add default values for DOTNET_HOME in corehost

fixes #234

src/corehost/inc/pal.h

@@ -108,6 +108,8 @@ namespace pal
     bool load_library(const char_t* path, dll_t& dll);
     proc_t get_symbol(dll_t library, const char* name);
     void unload_library(dll_t library);
+
+    bool find_coreclr(pal::string_t& recv);
 }
 
 #endif // PAL_H

src/corehost/inc/utils.h

@@ -11,5 +11,6 @@ pal::string_t get_executable(const pal::string_t& filename);
 pal::string_t get_directory(const pal::string_t& path);
 pal::string_t get_filename(const pal::string_t& path);
 void append_path(pal::string_t& path1, const pal::char_t* path2);
+bool coreclr_exists_in_dir(const pal::string_t& candidate);
 
 #endif

src/corehost/src/args.cpp

@@ -79,6 +79,14 @@ bool parse_arguments(const int argc, const pal::char_t* argv[], arguments_t& arg
         append_path(home_str, _X("coreclr"));
         args.clr_path.assign(home_str);
     }
+    else
+    {
+        // Use platform-specific search algorithm
+        if (pal::find_coreclr(home_str))
+        {
+            args.clr_path.assign(home_str);
+        }
+    }
 
     return true;
 }

src/corehost/src/main.cpp

@@ -214,14 +214,14 @@ int main(const int argc, const pal::char_t* argv[])
     trace::info(_X("preparing to launch: %s"), app_name.c_str());
     trace::info(_X("using app base: %s"), app_base.c_str());
 
-    // Check for and load tpa file
+    // Check for and load deps file
     pal::string_t tpafile_path;
     get_tpafile_path(app_base, app_name, tpafile_path);
-    trace::info(_X("checking for TPA File at: %s"), tpafile_path.c_str());
+    trace::info(_X("checking for .deps File at: %s"), tpafile_path.c_str());
     tpafile tpa;
     if (!tpa.load(tpafile_path))
     {
-        trace::error(_X("invalid TPA file"));
+        trace::error(_X("invalid .deps file"));
         return 1;
     }
     return run(args, app_base, tpa);

src/corehost/src/pal.unix.cpp

@@ -19,6 +19,32 @@
 #define symlinkEntrypointExecutable "/proc/curproc/exe"
 #endif
 
+bool coreclr_exists_in_dir(const pal::string_t& candidate)
+{
+    pal::string_t test(candidate);
+    append_path(test, _X("runtime"));
+    append_path(test, LIBCORECLR_NAME);
+    return pal::file_exists(test);
+}
+
+bool pal::find_coreclr(pal::string_t& recv)
+{
+    pal::string_t candidate;
+    pal::string_t test;
+
+    // Try %LocalAppData%\dotnet
+    if (pal::getenv(_X("LocalAppData"), candidate)) {
+        append_path(candidate, _X("dotnet"));
+        if (coreclr_exists_in_dir(candidate)) {
+            recv.assign(candidate);
+            return true;
+        }
+    }
+
+    // TODO: Try somewhere in Program Files, see https://github.com/dotnet/cli/issues/249
+    return false;
+}
+
 bool pal::load_library(const char_t* path, dll_t& dll)
 {
     dll = dlopen(path, RTLD_LAZY);

src/corehost/src/pal.windows.cpp

@@ -10,6 +10,24 @@
 
 static std::wstring_convert<std::codecvt_utf8<wchar_t>, wchar_t> g_converter;
 
+bool pal::find_coreclr(pal::string_t& recv)
+{
+    pal::string_t candidate;
+    pal::string_t test;
+
+    // Try %LocalAppData%\dotnet
+    if (pal::getenv(_X("LocalAppData"), candidate)) {
+        append_path(candidate, _X("dotnet"));
+        if (coreclr_exists_in_dir(candidate)) {
+            recv.assign(candidate);
+            return true;
+        }
+    }
+
+    // TODO: Try somewhere in Program Files, see https://github.com/dotnet/cli/issues/249
+    return false;
+}
+
 bool pal::load_library(const char_t* path, dll_t& dll)
 {
     dll = ::LoadLibraryW(path);

src/corehost/src/utils.cpp

@@ -3,6 +3,14 @@
 
 #include "utils.h"
 
+bool coreclr_exists_in_dir(const pal::string_t& candidate)
+{
+    pal::string_t test(candidate);
+    append_path(test, _X("runtime"));
+    append_path(test, LIBCORECLR_NAME);
+    return pal::file_exists(test);
+}
+
 bool ends_with(const pal::string_t& value, const pal::string_t& suffix)
 {
     return suffix.length() <= value.length() &&