From 8234e723f0006d1e310f42ba235451e2d53a13ee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <chfast@gmail.com>
Date: Mon, 4 Nov 2019 16:22:55 +0100
Subject: [PATCH] loader: Simplify logic for finding create function

The loader library no longer tries EVMC create function names with removed prefixes.
---
 include/evmc/loader.h          | 13 ++++---------
 lib/loader/loader.c            | 10 +---------
 test/unittests/test_loader.cpp | 15 +++++++++++----
 3 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/include/evmc/loader.h b/include/evmc/loader.h
index 7a019a5..523139e 100644
--- a/include/evmc/loader.h
+++ b/include/evmc/loader.h
@@ -61,21 +61,16 @@ enum evmc_loader_error_code
  * After the DLL is successfully loaded the function tries to find the EVM create function in the
  * library. The `filename` is used to guess the EVM name and the name of the create function.
  * The create function name is constructed by the following rules. Consider example path:
- * "/ethereum/libexample-interpreter.so".
+ * "/ethereum/libexample-interpreter.so.1.0".
  * - the filename is taken from the path:
- *   "libexample-interpreter.so",
- * - the "lib" prefix and file extension are stripped from the name:
+ *   "libexample-interpreter.so.1.0",
+ * - the "lib" prefix and all file extensions are stripped from the name:
  *   "example-interpreter"
  * - all "-" are replaced with "_" to construct _base name_:
  *   "example_interpreter",
  * - the function name "evmc_create_" + _base name_ is searched in the library:
  *   "evmc_create_example_interpreter",
- * - if function not found, the _base name_ is shorten by skipping the first word separated by "_":
- *   "interpreter",
- * - then, the function of the shorter name "evmc_create_" + _base name_ is searched in the library:
- *   "evmc_create_interpreter",
- * - the name shortening continues until a function is found or the name cannot be shorten more,
- * - lastly, when no function found, the function name "evmc_create" is searched in the library.
+ * - if the function is not found, the function name "evmc_create" is searched in the library.
  *
  * If the create function is found in the library, the pointer to the function is returned.
  * Otherwise, the ::EVMC_LOADER_SYMBOL_NOT_FOUND error code is signaled and NULL is returned.
diff --git a/lib/loader/loader.c b/lib/loader/loader.c
index 245a174..d820054 100644
--- a/lib/loader/loader.c
+++ b/lib/loader/loader.c
@@ -163,15 +163,7 @@ evmc_create_fn evmc_load(const char* filename, enum evmc_loader_error_code* erro
         *dash_pos++ = '_';
 
     // Search for the built function name.
-    while ((create_fn = DLL_GET_CREATE_FN(handle, prefixed_name)) == NULL)
-    {
-        // Shorten the base name by skipping the `word_` segment.
-        const char* shorter_name_pos = strchr(base_name, '_');
-        if (!shorter_name_pos)
-            break;
-
-        memmove(base_name, shorter_name_pos + 1, strlen(shorter_name_pos) + 1);
-    }
+    create_fn = DLL_GET_CREATE_FN(handle, prefixed_name);
 
     if (!create_fn)
         create_fn = DLL_GET_CREATE_FN(handle, "evmc_create");
diff --git a/test/unittests/test_loader.cpp b/test/unittests/test_loader.cpp
index e0cc510..e2cd3f7 100644
--- a/test/unittests/test_loader.cpp
+++ b/test/unittests/test_loader.cpp
@@ -188,14 +188,12 @@ TEST_F(loader, load_empty_path)
     EXPECT_TRUE(evmc_last_error_msg() == nullptr);
 }
 
-TEST_F(loader, load_prefix_aaa)
+TEST_F(loader, load_aaa)
 {
     auto paths = {
         "./aaa.evm",
         "aaa.evm",
         "unittests/libaaa.so",
-        "unittests/double-prefix-aaa.evm",
-        "unittests/double_prefix_aaa.evm",
     };
 
     const auto expected_vm_ptr = reinterpret_cast<evmc_vm*>(0xaaa);
@@ -285,7 +283,16 @@ TEST_F(loader, load_windows_path)
 
 TEST_F(loader, load_symbol_not_found)
 {
-    auto paths = {"libaaa1.so", "eee2.so", "libeee3.x", "eee4", "_", "lib_.so"};
+    auto paths = {
+        "libaaa1.so",
+        "eee2.so",
+        "libeee3.x",
+        "eee4",
+        "_",
+        "lib_.so",
+        "unittests/double-prefix-aaa.evm",
+        "unittests/double_prefix_aaa.evm",
+    };
 
     for (auto& path : paths)
     {