examples

commit 96e8d55747cc8e0e1b0082464be2ca874567976b
parent e40ef4b5852d4a92d198f57dd42f15693ee1190b
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Tue, 16 Aug 2022 23:07:18 +0100

hush: Make hush actually work as a shell

Diffstat:
M
src/hush.cpp
 | 
75
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------

1 file changed, 68 insertions(+), 7 deletions(-)
diff --git a/src/hush.cpp b/src/hush.cpp
@@ -2,10 +2,42 @@
 #include <sstream>
 #include <cstdlib>
 #include <memory>
+#include <vector>
+#include <map>
 #include <unistd.h>
+#include <sys/wait.h>
+#include <err.h>
 
 using namespace std;
 
+void show_clear_warn(char const* msg)
+{
+	if (errno)
+		perror(msg);
+	errno = 0;
+}
+
+int cd(std::vector<char*> const& argv)
+{
+	if (argv.size() < 2)
+	{
+		cerr << "cd: not enough arguments\n";
+		return 1;
+	}
+	if (argv.size() > 2)
+	{
+		cerr << "cd: too many arguments\n";
+		return 1;
+	}
+	int res = chdir(argv[1]);
+	show_clear_warn("cd");
+	return res;
+}
+
+map<string, int(*)(std::vector<char*> const&)> intrinsics = {
+	{"cd", cd}
+};
+
 auto pwd(void)
 ->	unique_ptr<char, void(*)(void*)>
 {
@@ -16,21 +48,50 @@ int main(int, char**)
 {
 	string buf;
 
-	auto wd = pwd();
-
 	for (;;)
 	{
+		auto wd = pwd();
+
 		cout << '[' << wd.get() << "] " << flush;
 		if (!getline(cin, buf))
 			break;
 
-		cout << buf << '\n';
-
 		istringstream is(buf);
-		while (getline(is, buf, '\0'))
-			cout << "  " << buf;
+		vector<string> args;
+		while (getline(is, buf, ' '))
+			args.push_back(buf);
+
+		if (args.empty())
+		{
+			cout << '\n';
+			continue;
+		}
+		string arg0 = args.front();
+		std::vector<char*> argp;
+		for (auto& a : args)
+		{
+			a.push_back('\0');
+			argp.push_back(a.data());
+		}
+
+		if (intrinsics.contains(arg0))
+		{
+			intrinsics[arg0](argp);
+			continue;
+		}
+		argp.push_back(nullptr);
 
-		cout << '\n';
+		if (fork())
+		{
+			int status;
+			wait(&status);
+			if (WEXITSTATUS(status))
+				std::cout << "\nResult: " << WEXITSTATUS(status) << '\n';
+		} else
+		{
+			execvp(argp[0], argp.data());
+			err(66, "execv");
+		}
 	}
 
 	cout << "Done!\n";