sh: Add a few more shell builtins

shell/CMakeLists.txt

@@ -2,6 +2,9 @@ set(SOURCES
     main.cpp
     sh.h
     builtin/cd.cpp
+    builtin/exit.cpp
+    builtin/set.cpp
+    builtin/unset.cpp
 )
 
 add_executable(sh ${SOURCES})

shell/builtin/exit.cpp

@@ -0,0 +1,20 @@
+#include "sh.h"
+#include <os/ArgumentParser.h>
+#include <stdlib.h>
+
+shell_builtin_t builtin_exit = [](int argc, char** argv) -> Result<void> {
+    StringView exit_status;
+
+    os::ArgumentParser parser;
+    parser.set_should_exit_on_bad_usage(false);
+    parser.add_description("Exit the shell (shell builtin)"_sv);
+    parser.add_system_program_info("exit"_sv);
+    parser.add_positional_argument(exit_status, "status"_sv, false);
+    if (!TRY(parser.parse(argc, argv))) return {};
+
+    int status = 0;
+
+    if (!exit_status.is_empty()) { status = (int)strtoul(exit_status.chars(), nullptr, 10); }
+
+    exit(status);
+};

shell/builtin/set.cpp

@@ -0,0 +1,24 @@
+#include "sh.h"
+#include <errno.h>
+#include <os/ArgumentParser.h>
+#include <stdlib.h>
+
+shell_builtin_t builtin_set = [](int argc, char** argv) -> Result<void> {
+    StringView name;
+    StringView value;
+    bool preserve { false };
+
+    os::ArgumentParser parser;
+    parser.set_should_exit_on_bad_usage(false);
+    parser.add_description("Set an environment variable (shell builtin)"_sv);
+    parser.add_system_program_info("set"_sv);
+    parser.add_positional_argument(name, "name"_sv, true);
+    parser.add_positional_argument(value, "value"_sv, true);
+    parser.add_switch_argument(preserve, 'p', "preserve"_sv,
+                               "preserve the environment variable if it already exists"_sv);
+    if (!TRY(parser.parse(argc, argv))) return {};
+
+    if (setenv(name.chars(), value.chars(), !preserve) < 0) return err(errno);
+
+    return {};
+};

shell/builtin/unset.cpp

@@ -0,0 +1,19 @@
+#include "sh.h"
+#include <errno.h>
+#include <os/ArgumentParser.h>
+#include <stdlib.h>
+
+shell_builtin_t builtin_unset = [](int argc, char** argv) -> Result<void> {
+    StringView name;
+
+    os::ArgumentParser parser;
+    parser.set_should_exit_on_bad_usage(false);
+    parser.add_description("Remove an environment variable (shell builtin)"_sv);
+    parser.add_system_program_info("unset"_sv);
+    parser.add_positional_argument(name, "name"_sv, true);
+    if (!TRY(parser.parse(argc, argv))) return {};
+
+    if (unsetenv(name.chars()) < 0) return err(errno);
+
+    return {};
+};

shell/main.cpp

@@ -19,6 +19,9 @@
 #include <luna/HashMap.h>
 
 extern shell_builtin_t builtin_cd;
+extern shell_builtin_t builtin_exit;
+extern shell_builtin_t builtin_set;
+extern shell_builtin_t builtin_unset;
 
 static HashMap<StringView, shell_builtin_t> s_builtins;
 
@@ -44,6 +47,25 @@ static Result<void> init_builtins()
     s_builtins = {};
 
     TRY(s_builtins.try_set("cd"_sv, builtin_cd));
+    TRY(s_builtins.try_set("exit"_sv, builtin_exit));
+    TRY(s_builtins.try_set("set"_sv, builtin_set));
+    TRY(s_builtins.try_set("unset"_sv, builtin_unset));
+
+    return {};
+}
+
+static Result<void> builtin_wrapper(const Vector<String>& args, shell_builtin_t builtin)
+{
+    Vector<const char*> argv;
+    for (const auto& arg : args) { TRY(argv.try_append(arg.chars())); }
+    TRY(argv.try_append(nullptr));
+
+    auto rc = builtin((int)args.size(), const_cast<char**>(argv.data()));
+    if (rc.has_error())
+    {
+        errno = rc.error();
+        perror(argv[0]);
+    }
 
     return {};
 }
@@ -73,6 +95,7 @@ Result<int> luna_main(int argc, char** argv)
     parser.add_value_argument(command, 'c', "command"_sv, "execute a single command and then exit"_sv);
     parser.parse(argc, argv);
 
+    // TODO: This does not properly handle builtins.
     if (!command.is_empty()) TRY(execute_command(command));
 
     if (path == "-") { input_file = File::standard_input(); }
@@ -103,7 +126,7 @@ Result<int> luna_main(int argc, char** argv)
         tcsetpgrp(STDIN_FILENO, getpgid(0));
     }
 
-    init_builtins();
+    TRY(init_builtins());
 
     while (1)
     {
@@ -146,16 +169,7 @@ Result<int> luna_main(int argc, char** argv)
             {
                 auto builtin = maybe_builtin.value();
 
-                Vector<const char*> argv;
-                for (const auto& arg : args) { TRY(argv.try_append(arg.chars())); }
-                TRY(argv.try_append(nullptr));
-
-                auto rc = builtin((int)args.size(), const_cast<char**>(argv.data()));
-                if (rc.has_error())
-                {
-                    errno = rc.error();
-                    perror(argv[0]);
-                }
+                TRY(builtin_wrapper(args, builtin));
 
                 continue;
             }