Added kill builtin

sh.c

@@ -1,4 +1,4 @@
-#define _POSIX_C_SOURCE 200809L
+#define _XOPEN_SOURCE 700
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -15,8 +15,10 @@
 
 char** create_argv(char* command);
 int get_argc(char* command);
+int get_argc_argv(char * argv[]);
 char* prompt();
 int cd(char* path);
+int _kill(int argc, char * argv[]);
 
 int main() {
   char** argv;
@@ -37,6 +39,10 @@ int main() {
       /* causes the fork to get skipped */
       continue;
     }
+    else if(strcmp(argv[0], "kill") == 0) {
+      _kill(get_argc_argv(argv), argv);
+      continue;
+    }
     else if(strcmp(argv[0], "exit") == 0 ||
       strcmp(argv[0], "quit") == 0) {
       exit(0);
@@ -135,6 +141,83 @@ int get_argc(char* command) {
   return argc;
 }
 
+int get_argc_argv(char * argv[]) {
+  int argc = 0;
+  while(argv[argc] != NULL) {
+    argc++;
+  }
+  return argc;
+}
+
 int cd(char* path) {
   return chdir(path);
 }
+
+int get_signum(char * signame) {
+  if(strcmp(signame, "SIGHUP") == 0) {
+    return 1;
+  }
+  else if(strcmp(signame, "SIGINT") == 0) {
+    return 2;
+  }
+  else if(strcmp(signame, "SIGQUIT") == 0) {
+    return 3;
+  }
+  else if(strcmp(signame, "SIGABRT") == 0) {
+    return 6;
+  }
+  else if(strcmp(signame, "SIGKILL") == 0) {
+    return 9;
+  }
+  else if(strcmp(signame, "SIGALRM") == 0) {
+    return 14;
+  }
+  else if(strcmp(signame, "SIGTERM") == 0) {
+    return 15;
+  }
+}
+
+int _kill(int argc, char * argv[]) {
+  int signal = 0; pid_t pid; char c;
+  int write_signame = 0, error = 0;
+
+  while((c = getopt(argc, argv, "s:l")) != -1) {
+    switch(c) {
+      case 's': signal = get_signum(optarg); break;
+      case 'l': write_signame = 1; break;
+    }
+  }
+
+  if(signal == 0 && argv[1][0] == '-' && write_signame == 0) {
+    if(argv[1][1] >= '0' && argv[1][1] <= '9') {
+      signal = atoi((argv[1])+1);
+    }
+    else {
+      signal = get_signum((argv[1])+1);
+    }
+  }
+
+  if(write_signame) {
+    if(argc > 2) {
+      /* TODO: Figure out how to get exit status from $? */
+    }
+    else {
+      printf("SIGHUP\n");
+      printf("SIGINT\n");
+      printf("SIGQUIT\n");
+      printf("SIGABRT\n");
+      printf("SIGKILL\n");
+      printf("SIGALRM\n");
+      printf("SIGTERM\n");
+      return 0;
+    }
+  }
+  else {
+    for(int i = optind; i < argc && argv[i] != NULL; i++) {
+      pid = atoi(argv[optind]);
+      if(kill(pid, signal) != 0) {
+        error = 1;
+      }
+    }
+  }
+}