fs/tmp: make temp queries and path generator more robust

CMakeLists.txt

@@ -127,6 +127,7 @@ if (NOT WIN32)
         debug/crash_posix.cpp
         debug/fpe_posix.cpp
         debug/system_posix.cpp
+        fs/tmp_posix.cpp
         io_posix.cpp
         io_posix.hpp
         library_posix.hpp
@@ -153,6 +154,7 @@ if (WIN32)
         debug/fpe_win32.cpp
         debug/system_win32.cpp
         exe_win32.cpp
+        fs/tmp_win32.cpp
         io_win32.cpp
         io_win32.hpp
         library_win32.cpp
@@ -357,7 +359,6 @@ list (
     fourcc.hpp
     fs/scoped.cpp
     fs/scoped.hpp
-    fs/tmp_posix.cpp
     fs/tmp.hpp
     functor.hpp
     geom/fwd.hpp

fs/tmp_posix.cpp

@@ -11,6 +11,8 @@
 #include "./paths.hpp"
 #include "./posix/except.hpp"
 
+#include <unistd.h>
+
 
 ///////////////////////////////////////////////////////////////////////////////
 std::filesystem::path
@@ -25,8 +27,13 @@ std::filesystem::path
 cruft::fs::mktempfile (std::filesystem::path const &dir)
 {
     auto pattern = (dir / PACKAGE_NAME "-XXXXXX").native ();
-    if (!mkstemp (pattern.data ()))
+
+    auto const fd = mkstemp (pattern.data ());
+    if (fd < 0)
         cruft::posix::error::throw_code ();
+
+    cruft::posix::error::try_call(::close, fd);
+
     return pattern;
 }
 

fs/tmp_win32.cpp

@@ -0,0 +1,74 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright 2023, Danny Robson <danny@nerdcruft.net>
+ */
+
+#include "./tmp.hpp"
+
+#include "../paths.hpp"
+#include "../posix/except.hpp"
+
+#include <io.h>
+#include <direct.h>
+
+
+///////////////////////////////////////////////////////////////////////////////
+static std::filesystem::path
+_temp_path_at (std::filesystem::path const &root)
+{
+    // The pattern suffix we'll append to the temp directory.
+    //
+    // * We might as well append the package name for clarity
+    // * The libc call REQUIRES the string end with "XXXXXX"
+    char const SUFFIX[] = "/" PACKAGE_NAME "-XXXXXX";
+
+    std::string path;
+    path.reserve (root.string ().size () + sizeof (SUFFIX));
+    path  = root.string ();
+    path += SUFFIX;
+
+    if (auto const err = _mktemp_s (path.data (), path.size ()); err)
+        throw cruft::posix::error (err);
+
+    return path;
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+std::filesystem::path
+cruft::fs::mktempfile (std::filesystem::path const &dir)
+{
+    auto pattern = (dir / PACKAGE_NAME "-XXXXXX").string ();
+
+    auto const fd = mkstemp (pattern.data ());
+    if (fd < 0)
+        cruft::posix::error::throw_code ();
+
+    cruft::posix::error::try_call(::close, fd);
+
+    return pattern;
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+std::filesystem::path
+cruft::fs::mktmpdir (void)
+{
+    static constexpr int RETRIES = 10;
+
+    auto const root = cruft::paths::temp ();
+
+    for (int i = 0; i < RETRIES; ++i) {
+        auto const path = _temp_path_at (root);
+
+        if (_mkdir (path.string ().c_str ()))
+            continue;
+
+        return path;
+    }
+
+    throw std::runtime_error ("Unable to create tmpdir");
+}

paths_win32.cpp

@@ -36,3 +36,19 @@ cruft::paths::expand (std::filesystem::path const &val)
 
     return store;
 }
+
+
+///////////////////////////////////////////////////////////////////////////////
+std::filesystem::path
+cruft::paths::temp (void)
+{
+    std::string value;
+    value.resize (MAX_PATH + 1);
+
+    auto const size = GetTempPathA (value.size (), value.data ());
+    if (!size)
+        throw std::runtime_error ("Unable to locate temp");
+    value.resize (size);
+
+    return value;
+}