-/* Copyright (C) 1985, 1986, 1987, 1993, 1994 Free Software Foundation, Inc.
+/* Lock files for editing.
+ Copyright (C) 1985, 86, 87, 93, 94, 96, 98, 1999 Free Software Foundation, Inc.
This file is part of GNU Emacs.
Boston, MA 02111-1307, USA. */
+#include <config.h>
#include <sys/types.h>
#include <sys/stat.h>
-#include <config.h>
+#include <signal.h>
+#include <stdio.h>
#ifdef VMS
#include "vms-pwd.h"
#else
#include <pwd.h>
-#endif
+#endif /* not VMS */
-#include <errno.h>
#include <sys/file.h>
#ifdef USG
#include <fcntl.h>
+#include <string.h>
#endif /* USG */
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#ifdef __FreeBSD__
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#endif /* __FreeBSD__ */
+
#include "lisp.h"
-#include <paths.h>
#include "buffer.h"
+#include "charset.h"
+#include "coding.h"
+#include "systime.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>
+#include <time.h>
+#include <errno.h>
+#ifndef errno
+extern int errno;
#endif
-#endif /* not NONSYSTEM_DIR_LIBRARY */
-#ifndef MSDOS
-extern DIR *opendir ();
-#endif /* not MSDOS */
-#endif /* not SYSV_SYSTEM_DIR */
-extern int errno;
+/* The directory for writing temporary files. */
-extern char *egetenv ();
-extern char *strcpy ();
+Lisp_Object Vtemporary_file_directory;
-#ifdef DECLARE_GETPWUID_WITH_UID_T
-extern struct passwd *getpwuid (uid_t);
-#else
-extern struct passwd *getpwuid ();
+#ifdef CLASH_DETECTION
+
+#include <utmp.h>
+
+/* A file whose last-modified time is just after the most recent boot.
+ Define this to be NULL to disable checking for this file. */
+#ifndef BOOT_TIME_FILE
+#define BOOT_TIME_FILE "/var/run/random-seed"
#endif
-#ifdef CLASH_DETECTION
+#ifndef WTMP_FILE
+#define WTMP_FILE "/var/log/wtmp"
+#endif
-/* If system does not have symbolic links, it does not have lstat.
- In that case, use ordinary stat instead. */
+/* The strategy: to lock a file FN, create a symlink .#FN in FN's
+ directory, with link data `user@host.pid'. This avoids a single
+ mount (== failure) point for lock files.
+
+ When the host in the lock data is the current host, we can check if
+ the pid is valid with kill.
+
+ Otherwise, we could look at a separate file that maps hostnames to
+ reboot times to see if the remote pid can possibly be valid, since we
+ don't want Emacs to have to communicate via pipes or sockets or
+ whatever to other processes, either locally or remotely; rms says
+ that's too unreliable. Hence the separate file, which could
+ theoretically be updated by daemons running separately -- but this
+ whole idea is unimplemented; in practice, at least in our
+ environment, it seems such stale locks arise fairly infrequently, and
+ Emacs' standard methods of dealing with clashes suffice.
+
+ We use symlinks instead of normal files because (1) they can be
+ stored more efficiently on the filesystem, since the kernel knows
+ they will be small, and (2) all the info about the lock can be read
+ in a single system call (readlink). Although we could use regular
+ files to be useful on old systems lacking symlinks, nowadays
+ virtually all such systems are probably single-user anyway, so it
+ didn't seem worth the complication.
+
+ Similarly, we don't worry about a possible 14-character limit on
+ file names, because those are all the same systems that don't have
+ symlinks.
+
+ This is compatible with the locking scheme used by Interleaf (which
+ has contributed this implementation for Emacs), and was designed by
+ Ethan Jacobson, Kimbo Mundy, and others.
+
+ --karl@cs.umb.edu/karl@hq.ileaf.com. */
-#ifndef S_IFLNK
-#define lstat stat
-#endif
+\f
+/* Return the time of the last system boot. */
+
+static time_t boot_time;
+static int boot_time_initialized;
+extern Lisp_Object Vshell_file_name;
+
+static time_t
+get_boot_time ()
+{
+#if defined (BOOT_TIME) && ! defined (NO_WTMP_FILE)
+ int counter;
+#endif
-/* The name of the directory in which we keep lock files, with a '/'
- appended. */
-char *lock_dir;
+ if (boot_time_initialized)
+ return boot_time;
+ boot_time_initialized = 1;
-/* The name of the file in the lock directory which is used to
- arbitrate access to the entire directory. */
-#define SUPERLOCK_NAME "!!!SuperLock!!!"
+#if defined (CTL_KERN) && defined (KERN_BOOTTIME)
+ {
+ int mib[2];
+ size_t size;
+ struct timeval boottime_val;
+
+ mib[0] = CTL_KERN;
+ mib[1] = KERN_BOOTTIME;
+ size = sizeof (boottime_val);
+
+ if (sysctl (mib, 2, &boottime_val, &size, NULL, 0) >= 0)
+ {
+ boot_time = boottime_val.tv_sec;
+ return boot_time;
+ }
+ }
+#endif /* defined (CTL_KERN) && defined (KERN_BOOTTIME) */
-/* The name of the superlock file. This is SUPERLOCK_NAME appended to
- lock_dir. */
-char *superlock_file;
+ if (BOOT_TIME_FILE)
+ {
+ struct stat st;
+ if (stat (BOOT_TIME_FILE, &st) == 0)
+ {
+ boot_time = st.st_mtime;
+ return boot_time;
+ }
+ }
-/* Set LOCK to the name of the lock file for the filename FILE.
- char *LOCK; Lisp_Object FILE; */
+#if defined (BOOT_TIME) && ! defined (NO_WTMP_FILE)
+#ifndef CANNOT_DUMP
+ /* The utmp routines maintain static state.
+ Don't touch that state unless we are initialized,
+ since it might not survive dumping. */
+ if (! initialized)
+ return boot_time;
+#endif /* not CANNOT_DUMP */
+
+ /* Try to get boot time from utmp before wtmp,
+ since utmp is typically much smaller than wtmp.
+ Passing a null pointer causes get_boot_time_1
+ to inspect the default file, namely utmp. */
+ get_boot_time_1 ((char *) 0, 0);
+ if (boot_time)
+ return boot_time;
+
+ /* Try to get boot time from the current wtmp file. */
+ get_boot_time_1 (WTMP_FILE, 1);
+
+ /* If we did not find a boot time in wtmp, look at wtmp, and so on. */
+ for (counter = 0; counter < 20 && ! boot_time; counter++)
+ {
+ char cmd_string[100];
+ Lisp_Object tempname, filename;
+ int delete_flag = 0;
+
+ filename = Qnil;
+
+ sprintf (cmd_string, "%s.%d", WTMP_FILE, counter);
+ tempname = build_string (cmd_string);
+ if (! NILP (Ffile_exists_p (tempname)))
+ filename = tempname;
+ else
+ {
+ sprintf (cmd_string, "%s.%d.gz", WTMP_FILE, counter);
+ tempname = build_string (cmd_string);
+ if (! NILP (Ffile_exists_p (tempname)))
+ {
+ Lisp_Object args[6];
+ tempname = Fexpand_file_name (build_string ("wtmp"),
+ Vtemporary_file_directory);
+ tempname = Fmake_temp_name (tempname);
+ args[0] = Vshell_file_name;
+ args[1] = Qnil;
+ args[2] = Qnil;
+ args[3] = Qnil;
+ args[4] = build_string ("-c");
+ sprintf (cmd_string, "gunzip < %s.%d.gz > %s",
+ WTMP_FILE, counter, XSTRING (tempname)->data);
+ args[5] = build_string (cmd_string);
+ Fcall_process (6, args);
+ filename = tempname;
+ delete_flag = 1;
+ }
+ }
+
+ if (! NILP (filename))
+ {
+ get_boot_time_1 (XSTRING (filename)->data, 1);
+ if (delete_flag)
+ unlink (XSTRING (filename)->data);
+ }
+ }
-#ifndef HAVE_LONG_FILE_NAMES
+ return boot_time;
+#else
+ return 0;
+#endif
+}
-#define MAKE_LOCK_NAME(lock, file) \
- (lock = (char *) alloca (14 + strlen (lock_dir) + 1), \
- fill_in_lock_short_file_name (lock, (file)))
+#ifdef BOOT_TIME
+/* Try to get the boot time from wtmp file FILENAME.
+ This succeeds if that file contains a reboot record.
+ If FILENAME is zero, use the same file as before;
+ if no FILENAME has ever been specified, this is the utmp file.
+ Use the newest reboot record if NEWEST is nonzero,
+ the first reboot record otherwise.
+ Ignore all reboot records on or before BOOT_TIME.
+ Success is indicated by setting BOOT_TIME to a larger value. */
-fill_in_lock_short_file_name (lockfile, fn)
- register char *lockfile;
- register Lisp_Object fn;
+get_boot_time_1 (filename, newest)
+ char *filename;
+ int newest;
{
- register union
+ struct utmp ut, *utp;
+ int desc;
+
+ if (filename)
{
- 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 */
+ /* On some versions of IRIX, opening a nonexistent file name
+ is likely to crash in the utmp routines. */
+ desc = emacs_open (filename, O_RDONLY, 0);
+ if (desc < 0)
+ return;
+
+ emacs_close (desc);
+
+ utmpname (filename);
+ }
- crc.word[0] = crc.word[1] = 0;
+ setutent ();
- for (p = XSTRING (fn)->data; new = *p++; )
+ while (1)
{
- 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;
+ /* Find the next reboot record. */
+ ut.ut_type = BOOT_TIME;
+ utp = getutid (&ut);
+ if (! utp)
+ break;
+ /* Compare reboot times and use the newest one. */
+ if (utp->ut_time > boot_time)
+ {
+ boot_time = utp->ut_time;
+ if (! newest)
+ break;
+ }
+ /* Advance on element in the file
+ so that getutid won't repeat the same one. */
+ utp = getutent ();
+ if (! utp)
+ break;
}
- sprintf (lockfile, "%s%.2x%.2x%.2x%.2x%.2x%.2x%.2x", lock_dir,
- crc.byte[0], crc.byte[1], crc.byte[2], crc.byte[3],
- crc.byte[4], crc.byte[5], crc.byte[6]);
+ endutent ();
}
+#endif /* BOOT_TIME */
+\f
+/* Here is the structure that stores information about a lock. */
+
+typedef struct
+{
+ char *user;
+ char *host;
+ unsigned long pid;
+ time_t boot_time;
+} lock_info_type;
+
+/* When we read the info back, we might need this much more,
+ enough for decimal representation plus null. */
+#define LOCK_PID_MAX (4 * sizeof (unsigned long))
+
+/* Free the two dynamically-allocated pieces in PTR. */
+#define FREE_LOCK_INFO(i) do { xfree ((i).user); xfree ((i).host); } while (0)
-#else /* defined HAVE_LONG_FILE_NAMES */
+/* Write the name of the lock file for FN into LFNAME. Length will be
+ that of FN plus two more for the leading `.#' plus one for the null. */
#define MAKE_LOCK_NAME(lock, file) \
- (lock = (char *) alloca (XSTRING (file)->size + strlen (lock_dir) + 1), \
+ (lock = (char *) alloca (STRING_BYTES (XSTRING (file)) + 2 + 1), \
fill_in_lock_file_name (lock, (file)))
-
+static void
fill_in_lock_file_name (lockfile, fn)
register char *lockfile;
register Lisp_Object fn;
{
register char *p;
- strcpy (lockfile, lock_dir);
+ strcpy (lockfile, XSTRING (fn)->data);
+
+ /* Shift the nondirectory part of the file name (including the null)
+ right two characters. Here is one of the places where we'd have to
+ do something to support 14-character-max file names. */
+ for (p = lockfile + strlen (lockfile); p != lockfile && *p != '/'; p--)
+ p[2] = *p;
+
+ /* Insert the `.#'. */
+ p[1] = '.';
+ p[2] = '#';
+}
- p = lockfile + strlen (lockfile);
+/* Lock the lock file named LFNAME.
+ If FORCE is nonzero, we do so even if it is already locked.
+ Return 1 if successful, 0 if not. */
- strcpy (p, XSTRING (fn)->data);
+static int
+lock_file_1 (lfname, force)
+ char *lfname;
+ int force;
+{
+ register int err;
+ time_t boot_time;
+ char *user_name;
+ char *host_name;
+ char *lock_info_str;
+
+ if (STRINGP (Fuser_login_name (Qnil)))
+ user_name = (char *)XSTRING (Fuser_login_name (Qnil))->data;
+ else
+ user_name = "";
+ if (STRINGP (Fsystem_name ()))
+ host_name = (char *)XSTRING (Fsystem_name ())->data;
+ else
+ host_name = "";
+ lock_info_str = (char *)alloca (strlen (user_name) + strlen (host_name)
+ + LOCK_PID_MAX + 5);
+
+ boot_time = get_boot_time ();
+ if (boot_time)
+ sprintf (lock_info_str, "%s@%s.%lu:%lu", user_name, host_name,
+ (unsigned long) getpid (), (unsigned long) boot_time);
+ else
+ sprintf (lock_info_str, "%s@%s.%lu", user_name, host_name,
+ (unsigned long) getpid ());
- for (; *p; p++)
+ err = symlink (lock_info_str, lfname);
+ if (errno == EEXIST && force)
{
- if (*p == '/')
- *p = '!';
+ unlink (lfname);
+ err = symlink (lock_info_str, lfname);
}
+
+ return err == 0;
+}
+
+/* Return 1 if times A and B are no more than one second apart. */
+
+int
+within_one_second (a, b)
+ time_t a, b;
+{
+ return (a - b >= -1 && a - b <= 1);
}
-#endif /* !defined HAVE_LONG_FILE_NAMES */
+\f
+/* Return 0 if nobody owns the lock file LFNAME or the lock is obsolete,
+ 1 if another process owns it (and set OWNER (if non-null) to info),
+ 2 if the current process owns it,
+ or -1 if something is wrong with the locking mechanism. */
-static Lisp_Object
-lock_file_owner_name (lfname)
+static int
+current_lock_owner (owner, lfname)
+ lock_info_type *owner;
char *lfname;
{
- struct stat s;
- struct passwd *the_pw;
+#ifndef index
+ extern char *rindex (), *index ();
+#endif
+ int len, ret;
+ int local_owner = 0;
+ char *at, *dot, *colon;
+ char *lfinfo = 0;
+ int bufsize = 50;
+ /* Read arbitrarily-long contents of symlink. Similar code in
+ file-symlink-p in fileio.c. */
+ do
+ {
+ bufsize *= 2;
+ lfinfo = (char *) xrealloc (lfinfo, bufsize);
+ len = readlink (lfname, lfinfo, bufsize);
+ }
+ while (len >= bufsize);
+
+ /* If nonexistent lock file, all is well; otherwise, got strange error. */
+ if (len == -1)
+ {
+ xfree (lfinfo);
+ return errno == ENOENT ? 0 : -1;
+ }
- if (lstat (lfname, &s) == 0)
- the_pw = getpwuid (s.st_uid);
+ /* Link info exists, so `len' is its length. Null terminate. */
+ lfinfo[len] = 0;
+
+ /* Even if the caller doesn't want the owner info, we still have to
+ read it to determine return value, so allocate it. */
+ if (!owner)
+ {
+ owner = (lock_info_type *) alloca (sizeof (lock_info_type));
+ local_owner = 1;
+ }
+
+ /* Parse USER@HOST.PID:BOOT_TIME. If can't parse, return -1. */
+ /* The USER is everything before the first @. */
+ at = index (lfinfo, '@');
+ dot = rindex (lfinfo, '.');
+ if (!at || !dot)
+ {
+ xfree (lfinfo);
+ return -1;
+ }
+ len = at - lfinfo;
+ owner->user = (char *) xmalloc (len + 1);
+ strncpy (owner->user, lfinfo, len);
+ owner->user[len] = 0;
+
+ /* The PID is everything from the last `.' to the `:'. */
+ owner->pid = atoi (dot + 1);
+ colon = dot;
+ while (*colon && *colon != ':')
+ colon++;
+ /* After the `:', if there is one, comes the boot time. */
+ if (*colon == ':')
+ owner->boot_time = atoi (colon + 1);
else
- the_pw = 0;
+ owner->boot_time = 0;
+
+ /* The host is everything in between. */
+ len = dot - at - 1;
+ owner->host = (char *) xmalloc (len + 1);
+ strncpy (owner->host, at + 1, len);
+ owner->host[len] = 0;
- return (the_pw == 0 ? Qnil : build_string (the_pw->pw_name));
+ /* We're done looking at the link info. */
+ xfree (lfinfo);
+
+ /* On current host? */
+ if (STRINGP (Fsystem_name ())
+ && strcmp (owner->host, XSTRING (Fsystem_name ())->data) == 0)
+ {
+ if (owner->pid == getpid ())
+ ret = 2; /* We own it. */
+ else if (owner->pid > 0
+ && (kill (owner->pid, 0) >= 0 || errno == EPERM)
+ && (owner->boot_time == 0
+ || within_one_second (owner->boot_time, get_boot_time ())))
+ ret = 1; /* An existing process on this machine owns it. */
+ /* The owner process is dead or has a strange pid (<=0), so try to
+ zap the lockfile. */
+ else if (unlink (lfname) < 0)
+ ret = -1;
+ else
+ ret = 0;
+ }
+ else
+ { /* If we wanted to support the check for stale locks on remote machines,
+ here's where we'd do it. */
+ ret = 1;
+ }
+
+ /* Avoid garbage. */
+ if (local_owner || ret <= 0)
+ {
+ FREE_LOCK_INFO (*owner);
+ }
+ return ret;
}
+\f
+/* Lock the lock named LFNAME if possible.
+ Return 0 in that case.
+ Return positive if some other process owns the lock, and info about
+ that process in CLASHER.
+ Return -1 if cannot lock for any other reason. */
-/* lock_file locks file fn,
+static int
+lock_if_free (clasher, lfname)
+ lock_info_type *clasher;
+ register char *lfname;
+{
+ while (lock_file_1 (lfname, 0) == 0)
+ {
+ int locker;
+
+ if (errno != EEXIST)
+ return -1;
+
+ locker = current_lock_owner (clasher, lfname);
+ if (locker == 2)
+ {
+ FREE_LOCK_INFO (*clasher);
+ return 0; /* We ourselves locked it. */
+ }
+ else if (locker == 1)
+ return 1; /* Someone else has it. */
+ else if (locker == -1)
+ return -1; /* current_lock_owner returned strange error. */
+
+ /* We deleted a stale lock; try again to lock the file. */
+ }
+ return 0;
+}
+
+/* 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,
+ Do not (normally) call this 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,
+ When this 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
+ If the file is locked by someone else, this calls
ask-user-about-lock (a Lisp function) with two arguments,
- the file name and the name of the user who did the locking.
+ the file name and info about 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;
+ Lisp_Object fn;
{
- register Lisp_Object attack, orig_fn;
- register char *lfname;
+ register Lisp_Object attack, orig_fn, encoded_fn;
+ register char *lfname, *locker;
+ lock_info_type lock_info;
+ struct gcpro gcpro1;
+
+ /* Don't do locking while dumping Emacs.
+ Uncompressing wtmp files uses call-process, which does not work
+ in an uninitialized Emacs. */
+ if (! NILP (Vpurify_flag))
+ return;
orig_fn = fn;
+ GCPRO1 (fn);
fn = Fexpand_file_name (fn, Qnil);
+ encoded_fn = ENCODE_FILE (fn);
- MAKE_LOCK_NAME (lfname, fn);
+ /* Create the name of the lock-file for file fn */
+ MAKE_LOCK_NAME (lfname, encoded_fn);
/* See if this file is visited and has changed on disk since it was
visited. */
{
register Lisp_Object subject_buf;
+
subject_buf = get_truename_buffer (orig_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);
+
}
+ UNGCPRO;
/* 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 */
+ if (lock_if_free (&lock_info, lfname) <= 0)
+ /* Return now if we have locked it, or if lock creation failed */
return;
/* Else consider breaking the lock */
- attack = call2 (intern ("ask-user-about-lock"), fn,
- lock_file_owner_name (lfname));
+ locker = (char *) alloca (strlen (lock_info.user) + strlen (lock_info.host)
+ + LOCK_PID_MAX + 9);
+ sprintf (locker, "%s@%s (pid %lu)", lock_info.user, lock_info.host,
+ lock_info.pid);
+ FREE_LOCK_INFO (lock_info);
+
+ attack = call2 (intern ("ask-user-about-lock"), fn, build_string (locker));
if (!NILP (attack))
/* User says take the lock */
{
- lock_superlock (lfname);
- lock_file_1 (lfname, O_WRONLY) ;
- unlink (superlock_file);
+ lock_file_1 (lfname, 1);
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));
-}
-
-\f
void
unlock_file (fn)
register Lisp_Object fn;
register char *lfname;
fn = Fexpand_file_name (fn, Qnil);
+ fn = ENCODE_FILE (fn);
MAKE_LOCK_NAME (lfname, fn);
- lock_superlock (lfname);
-
- if (current_lock_owner_1 (lfname) == getpid ())
+ if (current_lock_owner (0, lfname) == 2)
unlink (lfname);
-
- unlink (superlock_file);
-}
-
-lock_superlock (lfname)
- char *lfname;
-{
- register int i, fd;
- DIR *lockdir;
-
- for (i = -20; i < 0 && (fd = open (superlock_file,
- 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_dir))
- closedir (lockdir);
-
- sleep (1);
- }
- if (fd >= 0)
- {
-#ifdef USG
- chmod (superlock_file, 0666);
-#else
- fchmod (fd, 0666);
-#endif
- write (fd, lfname, strlen (lfname));
- close (fd);
- }
}
void
register Lisp_Object tail;
register struct buffer *b;
- for (tail = Vbuffer_alist; GC_CONSP (tail); tail = XCONS (tail)->cdr)
+ for (tail = Vbuffer_alist; GC_CONSP (tail); tail = XCDR (tail))
{
- b = XBUFFER (XCONS (XCONS (tail)->car)->cdr);
+ b = XBUFFER (XCDR (XCAR (tail)));
if (STRINGP (b->file_truename) && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b))
- unlock_file (b->file_truename);
+ {
+ register char *lfname;
+
+ MAKE_LOCK_NAME (lfname, b->file_truename);
+
+ if (current_lock_owner (0, lfname) == 2)
+ unlink (lfname);
+ }
}
}
-
\f
DEFUN ("lock-buffer", Flock_buffer, Slock_buffer,
0, 1, 0,
return Qnil;
}
-\f
/* Unlock the file visited in buffer BUFFER. */
+void
unlock_buffer (buffer)
struct buffer *buffer;
{
(filename)
Lisp_Object filename;
{
+ Lisp_Object ret;
register char *lfname;
int owner;
+ lock_info_type locker;
filename = Fexpand_file_name (filename, Qnil);
MAKE_LOCK_NAME (lfname, filename);
- owner = current_lock_owner (lfname);
+ owner = current_lock_owner (&locker, lfname);
if (owner <= 0)
- return (Qnil);
- else if (owner == getpid ())
- return (Qt);
-
- return (lock_file_owner_name (lfname));
-}
+ ret = Qnil;
+ else if (owner == 2)
+ ret = Qt;
+ else
+ ret = build_string (locker.user);
+
+ if (owner > 0)
+ FREE_LOCK_INFO (locker);
+ return ret;
+}
\f
/* Initialization functions. */
+void
init_filelock ()
{
- char *new_name;
-
- lock_dir = egetenv ("EMACSLOCKDIR");
- if (! lock_dir)
- lock_dir = PATH_LOCK;
-
- /* Copy the name in case egetenv got it from a Lisp string. */
- new_name = (char *) xmalloc (strlen (lock_dir) + 2);
- strcpy (new_name, lock_dir);
- lock_dir = new_name;
-
- /* Make sure it ends with a slash. */
- if (lock_dir[strlen (lock_dir) - 1] != '/')
- strcat (lock_dir, "/");
-
- superlock_file = (char *) xmalloc ((strlen (lock_dir)
- + sizeof (SUPERLOCK_NAME)));
- strcpy (superlock_file, lock_dir);
- strcat (superlock_file, SUPERLOCK_NAME);
+ boot_time = 0;
+ boot_time_initialized = 0;
}
+void
syms_of_filelock ()
{
+ DEFVAR_LISP ("temporary-file-directory", &Vtemporary_file_directory,
+ "The directory for writing temporary files.");
+ Vtemporary_file_directory = Qnil;
+
defsubr (&Sunlock_buffer);
defsubr (&Slock_buffer);
defsubr (&Sfile_locked_p);