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Re: [PATCH] Support for filesystem watching (inotify)
From: |
Jan Djärv |
Subject: |
Re: [PATCH] Support for filesystem watching (inotify) |
Date: |
Sat, 4 Jun 2011 12:43:37 +0200 |
Hi.
In general, you should not call Lisp from the read fd callback. Recursive calls
into Lisp may fail. Instead post a Lisp event and handle it in keyboard.c and
some Lisp code.
Jan D.
4 jun 2011 kl. 00:34 skrev Rüdiger Sonderfeld <address@hidden>:
> Hello,
> I wrote a patch to support watching for file system events. It currently only
> works with inotify (Linux) but it could be extended to support kqueue
> (*BSD, OS X) or Win32. But I wanted to get some feedback first. Watching for
> filesystem events would be very useful for, e.g., dired or magit's status
> view.
>
> Here is a quick example (expects a directory foo containing a file bar):
>
> (file-watch "foo" #'(lambda (path events) (message "FS-Event: %s %s") path
> events)) :all)
> (delete-file "foo/bar")
> (file-unwatch "foo")
>
> So please tell me what you think of this.
>
> Regards,
> Rüdiger
>
>
> [PATCH] Added basic file system watching support.
>
> It currently only works with inotify/Linux. It adds file-watch and
> file-unwatch functions.
> ---
> configure.in | 14 +++
> src/Makefile.in | 2 +-
> src/emacs.c | 4 +
> src/filewatch.c | 242 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> src/lisp.h | 5 +
> 5 files changed, 266 insertions(+), 1 deletions(-)
> create mode 100644 src/filewatch.c
>
> diff --git a/configure.in b/configure.in
> index 77deef8..3263876 100644
> --- a/configure.in
> +++ b/configure.in
> @@ -169,6 +169,7 @@ OPTION_DEFAULT_ON([dbus],[don't compile with D-Bus
> support])
> OPTION_DEFAULT_ON([gconf],[don't compile with GConf support])
> OPTION_DEFAULT_ON([selinux],[don't compile with SELinux support])
> OPTION_DEFAULT_ON([gnutls],[don't use -lgnutls for SSL/TLS support])
> +OPTION_DEFAULT_ON([inotify],[don't compile with inotify (file-watch)
> support])
>
> ## For the times when you want to build Emacs but don't have
> ## a suitable makeinfo, and can live without the manuals.
> @@ -1978,6 +1979,19 @@ fi
> AC_SUBST(LIBGNUTLS_LIBS)
> AC_SUBST(LIBGNUTLS_CFLAGS)
>
> +dnl inotify is only available on GNU/Linux.
> +HAVE_INOTIFY=no
> +if test "${with_inotify}" = "yes"; then
> + AC_CHECK_HEADERS(sys/inotify.h)
> + if test "$ac_cv_header_sys_inotify_h" = yes ; then
> + AC_CHECK_FUNCS(inotify_init1 inotify_add_watch inotify_rm_watch,
> HAVE_INOTIFY=yes)
> + fi
> +fi
> +if test "${HAVE_INOTIFY}" = "yes"; then
> + AC_DEFINE(HAVE_INOTIFY, [1], [Define to 1 to use inotify])
> + AC_DEFINE(HAVE_FILEWATCH, [1], [Define to 1 to support filewatch])
> +fi
> +
> dnl Do not put whitespace before the #include statements below.
> dnl Older compilers (eg sunos4 cc) choke on it.
> HAVE_XAW3D=no
> diff --git a/src/Makefile.in b/src/Makefile.in
> index e119596..0cd6d6e 100644
> --- a/src/Makefile.in
> +++ b/src/Makefile.in
> @@ -354,7 +354,7 @@ base_obj = dispnew.o frame.o scroll.o xdisp.o menu.o
> $(XMENU_OBJ) window.o \
> syntax.o $(UNEXEC_OBJ) bytecode.o \
> process.o gnutls.o callproc.o \
> region-cache.o sound.o atimer.o \
> - doprnt.o intervals.o textprop.o composite.o xml.o \
> + doprnt.o intervals.o textprop.o composite.o xml.o filewatch.o \
> $(MSDOS_OBJ) $(MSDOS_X_OBJ) $(NS_OBJ) $(CYGWIN_OBJ) $(FONT_OBJ)
> obj = $(base_obj) $(NS_OBJC_OBJ)
>
> diff --git a/src/emacs.c b/src/emacs.c
> index 6bdd255..5ca5cda 100644
> --- a/src/emacs.c
> +++ b/src/emacs.c
> @@ -1550,6 +1550,10 @@ main (int argc, char **argv)
> syms_of_gnutls ();
> #endif
>
> +#ifdef HAVE_FILEWATCH
> + syms_of_filewatch ();
> +#endif /* HAVE_FILEWATCH */
> +
> #ifdef HAVE_DBUS
> syms_of_dbusbind ();
> #endif /* HAVE_DBUS */
> diff --git a/src/filewatch.c b/src/filewatch.c
> new file mode 100644
> index 0000000..5b7c130
> --- /dev/null
> +++ b/src/filewatch.c
> @@ -0,0 +1,242 @@
> +/* Watching file system changes.
> +
> +Copyright (C) 2011
> + Free Software Foundation, Inc.
> +
> +This file is part of GNU Emacs.
> +
> +GNU Emacs is free software: you can redistribute it and/or modify
> +it under the terms of the GNU General Public License as published by
> +the Free Software Foundation, either version 3 of the License, or
> +(at your option) any later version.
> +
> +GNU Emacs is distributed in the hope that it will be useful,
> +but WITHOUT ANY WARRANTY; without even the implied warranty of
> +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +GNU General Public License for more details.
> +
> +You should have received a copy of the GNU General Public License
> +along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
> +
> +#include <config.h>
> +
> +#ifdef HAVE_FILEWATCH
> +
> +#include <setjmp.h>
> +
> +#include "lisp.h"
> +#include "process.h"
> +
> +static Lisp_Object QCmodify, QCmove, QCattrib, QCdelete, QCfrom, QCto, QCall;
> +
> +#ifdef HAVE_INOTIFY
> +#include <sys/inotify.h>
> +#include <sys/ioctl.h>
> +
> +enum { uninitialized = -100 };
> +static int inotifyfd = uninitialized;
> +
> +// Assoc list of files being watched.
> +static Lisp_Object data;
> +
> +static void
> +inotify_callback(int fd, void *_, int for_read) {
> + eassert(for_read);
> + eassert(data);
> +
> + int to_read = 0;
> + if(ioctl(fd, FIONREAD, &to_read) == -1)
> + report_file_error("ioctl(2) on inotify", Qnil);
> + char *const buffer = xmalloc(to_read);
> + ssize_t const n = read(fd, buffer, to_read);
> + if(n < 0)
> + report_file_error("read from inotify", Qnil);
> + else if(n < to_read)
> + {
> + // TODO
> + message1("n < to_read");
> + }
> +
> + size_t i = 0;
> + while(i < (size_t)n)
> + {
> + struct inotify_event *ev = (struct inotify_event*)&buffer[i];
> +
> + Lisp_Object callback = Fassoc(make_number(ev->wd), data);
> + if(!NILP(callback))
> + {
> + Lisp_Object call[3];
> + call[0] = Fcar(Fcdr(Fcdr(callback))); /* callback */
> + call[1] = Fcar(Fcdr(callback)); /* path */
> +
> + /* TODO check how to handle UTF-8 in file names:
> + make_string_from_bytes NCHARS vs. NBYTES */
> + /* ev->len seems to be an arbitrary large number
> + and not the exact length of ev->name */
> + size_t const len = strlen(ev->name);
> + /* if a directory is watched name contains the name
> + of the file that was changed */
> + Lisp_Object name = make_string_from_bytes (ev->name, len, len);
> +
> + Lisp_Object events = Qnil;
> + if(ev->mask & (IN_MODIFY|IN_CREATE) )
> + events = Fcons(Fcons(QCmodify, name), events);
> + if(ev->mask & IN_MOVE_SELF)
> + events = Fcons(Fcons(QCmove, name), events);
> + if(ev->mask & IN_MOVED_FROM)
> + events = Fcons(Fcons(QCmove, Fcons(QCfrom, Fcons(name,
> make_number(ev->cookie)))), events);
> + if(ev->mask & IN_MOVED_TO)
> + events = Fcons(Fcons(QCmove, Fcons(QCto, Fcons(name,
> make_number(ev->cookie)))), events);
> + if(ev->mask & IN_ATTRIB)
> + events = Fcons(Fcons(QCattrib, name), events);
> + if(ev->mask & (IN_DELETE|IN_DELETE_SELF) )
> + events = Fcons(Fcons(QCdelete, name), events);
> +
> + if(!NILP(events))
> + {
> + call[2] = events;
> + Ffuncall(3, call);
> + }
> +
> + if(ev->mask & IN_IGNORED)
> + {
> + /* Event was removed automatically: Drop it from data list. */
> + message("File-watch: \"%s\" will be ignored", SSDATA(call[1]));
> + data = Fdelete(callback, data);
> + }
> + if(ev->mask & IN_Q_OVERFLOW)
> + message1("File watch: Inotify Queue Overflow!");
> + }
> +
> + i += sizeof(*ev) + ev->len;
> + }
> +
> + free(buffer);
> +}
> +
> +DEFUN ("file-watch", Ffile_watch, Sfile_watch, 3, MANY, 0,
> + doc: /* Watch a file or directory.
> +
> +file-watch watches the file or directory given in PATH. If a change occurs
> +CALLBACK is called with PATH as first argument and a list of changes as
> second
> +argument. FLAGS can be
> +
> +:modify -- notify when a file is modified or created.
> +
> +:move -- notify when a file/directory is moved.
> +
> +:attrib -- notify when attributes change.
> +
> +:delete -- notify when a file/directory is deleted.
> +
> +:all -- notify for all of the above.
> +
> +Watching a directory is not recursive. CALLBACK receives the events as a list
> +with each list element being a list containing information about an event.
> The
> +first element is a flag symbol. If a directory is watched the second element
> is
> +the name of the file that changed. If a file is moved from or to the
> directory
> +the second element is either :from or :to and the third element is the file
> +name. A fourth element contains a numeric identifier (cookie) that can be
> used
> +to identify matching move operations if a file is moved inside the directory.
> +
> +Use `file-unwatch' to stop watching.
> +
> +usage: (file-watch PATH CALLBACK &rest FLAGS) */)
> + (size_t nargs, Lisp_Object *args)
> +{
> + if(nargs < 3)
> + return Qnil;
> +
> + CHECK_STRING(args[0]);
> +
> + if(inotifyfd == uninitialized)
> + {
> + inotifyfd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC);
> + if(inotifyfd == -1)
> + report_file_error("Initializing file watching", Qnil);
> + data = Qnil;
> + add_read_fd(inotifyfd, &inotify_callback, &data);
> + }
> + uint32_t mask = 0;
> + int i;
> + for(i = 2; i < nargs; ++i)
> + {
> + if(EQ(args[i], QCmodify))
> + mask |= IN_MODIFY | IN_CREATE;
> + else if(EQ(args[i], QCmove))
> + mask |= IN_MOVE_SELF | IN_MOVE;
> + else if(EQ(args[i], QCattrib))
> + mask |= IN_ATTRIB;
> + else if(EQ(args[i], QCdelete))
> + mask |= IN_DELETE_SELF | IN_DELETE;
> + else if(EQ(args[i], QCall))
> + mask |= IN_MODIFY | IN_CREATE | IN_MOVE_SELF | IN_MOVE | IN_ATTRIB
> + | IN_DELETE_SELF | IN_DELETE;
> + else /* TODO: should this be an error? */
> + message("Unkown parameter %s (ignored)",
> SSDATA(Fprin1_to_string(args[i], Qnil)));
> + }
> + int watchdesc = inotify_add_watch(inotifyfd, SSDATA(args[0]), mask);
> + if(watchdesc == -1) {
> + report_file_error("Watching file", Qnil);
> + }
> + data = Fcons(Fcons(make_number(watchdesc), Flist(2, args)), data);
> + return Qt;
> +}
> +
> +DEFUN ("file-unwatch", Ffile_unwatch, Sfile_unwatch, 1, 1, 0,
> + doc: /* Stop watching a file or directory. */)
> + (Lisp_Object path)
> +{
> + if(inotifyfd == uninitialized)
> + return Qnil;
> + CHECK_STRING(path);
> +
> + Lisp_Object x = data;
> + Lisp_Object cell, path_data;
> + while(!NILP(x))
> + {
> + cell = Fcar(x);
> + x = Fcdr(x);
> + path_data = Fcdr(cell);
> + if(!NILP(path_data) && STRINGP(Fcar(path_data))
> + && Fstring_equal(Fcar(path_data), path)
> + && NUMBERP(Fcar(cell)))
> + {
> + int const magicno = XINT(Fcar(cell));
> + data = Fdelete(cell, data);
> + if(inotify_rm_watch(inotifyfd, magicno) == -1)
> + report_file_error("Unwatch path", Qnil);
> + return Qt;
> + }
> + }
> + return Qnil;
> +}
> +
> +#else /* HAVE_INOTIFY */
> +#error "Filewatch defined but no watch mechanism (inotify) available"
> +#endif /* HAVE_INOTIFY */
> +
> +void
> +syms_of_filewatch (void)
> +{
> + QCmodify = intern_c_string (":modify");
> + staticpro (&QCmodify);
> + QCmove = intern_c_string (":move");
> + staticpro (&QCmove);
> + QCattrib = intern_c_string (":attrib");
> + staticpro (&QCattrib);
> + QCdelete = intern_c_string (":delete");
> + staticpro (&QCdelete);
> + QCfrom = intern_c_string (":from");
> + staticpro (&QCfrom);
> + QCto = intern_c_string (":to");
> + staticpro (&QCto);
> + QCall = intern_c_string (":all");
> + staticpro (&QCall);
> +
> + defsubr (&Sfile_watch);
> + defsubr (&Sfile_unwatch);
> +}
> +
> +
> +#endif /* HAVE_FILEWATCH */
> diff --git a/src/lisp.h b/src/lisp.h
> index 85838d1..3ed5281 100644
> --- a/src/lisp.h
> +++ b/src/lisp.h
> @@ -3405,6 +3405,11 @@ EXFUN (Fxw_display_color_p, 1);
> EXFUN (Fx_focus_frame, 1);
> #endif
>
> +/* Defined in filewatch.c */
> +#ifdef HAVE_FILEWATCH
> +extern void syms_of_filewatch (void);
> +#endif
> +
> /* Defined in xfaces.c */
> extern Lisp_Object Qdefault, Qtool_bar, Qregion, Qfringe;
> extern Lisp_Object Qheader_line, Qscroll_bar, Qcursor, Qborder, Qmouse, Qmenu;
> --
> 1.7.5.2
>
- [PATCH] Support for filesystem watching (inotify), Rüdiger Sonderfeld, 2011/06/04
- Re: [PATCH] Support for filesystem watching (inotify), joakim, 2011/06/04
- Re: [PATCH] Support for filesystem watching (inotify),
Jan Djärv <=
- Re: [PATCH update2] Support for filesystem watching (inotify), Rüdiger Sonderfeld, 2011/06/04
- Re: [PATCH update2] Support for filesystem watching (inotify), Jan Djärv, 2011/06/05
- Re: [PATCH update2] Support for filesystem watching (inotify), Andreas Schwab, 2011/06/05
- Re: [PATCH update2] Support for filesystem watching (inotify), Rüdiger Sonderfeld, 2011/06/05
- Re: [PATCH update2] Support for filesystem watching (inotify), John Yates, 2011/06/05
- Re: [PATCH update2] Support for filesystem watching (inotify), Rüdiger Sonderfeld, 2011/06/05
- Re: [PATCH update2] Support for filesystem watching (inotify), Eli Zaretskii, 2011/06/05
- Re: [PATCH update2] Support for filesystem watching (inotify), Rüdiger Sonderfeld, 2011/06/07