                if (second)
-                {
-                  second = false;
-                  next_make (l, pos); // Skip the source file.
+                    if (restart)
+                      l6 ([&]{trace << "restarting";});
+                  }
                 }
-
-                while (pos != l.size ())
+                else
                 {
-                  string f (next_make (l, pos));
-
-                  // Skip until where we left off.
+                  // Make dependency declaration.
                   //
-                  if (skip != 0)
+                  size_t pos (0);
+
+                  if (first)
                   {
-                    skip--;
-                    continue;
+                    // Empty output should mean the wait() call below will
+                    // return false.
+                    //
+                    if (l.empty ())
+                    {
+                      bad_error = true;
+                      break;
+                    }
+
+                    assert (l[0] == '^' && l[1] == ':' && l[2] == ' ');
+
+                    first = false;
+                    second = true;
+
+                    // While normally we would have the source file on the
+                    // first line, if too long, it will be moved to the next
+                    // line and all we will have on this line is "^: \".
+                    //
+                    if (l.size () == 4 && l[3] == '\\')
+                      continue;
+                    else
+                      pos = 3; // Skip "^: ".
+
+                    // Fall through to the 'second' block.
                   }
 
-                  restart = add (path (move (f)), false);
-                  skip_count++;
+                  if (second)
+                  {
+                    second = false;
+                    next_make (l, pos); // Skip the source file.
+                  }
 
-                  if (restart)
+                  while (pos != l.size ())
                   {
-                    l6 ([&]{trace << "restarting";});
-                    break;
+                    string f (next_make (l, pos));
+
+                    // Skip until where we left off.
+                    //
+                    if (skip != 0)
+                    {
+                      skip--;
+                      continue;
+                    }
+
+                    restart = add (path (move (f)), false);
+                    skip_count++;
+
+                    if (restart)
+                    {
+                      l6 ([&]{trace << "restarting";});
+                      break;
+                    }
                   }
                 }
               }
-            }
 
-            // We may not have read all the output (e.g., due to a restart).
-            // Before we used to just close the file descriptor to signal to
-            // the other end that we are not interested in the rest. This
-            // works fine with GCC but Clang (3.7.0) finds this impolite and
-            // complains, loudly (broken pipe). So now we are going to skip
-            // until the end.
-            //
-            // Also, in case of VC++, we are parsing stderr and if things go
-            // south, we need to copy the diagnostics for the user to see.
-            //
-            if (!is.eof ())
-            {
-              if (cid == "msvc" && bad_error)
+              // In case of VC++, we are parsing stderr and if things go south,
+              // we need to copy the diagnostics for the user to see.
+              //
+              if (!is.eof () && cid == "msvc" && bad_error)
                 *diag_stream << is.rdbuf ();
-              else
-                is.ignore (numeric_limits<streamsize>::max ());
-            }
 
-            is.close ();
+              is.close ();
 
-            // We assume the child process issued some diagnostics.
-            //
-            if (!pr.wait ())
+              // We assume the child process issued some diagnostics.
+              //
+              if (!pr.wait ())
+              {
+                if (!good_error) // Ignore expected errors (restart).
+                  throw failed ();
+              }
+              else if (bad_error)
+                fail << "expected error exist status from C++ compiler";
+            }
+            catch (const ifdstream::failure&)
             {
-              if (!good_error) // Ignore expected errors (restart).
-                throw failed ();
+              pr.wait ();
+              fail << "unable to read C++ compiler header dependency output";
             }
-            else if (bad_error)
-              fail << "expected error exist status from C++ compiler";
-
           }
           catch (const process_error& e)
           {
diff --git a/build2/cxx/link.cxx b/build2/cxx/link.cxx
index e714bc1..19bf6d9 100644
--- a/build2/cxx/link.cxx
+++ b/build2/cxx/link.cxx
@@ -56,27 +56,31 @@ namespace build2
       try
       {
         process pr (args.data (), 0, -1); // Open pipe to stdout.
-        ifdstream is (pr.in_ofd);
 
-        while (!is.eof ())
+        try
         {
-          string s;
-          getline (is, s);
-
-          if (is.fail () && !is.eof ())
-            fail << "error reading C++ compiler -print-search-dirs output";
+          ifdstream is (pr.in_ofd, fdstream_mode::skip, ifdstream::badbit);
 
-          if (s.compare (0, 12, "libraries: =") == 0)
+          string s;
+          while (getline (is, s))
           {
-            l.assign (s, 12, string::npos);
-            break;
+            if (s.compare (0, 12, "libraries: =") == 0)
+            {
+              l.assign (s, 12, string::npos);
+              break;
+            }
           }
-        }
 
-        is.close (); // Don't block.
+          is.close (); // Don't block.
 
-        if (!pr.wait ())
-          throw failed ();
+          if (!pr.wait ())
+            throw failed ();
+        }
+        catch (const ifdstream::failure&)
+        {
+          pr.wait ();
+          fail << "error reading C++ compiler -print-search-dirs output";
+        }
       }
       catch (const process_error& e)
       {
@@ -1147,7 +1151,6 @@ namespace build2
               try
               {
                 ofdstream os (pr.out_fd);
-                os.exceptions (ofdstream::badbit | ofdstream::failbit);
 
                 // 1 is resource ID, 24 is RT_MANIFEST. We also need to escape
                 // Windows path backslashes.
@@ -1170,15 +1173,16 @@ namespace build2
                 os << "\"" << endl;
 
                 os.close ();
+
+                if (!pr.wait ())
+                  throw failed (); // Assume diagnostics issued.
               }
-              catch (const ofdstream::failure&)
+              catch (const ofdstream::failure& e)
               {
                 if (pr.wait ()) // Ignore if child failed.
-                  fail << "unable to pipe resource file to " << args[0];
+                  fail << "unable to pipe resource file to " << args[0]
+                       << ": " << e.what ();
               }
-
-              if (!pr.wait ())
-                throw failed (); // Assume diagnostics issued.
             }
             catch (const process_error& e)
             {
diff --git a/build2/cxx/msvc.cxx b/build2/cxx/msvc.cxx
index 97d8fd5..294ac03 100644
--- a/build2/cxx/msvc.cxx
+++ b/build2/cxx/msvc.cxx
@@ -89,56 +89,63 @@ namespace build2
       // redirect stderr to stdout.
       //
       process pr (start_run (args, false));
-      ifdstream is (pr.in_ofd);
 
       bool obj (false), dll (false);
-
       string s;
-      while (getline (is, s))
-      {
-        // Detect the one error we should let through.
-        //
-        if (s.compare (0, 18, "unable to execute ") == 0)
-          break;
 
-        // The lines we are interested in seem to have this form (though
-        // presumably the "Archive member name at" part can be translated):
-        //
-        // Archive member name at 746: [...]hello.dll[/][ ]*
-        // Archive member name at 8C70: [...]hello.lib.obj[/][ ]*
-        //
-        size_t n (s.size ());
-
-        for (; n != 0 && s[n - 1] == ' '; --n) ; // Skip trailing spaces.
+      try
+      {
+        ifdstream is (pr.in_ofd, fdstream_mode::skip, ifdstream::badbit);
 
-        if (n >= 7) // At least ": X.obj" or ": X.dll".
+        while (getline (is, s))
         {
-          --n;
-
-          if (s[n] == '/') // Skip trailing slash if one is there.
+          // Detect the one error we should let through.
+          //
+          if (s.compare (0, 18, "unable to execute ") == 0)
+            break;
+
+          // The lines we are interested in seem to have this form (though
+          // presumably the "Archive member name at" part can be translated):
+          //
+          // Archive member name at 746: [...]hello.dll[/][ ]*
+          // Archive member name at 8C70: [...]hello.lib.obj[/][ ]*
+          //
+          size_t n (s.size ());
+
+          for (; n != 0 && s[n - 1] == ' '; --n) ; // Skip trailing spaces.
+
+          if (n >= 7) // At least ": X.obj" or ": X.dll".
+          {
             --n;
 
-          n -= 3; // Beginning of extension.
+            if (s[n] == '/') // Skip trailing slash if one is there.
+              --n;
 
-          if (s[n] == '.')
-          {
-            // Make sure there is ": ".
-            //
-            size_t p (s.rfind (':', n - 1));
+            n -= 3; // Beginning of extension.
 
-            if (p != string::npos && s[p + 1] == ' ')
+            if (s[n] == '.')
             {
-              if (s.compare (n + 1, 3, "obj") == 0) // @@ CASE
-                obj = true;
-
-              if (s.compare (n + 1, 3, "dll") == 0) // @@ CASE
-                dll = true;
+              // Make sure there is ": ".
+              //
+              size_t p (s.rfind (':', n - 1));
+
+              if (p != string::npos && s[p + 1] == ' ')
+              {
+                if (s.compare (n + 1, 3, "obj") == 0) // @@ CASE
+                  obj = true;
+
+                if (s.compare (n + 1, 3, "dll") == 0) // @@ CASE
+                  dll = true;
+              }
             }
           }
         }
       }
-
-      is.close (); // Don't block.
+      catch (const ifdstream::failure&)
+      {
+        // Presumably the child process failed. Let finish_run() deal with
+        // that.
+      }
 
       if (!finish_run (args, false, pr, s))
         return otype::e;
diff --git a/build2/cxx/windows-manifest.cxx b/build2/cxx/windows-manifest.cxx
index cabc6ca..915610d 100644
--- a/build2/cxx/windows-manifest.cxx
+++ b/build2/cxx/windows-manifest.cxx
@@ -2,8 +2,6 @@
 // copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
 // license   : MIT; see accompanying LICENSE file
 
-#include <fstream>
-
 #include <build2/scope>
 #include <build2/target>
 #include <build2/context>
@@ -103,12 +101,19 @@ namespace build2
 
       if (file_exists (mf))
       {
-        ifstream ifs (mf.string ());
-        string s;
-        getline (ifs, s, '\0');
-
-        if (s == m)
-          return mf;
+        try
+        {
+          ifdstream ifs (mf);
+          string s;
+          getline (ifs, s, '\0');
+
+          if (s == m)
+            return mf;
+        }
+        catch (const ifdstream::failure&)
+        {
+          // Whatever the reason we failed for , let's rewrite the file.
+        }
       }
 
       if (verb >= 3)
@@ -116,14 +121,13 @@ namespace build2
 
       try
       {
-        ofstream ofs;
-        ofs.exceptions (ofstream::failbit | ofstream::badbit);
-        ofs.open (mf.string (), ofstream::out | ofstream::trunc);
+        ofdstream ofs (mf);
         ofs << m;
+        ofs.close ();
       }
-      catch (const ofstream::failure&)
+      catch (const ofdstream::failure& e)
       {
-        fail << "unable to write to " << m;
+        fail << "unable to write to " << m << ": " << e.what ();
       }
 
       return mf;
diff --git a/build2/cxx/windows-rpath.cxx b/build2/cxx/windows-rpath.cxx
index b5bad5e..b52315c 100644
--- a/build2/cxx/windows-rpath.cxx
+++ b/build2/cxx/windows-rpath.cxx
@@ -5,7 +5,6 @@
 #include <errno.h> // E*
 
 #include <set>
-#include <fstream>
 
 #include <build2/scope>
 #include <build2/context>
@@ -167,9 +166,7 @@ namespace build2
 
       try
       {
-        ofstream ofs;
-        ofs.exceptions (ofstream::failbit | ofstream::badbit);
-        ofs.open (am.string ());
+        ofdstream ofs (am);
 
         ofs << "<?xml version='1.0' encoding='UTF-8' standalone='yes'?>\n"
             << "<assembly xmlns='urn:schemas-microsoft-com:asm.v1'\n"
@@ -265,10 +262,12 @@ namespace build2
         }
 
         ofs << "</assembly>\n";
+
+        ofs.close ();
       }
-      catch (const ofstream::failure&)
+      catch (const ofdstream::failure& e)
       {
-        fail << "unable to write to " << am;
+        fail << "unable to write to " << am << ": " << e.what ();
       }
     }
   }
diff --git a/build2/file.cxx b/build2/file.cxx
index 9ab01ce..2030d1c 100644
--- a/build2/file.cxx
+++ b/build2/file.cxx
@@ -4,7 +4,6 @@
 
 #include <build2/file>
 
-#include <fstream>
 #include <iostream> // cin
 
 #include <butl/filesystem> // file_exists()
@@ -85,26 +84,23 @@ namespace build2
     {
       bool sin (bf.string () == "-");
 
-      ifstream ifs;
-      if (!sin)
-      {
-        ifs.open (bf.string ());
+      ifdstream ifs;
 
-        if (!ifs.is_open ())
-          fail << "unable to open " << bf;
-      }
+      if (!sin)
+        ifs.open (bf);
+      else
+        cin.exceptions (ifdstream::failbit | ifdstream::badbit);
 
-      istream& is (sin ? std::cin : ifs);
-      is.exceptions (ifstream::failbit | ifstream::badbit);
+      istream& is (sin ? cin : ifs);
 
       l5 ([&]{trace << "sourcing " << bf;});
 
       parser p (boot);
       p.parse_buildfile (is, bf, root, base);
     }
-    catch (const ifstream::failure&)
+    catch (const ifdstream::failure& e)
     {
-      fail << "unable to read buildfile " << bf;
+      fail << "unable to read buildfile " << bf << ": " << e.what ();
     }
   }
 
@@ -274,11 +270,7 @@ namespace build2
   {
     try
     {
-      ifstream ifs (bf.string ());
-      if (!ifs.is_open ())
-        fail << "unable to open " << bf;
-
-      ifs.exceptions (ifstream::failbit | ifstream::badbit);
+      ifdstream ifs (bf);
 
       lexer lex (ifs, bf);
       token t (lex.next ());
@@ -303,9 +295,9 @@ namespace build2
       assert (v != nullptr);
       return move (*v); // Steal the value, the scope is going away.
     }
-    catch (const ifstream::failure&)
+    catch (const ifdstream::failure& e)
     {
-      fail << "unable to read buildfile " << bf;
+      fail << "unable to read buildfile " << bf << ": " << e.what ();
     }
 
     return value (); // Never reaches.
@@ -973,11 +965,7 @@ namespace build2
 
     try
     {
-      ifstream ifs (es.string ());
-      if (!ifs.is_open ())
-        fail (loc) << "unable to open " << es;
-
-      ifs.exceptions (ifstream::failbit | ifstream::badbit);
+      ifdstream ifs (es);
 
       l5 ([&]{trace << "importing " << es;});
 
@@ -988,9 +976,9 @@ namespace build2
       parser p;
       return p.parse_export_stub (ifs, es, iroot, ts);
     }
-    catch (const ifstream::failure&)
+    catch (const ifdstream::failure& e)
     {
-      fail (loc) << "unable to read buildfile " << es;
+      fail (loc) << "unable to read buildfile " << es << ": " << e.what ();
     }
 
     return names (); // Never reached.
diff --git a/build2/parser.cxx b/build2/parser.cxx
index 04accd2..99e4227 100644
--- a/build2/parser.cxx
+++ b/build2/parser.cxx
@@ -5,7 +5,6 @@
 #include <build2/parser>
 
 #include <cctype>   // is{alpha alnum}()
-#include <fstream>
 #include <iostream>
 
 #include <build2/version>
@@ -735,12 +734,7 @@ namespace build2
 
       try
       {
-        ifstream ifs (p.string ());
-
-        if (!ifs.is_open ())
-          fail (l) << "unable to open " << p;
-
-        ifs.exceptions (ifstream::failbit | ifstream::badbit);
+        ifdstream ifs (p);
 
         l5 ([&]{trace (t) << "entering " << p;});
 
@@ -766,9 +760,9 @@ namespace build2
         lexer_ = ol;
         path_ = op;
       }
-      catch (const ifstream::failure&)
+      catch (const ifdstream::failure& e)
       {
-        fail (l) << "unable to read buildfile " << p;
+        fail (l) << "unable to read buildfile " << p << ": " << e.what ();
       }
     }
 
@@ -871,12 +865,7 @@ namespace build2
 
       try
       {
-        ifstream ifs (p.string ());
-
-        if (!ifs.is_open ())
-          fail (l) << "unable to open " << p;
-
-        ifs.exceptions (ifstream::failbit | ifstream::badbit);
+        ifdstream ifs (p);
 
         l5 ([&]{trace (t) << "entering " << p;});
 
@@ -908,9 +897,9 @@ namespace build2
         lexer_ = ol;
         path_ = op;
       }
-      catch (const ifstream::failure&)
+      catch (const ifdstream::failure& e)
       {
-        fail (l) << "unable to read buildfile " << p;
+        fail (l) << "unable to read buildfile " << p << ": " << e.what ();
       }
 
       scope_ = ocs;
diff --git a/build2/utility.cxx b/build2/utility.cxx
index 15a0aee..c43d048 100644
--- a/build2/utility.cxx
+++ b/build2/utility.cxx
@@ -126,7 +126,7 @@ namespace build2
     // want to let through is the inability to execute the program itself.
     // We cannot reserve a special exit status to signal this so we will
     // just have to compare the output. This particular situation will
-    // result in a single error line printed by run_start() above.
+    // result in a single error line printed by start_run() above.
     //
     if (l.compare (0, 18, "unable to execute ") == 0)
       fail << l;
diff --git a/build2/utility.txx b/build2/utility.txx
index bf9d9ab..a00f3fb 100644
--- a/build2/utility.txx
+++ b/build2/utility.txx
@@ -13,24 +13,30 @@ namespace build2
        sha256* checksum)
   {
     process pr (start_run (args, err));
-    ifdstream is (pr.in_ofd);
 
     T r;
-
     string l; // Last line of output.
-    while (is.peek () != ifdstream::traits_type::eof () && // Keep last line.
-           getline (is, l))
+
+    try
     {
-      trim (l);
+      ifdstream is (pr.in_ofd);
 
-      if (checksum != nullptr)
-        checksum->append (l);
+      while (is.peek () != ifdstream::traits_type::eof () && // Keep last line.
+             getline (is, l))
+      {
+        trim (l);
 
-      if (r.empty ())
-        r = f (l);
-    }
+        if (checksum != nullptr)
+          checksum->append (l);
 
-    is.close (); // Don't block.
+        if (r.empty ())
+          r = f (l);
+      }
+    }
+    catch (const ifdstream::failure&)
+    {
+      // Presumably the child process failed. Let finish_run() deal with that.
+    }
 
     if (!(finish_run (args, err, pr, l) || ignore_exit))
       r = T ();