From 32e8dbc3558a7b9ddecad50a9eb241b5e36f6c02 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 31 Aug 2015 13:51:55 +0200
Subject: Add ability for process to change child's working directory

---
 butl/process     |  8 ++++++++
 butl/process.cxx | 13 +++++++++----
 butl/process.ixx | 14 ++++++++++++++
 3 files changed, 31 insertions(+), 4 deletions(-)
 create mode 100644 butl/process.ixx

diff --git a/butl/process b/butl/process
index cf18acd..c810b58 100644
--- a/butl/process
+++ b/butl/process
@@ -59,6 +59,12 @@ namespace butl
     //
     process (char const* args[], process& in, int out = 1, int err = 2);
 
+    // Versions of the above constructors that allow us to change the
+    // current working directory of the child process.
+    //
+    process (const char* cwd, char const*[], int = 0, int = 1, int = 2);
+    process (const char* cwd, char const*[], process& in, int = 1, int = 2);
+
     // 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.
@@ -85,4 +91,6 @@ namespace butl
   };
 }
 
+#include <butl/process.ixx>
+
 #endif // BUTL_PROCESS
diff --git a/butl/process.cxx b/butl/process.cxx
index a456217..9025bdb 100644
--- a/butl/process.cxx
+++ b/butl/process.cxx
@@ -5,7 +5,7 @@
 #include <butl/process>
 
 #ifndef _WIN32
-#  include <unistd.h>    // execvp, fork, dup2, pipe, {STDIN,STDERR}_FILENO
+#  include <unistd.h>    // execvp, fork, dup2, pipe, chdir, *_FILENO
 #  include <sys/wait.h>  // waitpid
 #else
 #  ifndef WIN32_LEAN_AND_MEAN
@@ -25,7 +25,7 @@ namespace butl
 #ifndef _WIN32
 
   process::
-  process (char const* args[], int in, int out, int err)
+  process (const char* cwd, char const* args[], int in, int out, int err)
   {
     int out_fd[2] = {in, 0};
     int in_ofd[2] = {0, out};
@@ -74,6 +74,11 @@ namespace butl
           throw process_error (errno, true);
       }
 
+      // Change current working directory if requested.
+      //
+      if (cwd != nullptr && chdir (cwd) != 0)
+        throw process_error (errno, true);
+
       if (execvp (args[0], const_cast<char**> (&args[0])) == -1)
         throw process_error (errno, true);
     }
@@ -93,8 +98,8 @@ namespace butl
   }
 
   process::
-  process (char const* args[], process& in, int out, int err)
-      : process (args, in.in_ofd, out, err)
+  process (const char* cwd, char const* args[], process& in, int out, int err)
+      : process (cwd, args, in.in_ofd, out, err)
   {
     assert (in.in_ofd != -1); // Should be a pipe.
     close (in.in_ofd); // Close it on our side.
diff --git a/butl/process.ixx b/butl/process.ixx
new file mode 100644
index 0000000..0506793
--- /dev/null
+++ b/butl/process.ixx
@@ -0,0 +1,14 @@
+// file      : butl/process.ixx -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+namespace butl
+{
+  inline process::
+  process (char const* args[], int in, int out, int err)
+      : process (nullptr, args, in, out, err) {}
+
+  inline process::
+  process (char const* args[], process& in, int out, int err)
+      : process (nullptr, args, in, out, err) {}
+}
-- 
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