icd: add basic posix icd discovery

icd/vendor.cpp

@@ -10,7 +10,7 @@ cruft::vk::icd::icd_t
 json::tree::io<cruft::vk::icd::icd_t>::deserialise (json::tree::node const &obj)
 {
     return {
-        .file_format_version = obj["'file_format_version"].as_string (),
+        .file_format_version = obj["file_format_version"].as_string (),
         .icd = {
             .library_path = obj["ICD"]["library_path"].as_string ().native (),
             .api_version = obj["ICD"]["api_version"].as_string (),

icd/vendor.hpp

@@ -8,6 +8,7 @@
 #include <experimental/filesystem>
 
 
+///////////////////////////////////////////////////////////////////////////////
 namespace cruft::vk::icd {
     struct icd_t {
         std::string file_format_version;
@@ -28,7 +29,11 @@ namespace cruft::vk::icd {
         vendor (::cruft::library &&);
 
         struct vtable_t {
-            VkResult (*CreateInstance) (const VkInstanceCreateInfo*, const VkAllocationCallbacks*, VkInstance*) noexcept;
+            VkResult (*CreateInstance) (
+                VkInstanceCreateInfo const*,
+                VkAllocationCallbacks const*,
+                VkInstance*
+            ) noexcept;
         } vtable;
 
     private:

icd/vendor_posix.cpp

@@ -0,0 +1,53 @@
+
+#include "vendor.hpp"
+
+#include <cruft/util/log.hpp>
+#include <cruft/util/posix/except.hpp>
+
+#include <cruft/json/tree.hpp>
+
+#include <wordexp.h>
+
+namespace fs = std::experimental::filesystem;
+
+
+///////////////////////////////////////////////////////////////////////////////
+std::vector<cruft::vk::icd::icd_t>
+cruft::vk::icd::enumerate (void)
+{
+    // The predefined, ordered, search locations for manifests
+    static char const *locations[] = {
+        "/usr/local/etc/vulkan/icd.d/",
+        "/usr/local/share/vulkan/icd.d/",
+        "/etc/vulkan/icd.d/",
+        "/usr/share/vulkan/icd.d/",
+        "$HOME/.local/share/vulkan/icd.d/",
+    };
+
+    std::vector<icd_t> found;
+
+    for (auto const &loc: locations) {
+        // We use wordexp rather than std::filesystem because we need to
+        // perform environment expansion to account of $HOME in at least one
+        // of the paths, so we may as well just use the same approach for
+        // everything else too.
+        wordexp_t words;
+        posix::error::try_call (wordexp, loc, &words, WRDE_NOCMD | WRDE_UNDEF);
+        std::unique_ptr<wordexp_t, decltype(&wordfree)> cleanup {&words, &wordfree};
+
+        // Just try to parse everything we can find in the directory (if it
+        // happens to exist) and fail out if it doesn't work. Marginally safer
+        // than doing various tests.
+        for (size_t i = 0; i < words.we_wordc; ++i) {
+            try {
+                for (auto const &path: fs::directory_iterator (words.we_wordv[i])) {
+                    found.push_back (from_json<icd_t> (*json::tree::parse (path)));
+                }
+            } catch (std::exception const &e) {
+                LOG_INFO("failed to parse icd manifest; %!", e.what ());
+            }
+        }
+    }
+
+    return found;
+}

tools/info.cpp

@@ -23,19 +23,17 @@
 int
 main (int, char**)
 {
-    auto all = cruft::vk::icd::enumerate ();
-    for (auto const &i: all) {
+    for (auto const &i: cruft::vk::icd::enumerate ()) {
         cruft::vk::icd::vendor v (i);
-    }
 
-
-    std::cout << "available_layers: [ "
-              << cruft::make_infix (cruft::vk::instance::available_layers ())
-              << " ]\n";
+        //std::cout << "available_layers: [ "
+        //    << cruft::make_infix (cruft::vk::instance::available_layers ())
+        //    << " ]\n";
 
         cruft::vk::instance instance;
         std::cout << "instance: " << instance << '\n';
 
         for (const auto &d: cruft::vk::physical_device::find (instance))
             std::cout << d << '\n';
+    }
 }