Merged jnlib into common.

1 files changed, 713 insertions, 0 deletions

diff --git a/common/dotlock.c b/common/dotlock.c
new file mode 100644
index 000000000..0d5a7bce9
--- /dev/null
+++ b/common/dotlock.c
@@ -0,0 +1,713 @@
+/* dotlock.c - dotfile locking
+ * Copyright (C) 1998, 2000, 2001, 2003, 2004, 
+ *               2005, 2006, 2008 Free Software Foundation, Inc.
+ *
+ * This file is part of JNLIB.
+ *
+ * JNLIB is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * JNLIB 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+#include <errno.h>
+#include <unistd.h>
+#ifdef  HAVE_DOSISH_SYSTEM
+# define WIN32_LEAN_AND_MEAN
+# include <windows.h>
+#else
+# include <sys/utsname.h>
+#endif
+#include <sys/types.h>
+#include <sys/time.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#ifdef HAVE_SIGNAL_H
+# include <signal.h>
+#endif
+
+#include "libjnlib-config.h"
+#include "stringhelp.h"
+#include "dotlock.h"
+#include "utf8conv.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
+
+
+/* The object describing a lock.  */
+struct dotlock_handle 
+{
+  struct dotlock_handle *next;
+  char *lockname;      /* Name of the actual lockfile.          */
+  int locked;          /* Lock status.                          */
+  int disable;         /* If true, locking is disabled.         */
+
+#ifdef HAVE_DOSISH_SYSTEM
+  HANDLE lockhd;       /* The W32 handle of the lock file.      */
+#else
+  char *tname;         /* Name of the lockfile template.        */
+  size_t nodename_off; /* Offset in TNAME of the nodename part. */
+  size_t nodename_len; /* Length of the nodename part.          */
+#endif /* HAVE_DOSISH_SYSTEM */
+};
+
+
+/* A list of of all lock handles. */
+static volatile dotlock_t all_lockfiles;
+
+/* If this has the value true all locking is disabled.  */
+static int never_lock;
+
+
+/* Local protototypes.  */
+#ifndef HAVE_DOSISH_SYSTEM
+static int read_lockfile (dotlock_t h, int *same_node);
+#endif /*!HAVE_DOSISH_SYSTEM*/
+
+
+
+
+/* Entirely disable all locking.  This function should be called
+   before any locking is done.  It may be called right at startup of
+   the process as it only sets a global value.  */
+void
+disable_dotlock(void)
+{
+  never_lock = 1;
+}
+
+
+
+/* Create a lockfile for a file name FILE_TO_LOCK and returns an
+   object of type dotlock_t which may be used later to actually acquire
+   the lock.  A cleanup routine gets installed to cleanup left over
+   locks or other files used internally by the lock mechanism.
+
+   Calling this function with NULL does only install the atexit
+   handler and may thus be used to assure that the cleanup is called
+   after all other atexit handlers.
+  
+   This function creates a lock file in the same directory as
+   FILE_TO_LOCK using that name and a suffix of ".lock".  Note that on
+   POSIX systems a temporary file ".#lk.<hostname>.pid[.threadid] is
+   used.
+
+   The function returns an new handle which needs to be released using
+   destroy_dotlock but gets also released at the termination of the
+   process.  On error NULL is returned.
+ */
+dotlock_t
+create_dotlock (const char *file_to_lock)
+{
+  static int initialized;
+  dotlock_t h;
+#ifndef  HAVE_DOSISH_SYSTEM
+  int  fd = -1;
+  char pidstr[16];
+  const char *nodename;
+  const char *dirpart;
+  int dirpartlen;
+  struct utsname utsbuf;
+  size_t tnamelen;
+#endif
+
+  if ( !initialized )
+    {
+      atexit (dotlock_remove_lockfiles);
+      initialized = 1;
+    }
+
+  if ( !file_to_lock )
+    return NULL;  /* Only initialization was requested.  */
+
+  h = jnlib_calloc (1, sizeof *h);
+  if (!h)
+    return NULL;
+
+  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
+  /*
+     This is the POSIX version which uses a temporary file and the
+     link system call to make locking an atomic operation.
+   */
+
+  snprintf (pidstr, sizeof pidstr, "%10d\n", (int)getpid() );
+
+  /* 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;
+
+  tnamelen = dirpartlen + 6 + 30 + strlen(nodename) + 10;
+  h->tname = jnlib_malloc (tnamelen + 1);
+  if (!h->tname)
+    {
+      all_lockfiles = h->next;
+      jnlib_free (h);
+      return NULL;
+    }
+  h->nodename_len = strlen (nodename);
+
+#ifndef __riscos__
+  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 ());
+#else /* __riscos__ */
+  snprintf (h->tname, tnamelen, "%.*s.lk%p/", dirpartlen, dirpart, h );
+  h->nodename_off = strlen (h->tname);
+  snprintf (h->tname+h->nodename_off, tnamelen - h->modename_off,
+            "%s/%d", nodename, (int)getpid () );
+#endif /* __riscos__ */
+
+  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;
+      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
+  h->lockname = jnlib_malloc ( strlen (file_to_lock) + 6 );
+  if (!h->lockname)
+    {
+      all_lockfiles = h->next;
+      unlink (h->tname);
+      jnlib_free (h->tname);
+      jnlib_free (h);
+      return NULL;
+    }
+  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;
+
+#else /* HAVE_DOSISH_SYSTEM */
+
+  /* The Windows version does not need a temporary file but uses the
+     plain lock file along with record locking.  We create this file
+     here so that we later do only need to do the file locking.  For
+     error reporting it is useful to keep the name of the file in the
+     handle.  */
+  h->next = all_lockfiles;
+  all_lockfiles = h;
+
+  h->lockname = jnlib_malloc ( strlen (file_to_lock) + 6 );
+  if (!h->lockname)
+    {
+      all_lockfiles = h->next;
+      jnlib_free (h);
+      return NULL;
+    }
+  strcpy (stpcpy(h->lockname, file_to_lock), EXTSEP_S "lock");
+
+  /* If would be nice if we would use the FILE_FLAG_DELETE_ON_CLOSE
+     along with FILE_SHARE_DELETE but that does not work due to a race
+     condition: Despite the OPEN_ALWAYS flag CreateFile may return an
+     error and we can't reliable create/open the lock file unless we
+     would wait here until it works - however there are other valid
+     reasons why a lock file can't be created and thus the process
+     would not stop as expected but spin til until Windows crashes.
+     Our solution is to keep the lock file open; that does not
+     harm. */ 
+  {
+#ifdef HAVE_W32CE_SYSTEM
+    wchar_t *wname = utf8_to_wchar (h->lockname);
+    
+    h->lockhd = INVALID_HANDLE_VALUE;
+    if (wname)
+      h->lockhd = CreateFile (wname,
+#else
+    h->lockhd = CreateFile (h->lockname,
+#endif
+                            GENERIC_READ|GENERIC_WRITE,
+                            FILE_SHARE_READ|FILE_SHARE_WRITE,
+                            NULL, OPEN_ALWAYS, 0, NULL);
+#ifdef HAVE_W32CE_SYSTEM
+    jnlib_free (wname);                           
+#endif
+  }
+  if (h->lockhd == INVALID_HANDLE_VALUE)
+    {
+      log_error (_("can't create `%s': %s\n"), h->lockname, w32_strerror (-1));
+      all_lockfiles = h->next;
+      jnlib_free (h->lockname);
+      jnlib_free (h);
+      return NULL;
+    }
+  return h;
+
+#endif /* HAVE_DOSISH_SYSTEM */
+}
+
+
+/* Destroy the local handle H and release the lock. */
+void
+destroy_dotlock (dotlock_t h)
+{
+  dotlock_t hprev, htmp;
+
+  if ( !h )
+    return;
+
+  /* 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;
+      }
+  
+  /* Then destroy the lock. */
+  if (!h->disable)
+    {
+#ifdef HAVE_DOSISH_SYSTEM
+      if (h->locked)
+        {
+          UnlockFile (h->lockhd, 0, 0, 1, 0);
+        }
+      CloseHandle (h->lockhd);
+#else /* !HAVE_DOSISH_SYSTEM */
+      if (h->locked && h->lockname)
+        unlink (h->lockname);
+      if (h->tname)
+        unlink (h->tname);
+      jnlib_free (h->tname);
+#endif /* HAVE_DOSISH_SYSTEM */
+      jnlib_free (h->lockname);
+    }
+  jnlib_free(h);
+}
+
+
+#ifndef HAVE_DOSISH_SYSTEM
+static int
+maybe_deadlock (dotlock_t h)
+{
+  dotlock_t r;
+
+  for ( r=all_lockfiles; r; r = r->next )
+    {
+      if ( r != h && r->locked )
+        return 1;
+    }
+  return 0;
+}
+#endif /*!HAVE_DOSISH_SYSTEM*/
+
+
+
+/* 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_t h, long timeout)
+{
+  int backoff = 0;
+#ifndef HAVE_DOSISH_SYSTEM
+  int  pid;
+  const char *maybe_dead="";
+  int same_node;
+#endif /*!HAVE_DOSISH_SYSTEM*/
+
+  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 HAVE_DOSISH_SYSTEM
+# 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)\n"), 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;
+#else /*HAVE_DOSISH_SYSTEM*/
+      int w32err;
+
+      if (LockFile (h->lockhd, 0, 0, 1, 0))
+        {
+          h->locked = 1;
+          return 0; /* okay */
+        }
+      w32err = GetLastError ();
+      if (w32err != ERROR_LOCK_VIOLATION)
+        {
+          log_error (_("lock `%s' not made: %s\n"),
+                     h->lockname, w32_strerror (w32err));
+          return -1;
+        }
+
+      if ( timeout == -1 ) 
+        {
+          /* Wait until lock has been released. */
+          log_info (_("waiting for lock %s...\n"), h->lockname);
+          Sleep ((1 + backoff)*1000);
+          if ( backoff < 10 )
+            backoff++ ;
+	}
+      else
+        return -1;
+#endif /*HAVE_DOSISH_SYSTEM*/
+    }
+  /*NOTREACHED*/
+}
+
+
+/* Release a lock.  Returns 0 on success.  */
+int
+release_dotlock (dotlock_t h)
+{
+#ifndef HAVE_DOSISH_SYSTEM
+  int pid, same_node;
+#endif
+
+  /* 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;
+    }
+
+#ifdef HAVE_DOSISH_SYSTEM
+  if (!UnlockFile (h->lockhd, 0, 0, 1, 0))
+    {
+      log_error ("release_dotlock: error removing lockfile `%s': %s\n",
+                 h->lockname, w32_strerror (-1));
+      return -1;
+    }
+#else
+
+  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'\n",
+                 h->lockname);
+      return -1;
+    }
+  /* Fixme: As an extra check we could check whether the link count is
+     now really at 1. */
+#else /* __riscos__ */
+  if ( renamefile (h->lockname, h->tname) ) 
+    {
+      log_error ("release_dotlock: error renaming lockfile `%s' to `%s'\n",
+                 h->lockname, h->tname);
+      return -1;
+    }
+#endif /* __riscos__ */
+
+#endif /* !HAVE_DOSISH_SYSTEM */
+  h->locked = 0;
+  return 0;
+}
+
+
+/* Read the lock file and return the pid, returns -1 on error.  True
+   will be stored in the integer at address SAME_NODE if the lock file
+   has been created on the same node. */
+#ifndef HAVE_DOSISH_SYSTEM
+static int
+read_lockfile (dotlock_t h, int *same_node )
+{
+  char buffer_space[10+1+70+1]; /* 70 is just an estimated value; node
+                                   name 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;
+      log_info ("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)
+        {
+          log_info ("error reading lockfile `%s'", 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)
+    {
+      log_info ("invalid size of lockfile `%s'", 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
+#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);
+      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;
+}
+#endif /* !HAVE_DOSISH_SYSTEM */
+
+
+/* Remove all lockfiles.  This is usually called by the atexit handler
+   installed by this module but may also be called by other
+   termination handlers.  */
+void
+dotlock_remove_lockfiles (void)
+{
+  dotlock_t h, h2;
+  
+  h = all_lockfiles;
+  all_lockfiles = NULL;
+    
+  while ( h )
+    {
+      h2 = h->next;
+      destroy_dotlock (h);
+      h = h2;
+    }
+}
+