From 9635692214cc6c3d19578bcadac4da68e0742740 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Thu, 25 Aug 2016 09:36:18 +0200
Subject: Add process::try_path_search()

---
 butl/process     | 26 ++++++++++++++++----------
 butl/process.cxx | 30 ++++++++++++++++++++++--------
 butl/process.ixx | 24 ++++++++++++++++++++++++
 3 files changed, 62 insertions(+), 18 deletions(-)

diff --git a/butl/process b/butl/process
index 7966309..96b161f 100644
--- a/butl/process
+++ b/butl/process
@@ -29,8 +29,8 @@ namespace butl
     process_error (int e, bool child)
         : system_error (e, std::system_category ()), child_ (child) {}
 #else
-    process_error (int e)
-        : system_error (e, std::system_category ()), child_ (false) {}
+    process_error (int e, bool child = false)
+        : system_error (e, std::system_category ()), child_ (child) {}
 
     process_error (const std::string& d, int e = ECHILD)
         : system_error (e, std::system_category (), d), child_ (false) {}
@@ -243,16 +243,22 @@ namespace butl
     path_search (const char* file, bool init, const dir_path& = dir_path ());
 
     static process_path
-    path_search (const std::string& f, bool i, const dir_path& fb = dir_path ())
-    {
-      return path_search (f.c_str (), i, fb);
-    }
+    path_search (const std::string&, bool, const dir_path& = dir_path ());
 
     static process_path
-    path_search (const path& f, bool i, const dir_path& fb = dir_path ())
-    {
-      return path_search (f.string ().c_str (), i, fb);
-    }
+    path_search (const path&, bool, const dir_path& = dir_path ());
+
+    // As above but if not found return empty process_path instead of
+    // throwing.
+    //
+    static process_path
+    try_path_search (const char*, bool, const dir_path& = dir_path ());
+
+    static process_path
+    try_path_search (const std::string&, bool, const dir_path& = dir_path ());
+
+    static process_path
+    try_path_search (const path&, bool, const dir_path& = dir_path ());
 
   public:
 #ifndef _WIN32
diff --git a/butl/process.cxx b/butl/process.cxx
index 37e9f72..ed26eb9 100644
--- a/butl/process.cxx
+++ b/butl/process.cxx
@@ -32,6 +32,8 @@
 #  include <butl/win32-utility>
 #endif
 
+#include <errno.h>
+
 #include <cassert>
 #include <cstddef> // size_t
 #include <cstring> // strlen(), strchr()
@@ -96,12 +98,24 @@ namespace butl
   process_path process::
   path_search (const char* f, bool init, const dir_path& fb)
   {
+    process_path r (try_path_search (f, init, fb));
+
+    if (r.empty ())
+      throw process_error (ENOENT, false);
+
+    return r;
+  }
+
+  process_path process::
+  try_path_search (const char* f, bool init, const dir_path& fb)
+  {
     process_path r (butl::path_search (f, fb));
 
-    path& rp (r.recall);
-    r.initial = init
-      ? f
-      : (rp.empty () ? (rp = path (f)) : rp).string ().c_str ();
+    if (!init && !r.empty ())
+    {
+      path& rp (r.recall);
+      r.initial = (rp.empty () ? (rp = path (f)) : rp).string ().c_str ();
+    }
 
     return r;
   }
@@ -117,7 +131,7 @@ namespace butl
 
     size_t fn (strlen (f));
 
-    process_path r (nullptr, path (), path ());
+    process_path r (f, path (), path ()); // Make sure it is not empty.
     path& rp (r.recall);
     path& ep (r.effect);
 
@@ -190,7 +204,7 @@ namespace butl
 
     // Did not find anything.
     //
-    throw process_error (ENOENT, false);
+    return process_path ();
   }
 
   process::
@@ -378,7 +392,7 @@ namespace butl
       ext = (e == nullptr || casecmp (e, ".exe") != 0);
     }
 
-    process_path r (nullptr, path (), path ());
+    process_path r (f, path (), path ()); // Make sure it is not empty.
     path& rp (r.recall);
     path& ep (r.effect);
 
@@ -519,7 +533,7 @@ namespace butl
 
     // Did not find anything.
     //
-    throw process_error (ENOENT);
+    return process_path ();
   }
 
   class auto_handle
diff --git a/butl/process.ixx b/butl/process.ixx
index 264f77c..83918bf 100644
--- a/butl/process.ixx
+++ b/butl/process.ixx
@@ -75,6 +75,30 @@ namespace butl
     return r;
   }
 
+  inline process_path process::
+  path_search (const std::string& f, bool i, const dir_path& fb)
+  {
+    return path_search (f.c_str (), i, fb);
+  }
+
+  inline process_path process::
+  path_search (const path& f, bool i, const dir_path& fb)
+  {
+    return path_search (f.string ().c_str (), i, fb);
+  }
+
+  inline process_path process::
+  try_path_search (const std::string& f, bool i, const dir_path& fb)
+  {
+    return try_path_search (f.c_str (), i, fb);
+  }
+
+  inline process_path process::
+  try_path_search (const path& f, bool i, const dir_path& fb)
+  {
+    return try_path_search (f.string ().c_str (), i, fb);
+  }
+
   inline process::
   process ()
       : handle (0),
-- 
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