From 8504149fc1c70ecc5c7743c3522ae70de68b0694 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 27 Feb 2019 10:07:57 +0200
Subject: Factor out Windows command line argument quoting to utility function

---
 libbutl/process.cxx | 55 +++++++++++++++++++++++++++++++++--------------------
 libbutl/process.mxx | 10 ++++++++++
 2 files changed, 44 insertions(+), 21 deletions(-)

diff --git a/libbutl/process.cxx b/libbutl/process.cxx
index fa2f583..c6bf7cb 100644
--- a/libbutl/process.cxx
+++ b/libbutl/process.cxx
@@ -1067,6 +1067,37 @@ namespace butl
     bool locked_ = true;
   };
 
+  const char* process::
+  quote_argument (const char* a, string& s)
+  {
+    // On Windows we need to protect values with spaces using quotes.
+    // Since there could be actual quotes in the value, we need to
+    // escape them.
+    //
+    bool q (*a == '\0' || strchr (a, ' ') != nullptr);
+
+    if (!q && strchr (a, '"') == nullptr)
+      return a;
+
+    s.clear ();
+
+    if (q)
+      s += '"';
+
+    for (size_t i (0), n (strlen (a)); i != n; ++i)
+    {
+      if (a[i] != '"')
+        s += a[i];
+      else
+        s += "\\\"";
+    }
+
+    if (q)
+      s += '"';
+
+    return s.c_str ();
+  }
+
   // Protected by process_spawn_mutex. See below for the gory details.
   //
   static map<string, bool> detect_msys_cache_;
@@ -1257,35 +1288,17 @@ namespace butl
     //
     string cmd_line;
     {
-      auto append = [&cmd_line] (const string& a)
+      auto append = [&cmd_line, buf = string ()] (const char* a) mutable
       {
         if (!cmd_line.empty ())
           cmd_line += ' ';
 
-        // On Windows we need to protect values with spaces using quotes.
-        // Since there could be actual quotes in the value, we need to escape
-        // them.
-        //
-        bool quote (a.empty () || a.find (' ') != string::npos);
-
-        if (quote)
-          cmd_line += '"';
-
-        for (size_t i (0); i < a.size (); ++i)
-        {
-          if (a[i] == '"')
-            cmd_line += "\\\"";
-          else
-            cmd_line += a[i];
-        }
-
-        if (quote)
-          cmd_line += '"';
+        cmd_line += quote_argument (a, buf);
       };
 
       if (batch)
       {
-        append (*batch);
+        append (batch->c_str ());
         append ("/c");
         append (pp.effect_string ());
       }
diff --git a/libbutl/process.mxx b/libbutl/process.mxx
index 8f9d2de..c18ae43 100644
--- a/libbutl/process.mxx
+++ b/libbutl/process.mxx
@@ -462,6 +462,16 @@ LIBBUTL_MODEXPORT namespace butl
     static void
     print (std::ostream&, const char* const args[], size_t n = 0);
 
+    // Quote and escape the specified command line argument. Return the
+    // original string if neither is necessary and a pointer to the provided
+    // buffer string containing the escaped version otherwise.
+    //
+#ifdef _WIN32
+    static const char*
+    quote_argument (const char*, std::string& buffer);
+#endif
+
+
   public:
     id_type
     id () const;
-- 
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