From 828dd435725ea315abd2ea9875325ee3b17041a9 Mon Sep 17 00:00:00 2001
From: "Nathan P. Reiner" <nathan@nathanreiner.xyz>
Date: Thu, 15 Dec 2022 18:20:33 +0100
Subject: did this while lecture (builtins, parsing, exec and env by stdlib)

---
 smash/builtin.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 smash/builtin.c

(limited to 'smash/builtin.c')

diff --git a/smash/builtin.c b/smash/builtin.c
new file mode 100644
index 0000000..ad9c839
--- /dev/null
+++ b/smash/builtin.c
@@ -0,0 +1,86 @@
+#include "builtin.h"
+
+#include "../lib/sys/exit.h"
+#include "../lib/cstr/cstr.h"
+#include "../lib/sys/io.h"
+
+u64 __find_builtin_function_by_name(const char *name);
+
+int __builtin_fn_exit(int argc, const char **argv);
+int __builtin_fn_cd(int argc, const char **argv);
+int __builtin_fn_help(int argc, const char **argv);
+
+char *builtin_names[] = {
+	"exit",
+	"cd",
+	"help",
+	0
+};
+
+int (*builtin_functions[])(int argc, const char **argv) = {
+	__builtin_fn_exit,
+	__builtin_fn_cd,
+	__builtin_fn_help
+};
+
+int __builtin_fn_exit(int argc, const char **argv)
+{
+	exit(0);
+}
+
+int __builtin_fn_cd(int argc, const char **argv)
+{
+	/* TODO: Implement */
+}
+
+int __builtin_fn_help(int argc, const char **argv)
+{
+	write(STDOUT_FD, "This is the help page...\n", 25);
+	write(STDOUT_FD, "TODO: help page\n", 16);
+	return 0;
+}
+
+u64 __find_builtin_function_by_name(const char *name)
+{
+	char **p = builtin_names;
+
+	while (*p) {
+		if (cstr_compare(*p, name) == 0)
+			return p - builtin_names;
+		++p;
+	}
+
+	return -1;
+
+}
+
+u8 has_builtin_with_name(const char *name)
+{
+	return __find_builtin_function_by_name(name) != -1;
+}
+
+int run_builtin(const char *name, const char **argv)
+{
+	int argc = 0;
+	u64 builtin_index = __find_builtin_function_by_name(name);
+	const char **p = argv;
+	while (*p) {
+		++argc;
+		++p;
+	}
+
+	return builtin_functions[builtin_index](argc, argv);
+}
+
+#ifdef BUILTIN_UNIT_TEST
+
+int main() {
+	const char *argv[] = { "lelp", 0 };
+
+	if (has_builtin_with_name(argv[0]))
+		return run_builtin(argv[0], argv);
+
+	return 0;
+}
+
+#endif
-- 
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