diff options
Diffstat (limited to 'src/filelock.c')
| -rw-r--r-- | src/filelock.c | 486 |
1 files changed, 0 insertions, 486 deletions
diff --git a/src/filelock.c b/src/filelock.c deleted file mode 100644 index d6ee952348b..00000000000 --- a/src/filelock.c +++ /dev/null @@ -1,486 +0,0 @@ -/* Copyright (C) 1985, 1986, 1987, 1993 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 2, 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; see the file COPYING. If not, write to -the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ - - -#include <sys/types.h> -#include <sys/stat.h> -#include <config.h> - -#ifdef VMS -#include "vms-pwd.h" -#else -#include <pwd.h> -#endif - -#include <errno.h> -#include <sys/file.h> -#ifdef USG -#include <fcntl.h> -#endif /* USG */ - -#include "lisp.h" -#include <paths.h> -#include "buffer.h" - -#ifdef SYSV_SYSTEM_DIR -#include <dirent.h> -#else /* not SYSV_SYSTEM_DIR */ -#ifdef NONSYSTEM_DIR_LIBRARY -#include "ndir.h" -#else /* not NONSYSTEM_DIR_LIBRARY */ -#ifdef MSDOS -#include <dirent.h> -#else -#include <sys/dir.h> -#endif -#endif /* not NONSYSTEM_DIR_LIBRARY */ -#ifndef MSDOS -extern DIR *opendir (); -#endif /* not MSDOS */ -#endif /* not SYSV_SYSTEM_DIR */ - -extern int errno; - -extern char *egetenv (); -extern char *strcpy (); - -#if defined (__bsdi__) || defined (DECLARE_GETPWUID_WITH_UID_T) -extern struct passwd *getpwuid (uid_t); -#else -extern struct passwd *getpwuid (); -#endif - -#ifdef CLASH_DETECTION - -/* If system does not have symbolic links, it does not have lstat. - In that case, use ordinary stat instead. */ - -#ifndef S_IFLNK -#define lstat stat -#endif - - -/* The name of the directory in which we keep lock files, with a '/' - appended. */ -char *lock_path; - -/* The name of the file in the lock directory which is used to - arbitrate access to the entire directory. */ -#define SUPERLOCK_NAME "!!!SuperLock!!!" - -/* The path to the superlock file. This is SUPERLOCK_NAME appended to - lock_path. */ -char *superlock_path; - -/* Set LOCK to the name of the lock file for the filename FILE. - char *LOCK; Lisp_Object FILE; */ - -#ifndef HAVE_LONG_FILE_NAMES - -#define MAKE_LOCK_PATH(lock, file) \ - (lock = (char *) alloca (14 + strlen (lock_path) + 1), \ - fill_in_lock_short_file_name (lock, (file))) - - -fill_in_lock_short_file_name (lockfile, fn) - register char *lockfile; - register Lisp_Object fn; -{ - register union - { - unsigned int word [2]; - unsigned char byte [8]; - } crc; - register unsigned char *p, new; - - /* 7-bytes cyclic code for burst correction on byte-by-byte basis. - the used polynomial is D^7 + D^6 + D^3 +1. pot@cnuce.cnr.it */ - - crc.word[0] = crc.word[1] = 0; - - for (p = XSTRING (fn)->data; new = *p++; ) - { - new += crc.byte[6]; - crc.byte[6] = crc.byte[5] + new; - crc.byte[5] = crc.byte[4]; - crc.byte[4] = crc.byte[3]; - crc.byte[3] = crc.byte[2] + new; - crc.byte[2] = crc.byte[1]; - crc.byte[1] = crc.byte[0]; - crc.byte[0] = new; - } - sprintf (lockfile, "%s%.2x%.2x%.2x%.2x%.2x%.2x%.2x", lock_path, - crc.byte[0], crc.byte[1], crc.byte[2], crc.byte[3], - crc.byte[4], crc.byte[5], crc.byte[6]); -} - -#else /* defined HAVE_LONG_FILE_NAMES */ - -#define MAKE_LOCK_PATH(lock, file) \ - (lock = (char *) alloca (XSTRING (file)->size + strlen (lock_path) + 1), \ - fill_in_lock_file_name (lock, (file))) - - -fill_in_lock_file_name (lockfile, fn) - register char *lockfile; - register Lisp_Object fn; -{ - register char *p; - - strcpy (lockfile, lock_path); - - p = lockfile + strlen (lockfile); - - strcpy (p, XSTRING (fn)->data); - - for (; *p; p++) - { - if (*p == '/') - *p = '!'; - } -} -#endif /* !defined HAVE_LONG_FILE_NAMES */ - -static Lisp_Object -lock_file_owner_name (lfname) - char *lfname; -{ - struct stat s; - struct passwd *the_pw; - - if (lstat (lfname, &s) == 0) - the_pw = getpwuid (s.st_uid); - return (the_pw == 0 ? Qnil : build_string (the_pw->pw_name)); -} - - -/* lock_file locks file fn, - meaning it serves notice on the world that you intend to edit that file. - This should be done only when about to modify a file-visiting - buffer previously unmodified. - Do not (normally) call lock_buffer for a buffer already modified, - as either the file is already locked, or the user has already - decided to go ahead without locking. - - When lock_buffer returns, either the lock is locked for us, - or the user has said to go ahead without locking. - - If the file is locked by someone else, lock_buffer calls - ask-user-about-lock (a Lisp function) with two arguments, - the file name and the name of the user who did the locking. - This function can signal an error, or return t meaning - take away the lock, or return nil meaning ignore the lock. */ - -/* The lock file name is the file name with "/" replaced by "!" - and put in the Emacs lock directory. */ -/* (ie., /ka/king/junk.tex -> /!/!ka!king!junk.tex). */ - -/* If HAVE_LONG_FILE_NAMES is not defined, the lock file name is the hex - representation of a 14-bytes CRC generated from the file name - and put in the Emacs lock directory (not very nice, but it works). - (ie., /ka/king/junk.tex -> /!/12a82c62f1c6da). */ - -void -lock_file (fn) - register Lisp_Object fn; -{ - register Lisp_Object attack; - register char *lfname; - - MAKE_LOCK_PATH (lfname, fn); - - /* See if this file is visited and has changed on disk since it was - visited. */ - { - register Lisp_Object subject_buf; - subject_buf = Fget_file_buffer (fn); - if (!NILP (subject_buf) - && NILP (Fverify_visited_file_modtime (subject_buf)) - && !NILP (Ffile_exists_p (fn))) - call1 (intern ("ask-user-about-supersession-threat"), fn); - } - - /* Try to lock the lock. */ - if (lock_if_free (lfname) <= 0) - /* Return now if we have locked it, or if lock dir does not exist */ - return; - - /* Else consider breaking the lock */ - attack = call2 (intern ("ask-user-about-lock"), fn, - lock_file_owner_name (lfname)); - if (!NILP (attack)) - /* User says take the lock */ - { - lock_superlock (lfname); - lock_file_1 (lfname, O_WRONLY) ; - unlink (superlock_path); - return; - } - /* User says ignore the lock */ -} - -/* Lock the lock file named LFNAME. - If MODE is O_WRONLY, we do so even if it is already locked. - If MODE is O_WRONLY | O_EXCL | O_CREAT, we do so only if it is free. - Return 1 if successful, 0 if not. */ - -int -lock_file_1 (lfname, mode) - int mode; char *lfname; -{ - register int fd; - char buf[20]; - - if ((fd = open (lfname, mode, 0666)) >= 0) - { -#ifdef USG - chmod (lfname, 0666); -#else - fchmod (fd, 0666); -#endif - sprintf (buf, "%d ", getpid ()); - write (fd, buf, strlen (buf)); - close (fd); - return 1; - } - else - return 0; -} - -/* Lock the lock named LFNAME if possible. - Return 0 in that case. - Return positive if lock is really locked by someone else. - Return -1 if cannot lock for any other reason. */ - -int -lock_if_free (lfname) - register char *lfname; -{ - register int clasher; - - while (lock_file_1 (lfname, O_WRONLY | O_EXCL | O_CREAT) == 0) - { - if (errno != EEXIST) - return -1; - clasher = current_lock_owner (lfname); - if (clasher != 0) - if (clasher != getpid ()) - return (clasher); - else return (0); - /* Try again to lock it */ - } - return 0; -} - -/* Return the pid of the process that claims to own the lock file LFNAME, - or 0 if nobody does or the lock is obsolete, - or -1 if something is wrong with the locking mechanism. */ - -int -current_lock_owner (lfname) - char *lfname; -{ - int owner = current_lock_owner_1 (lfname); - if (owner == 0 && errno == ENOENT) - return (0); - /* Is it locked by a process that exists? */ - if (owner != 0 && (kill (owner, 0) >= 0 || errno == EPERM)) - return (owner); - if (unlink (lfname) < 0) - return (-1); - return (0); -} - -int -current_lock_owner_1 (lfname) - char *lfname; -{ - register int fd; - char buf[20]; - int tem; - - fd = open (lfname, O_RDONLY, 0666); - if (fd < 0) - return 0; - tem = read (fd, buf, sizeof buf); - close (fd); - return (tem <= 0 ? 0 : atoi (buf)); -} - - -void -unlock_file (fn) - register Lisp_Object fn; -{ - register char *lfname; - - MAKE_LOCK_PATH (lfname, fn); - - lock_superlock (lfname); - - if (current_lock_owner_1 (lfname) == getpid ()) - unlink (lfname); - - unlink (superlock_path); -} - -lock_superlock (lfname) - char *lfname; -{ - register int i, fd; - DIR *lockdir; - - for (i = -20; i < 0 && (fd = open (superlock_path, - O_WRONLY | O_EXCL | O_CREAT, 0666)) < 0; - i++) - { - if (errno != EEXIST) - return; - - /* This seems to be necessary to prevent Emacs from hanging when the - competing process has already deleted the superlock, but it's still - in the NFS cache. So we force NFS to synchronize the cache. */ - if (lockdir = opendir (lock_path)) - closedir (lockdir); - - sleep (1); - } - if (fd >= 0) - { -#ifdef USG - chmod (superlock_path, 0666); -#else - fchmod (fd, 0666); -#endif - write (fd, lfname, strlen (lfname)); - close (fd); - } -} - -void -unlock_all_files () -{ - register Lisp_Object tail; - register struct buffer *b; - - for (tail = Vbuffer_alist; XGCTYPE (tail) == Lisp_Cons; - tail = XCONS (tail)->cdr) - { - b = XBUFFER (XCONS (XCONS (tail)->car)->cdr); - if (XTYPE (b->filename) == Lisp_String && - b->save_modified < BUF_MODIFF (b)) - unlock_file (b->filename); - } -} - - -DEFUN ("lock-buffer", Flock_buffer, Slock_buffer, - 0, 1, 0, - "Lock FILE, if current buffer is modified.\n\ -FILE defaults to current buffer's visited file,\n\ -or else nothing is done if current buffer isn't visiting a file.") - (fn) - Lisp_Object fn; -{ - if (NILP (fn)) - fn = current_buffer->filename; - else - CHECK_STRING (fn, 0); - if (current_buffer->save_modified < MODIFF - && !NILP (fn)) - lock_file (fn); - return Qnil; -} - -DEFUN ("unlock-buffer", Funlock_buffer, Sunlock_buffer, - 0, 0, 0, - "Unlock the file visited in the current buffer,\n\ -if it should normally be locked.") - () -{ - if (current_buffer->save_modified < MODIFF && - XTYPE (current_buffer->filename) == Lisp_String) - unlock_file (current_buffer->filename); - return Qnil; -} - - -/* Unlock the file visited in buffer BUFFER. */ - -unlock_buffer (buffer) - struct buffer *buffer; -{ - if (buffer->save_modified < BUF_MODIFF (buffer) && - XTYPE (buffer->filename) == Lisp_String) - unlock_file (buffer->filename); -} - -DEFUN ("file-locked-p", Ffile_locked_p, Sfile_locked_p, 0, 1, 0, - "Return nil if the FILENAME is not locked,\n\ -t if it is locked by you, else a string of the name of the locker.") - (fn) - Lisp_Object fn; -{ - register char *lfname; - int owner; - - fn = Fexpand_file_name (fn, Qnil); - - MAKE_LOCK_PATH (lfname, fn); - - owner = current_lock_owner (lfname); - if (owner <= 0) - return (Qnil); - else if (owner == getpid ()) - return (Qt); - - return (lock_file_owner_name (lfname)); -} - - -/* Initialization functions. */ - -init_filelock () -{ - lock_path = egetenv ("EMACSLOCKDIR"); - if (! lock_path) - lock_path = PATH_LOCK; - - /* Make sure it ends with a slash. */ - if (lock_path[strlen (lock_path) - 1] != '/') - { - char *new_path = (char *) xmalloc (strlen (lock_path) + 2); - strcpy (new_path, lock_path); - lock_path = new_path; - strcat (lock_path, "/"); - } - - superlock_path = (char *) xmalloc ((strlen (lock_path) - + sizeof (SUPERLOCK_NAME))); - strcpy (superlock_path, lock_path); - strcat (superlock_path, SUPERLOCK_NAME); -} - -syms_of_filelock () -{ - defsubr (&Sunlock_buffer); - defsubr (&Slock_buffer); - defsubr (&Sfile_locked_p); -} - -#endif /* CLASH_DETECTION */ |