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-rw-r--r--jnlib/dotlock.c557
1 files changed, 557 insertions, 0 deletions
diff --git a/jnlib/dotlock.c b/jnlib/dotlock.c
new file mode 100644
index 000000000..f5de8fa54
--- /dev/null
+++ b/jnlib/dotlock.c
@@ -0,0 +1,557 @@
+/* dotlock.c - dotfile locking
+ * Copyright (C) 1998, 2000, 2001, 2003, 2004,
+ * 2005, 2006 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG 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 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+ * USA.
+ */
+
+#include <config.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+#include <errno.h>
+#include <unistd.h>
+#ifndef HAVE_DOSISH_SYSTEM
+#include <sys/utsname.h>
+#endif
+#include <sys/types.h>
+#include <sys/time.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <signal.h>
+
+#include "libjnlib-config.h"
+#include "dotlock.h"
+
+#if !defined(DIRSEP_C) && !defined(EXTSEP_C) \
+ && !defined(DIRSEP_S) && !defined(EXTSEP_S)
+#ifdef HAVE_DOSISH_SYSTEM
+#define DIRSEP_C '\\'
+#define EXTSEP_C '.'
+#define DIRSEP_S "\\"
+#define EXTSEP_S "."
+#else
+#define DIRSEP_C '/'
+#define EXTSEP_C '.'
+#define DIRSEP_S "/"
+#define EXTSEP_S "."
+#endif
+#endif
+
+
+struct dotlock_handle
+{
+ struct dotlock_handle *next;
+ char *tname; /* Name of lockfile template. */
+ size_t nodename_off; /* Offset in TNAME of the nodename part. */
+ size_t nodename_len; /* Length of the nodename part. */
+ char *lockname; /* Name of the real lockfile. */
+ int locked; /* Lock status. */
+ int disable; /* When true, locking is disabled. */
+};
+
+
+static volatile DOTLOCK all_lockfiles;
+static int never_lock;
+
+static int read_lockfile (DOTLOCK h, int *same_node);
+
+void
+disable_dotlock(void)
+{
+ never_lock = 1;
+}
+
+/****************
+ * Create a lockfile with the given name and return an object of
+ * type DOTLOCK which may be used later to actually do the lock.
+ * A cleanup routine gets installed to cleanup left over locks
+ * or other files used together with the lock mechanism.
+ * Although the function is called dotlock, this does not necessarily
+ * mean that real lockfiles are used - the function may decide to
+ * use fcntl locking. Calling the function with NULL only install
+ * the atexit handler and maybe used to assure that the cleanup
+ * is called after all other atexit handlers.
+ *
+ * Notes: This function creates a lock file in the same directory
+ * as file_to_lock with the name "file_to_lock.lock"
+ * A temporary file ".#lk.<hostname>.pid[.threadid] is used.
+ * This function does nothing for Windoze.
+ */
+DOTLOCK
+create_dotlock( const char *file_to_lock )
+{
+ static int initialized;
+ DOTLOCK h;
+ int fd = -1;
+ char pidstr[16];
+ const char *nodename;
+ const char *dirpart;
+ int dirpartlen;
+#ifndef HAVE_DOSISH_SYSTEM
+ struct utsname utsbuf;
+#endif
+
+ if ( !initialized )
+ {
+ atexit( dotlock_remove_lockfiles );
+ initialized = 1;
+ }
+ if ( !file_to_lock )
+ return NULL; /* Only initialization was requested. */
+
+ h = jnlib_xcalloc ( 1, sizeof *h );
+ if( never_lock )
+ {
+ h->disable = 1;
+#ifdef _REENTRANT
+ /* fixme: aquire mutex on all_lockfiles */
+#endif
+ h->next = all_lockfiles;
+ all_lockfiles = h;
+ return h;
+ }
+
+#ifndef HAVE_DOSISH_SYSTEM
+ sprintf (pidstr, "%10d\n", (int)getpid() );
+ /* fixme: add the hostname to the second line (FQDN or IP addr?) */
+
+ /* Create a temporary file. */
+ if ( uname ( &utsbuf ) )
+ nodename = "unknown";
+ else
+ nodename = utsbuf.nodename;
+
+#ifdef __riscos__
+ {
+ char *iter = (char *) nodename;
+ for (; iter[0]; iter++)
+ if (iter[0] == '.')
+ iter[0] = '/';
+ }
+#endif /* __riscos__ */
+
+ if ( !(dirpart = strrchr ( file_to_lock, DIRSEP_C )) )
+ {
+ dirpart = EXTSEP_S;
+ dirpartlen = 1;
+ }
+ else
+ {
+ dirpartlen = dirpart - file_to_lock;
+ dirpart = file_to_lock;
+ }
+
+#ifdef _REENTRANT
+ /* fixme: aquire mutex on all_lockfiles */
+#endif
+ h->next = all_lockfiles;
+ all_lockfiles = h;
+
+ h->tname = jnlib_xmalloc ( dirpartlen + 6+30+ strlen(nodename) + 11 );
+ h->nodename_len = strlen (nodename);
+#ifndef __riscos__
+ sprintf (h->tname, "%.*s/.#lk%p.", dirpartlen, dirpart, h );
+ h->nodename_off = strlen (h->tname);
+ sprintf (h->tname+h->nodename_off, "%s.%d", nodename, (int)getpid ());
+#else /* __riscos__ */
+ sprintf (h->tname, "%.*s.lk%p/", dirpartlen, dirpart, h );
+ h->nodename_off = strlen (h->tname);
+ sprintf (h->tname+h->nodename_off, "%s/%d", nodename, (int)getpid () );
+#endif /* __riscos__ */
+
+ do
+ {
+ 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;
+ log_error ( "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;
+
+# ifdef _REENTRANT
+ /* release mutex */
+# endif
+#endif /* !HAVE_DOSISH_SYSTEM */
+ h->lockname = jnlib_xmalloc ( strlen (file_to_lock) + 6 );
+ strcpy (stpcpy(h->lockname, file_to_lock), EXTSEP_S "lock");
+ return h;
+ write_failed:
+ all_lockfiles = h->next;
+# ifdef _REENTRANT
+ /* fixme: release mutex */
+# endif
+ log_error ( "error writing to `%s': %s\n", h->tname, strerror(errno) );
+ close(fd);
+ unlink(h->tname);
+ jnlib_free(h->tname);
+ jnlib_free(h);
+ return NULL;
+}
+
+
+void
+destroy_dotlock ( DOTLOCK h )
+{
+#ifndef HAVE_DOSISH_SYSTEM
+ if ( h )
+ {
+ DOTLOCK hprev, htmp;
+
+ /* First remove the handle from our global list of all locks. */
+ for (hprev=NULL, htmp=all_lockfiles; htmp; hprev=htmp, htmp=htmp->next)
+ if (htmp == h)
+ {
+ if (hprev)
+ hprev->next = htmp->next;
+ else
+ all_lockfiles = htmp->next;
+ h->next = NULL;
+ break;
+ }
+
+ /* Second destroy the lock. */
+ if (!h->disable)
+ {
+ if (h->locked && h->lockname)
+ unlink (h->lockname);
+ if (h->tname)
+ unlink (h->tname);
+ jnlib_free (h->tname);
+ jnlib_free (h->lockname);
+ }
+ jnlib_free(h);
+ }
+#endif /*!HAVE_DOSISH_SYSTEM*/
+}
+
+
+
+static int
+maybe_deadlock( DOTLOCK h )
+{
+ DOTLOCK r;
+
+ for ( r=all_lockfiles; r; r = r->next )
+ {
+ if ( r != h && r->locked )
+ return 1;
+ }
+ return 0;
+}
+
+/****************
+ * Do a lock on H. A TIMEOUT of 0 returns immediately, -1 waits
+ * forever (hopefully not), other values are reserved (should then be
+ * timeouts in milliseconds). Returns: 0 on success
+ */
+int
+make_dotlock( DOTLOCK h, long timeout )
+{
+#ifdef HAVE_DOSISH_SYSTEM
+ return 0;
+#else
+ int pid;
+ const char *maybe_dead="";
+ int backoff=0;
+ int same_node;
+
+ if ( h->disable )
+ return 0; /* Locks are completely disabled. Return success. */
+
+ if ( h->locked )
+ {
+#ifndef __riscos__
+ log_debug("oops, `%s' is already locked\n", h->lockname );
+#endif /* !__riscos__ */
+ return 0;
+ }
+
+ for(;;)
+ {
+#ifndef __riscos__
+ if ( !link(h->tname, h->lockname) )
+ {
+ /* fixme: better use stat to check the link count */
+ h->locked = 1;
+ return 0; /* okay */
+ }
+ if ( errno != EEXIST )
+ {
+ log_error( "lock not made: link() failed: %s\n", strerror(errno) );
+ return -1;
+ }
+#else /* __riscos__ */
+ if ( !renamefile(h->tname, h->lockname) )
+ {
+ h->locked = 1;
+ return 0; /* okay */
+ }
+ if ( errno != EEXIST )
+ {
+ log_error( "lock not made: rename() failed: %s\n", strerror(errno) );
+ return -1;
+ }
+#endif /* __riscos__ */
+
+ if ( (pid = read_lockfile (h, &same_node)) == -1 )
+ {
+ if ( errno != ENOENT )
+ {
+ log_info ("cannot read lockfile\n");
+ return -1;
+ }
+ log_info( "lockfile disappeared\n");
+ continue;
+ }
+ else if ( pid == getpid() && same_node )
+ {
+ log_info( "Oops: lock already held by us\n");
+ h->locked = 1;
+ return 0; /* okay */
+ }
+ else if ( same_node && kill (pid, 0) && errno == ESRCH )
+ {
+#ifndef __riscos__
+ log_info ("removing stale lockfile (created by %d)", pid );
+ unlink (h->lockname);
+ continue;
+#else /* __riscos__ */
+ /* Under RISCOS we are *pretty* sure that the other task
+ is dead and therefore we remove the stale lock file. */
+ maybe_dead = " - probably dead - removing lock";
+ unlink(h->lockname);
+#endif /* __riscos__ */
+ }
+
+ if ( timeout == -1 )
+ {
+ /* Wait until lock has been released. */
+ struct timeval tv;
+
+ log_info ("waiting for lock (held by %d%s) %s...\n",
+ pid, maybe_dead, maybe_deadlock(h)? "(deadlock?) ":"");
+
+
+ /* We can't use sleep, cause signals may be blocked. */
+ tv.tv_sec = 1 + backoff;
+ tv.tv_usec = 0;
+ select(0, NULL, NULL, NULL, &tv);
+ if ( backoff < 10 )
+ backoff++ ;
+ }
+ else
+ return -1;
+ }
+ /*NOTREACHED*/
+#endif /* !HAVE_DOSISH_SYSTEM */
+}
+
+
+/****************
+ * release a lock
+ * Returns: 0 := success
+ */
+int
+release_dotlock( DOTLOCK h )
+{
+#ifdef HAVE_DOSISH_SYSTEM
+ return 0;
+#else
+ int pid, same_node;
+
+ /* To avoid atexit race conditions we first check whether there are
+ any locks left. It might happen that another atexit handler
+ tries to release the lock while the atexit handler of this module
+ already ran and thus H is undefined. */
+ if (!all_lockfiles)
+ return 0;
+
+ if ( h->disable )
+ return 0;
+
+ if ( !h->locked )
+ {
+ log_debug("oops, `%s' is not locked\n", h->lockname );
+ return 0;
+ }
+
+ pid = read_lockfile (h, &same_node);
+ if ( pid == -1 )
+ {
+ log_error( "release_dotlock: lockfile error\n");
+ return -1;
+ }
+ if ( pid != getpid() || !same_node )
+ {
+ log_error( "release_dotlock: not our lock (pid=%d)\n", pid);
+ return -1;
+ }
+#ifndef __riscos__
+ if ( unlink( h->lockname ) )
+ {
+ log_error( "release_dotlock: error removing lockfile `%s'",
+ h->lockname);
+ return -1;
+ }
+#else /* __riscos__ */
+ if ( renamefile(h->lockname, h->tname) )
+ {
+ log_error( "release_dotlock: error renaming lockfile `%s' to `%s'",
+ h->lockname, h->tname);
+ return -1;
+ }
+#endif /* __riscos__ */
+ /* fixme: check that the link count is now 1 */
+ h->locked = 0;
+ return 0;
+#endif /* !HAVE_DOSISH_SYSTEM */
+}
+
+
+/*
+ Read the lock file and return the pid, returns -1 on error. True
+ will be stored at SAME_NODE if the lock file has been created on
+ the same node.
+ */
+static int
+read_lockfile (DOTLOCK h, int *same_node )
+{
+#ifdef HAVE_DOSISH_SYSTEM
+ return 0;
+#else
+ char buffer_space[10+1+70+1]; /* 70 is just an estimated value; node
+ name are usually shorter. */
+ int fd, pid;
+ 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_xmalloc (expected_len);
+ else
+ buffer = buffer_space;
+
+ if ( (fd = open (h->lockname, O_RDONLY)) == -1 )
+ {
+ int e = errno;
+ log_info ("error opening lockfile `%s': %s\n",
+ h->lockname, strerror(errno) );
+ if (buffer != buffer_space)
+ jnlib_free (buffer);
+ 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)
+ {
+ log_info ("error reading lockfile `%s'", h->lockname );
+ close (fd);
+ if (buffer != buffer_space)
+ jnlib_free (buffer);
+ errno = 0; /* Do not return an inappropriate ERRNO. */
+ return -1;
+ }
+ p += res;
+ nread += res;
+ }
+ while (res && nread != expected_len);
+ close(fd);
+
+ if (nread < 11)
+ {
+ log_info ("invalid size of lockfile `%s'", h->lockname );
+ if (buffer != buffer_space)
+ jnlib_free (buffer);
+ errno = 0; /* Do not return an inappropriate ERRNO. */
+ return -1;
+ }
+
+ if (buffer[10] != '\n'
+ || (buffer[10] = 0, pid = atoi (buffer)) == -1
+#ifndef __riscos__
+ || !pid
+#else /* __riscos__ */
+ || (!pid && riscos_getpid())
+#endif /* __riscos__ */
+ )
+ {
+ log_error ("invalid pid %d in lockfile `%s'", pid, h->lockname );
+ if (buffer != buffer_space)
+ jnlib_free (buffer);
+ 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;
+#endif
+}
+
+
+void
+dotlock_remove_lockfiles()
+{
+#ifndef HAVE_DOSISH_SYSTEM
+ DOTLOCK h, h2;
+
+ h = all_lockfiles;
+ all_lockfiles = NULL;
+
+ while ( h )
+ {
+ h2 = h->next;
+ destroy_dotlock (h);
+ h = h2;
+ }
+#endif
+}
+
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