luzer: support command-line options

The patch brings support of LibFuzzer command-line options [1].
The options passed to `Fuzz()` function will be merged with
command-line options, but command-line options have higher
priority.

```
LUA_PATH="./luzer/?.lua;;" LUA_CPATH="./build/luzer/?.so;;" \
  tarantool examples/example_basic.lua -runs=100 -max_len=1024
```

1. https://llvm.org/docs/LibFuzzer.html#options

Author: ligurio

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Integration with libFuzzer's `FuzzedDataProvider`.
 - Examples with tests.
 - Documentation with usecases, API etc.
+- Support command-line options.
 
 ### Changed
 

luzer/CMakeLists.txt

@@ -41,6 +41,7 @@ set(custom_mutator_lib_source ${CMAKE_CURRENT_SOURCE_DIR}/custom_mutator_lib.c)
 add_library(custom_mutator SHARED ${custom_mutator_lib_source})
 target_include_directories(custom_mutator PRIVATE ${LUA_INCLUDE_DIR})
 target_link_libraries(custom_mutator PRIVATE ${LUA_LIBRARIES})
+target_link_libraries(custom_mutator PRIVATE luzer_impl)
 set_target_properties(custom_mutator PROPERTIES VERSION ${PROJECT_VERSION})
 set_target_properties(custom_mutator PROPERTIES SOVERSION 1)
 

luzer/init.lua

@@ -3,8 +3,53 @@ if not ok then
     error(("error on loading luzer_impl: %s"):format(luzer_impl))
 end
 
+local function starts_with(str, prefix)
+    return string.sub(str, 1, string.len(prefix)) == prefix
+end
+
+-- The fuzzing test based on LibFuzzer optionally accept a number
+-- of flags and zero or more paths to corpus directories as
+-- command line arguments:
+-- ./fuzzer [-flag1=val1 [-flag2=val2 ...] ] [dir1 [dir2 ...] ]
+--
+-- 1. https://llvm.org/docs/LibFuzzer.html#options
+local function parse_flag(str)
+    local flag_name, flag_val = string.match(str, "-([%l%p]+)=(%w+)")
+    if not flag_name or
+       not flag_val then
+        error(("bad flag: %s"):format(str))
+    end
+    return flag_name, flag_val
+end
+
+local function build_flags(arg, func_args)
+    local flags = {}
+    for _, arg_str in ipairs(arg) do
+        local name, value
+        if starts_with(arg_str, "-") then
+            name, value = parse_flag(arg_str)
+        else
+            name, value = "corpus", arg_str
+        end
+        flags[name] = value
+    end
+
+    for flag_name, flag_val in pairs(func_args) do
+        if not flags[flag_name] then
+            flags[flag_name] = flag_val
+        end
+    end
+
+    return flags
+end
+
+local function Fuzz(test_one_input, custom_mutator, func_args)
+    local flags = build_flags(arg, func_args)
+    luzer_impl.Fuzz(test_one_input, custom_mutator, flags)
+end
+
 return {
-    Fuzz = luzer_impl.Fuzz,
+    Fuzz = Fuzz,
     FuzzedDataProvider = luzer_impl.FuzzedDataProvider,
 
     _LLVM_VERSION = luzer_impl._LLVM_VERSION,

luzer/tests/CMakeLists.txt

@@ -31,13 +31,47 @@ set_tests_properties(luzer_e2e_test PROPERTIES
 )
 
 add_test(
-  NAME luzer_options_test
-  COMMAND ${LUA_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/test_options.lua
-  WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+  NAME luzer_options_corpus_path_via_table_test
+  COMMAND ${LUA_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/test_options_1.lua
+          -max_total_time=1
 )
-set_tests_properties(luzer_options_test PROPERTIES
+set_tests_properties(luzer_options_corpus_path_via_table_test PROPERTIES
   ENVIRONMENT "LUA_CPATH=${LUA_CPATH};LUA_PATH='${LUA_PATH}'"
-  PASS_REGULAR_EXPRESSION "ERROR: The required directory \"undefined\" does not exist"
+  PASS_REGULAR_EXPRESSION
+    "ERROR: The required directory \"undefined\" does not exist"
+)
+
+file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/seed_corpus)
+add_test(
+  NAME luzer_options_corpus_path_via_option_test
+  COMMAND ${LUA_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/test_options_1.lua
+          -runs=1 seed_corpus
+  WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+)
+set_tests_properties(luzer_options_corpus_path_via_option_test PROPERTIES
+  ENVIRONMENT "LUA_CPATH=${LUA_CPATH};LUA_PATH=${LUA_PATH}"
+  PASS_REGULAR_EXPRESSION "0 files found in seed_corpus"
+)
+
+add_test(
+  NAME luzer_options_seed_via_option_test
+  COMMAND ${LUA_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/test_options_2.lua
+          -runs=1 -seed=50
+  WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+)
+set_tests_properties(luzer_options_seed_via_option_test PROPERTIES
+  ENVIRONMENT "LUA_CPATH=${LUA_CPATH};LUA_PATH=${LUA_PATH}"
+  PASS_REGULAR_EXPRESSION "Seed: 50"
+)
+
+add_test(
+  NAME luzer_options_help_test
+  COMMAND ${LUA_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/test_options_2.lua
+          -help=1
+)
+set_tests_properties(luzer_options_help_test PROPERTIES
+  ENVIRONMENT "LUA_CPATH=${LUA_CPATH};LUA_PATH=${LUA_PATH}"
+  PASS_REGULAR_EXPRESSION "Usage:"
 )
 
 add_test(

luzer/tests/test_options.lua

@@ -0,0 +1,7 @@
+local luzer = require("luzer")
+
+local args = {
+    corpus = "undefined",
+    max_total_time = 1,
+}
+luzer.Fuzz(function() os.execute('sleep 0.1') end, nil, args)

luzer/tests/test_options_1.lua

@@ -0,0 +1,6 @@
+local luzer = require("luzer")
+
+local args = {
+    seed = 12345,
+}
+luzer.Fuzz(function() end, nil, args)