From f3f46a1656207a1c681e7c53cc3bd2c9a28fa887 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 4 Sep 2015 13:38:27 +0200
Subject: Allow calling process::wait() multiple types, make process move-only

---
 butl/process     | 11 ++++++++++-
 butl/process.cxx | 12 +++++++-----
 butl/process.ixx | 11 +++++++++++
 3 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/butl/process b/butl/process
index c810b58..534ad88 100644
--- a/butl/process
+++ b/butl/process
@@ -67,23 +67,32 @@ namespace butl
 
     // 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.
+    // process_error if anything goes wrong. This function can be
+    // called multiple times with subsequent calls simply returning
+    // the status.
     //
     bool
     wait ();
 
     ~process () {if (id != 0) wait ();}
 
+    // Move constructible-only type.
+    //
+    process (process&&);
+    process& operator= (process&&) = delete;
+
     process (const process&) = delete;
     process& operator= (const process&) = delete;
 
 #ifndef _WIN32
     typedef pid_t id_type;
+    typedef int status_type;
 #else
     typedef void* id_type; // Win32 HANDLE.
 #endif
 
     id_type id;
+    status_type status;
 
     int out_fd; // Write to this fd to send to the new process' stdin.
     int in_ofd; // Read from this fd to receive from the new process' stdout.
diff --git a/butl/process.cxx b/butl/process.cxx
index 9025bdb..194ea4e 100644
--- a/butl/process.cxx
+++ b/butl/process.cxx
@@ -108,12 +108,14 @@ namespace butl
   bool process::
   wait ()
   {
-    int status;
-    int r (waitpid (id, &status, 0));
-    id = 0; // We have tried.
+    if (id != 0)
+    {
+      int r (waitpid (id, &status, 0));
+      id = 0; // We have tried.
 
-    if (r == -1)
-      throw process_error (errno, false);
+      if (r == -1)
+        throw process_error (errno, false);
+    }
 
     return WIFEXITED (status) && WEXITSTATUS (status) == 0;
   }
diff --git a/butl/process.ixx b/butl/process.ixx
index 0506793..a0948e1 100644
--- a/butl/process.ixx
+++ b/butl/process.ixx
@@ -11,4 +11,15 @@ namespace butl
   inline process::
   process (char const* args[], process& in, int out, int err)
       : process (nullptr, args, in, out, err) {}
+
+  inline process::
+  process (process&& p)
+      : id (p.id),
+        status (p.status),
+        out_fd (p.out_fd),
+        in_ofd (p.in_ofd),
+        in_efd (p.in_efd)
+  {
+    p.id = 0;
+  }
 }
-- 
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