[PATCH] Editor file locking
Adam Byrtek / alpha
alpha at student.uci.agh.edu.pl
Wed Apr 2 17:37:08 UTC 2003
On Wed, Apr 02, 2003 at 11:37:07AM -0500, Pavel Roskin wrote:
> The patch looks good, but "Steal" and "Continue" looks a bit confusing for
> a new user. Maybe "Break lock" and "Ignore lock" would be better?
Yes, they sound better. 'Steal' and 'continue' was based on JED.
> Emacs 21.2.1 understands the locks created by mc, but mc doesn't under
> understand locks created by emacs, which have the timestamp after ":" at
Didn't test it with Emacs, just with JED. I thought that the format is
the same - my mistake. Fixed.
> the end. I think the lock should be honored regardless of whether its
> text can be fully parsed.
It is... but this issue was different. Mc treated the whole timestamp
as a pid... and thought that the process with this pid has died.
> Locks can be left by mc in the following scenario. First mc opens and
> starts editing. Second mc starts editing, the user chooses "Continue".
> Second mc exits without saving. First mc exits without saving. The lock
> remains.
Fixed patch attached.
Regards
Adam
--
_.|._ |_ _. : Adam Byrtek /alpha alpha at debian.org
(_|||_)| |(_| : http://krakow.linux.org.pl/ pgp 0xB25952C0
|
-------------- next part --------------
Index: edit/ChangeLog
===================================================================
RCS file: /cvs/gnome/mc/edit/ChangeLog,v
retrieving revision 1.157
diff -u -r1.157 ChangeLog
--- edit/ChangeLog 12 Mar 2003 07:07:27 -0000 1.157
+++ edit/ChangeLog 2 Apr 2003 17:35:23 -0000
@@ -1,0 +1,14 @@
+2003-04-01 Adam Byrtek <alpha at debian.org>
+
+ * editlock.c, editlock.h: New files. Implement file locking in
+ Emacs style, as documented in JED editor sources.
+ Makefile.am: Add those files to build tree.
+
+ * edit-widget.c (WEdit): New property 'locked', 0 on edit_init.
+ * edit.c (edit_modification): Lock buffer on modification.
+ * editcmd.c (edit_save_cmd, edit_save_as_cmd): Handle locking during
+ file save.
+ (edit_load_file_from_filename): Unlock. Remove 2 duplicate
+ lines (handled by edit_init).
+ (edit_quit_cmd): Unlock.
+
Index: edit/Makefile.am
===================================================================
RCS file: /cvs/gnome/mc/edit/Makefile.am,v
retrieving revision 1.5
diff -u -r1.5 Makefile.am
--- edit/Makefile.am 23 Dec 2002 10:13:35 -0000 1.5
+++ edit/Makefile.am 2 Apr 2003 17:35:23 -0000
@@ -9,6 +9,6 @@
libedit_a_SOURCES = \
bookmark.c edit.c editcmd.c editwidget.c editdraw.c editkeys.c \
editmenu.c editoptions.c editcmddef.h edit.h edit-widget.h \
- syntax.c wordproc.c
+ syntax.c wordproc.c editlock.c editlock.h
EXTRA_DIST = ChangeLog
Index: edit/edit-widget.h
===================================================================
RCS file: /cvs/gnome/mc/edit/edit-widget.h,v
retrieving revision 1.15
diff -u -r1.15 edit-widget.h
--- edit/edit-widget.h 12 Mar 2003 07:07:28 -0000 1.15
+++ edit/edit-widget.h 2 Apr 2003 17:35:23 -0000
@@ -56,6 +56,7 @@
unsigned char overwrite;
unsigned char modified; /* has the file been changed?: 1 if char inserted or
deleted at all since last load or save */
+ unsigned char locked; /* 1 if lock is held on current file */
unsigned char screen_modified; /* has the file been changed since the last screen draw? */
int delete_file; /* Has the file been created by the editor? Delete
it at end of editing when it hasn't been modified
Index: edit/edit.c
===================================================================
RCS file: /cvs/gnome/mc/edit/edit.c,v
retrieving revision 1.73
diff -u -r1.73 edit.c
--- edit/edit.c 23 Dec 2002 10:13:35 -0000 1.73
+++ edit/edit.c 2 Apr 2003 17:35:24 -0000
@@ -22,6 +22,7 @@
#include <config.h>
#include "edit.h"
+#include "editlock.h"
#include "edit-widget.h"
#include "editcmddef.h"
@@ -554,6 +555,7 @@
return 0;
}
edit->modified = 0;
+ edit->locked = 0;
edit_load_syntax (edit, 0, 0);
{
int color;
@@ -811,8 +813,12 @@
static inline void edit_modification (WEdit * edit)
{
edit->caches_valid = 0;
- edit->modified = 1;
edit->screen_modified = 1;
+
+ /* raise lock when file modified */
+ if (!edit->modified && !edit->delete_file)
+ edit->locked = edit_lock_file (edit->filename);
+ edit->modified = 1;
}
/*
Index: edit/editcmd.c
===================================================================
RCS file: /cvs/gnome/mc/edit/editcmd.c,v
retrieving revision 1.75
diff -u -r1.75 editcmd.c
--- edit/editcmd.c 19 Dec 2002 13:01:34 -0000 1.75
+++ edit/editcmd.c 2 Apr 2003 17:35:25 -0000
@@ -27,6 +27,7 @@
#include <ctype.h>
#include "edit.h"
+#include "editlock.h"
#include "editcmddef.h"
#include "edit-widget.h"
@@ -184,9 +185,6 @@
doupdate();
}
-/* "Oleg Yu. Repin" <repin at ssd.sscc.ru> added backup filenames
- ...thanks -paul */
-
/* If 0 (quick save) then a) create/truncate <filename> file,
b) save to <filename>;
if 1 (safe save) then a) save to <tempnam>,
@@ -438,6 +436,7 @@
{
/* This heads the 'Save As' dialog box */
char *exp = 0;
+ int save_lock = 0;
int different_filename = 0;
exp = edit_get_save_file (edit->filename, _(" Save As "));
@@ -465,8 +464,25 @@
return 0;
}
}
+ save_lock = edit_lock_file (exp);
+ } else {
+ /* filenames equal, check if already locked */
+ if (!edit->locked && !edit->delete_file)
+ save_lock = edit_lock_file (exp);
}
+
if (edit_save_file (edit, exp)) {
+ /* Succesful, so unlock both files */
+ if (strcmp (edit->filename, exp)) {
+ if (save_lock)
+ edit_unlock_file (exp);
+ if (edit->locked)
+ edit->locked = edit_unlock_file (edit->filename);
+ } else {
+ if (edit->locked || save_lock)
+ edit->locked = edit_unlock_file (edit->filename);
+ }
+
edit_set_filename (edit, exp);
g_free (exp);
edit->modified = 0;
@@ -476,6 +492,11 @@
edit->force |= REDRAW_COMPLETELY;
return 1;
} else {
+ /* Failed, so maintain modify (not save) lock */
+ if (strcmp (edit->filename, exp) && save_lock)
+ edit_unlock_file (exp);
+ if (save_lock)
+ edit->locked = edit_unlock_file (edit->filename);
g_free (exp);
edit_error_dialog (_(" Save As "),
get_sys_error (_
@@ -730,11 +751,22 @@
/* returns 1 on success */
int edit_save_cmd (WEdit * edit)
{
- if (!edit_save_file (edit, edit->filename))
+ int res, save_lock = 0;
+
+ if (!edit->locked && !edit->delete_file)
+ save_lock = edit_lock_file (edit->filename);
+ res = edit_save_file (edit, edit->filename);
+
+ /* Maintain modify (not save) lock on failure */
+ if ((res && edit->locked) || save_lock)
+ edit->locked = edit_unlock_file (edit->filename);
+
+ /* On failure try 'save as', it does locking on its own */
+ if (!res)
return edit_save_as_cmd (edit);
edit->force |= REDRAW_COMPLETELY;
- edit->modified = 0;
edit->delete_file = 0;
+ edit->modified = 0;
return 1;
}
@@ -750,7 +782,9 @@
}
}
edit->force |= REDRAW_COMPLETELY;
- edit->modified = 0;
+
+ if (edit->locked)
+ edit->locked = edit_unlock_file (edit->filename);
return edit_renew (edit); /* if this gives an error, something has really screwed up */
}
@@ -758,10 +792,17 @@
static int
edit_load_file_from_filename (WEdit * edit, char *exp)
{
- if (!edit_reload (edit, exp))
+ int prev_locked = edit->locked;
+ char *prev_filename = g_strdup (edit->filename);
+
+ if (!edit_reload (edit, exp)) {
+ g_free (prev_filename);
return 1;
- edit_set_filename (edit, exp);
- edit->modified = 0;
+ }
+
+ if (prev_locked)
+ edit_unlock_file (prev_filename);
+ g_free (prev_filename);
return 0;
}
@@ -2023,6 +2064,8 @@
return;
break;
case 2:
+ if (edit->locked)
+ edit->locked = edit_unlock_file (edit->filename);
if (edit->delete_file)
unlink (edit->filename);
break;
--- /dev/null 2003-01-13 01:13:32.000000000 +0100
+++ edit/editlock.h 2003-04-02 13:31:20.000000000 +0200
@@ -0,0 +1,7 @@
+#ifndef __EDIT_LOCK_H
+#define __EDIT_LOCK_H
+
+int edit_lock_file (char *fname);
+int edit_unlock_file (char *fname);
+
+#endif /* !__EDIT_LOCK_H */
--- /dev/null 2003-01-13 01:13:32.000000000 +0100
+++ edit/editlock.c 2003-04-02 19:33:11.000000000 +0200
@@ -0,0 +1,180 @@
+/* editor file locking.
+
+ Copyright (C) 2003 the Free Software Foundation
+
+ Authors: 2003 Adam Byrtek
+
+ This program 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 2 of the License, or
+ (at your option) any later version.
+
+ This program 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 this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307, USA.
+
+*/
+
+#include <config.h>
+#include "edit.h"
+#include "editlock.h"
+
+#include "src/wtools.h" /* edit_query_dialog () */
+
+#define BUF_SIZE 255
+#define PID_BUF_SIZE 10
+
+/* Locking scheme used in mcedit is based on a documentation found
+ in JED editor sources. Abstract from lock.c file (by John E. Davis):
+
+ The basic idea here is quite simple. Whenever a buffer is attached to
+ a file, and that buffer is modified, then attempt to lock the
+ file. Moreover, before writing to a file for any reason, lock the
+ file. The lock is really a protocol respected and not a real lock.
+ The protocol is this: If in the directory of the file is a
+ symbolic link with name ".#FILE", the FILE is considered to be locked
+ by the process specified by the link.
+*/
+
+/* Build user at host.domain.pid string (need to be freed) */
+static char *lock_build_name (char *fname)
+{
+ char host [BUF_SIZE], *user;
+
+ if (!((user = getpwuid (getuid ()) -> pw_name) ||
+ (user = getenv ("USER")) ||
+ (user = getenv ("USERNAME")) ||
+ (user = getenv ("LOGNAME"))))
+ user = "";
+
+ /* TODO: Use FQDN, no clean interface, so requires lot of code */
+ if (gethostname (host, BUF_SIZE-1) == -1)
+ *host='\0';
+
+ return g_strdup_printf ("%s@%s.%d", user, host, getpid ());
+}
+
+/* Extract pid from user at host.domain.pid string */
+static pid_t lock_extract_pid (char *str)
+{
+ int i;
+ char *p, pid[PID_BUF_SIZE];
+
+ /* Treat text between '.' and ':' or '\0' as pid */
+ for (p=str+strlen(str)-1; p>=str; p--)
+ if (*p == '.')
+ break;
+
+ i = 0;
+ for (p=p+1; p<str+strlen(str) && *p!=':' && i<PID_BUF_SIZE; p++)
+ pid[i++] = *p;
+ pid[i] = '\0';
+
+ return (pid_t) atol (pid);
+}
+
+/* Extract user at host.domain.pid from lock file (static string) */
+static char *lock_get_info (char *lockfname)
+{
+ int cnt;
+ static char buf[BUF_SIZE];
+
+ if ((cnt=readlink (lockfname, buf, BUF_SIZE-1)) == -1 || !buf || !*buf)
+ return NULL;
+ buf[cnt]='\0';
+ return buf;
+}
+
+
+/* Tries to raise file lock
+ Returns 1 on success, 0 on failure, -1 if abort */
+int edit_lock_file (char *fname)
+{
+ char *lockfname, *newlock, *msg, *lock;
+ struct stat statbuf;
+ pid_t pid;
+
+ /* Just to be sure (and don't lock new file) */
+ if (!fname || !*fname)
+ return 0;
+
+ /* Check if already locked */
+ lockfname = g_strconcat (".#", fname, NULL);
+ if (lstat (lockfname, &statbuf) == 0) {
+ lock = lock_get_info (lockfname);
+ if (!lock) {
+ g_free (lockfname);
+ return 0;
+ }
+ pid = lock_extract_pid (lock);
+
+ /* Check if locking process alive, ask user if required */
+ if (!pid || !(kill (pid, 0) == -1 && errno == ESRCH)) {
+ msg = g_strconcat ( fname, _(" is already locked by "), lock , NULL);
+ /* TODO: Implement "Abort" - needs to rewind undo stack */
+ switch (edit_query_dialog2 (_ ("File locked"), msg,
+ _ ("&Steal"), _ ("&Continue"))) {
+ case 0 :
+ break;
+ case 1 : case -1 :
+ g_free (lockfname);
+ g_free (msg);
+ return 0;
+ }
+ g_free (msg);
+ }
+ unlink (lockfname);
+ }
+
+ /* Create lock symlink */
+ newlock = lock_build_name (fname);
+ if (symlink (newlock, lockfname) == -1) {
+ g_free (lockfname);
+ g_free (newlock);
+ return 0;
+ }
+
+ g_free (lockfname);
+ g_free (newlock);
+ return 1;
+}
+
+/* Lowers file lock if possible
+ Always returns 0 to make 'lock = edit_unlock_file (f)' possible */
+int edit_unlock_file (char *fname)
+{
+ char *lockfname, *lock;
+ struct stat statbuf;
+
+ /* Just to be sure */
+ if (!fname || !*fname)
+ return 0;
+
+ lockfname = g_strconcat (".#", fname, NULL);
+
+ /* Check if lock exists */
+ if (lstat (lockfname, &statbuf) == -1) {
+ g_free (lockfname);
+ return 0;
+ }
+
+ lock = lock_get_info (lockfname);
+ if (lock) {
+ /* Don't touch if lock is not ours */
+ if (lock_extract_pid (lock) != getpid ()) {
+ g_free (lockfname);
+ return 0;
+ }
+ }
+
+ /* Remove lock */
+ unlink (lockfname);
+ g_free (lockfname);
+ return 0;
+}
More information about the mc-devel
mailing list