-/* Copyright (C) 1985, 86, 87, 93, 94, 96 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"
#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 "buffer.h"
+#include "charset.h"
+#include "coding.h"
+#include "systime.h"
#include <time.h>
-#include <utmp.h>
#include <errno.h>
#ifndef errno
extern int errno;
#endif
+/* The directory for writing temporary files. */
+
+Lisp_Object Vtemporary_file_directory;
+
#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
+
+#ifndef WTMP_FILE
+#define WTMP_FILE "/var/log/wtmp"
+#endif
/* 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
/* 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 ()
{
- struct utmp ut, *utp;
+#if defined (BOOT_TIME) && ! defined (NO_WTMP_FILE)
+ int counter;
+#endif
+
+ if (boot_time_initialized)
+ return boot_time;
+ boot_time_initialized = 1;
+#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) */
+
+ if (BOOT_TIME_FILE)
+ {
+ struct stat st;
+ if (stat (BOOT_TIME_FILE, &st) == 0)
+ {
+ boot_time = st.st_mtime;
+ return boot_time;
+ }
+ }
+
+#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;
- utmpname ("/var/log/wtmp");
- ut.ut_type = BOOT_TIME;
- utp = getutid (&ut);
- endutent ();
+ /* 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);
+ }
+ }
+
+ return boot_time;
+#else
+ return 0;
+#endif
+}
+
+#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. */
+
+get_boot_time_1 (filename, newest)
+ char *filename;
+ int newest;
+{
+ struct utmp ut, *utp;
+ int desc;
+
+ if (filename)
+ {
+ /* 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);
- if (!utp)
- return boot_time = 1;
- return boot_time = utp->ut_time;
+ utmpname (filename);
+ }
+
+ setutent ();
+
+ while (1)
+ {
+ /* 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;
+ }
+ endutent ();
}
+#endif /* BOOT_TIME */
\f
/* Here is the structure that stores information about a lock. */
/* 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_byte + 2 + 1), \
+ (lock = (char *) alloca (STRING_BYTES (XSTRING (file)) + 2 + 1), \
fill_in_lock_file_name (lock, (file)))
static void
int force;
{
register int err;
+ time_t boot_time;
char *user_name;
char *host_name;
char *lock_info_str;
lock_info_str = (char *)alloca (strlen (user_name) + strlen (host_name)
+ LOCK_PID_MAX + 5);
- sprintf (lock_info_str, "%s@%s.%lu:%lu", user_name, host_name,
- (unsigned long) getpid (), (unsigned long) get_boot_time ());
+ 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 ());
err = symlink (lock_info_str, lfname);
if (errno == EEXIST && force)
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);
+}
\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),
#ifndef index
extern char *rindex (), *index ();
#endif
- int o, p, len, ret;
+ int len, ret;
int local_owner = 0;
char *at, *dot, *colon;
char *lfinfo = 0;
else if (owner->pid > 0
&& (kill (owner->pid, 0) >= 0 || errno == EPERM)
&& (owner->boot_time == 0
- || owner->boot_time == get_boot_time ()))
+ || 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. */
lock_info_type *clasher;
register char *lfname;
{
- if (lock_file_1 (lfname, 0) == 0)
+ while (lock_file_1 (lfname, 0) == 0)
{
int locker;
}
else if (locker == 1)
return 1; /* Someone else has it. */
+ else if (locker == -1)
+ return -1; /* current_lock_owner returned strange error. */
- return -1; /* Something's wrong. */
+ /* We deleted a stale lock; try again to lock the file. */
}
return 0;
}
void
lock_file (fn)
- register Lisp_Object fn;
+ Lisp_Object fn;
{
- register Lisp_Object attack, orig_fn;
+ 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);
/* Create the name of the lock-file for file fn */
- MAKE_LOCK_NAME (lfname, 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 (&lock_info, lfname) <= 0)
register char *lfname;
fn = Fexpand_file_name (fn, Qnil);
+ fn = ENCODE_FILE (fn);
MAKE_LOCK_NAME (lfname, fn);
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))
{
register char *lfname;
\f
/* Initialization functions. */
+void
+init_filelock ()
+{
+ 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);
HCoop / bpt / emacs.git / blobdiff