Simplify student cli execution by inferring lab with files in cwd (#62)

* add get_assignment_by_pathname function to global registrar

* add behavior to student mode to infer assignment when not specified

* add indirection operator to asmdata for nicer semantics

* add tests for a very basic "dumb" assignment

Author: Terracom12

include/asmgrader/api/asm_data.hpp

@@ -26,6 +26,8 @@ class AsmData
     // NOLINTNEXTLINE(google-runtime-operator) - nicer semantics?
     std::uintptr_t operator&() const { return address_; }
 
+    Result<T> operator*() const { return get_value(); }
+
     std::uintptr_t get_address() const { return address_; }
 
     /// Get the value currently present in the asm program

include/asmgrader/api/asm_symbol.hpp

@@ -50,7 +50,7 @@ class AsmSymbolResult : public Result<T>
 };
 
 template <typename T>
-class AsmSymbol : AsmData<T>
+class AsmSymbol : public AsmData<T>
 {
 public:
     AsmSymbol(Program& prog, std::string name, std::uintptr_t address);

include/asmgrader/common/linux.hpp

@@ -1,11 +1,13 @@
 #pragma once
 
+#include <asmgrader/common/aliases.hpp>
 #include <asmgrader/common/expected.hpp>
 #include <asmgrader/common/extra_formatters.hpp>
 #include <asmgrader/logging.hpp>
 
 #include <fmt/format.h>
 #include <fmt/ostream.h>
+#include <gsl/zstring>
 #include <libassert/assert.hpp>
 #include <range/v3/algorithm/transform.hpp>
 
@@ -106,6 +108,23 @@ inline Expected<> kill(pid_t pid, int sig) {
     return {};
 }
 
+/// see access(2)
+/// returns success/failure; logs failure at debug level
+inline Expected<> access(gsl::czstring path, int mode) {
+    ASSERT((static_cast<u64>(mode) & ~static_cast<u64>(R_OK | W_OK | X_OK | F_OK)) == 0, mode);
+
+    int res = ::access(path, mode);
+
+    if (res == -1) {
+        auto err = make_error_code(errno);
+
+        LOG_DEBUG("access failed: '{}'", err);
+        return err;
+    }
+
+    return {};
+}
+
 /// args and envp do NOT need to have an extra NULL element; this is added for you.
 /// see execve(2)
 /// returns success/failure; logs failure at debug level

include/asmgrader/registrars/global_registrar.hpp

@@ -36,12 +36,12 @@ class GlobalRegistrar
     void add_test(std::unique_ptr<TestBase> test) noexcept;
 
     template <typename Func>
-        requires(std::is_void_v<std::invoke_result_t<Func, Assignment>>)
+        requires(std::is_void_v<std::invoke_result_t<Func, Assignment&>>)
     void for_each_assignment(Func&& fun);
 
     template <typename Func>
-        requires(!std::is_void_v<std::invoke_result_t<Func, Assignment>>)
-    std::vector<std::invoke_result_t<Func, Assignment>> for_each_assignment(Func&& fun);
+        requires(!std::is_void_v<std::invoke_result_t<Func, Assignment&>>)
+    std::vector<std::invoke_result_t<Func, Assignment&>> for_each_assignment(Func&& fun);
 
     auto get_assignments() noexcept {
         return registered_assignments_ |
@@ -61,6 +61,18 @@ class GlobalRegistrar
         return std::nullopt;
     }
 
+    std::optional<std::reference_wrapper<Assignment>> get_assignment_by_pathname(std::string_view pathname) {
+        auto name_matcher = [pathname](const std::unique_ptr<Assignment>& assignment) {
+            return assignment->get_exec_path() == pathname;
+        };
+
+        if (auto iter = ranges::find_if(registered_assignments_, name_matcher); iter != registered_assignments_.end()) {
+            return **iter;
+        }
+
+        return std::nullopt;
+    }
+
     /// Find the assignment corresponding to the `Assignment` attribute of metadata,
     /// or create a new assignment if one does not exist.
     template <typename... MetadataAttrs>
@@ -102,16 +114,16 @@ Assignment& GlobalRegistrar::find_or_create_assignment(metadata::Metadata<Metada
 }
 
 template <typename Func>
-    requires(std::is_void_v<std::invoke_result_t<Func, Assignment>>)
+    requires(std::is_void_v<std::invoke_result_t<Func, Assignment&>>)
 void GlobalRegistrar::for_each_assignment(Func&& fun) {
-    for (auto& assignement : get_assignments()) {
-        std::forward<Func>(fun)(assignement);
+    for (auto& assignment : get_assignments()) {
+        std::forward<Func>(fun)(assignment);
     }
 }
 
 template <typename Func>
-    requires(!std::is_void_v<std::invoke_result_t<Func, Assignment>>)
-std::vector<std::invoke_result_t<Func, Assignment>> GlobalRegistrar::for_each_assignment(Func&& fun) {
+    requires(!std::is_void_v<std::invoke_result_t<Func, Assignment&>>)
+std::vector<std::invoke_result_t<Func, Assignment&>> GlobalRegistrar::for_each_assignment(Func&& fun) {
     std::vector<std::invoke_result_t<Func, Assignment>> result;
     result.reserve(registered_assignments_.size());
 

src/app/student_app.cpp

@@ -1,5 +1,7 @@
 #include "app/student_app.hpp"
 
+#include "api/assignment.hpp"
+#include "common/linux.hpp"
 #include "grading_session.hpp"
 #include "logging.hpp"
 #include "output/plaintext_serializer.hpp"
@@ -9,29 +11,109 @@
 #include "test_runner.hpp"
 #include "user/program_options.hpp"
 
+#include <fmt/base.h>
 #include <fmt/format.h>
 #include <libassert/assert.hpp>
+#include <range/v3/view/transform.hpp>
 
 #include <cstdlib>
+#include <filesystem>
+#include <functional>
 #include <memory>
 #include <optional>
+#include <string>
+#include <string_view>
+#include <vector>
+
+#include <unistd.h>
 
 namespace asmgrader {
 
+namespace {
+
+bool can_execute(const std::filesystem::path& path) {
+    namespace fs = std::filesystem;
+
+    if (!fs::is_regular_file(path)) {
+        LOG_TRACE("{} is not a regular file", path);
+        return false;
+    }
+
+    if (!linux::access(path.c_str(), X_OK)) {
+        LOG_TRACE("{} is not executable by this program", path);
+        return false;
+    }
+
+    return true;
+}
+
+std::reference_wrapper<Assignment> infer_assignment_or_exit() {
+    namespace fs = std::filesystem;
+
+    auto& registrar = GlobalRegistrar::get();
+
+    std::vector<std::reference_wrapper<Assignment>> infer_res;
+
+    for (fs::path cwd = fs::current_path(); const auto& dirent : fs::directory_iterator{cwd}) {
+        const auto& path = dirent.path();
+        std::string pathname = path.filename().string();
+        LOG_TRACE("Checking if {:?} matches any assignments {}", pathname, dirent.path());
+
+        if (!can_execute(path)) {
+            continue;
+        }
+
+        if (auto found = registrar.get_assignment_by_pathname(pathname)) {
+            LOG_TRACE("{:?} matches an assignment", pathname);
+            infer_res.push_back(found.value());
+        }
+    }
+
+    if (infer_res.size() == 0) {
+        fmt::println(stderr, "Could not infer assignment based on files in the current working directory! Please "
+                             "either change directories or specify the assignment explicitly by name. Exiting.");
+        std::exit(1);
+    }
+
+    if (infer_res.size() > 1) {
+        fmt::println(
+            stderr,
+            "More than 1 valid assignment found in current working directory when attempting to infer "
+            "assignment.\nThis is ambiguous! Please specify the assignment explicitly by name.\n(Found: {::?})",
+            infer_res |
+                ranges::views::transform([](auto& assignment_ref) { return assignment_ref.get().get_exec_path(); }));
+        std::exit(1);
+    }
+
+    // infer_res.size() == 1
+    return infer_res.front();
+}
+
+} // namespace
+
+Assignment& StudentApp::get_assignment_or_exit() const {
+    if (OPTS.assignment_name.empty()) {
+        LOG_DEBUG("Assignment unspecified; attempting to infer based on files in cwd.");
+        return infer_assignment_or_exit();
+    }
+
+    auto opt_assignment = GlobalRegistrar::get().get_assignment(OPTS.assignment_name);
+    ASSERT(opt_assignment.has_value(), "Internal error locating assignment", OPTS.assignment_name);
+
+    return opt_assignment.value();
+}
+
 int StudentApp::run_impl() {
     LOG_TRACE("Registered tests: {::}", GlobalRegistrar::get().for_each_assignment([](const Assignment& assignment) {
         return fmt::format("{:?}: {}", assignment.get_name(), assignment.get_test_names());
     }));
 
-    auto assignment = GlobalRegistrar::get().get_assignment(OPTS.assignment_name);
-
-    // should be verified by CLI; double-check here just in case
-    ASSERT(assignment, "Error locating assignment {}", OPTS.assignment_name);
+    Assignment& assignment = get_assignment_or_exit();
 
     StdoutSink output_sink;
     std::shared_ptr output_serializer =
         std::make_shared<PlainTextSerializer>(output_sink, OPTS.colorize_option, OPTS.verbosity);
-    AssignmentTestRunner runner{*assignment, output_serializer, OPTS.tests_filter};
+    AssignmentTestRunner runner{assignment, output_serializer, OPTS.tests_filter};
 
     output_serializer->on_run_metadata(RunMetadata{});
     AssignmentResult res = runner.run_all(OPTS.file_name);

src/app/student_app.hpp

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "api/assignment.hpp"
 #include "app/app.hpp" // IWYU pragma: export
 
 namespace asmgrader {
@@ -11,6 +12,8 @@ class StudentApp final : public App
 
 private:
     int run_impl() override;
+
+    Assignment& get_assignment_or_exit() const;
 };
 
 } // namespace asmgrader

src/user/cl_args.cpp

@@ -61,11 +61,22 @@ void CommandLineArgs::setup_parser() {
     //  maybe want to switch to another lib, or just do it myself. Need arg choices in help.
 
     // clang-format off
+    std::string assignment_help_str = fmt::format("The assignment to run tests on.\n"
+#ifndef PROFESSOR_VERSION
+            "If left unspecified, will attempt to infer the assignment based on files in the current working directory.\n"
+#endif
+            "One of: {}", assignment_names.empty() ? "<No assignments; this is probably an error>" : fmt::format("{:n}", assignment_names));
     auto& assignment_arg = arg_parser_.add_argument("assignment")
         .store_into(opts_buffer_.assignment_name)
-        // Add all assignment names to help msg, since argparse won't add choices by
-        // default for some reason
-        .help(fmt::format("The assignment to run tests on\nOne of: {:n}", assignment_names));
+#ifdef PROFESSOR_VERSION
+        .help(assignment_help_str);
+#else
+        // inferring the lab is only supported in student mode for now
+        .nargs(0, 1)  // [optional]
+        .help(assignment_help_str);
+#endif // !PROFESSOR_VERSION
+    // Add all assignment names to help msg, since argparse won't add choices by
+    // default for some reason
     GlobalRegistrar::get().for_each_assignment([&](const Assignment& assignment) {
         assignment_arg.add_choice(assignment.get_name());
     });

src/user/program_options.hpp

@@ -116,6 +116,17 @@ struct ProgramOptions
 
         TRY(ensure_is_directory(search_path, "Search path {:?}"));
 
+        // Only check the database path if it's not the default
+        // non-existance will be handled properly in ProfessorApp
+        if (database_path != DEFAULT_DATABASE_PATH) {
+            TRY(ensure_is_regular_file(database_path, "Database file {:?}"));
+        }
+
+        // If the assignment name is empty, we're going to be attempting to infer it elsewhere
+        if (assignment_name.empty()) {
+            return {};
+        }
+
         // The CLI should verify that the specified assignment is valid
         // We'll check here just in case and return an error if it's not
         auto assignment = TRYE(GlobalRegistrar::get().get_assignment(assignment_name),
@@ -129,12 +140,6 @@ struct ProgramOptions
             TRY(Program::check_is_compat_elf(exec_file_name));
         }
 
-        // Only check the database path if it's not the default
-        // non-existance will be handled properly in ProfessorApp
-        if (database_path != DEFAULT_DATABASE_PATH) {
-            TRY(ensure_is_regular_file(database_path, "Database file {:?}"));
-        }
-
         return {};
     }
 };