fsevent.rb

#!/usr/bin/env -S ruby -w

$: << File.expand_path("~/Links/RI/lib")
$: << File.expand_path("~/Links/ZT/lib")

require "rubygems"
require "inline"

class X
  inline :C do |builder|
    builder.include "<CoreServices/CoreServices.h>"

    builder.prefix <<~'EOC'
        static _Noreturn void callback(ConstFSEventStreamRef streamRef,
                             void *clientCallBackInfo,
                             size_t numEvents,
                             void *eventPaths,
                             const FSEventStreamEventFlags eventFlags[],
                             const FSEventStreamEventId eventIds[]) {
          for (size_t i = 0; i < numEvents; i++) {
            char* path = ((char**)eventPaths)[i];
            printf("%s\n", path);
          }

          exit(0);
        }
    EOC

    builder.c <<~EOC
        void watch(char * path) {
          CFStringRef pathToWatch = CFStringCreateWithCString(kCFAllocatorDefault, path, kCFStringEncodingUTF8);
          CFArrayRef pathsToWatch = CFArrayCreate(NULL, (const void **)&pathToWatch, 1, NULL);
          void *callbackInfo = NULL;
          FSEventStreamRef stream;
          CFAbsoluteTime latency = 1.0;

          stream = FSEventStreamCreate(kCFAllocatorDefault,
                                       callback,
                                       callbackInfo,
                                       pathsToWatch,
                                       kFSEventStreamEventIdSinceNow,
                                       latency,
                                       kFSEventStreamCreateFlagNone);

          // Add stream to run loop
          FSEventStreamScheduleWithRunLoop(stream, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
          FSEventStreamStart(stream);
          CFRunLoopRun();

          // Exit
          return 2;
        }
    EOC
  end
end

X.new.watch "/Users/ryan/Work/p4/zss/src"