// vim:syntax=c
/* 
 * Pike inotify module.
 * Copyright (C) 2009 Arne Goedeke
 * 
 */

#include 
#include 

#include "global.h"
#include "interpret.h"
#include "module.h"
#include "program.h"
#include "stralloc.h"
#include "svalue.h"
#include "object.h"
#include "pike_types.h"
#include "builtin_functions.h"

DECLARATIONS

/*! @module Public
 */

/*! @module System
 */

/*! @module Inotify
 */

/*! @decl constant IN_ACCESS
 *! @decl constant IN_ATTRIB
 *! @decl constant IN_CLOSE_WRITE
 *! @decl constant IN_CLOSE_NOWRITE
 *! @decl constant IN_CREATE
 *! @decl constant IN_DELETE
 *! @decl constant IN_DELETE_SELF
 *! @decl constant IN_MODIFY
 *! @decl constant IN_MOVE_SELF
 *! @decl constant IN_MOVED_FROM
 *! @decl constant IN_MODED_TO
 *! @decl constant IN_OPEN
 *! @decl constant IN_MOVE
 *! @decl constant IN_CLOSE
 *! @decl constant IN_DONT_FOLLOW
 *! @decl constant IN_MASK_ADD
 *! @decl constant IN_ONESHOT
 *! @decl constant IN_ONLYDIR
 *! @decl constant IN_IGNORED
 *! @decl constant IN_ISDIR
 *! @decl constant IN_Q_OVERFLOW
 *! @decl constant IN_UNMOUNT
 *! 	Please have a look at the inotify(7) manpage for information about these constants. 
 *! @note
 *! 	Some constants may not be available when the module has been compiled on a machine
 *! 	with an old kernel (before 2.6.15). See the manpage for more details.
 */

/*! @decl array parse_event(string data)
 *! Parses one inotify_event struct from @expr{data@}. 
 *! @returns
 *! 	Returns an array consisting of
 *! 	@ul
 *! 		@item
 *! 			The watch descriptor returned by @[add_watch()] when the watch
 *! 			for this file was added.
 *! 		@item
 *! 			An integer that describes the event that occured. See the inotify
 *! 			manpage for a list of possible events and their numerical identifiers.
 *! 		@item
 *! 			An integer cookie that can be used to group together different events
 *! 			that were triggered by moving a file from one location to another.
 *! 		@item
 *! 			The name of the file. This will only be present if the event happened to
 *! 			a file in a directory that was watched, e.g. with @[Public.System.Inotify.IN_CREATE].
 *! 			Otherwise this will be 0.
 *! 		@item
 *! 			The length of the data that has been parsed. In case a string contains more than one
 *! 			inotify events, this parse function has to be called again with the rest as an argument.
 *! 	@endul
 */
PIKEFUN array parse_event(string data) {
	struct inotify_event * event;
	size_t len;
	pop_n_elems(args);

	if ((size_t)data->len < sizeof(struct inotify_event)) {
		Pike_error("Malformed data.\n");
	}

	event = (struct inotify_event *)data->str;

	if (event->len > data->len - sizeof(struct inotify_event)) {
		Pike_error("Data missing.\n");	
	}

	push_int((int)event->wd);
	push_int((int)event->mask);
	push_int((int)event->cookie);

	if (event->len && (len = strlen(event->name))) {
		push_string(make_shared_binary_string(event->name, len));
	} else {
		push_int(0);
	}

	push_int((int)(event->len + sizeof(struct inotify_event)));

	f_aggregate(5);
}

/*! @class _Instance
 *! 	Simple wrapper class that gives direct access to the inotify(7) interface. On create an
 *! 	inotify instance is initiated by calling inotify_init(2). Every object of this class has 
 *! 	its own inotify file descriptor. Use this class only if you want direct access to the 
 *! 	file descriptor to read from it manually. For a more user-friendly inferface use 
 *! 	@[Public.System.Inotify.Instance].
 */
PIKECLASS _Instance {
	CVAR int fd;

	/*! @decl int add_watch(string file, int mask)
	 *! Add a watch for a certain file/dir and certain events. Adding more than one watch
	 *! for a file will overwrite the previous watch unless @[Public.System.Inotify.IN_MASK_ADD]
	 *! is ORed to the mask.
	 *! @param file
	 *! 	Name of the file that should be watched. Can be either a directory or a file.
	 *! @param mask
	 *! 	Integer mask specifying the event. This can be a combination of different event types
	 *! 	combined using bitwise OR. See the inotify manpage for possible values and their description.
	 *! 	The values defined by the inotify header file are exported by @[Public.System.Inotify] 
	 *! 	as constants using the same names (e.g. @[Public.System.Inotify.IN_CREATE]).
	 *! @note
	 *! 	Subdirectories are not watched. If you want to watch subdirectories aswell, its necessary
	 *! 	to add watches for them individually.
	 */
	PIKEFUN int add_watch(string file, int mask) {
		INT32 err;
		pop_n_elems(args);

		if (file->size_shift) {
			Pike_error("Widestring filenames not allowed.\n");
		}

		err = inotify_add_watch(THIS->fd, file->str, (INT32)mask);	

		if (err == -1) {
			Pike_error("inotify_add_watch failed with errno %d", errno);
		} else {
			push_int(err);	
		}
	}

	/*! @decl int get_fd()
	 *! @returns
	 *! 	Returns the file descriptor that is associated to the inotify instance.
	 */
	PIKEFUN int get_fd() {
		push_int(THIS->fd);	
	}
	
	/*! @decl int rm_watch(int wd)
	 *! Remove a watch.
	 *! @param wd
	 *! 	The watch descriptor that was returned by @[add_watch()].
	 */
	PIKEFUN void rm_watch(int wd) {
		INT32 err;
		pop_n_elems(args);

		err = inotify_rm_watch(THIS->fd, wd);

		if (err == 0) {
			return;
		}

		if (errno == EINVAL) {
			Pike_error("Wrong argument to rm_watch().\n");
		} else if (errno == EBADF) {
			Pike_error("Oups. I feel funny inside.\n");
		}
	}

	INIT {
		THIS->fd = inotify_init();

		if (THIS->fd == -1) switch (errno) {
		case EMFILE: Pike_error("User limit on inotify instances reached.\n");
		case ENFILE: Pike_error("User limit on file descriptors reached.\n");
		case ENOMEM: Pike_error("No free kernel memory available.\n");
		}
	}

	EXIT {
		close(THIS->fd);
	}
}

/*! @endclass
 */

#define ADD_ICONST(name) do {			\
	add_integer_constant(#name, name, 0);	\
} while(0);


PIKE_MODULE_INIT {
	ADD_ICONST(IN_ACCESS);
	ADD_ICONST(IN_ATTRIB);
	ADD_ICONST(IN_CLOSE_WRITE);
	ADD_ICONST(IN_CLOSE_NOWRITE);
	ADD_ICONST(IN_CREATE);
	ADD_ICONST(IN_DELETE);
	ADD_ICONST(IN_DELETE_SELF);
	ADD_ICONST(IN_MODIFY);
	ADD_ICONST(IN_MOVE_SELF);
	ADD_ICONST(IN_MOVED_FROM);
	ADD_ICONST(IN_MOVED_TO);
	ADD_ICONST(IN_OPEN);

	ADD_ICONST(IN_MOVE);
	ADD_ICONST(IN_CLOSE);

// some of these came with 2.6.15 linux and 2.5 glibc
#ifdef IN_DONT_FOLLOW
	ADD_ICONST(IN_DONT_FOLLOW);
#endif
#ifdef IN_MASK_ADD
	ADD_ICONST(IN_MASK_ADD);
#endif
	ADD_ICONST(IN_ONESHOT);
#ifdef IN_ONLYDIR
	ADD_ICONST(IN_ONLYDIR);
#endif

	ADD_ICONST(IN_IGNORED);
	ADD_ICONST(IN_ISDIR);
	ADD_ICONST(IN_Q_OVERFLOW);
	ADD_ICONST(IN_UNMOUNT);

	INIT
}

PIKE_MODULE_EXIT {
	EXIT
}

/*! @endmodule
 */
/*! @endmodule
 */
/*! @endmodule
 */