userspace: Implement kill utility

userspace/programs/CMakeLists.txt

@@ -20,6 +20,7 @@ set(USERSPACE_PROGRAMS
 	id
 	image
 	init
+	kill
 	less
 	ln
 	loadfont

userspace/programs/kill/CMakeLists.txt

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

userspace/programs/kill/main.cpp

@@ -0,0 +1,174 @@
+#include <ctype.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct signal_t
+{
+	const char* name;
+	int value;
+};
+
+static constexpr signal_t s_signals[] {
+#define SIGNAL(name) { #name, name }
+	SIGNAL(SIGABRT),
+	SIGNAL(SIGALRM),
+	SIGNAL(SIGBUS),
+	SIGNAL(SIGCHLD),
+	SIGNAL(SIGCONT),
+	SIGNAL(SIGFPE),
+	SIGNAL(SIGHUP),
+	SIGNAL(SIGILL),
+	SIGNAL(SIGINT),
+	SIGNAL(SIGKILL),
+	SIGNAL(SIGPIPE),
+	SIGNAL(SIGQUIT),
+	SIGNAL(SIGSEGV),
+	SIGNAL(SIGSTOP),
+	SIGNAL(SIGTERM),
+	SIGNAL(SIGTSTP),
+	SIGNAL(SIGTTIN),
+	SIGNAL(SIGTTOU),
+	SIGNAL(SIGUSR1),
+	SIGNAL(SIGUSR2),
+	SIGNAL(SIGPOLL),
+	SIGNAL(SIGPROF),
+	SIGNAL(SIGSYS),
+	SIGNAL(SIGTRAP),
+	SIGNAL(SIGURG),
+	SIGNAL(SIGVTALRM),
+	SIGNAL(SIGXCPU),
+	SIGNAL(SIGXFSZ),
+	SIGNAL(SIGWINCH),
+	SIGNAL(SIGCANCEL),
+#undef SIGNAL
+};
+
+[[noreturn]] static void exit_with_error(const char* format, ...)
+{
+	va_list args;
+	va_start(args, format);
+	vfprintf(stderr, format, args);
+	va_end(args);
+	exit(1);
+	__builtin_unreachable();
+}
+
+static int signal_name_to_number(const char* name)
+{
+	for (const auto& signal : s_signals)
+		if (strcasecmp(signal.name + 3, name) == 0 || strcasecmp(signal.name, name) == 0)
+			return signal.value;
+	exit_with_error("unknown signal '%s'\n", name);
+}
+
+static int parse_int(const char* string)
+{
+	errno = 0;
+	char* endptr;
+	const int result = strtol(string, &endptr, 0);
+	if (*endptr != '\0' || errno)
+		exit_with_error("invalid integer '%s'\n", string);
+	return result;
+}
+
+static int list_signals(char** signals)
+{
+	if (signals[0] == nullptr)
+	{
+		for (const auto& signal : s_signals)
+		{
+			if (&signal != s_signals)
+				printf(" ");
+			printf("%s", signal.name);
+		}
+		printf("\n");
+		return 0;
+	}
+
+	int ret = 0;
+
+	while (*signals)
+	{
+		bool found = false;
+
+		if (isdigit(**signals))
+		{
+			const int sig = parse_int(*signals);
+			for (const auto& signal : s_signals)
+			{
+				if (signal.value != sig)
+					continue;
+				printf("%s\n", signal.name + 3);
+				found = true;
+				break;
+			}
+		}
+		else
+		{
+			for (const auto& signal : s_signals)
+			{
+				if (strcasecmp(signal.name, *signals) != 0 && strcasecmp(signal.name + 3, *signals) != 0)
+					continue;
+				printf("%d\n", signal.value);
+				found = true;
+				break;
+			}
+		}
+
+		if (!found)
+			fprintf(stderr, "unknown signal: %s\n", *signals);
+
+		signals++;
+	}
+
+	return ret;
+}
+
+int main(int argc, char** argv)
+{
+	if (argc >= 2 && strcmp(argv[1], "-l") == 0)
+		return list_signals(argv + 2);
+
+	int sig = SIGTERM;
+
+	int i = 1;
+	for (; i < argc; i++)
+	{
+		if (argv[i][0] != '-')
+			break;
+		if (argv[i][1] == '-' && argv[i][2] == '\0')
+		{
+			i++;
+			break;
+		}
+
+		if (argv[i][1] == 's' && argv[i][2] == '\0')
+		{
+			if (i + 1 >= argc)
+				exit_with_error("missing signal name\n");
+			sig = signal_name_to_number(argv[i + 1]);
+			i++;
+		}
+		else if (argv[i][2] == '-' || isdigit(argv[i][1]))
+		{
+			sig = parse_int(argv[i] + 1);
+		}
+		else
+		{
+			sig = signal_name_to_number(argv[i] + 1);
+		}
+	}
+
+	if (i >= argc)
+		exit_with_error("missing pids\n");
+
+	for (; i < argc; i++)
+		if (kill(parse_int(argv[i]), sig) == -1)
+			perror("kill");
+
+	return 0;
+}