static int
lock_file_1 (char *lfname, int force)
{
int err;
int symlink_errno;
USE_SAFE_ALLOCA;
/* Call this first because it can GC. */
printmax_t boot = get_boot_time ();
Lisp_Object luser_name = Fuser_login_name (Qnil);
char const *user_name = STRINGP (luser_name) ? SSDATA (luser_name) : "";
Lisp_Object lhost_name = Fsystem_name ();
char const *host_name = STRINGP (lhost_name) ? SSDATA (lhost_name) : "";
ptrdiff_t lock_info_size = (strlen (user_name) + strlen (host_name)
+ 2 * INT_STRLEN_BOUND (printmax_t)
+ sizeof "@.:");
char *lock_info_str = SAFE_ALLOCA (lock_info_size);
printmax_t pid = getpid ();
esprintf (lock_info_str, boot ? "%s@%s.%"pMd":%"pMd : "%s@%s.%"pMd,
user_name, host_name, pid, boot);
err = symlink (lock_info_str, lfname);
if (errno == EEXIST && force)
{
unlink (lfname);
err = symlink (lock_info_str, lfname);
}
symlink_errno = errno;
SAFE_FREE ();
errno = symlink_errno;
return err == 0;
}
static int
lock_file_1 (char *lfname, int force)
{
register int err;
time_t boot;
const char *user_name;
const char *host_name;
char *lock_info_str;
/* Call this first because it can GC. */
boot = get_boot_time ();
if (STRINGP (Fuser_login_name (Qnil)))
user_name = SSDATA (Fuser_login_name (Qnil));
else
user_name = "";
if (STRINGP (Fsystem_name ()))
host_name = SSDATA (Fsystem_name ());
else
host_name = "";
lock_info_str = (char *)alloca (strlen (user_name) + strlen (host_name)
+ LOCK_PID_MAX + 30);
if (boot)
sprintf (lock_info_str, "%s@%s.%lu:%lu", user_name, host_name,
(unsigned long) getpid (), (unsigned long) boot);
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)
{
unlink (lfname);
err = symlink (lock_info_str, lfname);
}
return err == 0;
}
static int
current_lock_owner (lock_info_type *owner, char *lfname)
{
int ret;
ptrdiff_t len;
lock_info_type local_owner;
intmax_t n;
char *at, *dot, *colon;
char readlink_buf[READLINK_BUFSIZE];
char *lfinfo = emacs_readlink (lfname, readlink_buf);
/* If nonexistent lock file, all is well; otherwise, got strange error. */
if (!lfinfo)
return errno == ENOENT ? 0 : -1;
/* Even if the caller doesn't want the owner info, we still have to
read it to determine return value. */
if (!owner)
owner = &local_owner;
/* Parse [email protected]:BOOT_TIME. If can't parse, return -1. */
/* The USER is everything before the last @. */
at = strrchr (lfinfo, '@');
dot = strrchr (lfinfo, '.');
if (!at || !dot)
{
if (lfinfo != readlink_buf)
xfree (lfinfo);
return -1;
}
len = at - lfinfo;
owner->user = xmalloc (len + 1);
memcpy (owner->user, lfinfo, len);
owner->user[len] = 0;
/* The PID is everything from the last `.' to the `:'. */
errno = 0;
n = strtoimax (dot + 1, NULL, 10);
owner->pid =
((0 <= n && n <= TYPE_MAXIMUM (pid_t)
&& (TYPE_MAXIMUM (pid_t) < INTMAX_MAX || errno != ERANGE))
? n : 0);
colon = strchr (dot + 1, ':');
/* After the `:', if there is one, comes the boot time. */
n = 0;
if (colon)
{
errno = 0;
n = strtoimax (colon + 1, NULL, 10);
}
owner->boot_time =
((0 <= n && n <= TYPE_MAXIMUM (time_t)
&& (TYPE_MAXIMUM (time_t) < INTMAX_MAX || errno != ERANGE))
? n : 0);
/* The host is everything in between. */
len = dot - at - 1;
owner->host = xmalloc (len + 1);
memcpy (owner->host, at + 1, len);
owner->host[len] = 0;
/* We're done looking at the link info. */
if (lfinfo != readlink_buf)
xfree (lfinfo);
/* On current host? */
if (STRINGP (Fsystem_name ())
&& strcmp (owner->host, SSDATA (Fsystem_name ())) == 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 (owner == &local_owner || ret <= 0)
{
FREE_LOCK_INFO (*owner);
}
return ret;
}
static int
current_lock_owner (lock_info_type *owner, char *lfname)
{
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);
errno = 0;
len = readlink (lfname, lfinfo, bufsize);
#ifdef ERANGE
/* HP-UX reports ERANGE if the buffer is too small. */
if (len == -1 && errno == ERANGE)
len = bufsize;
#endif
}
while (len >= bufsize);
/* If nonexistent lock file, all is well; otherwise, got strange error. */
if (len == -1)
{
xfree (lfinfo);
return errno == ENOENT ? 0 : -1;
}
/* 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 [email protected]:BOOT_TIME. If can't parse, return -1. */
/* The USER is everything before the last @. */
at = strrchr (lfinfo, '@');
dot = strrchr (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
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;
/* We're done looking at the link info. */
xfree (lfinfo);
/* On current host? */
if (STRINGP (Fsystem_name ())
&& strcmp (owner->host, SSDATA (Fsystem_name ())) == 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;
}
