dotlock_t
dotlock_create (const char *file_to_lock, unsigned int flags)
{
static int initialized;
dotlock_t h;
if ( !initialized )
{
atexit (dotlock_remove_lockfiles);
initialized = 1;
}
if ( !file_to_lock )
return NULL; /* Only initialization was requested. */
if (flags)
{
jnlib_set_errno (EINVAL);
return NULL;
}
h = jnlib_calloc (1, sizeof *h);
if (!h)
return NULL;
h->extra_fd = -1;
if (never_lock)
{
h->disable = 1;
LOCK_all_lockfiles ();
h->next = all_lockfiles;
all_lockfiles = h;
UNLOCK_all_lockfiles ();
return h;
}
#ifdef HAVE_DOSISH_SYSTEM
return dotlock_create_w32 (h, file_to_lock);
#else /*!HAVE_DOSISH_SYSTEM */
return dotlock_create_unix (h, file_to_lock);
#endif /*!HAVE_DOSISH_SYSTEM*/
}
time_t
timegm (struct tm *tm)
{
#ifdef HAVE_W32_SYSTEM
/* This one is thread safe. */
SYSTEMTIME st;
FILETIME ft;
unsigned long long cnsecs;
st.wYear = tm->tm_year + 1900;
st.wMonth = tm->tm_mon + 1;
st.wDay = tm->tm_mday;
st.wHour = tm->tm_hour;
st.wMinute = tm->tm_min;
st.wSecond = tm->tm_sec;
st.wMilliseconds = 0; /* Not available. */
st.wDayOfWeek = 0; /* Ignored. */
/* System time is UTC thus the conversion is pretty easy. */
if (!SystemTimeToFileTime (&st, &ft))
{
jnlib_set_errno (EINVAL);
return (time_t)(-1);
}
cnsecs = (((unsigned long long)ft.dwHighDateTime << 32)
| ft.dwLowDateTime);
cnsecs -= 116444736000000000ULL; /* The filetime epoch is 1601-01-01. */
return (time_t)(cnsecs / 10000000ULL);
#else /* (Non thread safe implementation!) */
time_t answer;
char *zone;
zone=getenv("TZ");
putenv("TZ=UTC");
tzset();
answer=mktime(tm);
if(zone)
{
static char *old_zone;
if (!old_zone)
{
old_zone = malloc(3+strlen(zone)+1);
if (old_zone)
{
strcpy(old_zone,"TZ=");
strcat(old_zone,zone);
}
}
if (old_zone)
putenv (old_zone);
}
else
gnupg_unsetenv("TZ");
tzset();
return answer;
#endif
}
/* Unix specific code of make_dotlock. Returns 0 on success and -1 on
error. */
static int
dotlock_take_unix (dotlock_t h, long timeout)
{
int wtime = 0;
int sumtime = 0;
int pid;
int lastpid = -1;
int ownerchanged;
const char *maybe_dead="";
int same_node;
again:
if (h->use_o_excl)
{
/* No hardlink support - use open(O_EXCL). */
int fd;
do
{
jnlib_set_errno (0);
fd = open (h->lockname, O_WRONLY|O_CREAT|O_EXCL,
S_IRUSR|S_IRGRP|S_IROTH|S_IWUSR );
}
while (fd == -1 && errno == EINTR);
if (fd == -1 && errno == EEXIST)
; /* Lock held by another process. */
else if (fd == -1)
{
my_error_2 ("lock not made: open(O_EXCL) of `%s' failed: %s\n",
h->lockname, strerror (errno));
return -1;
}
else
{
char pidstr[16];
snprintf (pidstr, sizeof pidstr, "%10d\n", (int)getpid());
if (write (fd, pidstr, 11 ) == 11
&& write (fd, h->tname + h->nodename_off,h->nodename_len)
== h->nodename_len
&& write (fd, "\n", 1) == 1
&& !close (fd))
{
h->locked = 1;
return 0;
}
/* Write error. */
my_error_2 ("lock not made: writing to `%s' failed: %s\n",
h->lockname, strerror (errno));
close (fd);
unlink (h->lockname);
return -1;
}
}
else /* Standard method: Use hardlinks. */
{
struct stat sb;
link (h->tname, h->lockname);
if (stat (h->tname, &sb))
{
my_error_1 ("lock not made: Oops: stat of tmp file failed: %s\n",
strerror (errno));
/* In theory this might be a severe error: It is possible
that link succeeded but stat failed due to changed
permissions. We can't do anything about it, though. */
return -1;
}
if (sb.st_nlink == 2)
{
h->locked = 1;
return 0; /* Okay. */
}
}
/* Check for stale lock files. */
if ( (pid = read_lockfile (h, &same_node)) == -1 )
{
if ( errno != ENOENT )
{
my_info_0 ("cannot read lockfile\n");
return -1;
}
my_info_0 ("lockfile disappeared\n");
goto again;
}
else if ( pid == getpid() && same_node )
{
my_info_0 ("Oops: lock already held by us\n");
h->locked = 1;
return 0; /* okay */
}
else if ( same_node && kill (pid, 0) && errno == ESRCH )
{
/* Note: It is unlikley that we get a race here unless a pid is
reused too fast or a new process with the same pid as the one
of the stale file tries to lock right at the same time as we. */
my_info_1 (_("removing stale lockfile (created by %d)\n"), pid);
unlink (h->lockname);
goto again;
}
if (lastpid == -1)
lastpid = pid;
ownerchanged = (pid != lastpid);
if (timeout)
{
struct timeval tv;
/* Wait until lock has been released. We use increasing retry
intervals of 50ms, 100ms, 200ms, 400ms, 800ms, 2s, 4s and 8s
but reset it if the lock owner meanwhile changed. */
if (!wtime || ownerchanged)
wtime = 50;
else if (wtime < 800)
wtime *= 2;
else if (wtime == 800)
wtime = 2000;
else if (wtime < 8000)
wtime *= 2;
if (timeout > 0)
{
if (wtime > timeout)
wtime = timeout;
timeout -= wtime;
}
sumtime += wtime;
if (sumtime >= 1500)
{
sumtime = 0;
my_info_3 (_("waiting for lock (held by %d%s) %s...\n"),
pid, maybe_dead, maybe_deadlock(h)? _("(deadlock?) "):"");
}
tv.tv_sec = wtime / 1000;
tv.tv_usec = (wtime % 1000) * 1000;
select (0, NULL, NULL, NULL, &tv);
goto again;
}
jnlib_set_errno (EACCES);
return -1;
}
/* Locking core for Unix. It used a temporary file and the link
system call to make locking an atomic operation. */
static dotlock_t
dotlock_create_unix (dotlock_t h, const char *file_to_lock)
{
int fd = -1;
char pidstr[16];
const char *nodename;
const char *dirpart;
int dirpartlen;
struct utsname utsbuf;
size_t tnamelen;
snprintf (pidstr, sizeof pidstr, "%10d\n", (int)getpid() );
/* Create a temporary file. */
if ( uname ( &utsbuf ) )
nodename = "unknown";
else
nodename = utsbuf.nodename;
if ( !(dirpart = strrchr (file_to_lock, DIRSEP_C)) )
{
dirpart = EXTSEP_S;
dirpartlen = 1;
}
else
{
dirpartlen = dirpart - file_to_lock;
dirpart = file_to_lock;
}
LOCK_all_lockfiles ();
h->next = all_lockfiles;
all_lockfiles = h;
tnamelen = dirpartlen + 6 + 30 + strlen(nodename) + 10 + 1;
h->tname = jnlib_malloc (tnamelen + 1);
if (!h->tname)
{
all_lockfiles = h->next;
UNLOCK_all_lockfiles ();
jnlib_free (h);
return NULL;
}
h->nodename_len = strlen (nodename);
snprintf (h->tname, tnamelen, "%.*s/.#lk%p.", dirpartlen, dirpart, h );
h->nodename_off = strlen (h->tname);
snprintf (h->tname+h->nodename_off, tnamelen - h->nodename_off,
"%s.%d", nodename, (int)getpid ());
do
{
jnlib_set_errno (0);
fd = open (h->tname, O_WRONLY|O_CREAT|O_EXCL,
S_IRUSR|S_IRGRP|S_IROTH|S_IWUSR );
}
while (fd == -1 && errno == EINTR);
if ( fd == -1 )
{
all_lockfiles = h->next;
UNLOCK_all_lockfiles ();
my_error_2 (_("failed to create temporary file `%s': %s\n"),
h->tname, strerror(errno));
jnlib_free (h->tname);
jnlib_free (h);
return NULL;
}
if ( write (fd, pidstr, 11 ) != 11 )
goto write_failed;
if ( write (fd, nodename, strlen (nodename) ) != strlen (nodename) )
goto write_failed;
if ( write (fd, "\n", 1 ) != 1 )
goto write_failed;
if ( close (fd) )
goto write_failed;
/* Check whether we support hard links. */
switch (use_hardlinks_p (h->tname))
{
case 0: /* Yes. */
break;
case 1: /* No. */
unlink (h->tname);
h->use_o_excl = 1;
break;
default:
my_error_2 ("can't check whether hardlinks are supported for `%s': %s\n",
h->tname, strerror(errno));
goto write_failed;
}
h->lockname = jnlib_malloc (strlen (file_to_lock) + 6 );
if (!h->lockname)
{
all_lockfiles = h->next;
UNLOCK_all_lockfiles ();
unlink (h->tname);
jnlib_free (h->tname);
jnlib_free (h);
return NULL;
}
strcpy (stpcpy (h->lockname, file_to_lock), EXTSEP_S "lock");
UNLOCK_all_lockfiles ();
if (h->use_o_excl)
my_debug_1 ("locking for `%s' done via O_EXCL\n", h->lockname);
return h;
write_failed:
all_lockfiles = h->next;
UNLOCK_all_lockfiles ();
my_error_2 (_("error writing to `%s': %s\n"), h->tname, strerror (errno));
close (fd);
unlink (h->tname);
jnlib_free (h->tname);
jnlib_free (h);
return NULL;
}
static int
read_lockfile (dotlock_t h, int *same_node )
{
char buffer_space[10+1+70+1]; /* 70 is just an estimated value; node
names are usually shorter. */
int fd;
int pid = -1;
char *buffer, *p;
size_t expected_len;
int res, nread;
*same_node = 0;
expected_len = 10 + 1 + h->nodename_len + 1;
if ( expected_len >= sizeof buffer_space)
{
buffer = jnlib_malloc (expected_len);
if (!buffer)
return -1;
}
else
buffer = buffer_space;
if ( (fd = open (h->lockname, O_RDONLY)) == -1 )
{
int e = errno;
my_info_2 ("error opening lockfile `%s': %s\n",
h->lockname, strerror(errno) );
if (buffer != buffer_space)
jnlib_free (buffer);
jnlib_set_errno (e); /* Need to return ERRNO here. */
return -1;
}
p = buffer;
nread = 0;
do
{
res = read (fd, p, expected_len - nread);
if (res == -1 && errno == EINTR)
continue;
if (res < 0)
{
my_info_1 ("error reading lockfile `%s'\n", h->lockname );
close (fd);
if (buffer != buffer_space)
jnlib_free (buffer);
jnlib_set_errno (0); /* Do not return an inappropriate ERRNO. */
return -1;
}
p += res;
nread += res;
}
while (res && nread != expected_len);
close(fd);
if (nread < 11)
{
my_info_1 ("invalid size of lockfile `%s'\n", h->lockname);
if (buffer != buffer_space)
jnlib_free (buffer);
jnlib_set_errno (0); /* Better don't return an inappropriate ERRNO. */
return -1;
}
if (buffer[10] != '\n'
|| (buffer[10] = 0, pid = atoi (buffer)) == -1
|| !pid )
{
my_error_2 ("invalid pid %d in lockfile `%s'\n", pid, h->lockname);
if (buffer != buffer_space)
jnlib_free (buffer);
jnlib_set_errno (0);
return -1;
}
if (nread == expected_len
&& !memcmp (h->tname+h->nodename_off, buffer+11, h->nodename_len)
&& buffer[11+h->nodename_len] == '\n')
*same_node = 1;
if (buffer != buffer_space)
jnlib_free (buffer);
return pid;
}
