BuildSystem: Cleanup userspace directory layout

userspace programs are now in userspace/programs
userspace tests are now in userspace/tests

This makes listing userspace projects much cleaner. Libraries were
already separated to their own directory, so other programs should also.

userspace/programs/init/CMakeLists.txt

@@ -0,0 +1,9 @@
+set(SOURCES
+	main.cpp
+)
+
+add_executable(init ${SOURCES})
+banan_include_headers(init ban)
+banan_link_library(init libc)
+
+install(TARGETS init OPTIONAL)

userspace/programs/init/main.cpp

@@ -0,0 +1,138 @@
+#include <BAN/String.h>
+#include <BAN/Optional.h>
+#include <BAN/Vector.h>
+
+#include <ctype.h>
+#include <fcntl.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/banan-os.h>
+#include <termios.h>
+
+void initialize_stdio()
+{
+	const char* tty = "/dev/tty";
+	if (open(tty, O_RDONLY | O_TTY_INIT) != 0) _exit(1);
+	if (open(tty, O_WRONLY) != 1) _exit(1);
+	if (open(tty, O_WRONLY) != 2) _exit(1);
+	if (open("/dev/debug", O_WRONLY) != 3) _exit(1);
+}
+
+int main()
+{
+	initialize_stdio();
+
+	if (signal(SIGINT, [](int) {}) == SIG_ERR)
+		perror("signal");
+
+	if (load_keymap("/usr/share/keymaps/us.keymap") == -1)
+		perror("load_keymap");
+
+	if (fork() == 0)
+	{
+		execl("/bin/dhcp-client", "dhcp-client", NULL);
+		exit(1);
+	}
+
+	if (fork() == 0)
+	{
+		execl("/bin/resolver", "resolver", NULL);
+		exit(1);
+	}
+
+	bool first = true;
+
+	termios termios;
+	tcgetattr(STDIN_FILENO, &termios);
+
+	while (true)
+	{
+		tcsetattr(STDIN_FILENO, TCSANOW, &termios);
+
+		char name_buffer[128];
+
+		while (!first)
+		{
+			printf("username: ");
+			fflush(stdout);
+
+			ssize_t nread = read(STDIN_FILENO, name_buffer, sizeof(name_buffer) - 1);
+			if (nread == -1)
+			{
+				perror("read");
+				return 1;
+			}
+			if (nread <= 1 || name_buffer[nread - 1] != '\n')
+				continue;
+			name_buffer[nread - 1] = '\0';
+			break;
+		}
+
+		if (first)
+		{
+			strcpy(name_buffer, "user");
+			first = false;
+		}
+
+		auto* pwd = getpwnam(name_buffer);
+		if (pwd == nullptr)
+			continue;
+
+		if (chown("/dev/tty", pwd->pw_uid, pwd->pw_gid) == -1)
+		{
+			perror("chown");
+			continue;
+		}
+
+		if (chmod("/dev/tty", 0600) == -1)
+		{
+			perror("chmod");
+			continue;
+		}
+
+		pid_t pid = fork();
+		if (pid == 0)
+		{
+			pid_t pgrp = setpgrp();
+			if (tcsetpgrp(0, pgrp) == -1)
+			{
+				perror("tcsetpgrp");
+				exit(1);
+			}
+
+			printf("Welcome back %s!\n", pwd->pw_name);
+
+			if (setgid(pwd->pw_gid) == -1)
+				perror("setgid");
+			if (setuid(pwd->pw_uid) == -1)
+				perror("setuid");
+
+			setenv("PATH", "/bin:/usr/bin", 0);
+
+			setenv("HOME", pwd->pw_dir, 1);
+			chdir(pwd->pw_dir);
+
+			execl(pwd->pw_shell, pwd->pw_shell, nullptr);
+			perror("execl");
+
+			exit(1);
+		}
+
+		endpwent();
+
+		if (pid == -1)
+		{
+			perror("fork");
+			break;
+		}
+
+		int status;
+		waitpid(pid, &status, 0);
+
+		if (tcsetpgrp(0, getpgrp()) == -1)
+			perror("tcsetpgrp");
+	}
+
+}