kill: add signum argument

userland/kill.c

@@ -1,20 +1,46 @@
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
-int main(int argc, char* argv[]) {
-    if (argc != 2) {
-        dprintf(STDERR_FILENO, "Usage: kill PID\n");
-        return EXIT_FAILURE;
+static void usage(void) {
+    dprintf(STDERR_FILENO, "Usage: kill [-SIGNUM] PID\n");
+    exit(EXIT_FAILURE);
+}
+
+static int parse_signum(const char* s) {
+    if (str_is_uint(s))
+        return atoi(s);
+    for (int i = 0; i < NSIG; ++i) {
+        if (!strcmp(s, sys_signame[i]))
+            return i;
     }
-    const char* pid_str = argv[1];
-    if (!str_is_uint(pid_str)) {
-        dprintf(STDERR_FILENO, "Illegal pid: %s\n", pid_str);
-        return EXIT_FAILURE;
+    return -1;
+}
+
+int main(int argc, char* argv[]) {
+    if (argc < 2)
+        usage();
+
+    pid_t pid = -1;
+    int signum = SIGTERM;
+    for (int i = 1; i < argc; ++i) {
+        const char* arg = argv[i];
+        if (arg[0] == '-') {
+            signum = parse_signum(arg + 1);
+            if (signum < 0 || signum >= NSIG)
+                usage();
+        } else if (str_is_uint(arg)) {
+            pid = atoi(arg);
+        } else {
+            usage();
+        }
     }
-    pid_t pid = atoi(pid_str);
-    if (kill(pid, SIGTERM) < 0) {
+    if (pid < 0)
+        usage();
+
+    if (kill(pid, signum) < 0) {
         perror("kill");
         return EXIT_FAILURE;
     }