Switched from GNU Readline to custom Readline function

to make arsh more compatible with other Unix-Like systems

- Fixed small memory leak

README.org

@@ -6,8 +6,9 @@ Simple shell for Unix-like systems written in C, that has a funny name (for germ
 - ~cd~ builtin command
 - ~exit~ builtin command
 - ~CTRL+C~ stops running command
+- Custom ~readline~ function
 * Build
-To build it, you need ~readline~ library. Then use
+To build it, you don't need any external dependencies. Example with ~gcc~:
 #+begin_src shell
-gcc main.c -O3 -lreadline -o arsh
+gcc main.c -O3 -o arsh
 #+end_src 

main.c

@@ -3,7 +3,6 @@
 #include <unistd.h>
 #include <stdint.h>
 #include <stdio.h>
-#include <readline/readline.h>
 #include <sys/wait.h>
 #include <signal.h>
 #include <setjmp.h>
@@ -20,6 +19,31 @@ void sigint_handler(int signo)
   }
   siglongjmp(restart_jmp_buf, restart_value);
 }
+static constexpr size_t max_line = 1024;
+static char string_buffer[max_line];
+char* readline(char* print)
+{
+  if(print)
+  {
+    printf("%s", print);
+  }
+  if((fgets(string_buffer, max_line, stdin) == NULL) && ferror(stdin))
+  {
+    perror("fgets error");
+  }
+  
+  size_t length = strlen(string_buffer);
+  if(length == 0)
+  {
+    return NULL;
+  }
+  //Remove trailing \n
+  if (length > 0 && string_buffer[length - 1] == '\n')
+  {
+    string_buffer[length - 1] = '\0';
+  }
+  return string_buffer;
+}
 
 char** split_input(char* input)
 {
@@ -71,9 +95,14 @@ int main()
     char* input = readline("arsh> ");
     if(input == NULL) //CTRL + D
     {
-      continue;
+      printf("\nexit\n");
+      exit(0);
     }
     char** command = split_input(input);
+    if(command[0] == NULL)
+    {
+      goto cleanup;
+    }
     
     if(strcmp(command[0], "cd") == 0)
     {
@@ -82,7 +111,7 @@ int main()
 	perror(command[1]);
       }
 
-      continue; //skip fork()
+      goto cleanup; //skip fork()
     }
     if(strcmp(command[0], "exit") == 0)
     {
@@ -111,7 +140,8 @@ int main()
       waitpid(child_pid, &stat_loc, WUNTRACED);
     }
 
-    free(input);
+cleanup:
+
     free(command);
   }
 }