test: tmpd: Replace createVpnorRoot() with VpnorRoot class

The VpnorRoot class prepares a temporary directory for use as a VPNOR
backing store. Implementing it as a class allows us to use RAII to get
it to clean up after itself.

Change-Id: Ia5a839e751f8dc2126a4c0b474e9a7b8593cfd57
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/test/vpnor/tmpd.hpp b/test/vpnor/tmpd.hpp
index ab27377..d684706 100644
--- a/test/vpnor/tmpd.hpp
+++ b/test/vpnor/tmpd.hpp
@@ -10,8 +10,6 @@
 #include "config.h"
 #include "pnor_partition_table.hpp"
 
-namespace fs = std::experimental::filesystem;
-
 namespace openpower
 {
 namespace virtual_pnor
@@ -19,35 +17,62 @@
 namespace test
 {
 
-template <std::size_t N>
-void createVpnorTree(fs::path &root, const std::string (&toc)[N],
-                     size_t blockSize)
+namespace fs = std::experimental::filesystem;
+
+class VpnorRoot
 {
-    fs::path tocFilePath{root};
-    tocFilePath /= PARTITION_TOC_FILE;
-    std::ofstream tocFile(tocFilePath.c_str());
-
-    for (const std::string &line : toc)
+  public:
+    template <std::size_t N>
+    VpnorRoot(const std::string (&toc)[N], size_t blockSize)
     {
-        pnor_partition part;
+        char tmplt[] = "/tmp/vpnor_root.XXXXXX";
+        char* tmpdir = mkdtemp(tmplt);
+        root = fs::path{tmpdir};
 
-        openpower::virtual_pnor::parseTocLine(line, blockSize, part);
+        fs::path tocFilePath{root};
+        tocFilePath /= PARTITION_TOC_FILE;
+        std::ofstream tocFile(tocFilePath.c_str());
 
-        /* Populate the partition in the tree */
-        fs::path partitionFilePath{root};
-        partitionFilePath /= part.data.name;
-        std::ofstream partitionFile(partitionFilePath.c_str());
-        std::vector<char> empty(part.data.size, 0);
-        partitionFile.write(empty.data(), empty.size());
-        partitionFile.close();
+        for (const std::string& line : toc)
+        {
+            pnor_partition part;
 
-        /* Update the ToC if the partition file was created */
-        tocFile.write(line.c_str(), line.length());
-        tocFile.write("\n", 1);
+            openpower::virtual_pnor::parseTocLine(line, blockSize, part);
+
+            /* Populate the partition in the tree */
+            fs::path partitionFilePath{root};
+            partitionFilePath /= part.data.name;
+            std::ofstream partitionFile(partitionFilePath.c_str());
+            std::vector<char> empty(part.data.size, 0);
+            partitionFile.write(empty.data(), empty.size());
+            partitionFile.close();
+
+            /* Update the ToC if the partition file was created */
+            tocFile.write(line.c_str(), line.length());
+            tocFile.write("\n", 1);
+        }
+
+        tocFile.close();
     }
 
-    tocFile.close();
-}
+    VpnorRoot(const VpnorRoot&) = delete;
+    VpnorRoot& operator=(const VpnorRoot&) = delete;
+    VpnorRoot(VpnorRoot&&) = delete;
+    VpnorRoot& operator=(VpnorRoot&&) = delete;
+
+    ~VpnorRoot()
+    {
+        fs::remove_all(root);
+    }
+    const fs::path& path()
+    {
+        return root;
+    }
+    size_t write(const std::string& name, const void* data, size_t len);
+
+  private:
+    fs::path root;
+};
 
 } // test
 } // virtual_pnor