Adding upstream version 2.2.40.upstream/2.2.40

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2698 insertions, 0 deletions

diff --git a/common/iobuf.c b/common/iobuf.c
new file mode 100644
index 0000000..6370efb
--- /dev/null
+++ b/common/iobuf.c
@@ -0,0 +1,2698 @@
+/* iobuf.c  -  File Handling for OpenPGP.
+ * Copyright (C) 1998, 1999, 2000, 2001, 2003, 2004, 2006, 2007, 2008,
+ *               2009, 2010, 2011  Free Software Foundation, Inc.
+ * Copyright (C) 2015  g10 Code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of either
+ *
+ *   - 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.
+ *
+ * or
+ *
+ *   - 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.
+ *
+ * or both in parallel, as here.
+ *
+ * This file 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, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+#include <assert.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#ifdef HAVE_W32_SYSTEM
+# ifdef HAVE_WINSOCK2_H
+#  include <winsock2.h>
+# endif
+# include <windows.h>
+#endif
+#ifdef __riscos__
+# include <kernel.h>
+# include <swis.h>
+#endif /* __riscos__ */
+
+#include <assuan.h>
+
+#include "util.h"
+#include "sysutils.h"
+#include "iobuf.h"
+
+/*-- Begin configurable part.  --*/
+
+/* The size of the internal buffers.
+   NOTE: If you change this value you MUST also adjust the regression
+   test "armored_key_8192" in armor.test! */
+#define IOBUF_BUFFER_SIZE  8192
+
+/* To avoid a potential DoS with compression packets we better limit
+   the number of filters in a chain.  */
+#define MAX_NESTING_FILTER 64
+
+/*-- End configurable part.  --*/
+
+
+#ifdef HAVE_W32_SYSTEM
+# ifdef HAVE_W32CE_SYSTEM
+#  define FD_FOR_STDIN  (es_fileno (es_stdin))
+#  define FD_FOR_STDOUT (es_fileno (es_stdout))
+# else
+#  define FD_FOR_STDIN  (GetStdHandle (STD_INPUT_HANDLE))
+#  define FD_FOR_STDOUT (GetStdHandle (STD_OUTPUT_HANDLE))
+# endif
+#else /*!HAVE_W32_SYSTEM*/
+# define FD_FOR_STDIN  (0)
+# define FD_FOR_STDOUT (1)
+#endif /*!HAVE_W32_SYSTEM*/
+
+
+/* The context used by the file filter.  */
+typedef struct
+{
+  gnupg_fd_t fp;       /* Open file pointer or handle.  */
+  int keep_open;
+  int no_cache;
+  int eof_seen;
+  int print_only_name; /* Flags indicating that fname is not a real file.  */
+  char fname[1];       /* Name of the file.  */
+} file_filter_ctx_t;
+
+/* The context used by the estream filter.  */
+typedef struct
+{
+  estream_t fp;        /* Open estream handle.  */
+  int keep_open;
+  int no_cache;
+  int eof_seen;
+  int print_only_name; /* Flags indicating that fname is not a real file.  */
+  char fname[1];       /* Name of the file.  */
+} file_es_filter_ctx_t;
+
+
+/* Object to control the "close cache".  */
+struct close_cache_s
+{
+  struct close_cache_s *next;
+  gnupg_fd_t fp;
+  char fname[1];
+};
+typedef struct close_cache_s *close_cache_t;
+static close_cache_t close_cache;
+
+int iobuf_debug_mode;
+
+
+#ifdef HAVE_W32_SYSTEM
+typedef struct
+{
+  int sock;
+  int keep_open;
+  int no_cache;
+  int eof_seen;
+  int print_only_name;	/* Flag indicating that fname is not a real file.  */
+  char fname[1];	/* Name of the file */
+
+} sock_filter_ctx_t;
+#endif /*HAVE_W32_SYSTEM*/
+
+/* The first partial length header block must be of size 512 to make
+ * it easier (and more efficient) we use a min. block size of 512 for
+ * all chunks (but the last one) */
+#define OP_MIN_PARTIAL_CHUNK	  512
+#define OP_MIN_PARTIAL_CHUNK_2POW 9
+
+/* The context we use for the block filter (used to handle OpenPGP
+   length information header).  */
+typedef struct
+{
+  int use;
+  size_t size;
+  size_t count;
+  int partial;	   /* 1 = partial header, 2 in last partial packet.  */
+  char *buffer;	   /* Used for partial header.  */
+  size_t buflen;   /* Used size of buffer.  */
+  int first_c;	   /* First character of a partial header (which is > 0).  */
+  int eof;
+}
+block_filter_ctx_t;
+
+
+/* Local prototypes.  */
+static int underflow (iobuf_t a, int clear_pending_eof);
+static int underflow_target (iobuf_t a, int clear_pending_eof, size_t target);
+static int translate_file_handle (int fd, int for_write);
+
+/* Sends any pending data to the filter's FILTER function.  Note: this
+   works on the filter and not on the whole pipeline.  That is,
+   iobuf_flush doesn't necessarily cause data to be written to any
+   underlying file; it just causes any data buffered at the filter A
+   to be sent to A's filter function.
+
+   If A is a IOBUF_OUTPUT_TEMP filter, then this also enlarges the
+   buffer by IOBUF_BUFFER_SIZE.
+
+   May only be called on an IOBUF_OUTPUT or IOBUF_OUTPUT_TEMP filters.  */
+static int filter_flush (iobuf_t a);
+
+
+
+/* This is a replacement for strcmp.  Under W32 it does not
+   distinguish between backslash and slash.  */
+static int
+fd_cache_strcmp (const char *a, const char *b)
+{
+#ifdef HAVE_DOSISH_SYSTEM
+  for (; *a && *b; a++, b++)
+    {
+      if (*a != *b && !((*a == '/' && *b == '\\')
+                        || (*a == '\\' && *b == '/')) )
+        break;
+    }
+  return *(const unsigned char *)a - *(const unsigned char *)b;
+#else
+  return strcmp (a, b);
+#endif
+}
+
+
+/*
+ * Invalidate (i.e. close) a cached iobuf
+ */
+static int
+fd_cache_invalidate (const char *fname)
+{
+  close_cache_t cc;
+  int rc = 0;
+
+  assert (fname);
+  if (DBG_IOBUF)
+    log_debug ("fd_cache_invalidate (%s)\n", fname);
+
+  for (cc = close_cache; cc; cc = cc->next)
+    {
+      if (cc->fp != GNUPG_INVALID_FD && !fd_cache_strcmp (cc->fname, fname))
+	{
+	  if (DBG_IOBUF)
+	    log_debug ("                did (%s)\n", cc->fname);
+#ifdef HAVE_W32_SYSTEM
+	  if (!CloseHandle (cc->fp))
+            rc = -1;
+#else
+	  rc = close (cc->fp);
+#endif
+	  cc->fp = GNUPG_INVALID_FD;
+	}
+    }
+  return rc;
+}
+
+
+/* Try to sync changes to the disk.  This is to avoid data loss during
+   a system crash in write/close/rename cycle on some file
+   systems.  */
+static int
+fd_cache_synchronize (const char *fname)
+{
+  int err = 0;
+
+#ifdef HAVE_FSYNC
+  close_cache_t cc;
+
+  if (DBG_IOBUF)
+    log_debug ("fd_cache_synchronize (%s)\n", fname);
+
+  for (cc=close_cache; cc; cc = cc->next )
+    {
+      if (cc->fp != GNUPG_INVALID_FD && !fd_cache_strcmp (cc->fname, fname))
+	{
+	  if (DBG_IOBUF)
+	    log_debug ("                 did (%s)\n", cc->fname);
+
+	  err = fsync (cc->fp);
+	}
+    }
+#else
+  (void)fname;
+#endif /*HAVE_FSYNC*/
+
+  return err;
+}
+
+
+static gnupg_fd_t
+direct_open (const char *fname, const char *mode, int mode700)
+{
+#ifdef HAVE_W32_SYSTEM
+  unsigned long da, cd, sm;
+  HANDLE hfile;
+
+  (void)mode700;
+  /* Note, that we do not handle all mode combinations */
+
+  /* According to the ReactOS source it seems that open() of the
+   * standard MSW32 crt does open the file in shared mode which is
+   * something new for MS applications ;-)
+   */
+  if (strchr (mode, '+'))
+    {
+      if (fd_cache_invalidate (fname))
+        return GNUPG_INVALID_FD;
+      da = GENERIC_READ | GENERIC_WRITE;
+      cd = OPEN_EXISTING;
+      sm = FILE_SHARE_READ | FILE_SHARE_WRITE;
+    }
+  else if (strchr (mode, 'w'))
+    {
+      if (fd_cache_invalidate (fname))
+        return GNUPG_INVALID_FD;
+      da = GENERIC_WRITE;
+      cd = CREATE_ALWAYS;
+      sm = FILE_SHARE_WRITE;
+    }
+  else
+    {
+      da = GENERIC_READ;
+      cd = OPEN_EXISTING;
+      sm = FILE_SHARE_READ;
+    }
+
+  /* We always use the Unicode version because it supports file names
+   * longer than MAX_PATH.  (requires gpgrt 1.45) */
+  if (1)
+    {
+      wchar_t *wfname = gpgrt_fname_to_wchar (fname);
+      if (wfname)
+        {
+          hfile = CreateFileW (wfname, da, sm, NULL, cd,
+                               FILE_ATTRIBUTE_NORMAL, NULL);
+          xfree (wfname);
+        }
+      else
+        hfile = INVALID_HANDLE_VALUE;
+    }
+
+  return hfile;
+
+#else /*!HAVE_W32_SYSTEM*/
+
+  int oflag;
+  int cflag = S_IRUSR | S_IWUSR;
+
+  if (!mode700)
+    cflag |= S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
+
+  /* Note, that we do not handle all mode combinations */
+  if (strchr (mode, '+'))
+    {
+      if (fd_cache_invalidate (fname))
+        return GNUPG_INVALID_FD;
+      oflag = O_RDWR;
+    }
+  else if (strchr (mode, 'w'))
+    {
+      if (fd_cache_invalidate (fname))
+        return GNUPG_INVALID_FD;
+      oflag = O_WRONLY | O_CREAT | O_TRUNC;
+    }
+  else
+    {
+      oflag = O_RDONLY;
+    }
+#ifdef O_BINARY
+  if (strchr (mode, 'b'))
+    oflag |= O_BINARY;
+#endif
+
+#ifdef __riscos__
+  {
+    struct stat buf;
+
+    /* Don't allow iobufs on directories */
+    if (!stat (fname, &buf) && S_ISDIR (buf.st_mode) && !S_ISREG (buf.st_mode))
+      return __set_errno (EISDIR);
+  }
+#endif
+  return open (fname, oflag, cflag);
+
+#endif /*!HAVE_W32_SYSTEM*/
+}
+
+
+/*
+ * Instead of closing an FD we keep it open and cache it for later reuse
+ * Note that this caching strategy only works if the process does not chdir.
+ */
+static void
+fd_cache_close (const char *fname, gnupg_fd_t fp)
+{
+  close_cache_t cc;
+
+  assert (fp);
+  if (!fname || !*fname)
+    {
+#ifdef HAVE_W32_SYSTEM
+      CloseHandle (fp);
+#else
+      close (fp);
+#endif
+      if (DBG_IOBUF)
+	log_debug ("fd_cache_close (%d) real\n", (int)fp);
+      return;
+    }
+  /* try to reuse a slot */
+  for (cc = close_cache; cc; cc = cc->next)
+    {
+      if (cc->fp == GNUPG_INVALID_FD && !fd_cache_strcmp (cc->fname, fname))
+	{
+	  cc->fp = fp;
+	  if (DBG_IOBUF)
+	    log_debug ("fd_cache_close (%s) used existing slot\n", fname);
+	  return;
+	}
+    }
+  /* add a new one */
+  if (DBG_IOBUF)
+    log_debug ("fd_cache_close (%s) new slot created\n", fname);
+  cc = xcalloc (1, sizeof *cc + strlen (fname));
+  strcpy (cc->fname, fname);
+  cc->fp = fp;
+  cc->next = close_cache;
+  close_cache = cc;
+}
+
+/*
+ * Do a direct_open on FNAME but first try to reuse one from the fd_cache
+ */
+static gnupg_fd_t
+fd_cache_open (const char *fname, const char *mode)
+{
+  close_cache_t cc;
+
+  assert (fname);
+  for (cc = close_cache; cc; cc = cc->next)
+    {
+      if (cc->fp != GNUPG_INVALID_FD && !fd_cache_strcmp (cc->fname, fname))
+	{
+	  gnupg_fd_t fp = cc->fp;
+	  cc->fp = GNUPG_INVALID_FD;
+	  if (DBG_IOBUF)
+	    log_debug ("fd_cache_open (%s) using cached fp\n", fname);
+#ifdef HAVE_W32_SYSTEM
+	  if (SetFilePointer (fp, 0, NULL, FILE_BEGIN) == 0xffffffff)
+	    {
+	      log_error ("rewind file failed on handle %p: ec=%d\n",
+			 fp, (int) GetLastError ());
+	      fp = GNUPG_INVALID_FD;
+	    }
+#else
+	  if (lseek (fp, 0, SEEK_SET) == (off_t) - 1)
+	    {
+	      log_error ("can't rewind fd %d: %s\n", fp, strerror (errno));
+	      fp = GNUPG_INVALID_FD;
+	    }
+#endif
+	  return fp;
+	}
+    }
+  if (DBG_IOBUF)
+    log_debug ("fd_cache_open (%s) not cached\n", fname);
+  return direct_open (fname, mode, 0);
+}
+
+
+static int
+file_filter (void *opaque, int control, iobuf_t chain, byte * buf,
+	     size_t * ret_len)
+{
+  file_filter_ctx_t *a = opaque;
+  gnupg_fd_t f = a->fp;
+  size_t size = *ret_len;
+  size_t nbytes = 0;
+  int rc = 0;
+
+  (void)chain; /* Not used.  */
+
+  if (control == IOBUFCTRL_UNDERFLOW)
+    {
+      assert (size); /* We need a buffer.  */
+      if (a->eof_seen)
+	{
+	  rc = -1;
+	  *ret_len = 0;
+	}
+      else
+	{
+#ifdef HAVE_W32_SYSTEM
+	  unsigned long nread;
+
+	  nbytes = 0;
+	  if (!ReadFile (f, buf, size, &nread, NULL))
+	    {
+	      int ec = (int) GetLastError ();
+	      if (ec != ERROR_BROKEN_PIPE)
+		{
+		  rc = gpg_error_from_errno (ec);
+		  log_error ("%s: read error: ec=%d\n", a->fname, ec);
+		}
+	    }
+	  else if (!nread)
+	    {
+	      a->eof_seen = 1;
+	      rc = -1;
+	    }
+	  else
+	    {
+	      nbytes = nread;
+	    }
+
+#else
+
+	  int n;
+
+	  nbytes = 0;
+	  do
+	    {
+	      n = read (f, buf, size);
+	    }
+	  while (n == -1 && errno == EINTR);
+	  if (n == -1)
+	    {			/* error */
+	      if (errno != EPIPE)
+		{
+		  rc = gpg_error_from_syserror ();
+		  log_error ("%s: read error: %s\n",
+			     a->fname, strerror (errno));
+		}
+	    }
+	  else if (!n)
+	    {			/* eof */
+	      a->eof_seen = 1;
+	      rc = -1;
+	    }
+	  else
+	    {
+	      nbytes = n;
+	    }
+#endif
+	  *ret_len = nbytes;
+	}
+    }
+  else if (control == IOBUFCTRL_FLUSH)
+    {
+      if (size)
+	{
+#ifdef HAVE_W32_SYSTEM
+	  byte *p = buf;
+	  unsigned long n;
+
+	  nbytes = size;
+	  do
+	    {
+	      if (size && !WriteFile (f, p, nbytes, &n, NULL))
+		{
+		  int ec = (int) GetLastError ();
+		  rc = gpg_error_from_errno (ec);
+		  log_error ("%s: write error: ec=%d\n", a->fname, ec);
+		  break;
+		}
+	      p += n;
+	      nbytes -= n;
+	    }
+	  while (nbytes);
+	  nbytes = p - buf;
+#else
+	  byte *p = buf;
+	  int n;
+
+	  nbytes = size;
+	  do
+	    {
+	      do
+		{
+		  n = write (f, p, nbytes);
+		}
+	      while (n == -1 && errno == EINTR);
+	      if (n > 0)
+		{
+		  p += n;
+		  nbytes -= n;
+		}
+	    }
+	  while (n != -1 && nbytes);
+	  if (n == -1)
+	    {
+	      rc = gpg_error_from_syserror ();
+	      log_error ("%s: write error: %s\n", a->fname, strerror (errno));
+	    }
+	  nbytes = p - buf;
+#endif
+	}
+      *ret_len = nbytes;
+    }
+  else if (control == IOBUFCTRL_INIT)
+    {
+      a->eof_seen = 0;
+      a->keep_open = 0;
+      a->no_cache = 0;
+    }
+  else if (control == IOBUFCTRL_DESC)
+    {
+      mem2str (buf, "file_filter(fd)", *ret_len);
+    }
+  else if (control == IOBUFCTRL_FREE)
+    {
+      if (f != FD_FOR_STDIN && f != FD_FOR_STDOUT)
+	{
+	  if (DBG_IOBUF)
+	    log_debug ("%s: close fd/handle %d\n", a->fname, FD2INT (f));
+	  if (!a->keep_open)
+	    fd_cache_close (a->no_cache ? NULL : a->fname, f);
+	}
+      xfree (a); /* We can free our context now. */
+    }
+
+  return rc;
+}
+
+
+/* Similar to file_filter but using the estream system.  */
+static int
+file_es_filter (void *opaque, int control, iobuf_t chain, byte * buf,
+                size_t * ret_len)
+{
+  file_es_filter_ctx_t *a = opaque;
+  estream_t f = a->fp;
+  size_t size = *ret_len;
+  size_t nbytes = 0;
+  int rc = 0;
+
+  (void)chain; /* Not used.  */
+
+  if (control == IOBUFCTRL_UNDERFLOW)
+    {
+      assert (size); /* We need a buffer.  */
+      if (a->eof_seen)
+	{
+	  rc = -1;
+	  *ret_len = 0;
+	}
+      else
+	{
+          nbytes = 0;
+          rc = es_read (f, buf, size, &nbytes);
+	  if (rc == -1)
+	    {			/* error */
+              rc = gpg_error_from_syserror ();
+              log_error ("%s: read error: %s\n", a->fname, strerror (errno));
+	    }
+	  else if (!nbytes)
+	    {			/* eof */
+	      a->eof_seen = 1;
+	      rc = -1;
+	    }
+	  *ret_len = nbytes;
+	}
+    }
+  else if (control == IOBUFCTRL_FLUSH)
+    {
+      if (size)
+	{
+	  byte *p = buf;
+	  size_t nwritten;
+
+	  nbytes = size;
+	  do
+	    {
+              nwritten = 0;
+              if (es_write (f, p, nbytes, &nwritten))
+                {
+                  rc = gpg_error_from_syserror ();
+                  log_error ("%s: write error: %s\n",
+                             a->fname, strerror (errno));
+                  break;
+                }
+              p += nwritten;
+              nbytes -= nwritten;
+	    }
+	  while (nbytes);
+	  nbytes = p - buf;
+	}
+      *ret_len = nbytes;
+    }
+  else if (control == IOBUFCTRL_INIT)
+    {
+      a->eof_seen = 0;
+      a->no_cache = 0;
+    }
+  else if (control == IOBUFCTRL_DESC)
+    {
+      mem2str (buf, "estream_filter", *ret_len);
+    }
+  else if (control == IOBUFCTRL_FREE)
+    {
+      if (f != es_stdin && f != es_stdout)
+	{
+	  if (DBG_IOBUF)
+	    log_debug ("%s: es_fclose %p\n", a->fname, f);
+	  if (!a->keep_open)
+	    es_fclose (f);
+	}
+      f = NULL;
+      xfree (a); /* We can free our context now. */
+    }
+
+  return rc;
+}
+
+
+#ifdef HAVE_W32_SYSTEM
+/* Because network sockets are special objects under Lose32 we have to
+   use a dedicated filter for them. */
+static int
+sock_filter (void *opaque, int control, iobuf_t chain, byte * buf,
+	     size_t * ret_len)
+{
+  sock_filter_ctx_t *a = opaque;
+  size_t size = *ret_len;
+  size_t nbytes = 0;
+  int rc = 0;
+
+  (void)chain;
+
+  if (control == IOBUFCTRL_UNDERFLOW)
+    {
+      assert (size);		/* need a buffer */
+      if (a->eof_seen)
+	{
+	  rc = -1;
+	  *ret_len = 0;
+	}
+      else
+	{
+	  int nread;
+
+	  nread = recv (a->sock, buf, size, 0);
+	  if (nread == SOCKET_ERROR)
+	    {
+	      int ec = (int) WSAGetLastError ();
+	      rc = gpg_error_from_errno (ec);
+	      log_error ("socket read error: ec=%d\n", ec);
+	    }
+	  else if (!nread)
+	    {
+	      a->eof_seen = 1;
+	      rc = -1;
+	    }
+	  else
+	    {
+	      nbytes = nread;
+	    }
+	  *ret_len = nbytes;
+	}
+    }
+  else if (control == IOBUFCTRL_FLUSH)
+    {
+      if (size)
+	{
+	  byte *p = buf;
+	  int n;
+
+	  nbytes = size;
+	  do
+	    {
+	      n = send (a->sock, p, nbytes, 0);
+	      if (n == SOCKET_ERROR)
+		{
+		  int ec = (int) WSAGetLastError ();
+		  rc = gpg_error_from_errno (ec);
+		  log_error ("socket write error: ec=%d\n", ec);
+		  break;
+		}
+	      p += n;
+	      nbytes -= n;
+	    }
+	  while (nbytes);
+	  nbytes = p - buf;
+	}
+      *ret_len = nbytes;
+    }
+  else if (control == IOBUFCTRL_INIT)
+    {
+      a->eof_seen = 0;
+      a->keep_open = 0;
+      a->no_cache = 0;
+    }
+  else if (control == IOBUFCTRL_DESC)
+    {
+      mem2str (buf, "sock_filter", *ret_len);
+    }
+  else if (control == IOBUFCTRL_FREE)
+    {
+      if (!a->keep_open)
+	closesocket (a->sock);
+      xfree (a);		/* we can free our context now */
+    }
+  return rc;
+}
+#endif /*HAVE_W32_SYSTEM*/
+
+/****************
+ * This is used to implement the block write mode.
+ * Block reading is done on a byte by byte basis in readbyte(),
+ * without a filter
+ */
+static int
+block_filter (void *opaque, int control, iobuf_t chain, byte * buffer,
+	      size_t * ret_len)
+{
+  block_filter_ctx_t *a = opaque;
+  char *buf = (char *)buffer;
+  size_t size = *ret_len;
+  int c, needed, rc = 0;
+  char *p;
+
+  if (control == IOBUFCTRL_UNDERFLOW)
+    {
+      size_t n = 0;
+
+      p = buf;
+      assert (size);		/* need a buffer */
+      if (a->eof)		/* don't read any further */
+	rc = -1;
+      while (!rc && size)
+	{
+	  if (!a->size)
+	    {			/* get the length bytes */
+	      if (a->partial == 2)
+		{
+		  a->eof = 1;
+		  if (!n)
+		    rc = -1;
+		  break;
+		}
+	      else if (a->partial)
+		{
+		  /* These OpenPGP introduced huffman like encoded length
+		   * bytes are really a mess :-( */
+		  if (a->first_c)
+		    {
+		      c = a->first_c;
+		      a->first_c = 0;
+		    }
+		  else if ((c = iobuf_get (chain)) == -1)
+		    {
+		      log_error ("block_filter: 1st length byte missing\n");
+		      rc = GPG_ERR_BAD_DATA;
+		      break;
+		    }
+		  if (c < 192)
+		    {
+		      a->size = c;
+		      a->partial = 2;
+		      if (!a->size)
+			{
+			  a->eof = 1;
+			  if (!n)
+			    rc = -1;
+			  break;
+			}
+		    }
+		  else if (c < 224)
+		    {
+		      a->size = (c - 192) * 256;
+		      if ((c = iobuf_get (chain)) == -1)
+			{
+			  log_error
+			    ("block_filter: 2nd length byte missing\n");
+			  rc = GPG_ERR_BAD_DATA;
+			  break;
+			}
+		      a->size += c + 192;
+		      a->partial = 2;
+		      if (!a->size)
+			{
+			  a->eof = 1;
+			  if (!n)
+			    rc = -1;
+			  break;
+			}
+		    }
+		  else if (c == 255)
+		    {
+		      a->size = iobuf_get_noeof (chain) << 24;
+		      a->size |= iobuf_get_noeof (chain) << 16;
+		      a->size |= iobuf_get_noeof (chain) << 8;
+		      if ((c = iobuf_get (chain)) == -1)
+			{
+			  log_error ("block_filter: invalid 4 byte length\n");
+			  rc = GPG_ERR_BAD_DATA;
+			  break;
+			}
+		      a->size |= c;
+                      a->partial = 2;
+                      if (!a->size)
+                        {
+                          a->eof = 1;
+                          if (!n)
+                            rc = -1;
+                          break;
+			}
+		    }
+		  else
+		    { /* Next partial body length. */
+		      a->size = 1 << (c & 0x1f);
+		    }
+		  /*  log_debug("partial: ctx=%p c=%02x size=%u\n", a, c, a->size); */
+		}
+	      else
+		BUG ();
+	    }
+
+	  while (!rc && size && a->size)
+	    {
+	      needed = size < a->size ? size : a->size;
+	      c = iobuf_read (chain, p, needed);
+	      if (c < needed)
+		{
+		  if (c == -1)
+		    c = 0;
+		  log_error
+		    ("block_filter %p: read error (size=%lu,a->size=%lu)\n",
+		     a, (ulong) size + c, (ulong) a->size + c);
+		  rc = GPG_ERR_BAD_DATA;
+		}
+	      else
+		{
+		  size -= c;
+		  a->size -= c;
+		  p += c;
+		  n += c;
+		}
+	    }
+	}
+      *ret_len = n;
+    }
+  else if (control == IOBUFCTRL_FLUSH)
+    {
+      if (a->partial)
+	{			/* the complicated openpgp scheme */
+	  size_t blen, n, nbytes = size + a->buflen;
+
+	  assert (a->buflen <= OP_MIN_PARTIAL_CHUNK);
+	  if (nbytes < OP_MIN_PARTIAL_CHUNK)
+	    {
+	      /* not enough to write a partial block out; so we store it */
+	      if (!a->buffer)
+		a->buffer = xmalloc (OP_MIN_PARTIAL_CHUNK);
+	      memcpy (a->buffer + a->buflen, buf, size);
+	      a->buflen += size;
+	    }
+	  else
+	    {			/* okay, we can write out something */
+	      /* do this in a loop to use the most efficient block lengths */
+	      p = buf;
+	      do
+		{
+		  /* find the best matching block length - this is limited
+		   * by the size of the internal buffering */
+		  for (blen = OP_MIN_PARTIAL_CHUNK * 2,
+		       c = OP_MIN_PARTIAL_CHUNK_2POW + 1; blen <= nbytes;
+		       blen *= 2, c++)
+		    ;
+		  blen /= 2;
+		  c--;
+		  /* write the partial length header */
+		  assert (c <= 0x1f);	/*;-) */
+		  c |= 0xe0;
+		  iobuf_put (chain, c);
+		  if ((n = a->buflen))
+		    {		/* write stuff from the buffer */
+		      assert (n == OP_MIN_PARTIAL_CHUNK);
+		      if (iobuf_write (chain, a->buffer, n))
+			rc = gpg_error_from_syserror ();
+		      a->buflen = 0;
+		      nbytes -= n;
+		    }
+		  if ((n = nbytes) > blen)
+		    n = blen;
+		  if (n && iobuf_write (chain, p, n))
+		    rc = gpg_error_from_syserror ();
+		  p += n;
+		  nbytes -= n;
+		}
+	      while (!rc && nbytes >= OP_MIN_PARTIAL_CHUNK);
+	      /* store the rest in the buffer */
+	      if (!rc && nbytes)
+		{
+		  assert (!a->buflen);
+		  assert (nbytes < OP_MIN_PARTIAL_CHUNK);
+		  if (!a->buffer)
+		    a->buffer = xmalloc (OP_MIN_PARTIAL_CHUNK);
+		  memcpy (a->buffer, p, nbytes);
+		  a->buflen = nbytes;
+		}
+	    }
+	}
+      else
+	BUG ();
+    }
+  else if (control == IOBUFCTRL_INIT)
+    {
+      if (DBG_IOBUF)
+	log_debug ("init block_filter %p\n", a);
+      if (a->partial)
+	a->count = 0;
+      else if (a->use == IOBUF_INPUT)
+	a->count = a->size = 0;
+      else
+	a->count = a->size;	/* force first length bytes */
+      a->eof = 0;
+      a->buffer = NULL;
+      a->buflen = 0;
+    }
+  else if (control == IOBUFCTRL_DESC)
+    {
+      mem2str (buf, "block_filter", *ret_len);
+    }
+  else if (control == IOBUFCTRL_FREE)
+    {
+      if (a->use == IOBUF_OUTPUT)
+	{			/* write the end markers */
+	  if (a->partial)
+	    {
+	      u32 len;
+	      /* write out the remaining bytes without a partial header
+	       * the length of this header may be 0 - but if it is
+	       * the first block we are not allowed to use a partial header
+	       * and frankly we can't do so, because this length must be
+	       * a power of 2. This is _really_ complicated because we
+	       * have to check the possible length of a packet prior
+	       * to it's creation: a chain of filters becomes complicated
+	       * and we need a lot of code to handle compressed packets etc.
+	       *   :-(((((((
+	       */
+	      /* construct header */
+	      len = a->buflen;
+	      /*log_debug("partial: remaining length=%u\n", len ); */
+	      if (len < 192)
+		rc = iobuf_put (chain, len);
+	      else if (len < 8384)
+		{
+		  if (!(rc = iobuf_put (chain, ((len - 192) / 256) + 192)))
+		    rc = iobuf_put (chain, ((len - 192) % 256));
+		}
+	      else
+		{		/* use a 4 byte header */
+		  if (!(rc = iobuf_put (chain, 0xff)))
+		    if (!(rc = iobuf_put (chain, (len >> 24) & 0xff)))
+		      if (!(rc = iobuf_put (chain, (len >> 16) & 0xff)))
+			if (!(rc = iobuf_put (chain, (len >> 8) & 0xff)))
+			  rc = iobuf_put (chain, len & 0xff);
+		}
+	      if (!rc && len)
+		rc = iobuf_write (chain, a->buffer, len);
+	      if (rc)
+		{
+		  log_error ("block_filter: write error: %s\n",
+			     strerror (errno));
+		  rc = gpg_error_from_syserror ();
+		}
+	      xfree (a->buffer);
+	      a->buffer = NULL;
+	      a->buflen = 0;
+	    }
+	  else
+	    BUG ();
+	}
+      else if (a->size)
+	{
+	  log_error ("block_filter: pending bytes!\n");
+	}
+      if (DBG_IOBUF)
+	log_debug ("free block_filter %p\n", a);
+      xfree (a);		/* we can free our context now */
+    }
+
+  return rc;
+}
+
+#define MAX_IOBUF_DESC 32
+/*
+ * Fill the buffer by the description of iobuf A.
+ * The buffer size should be MAX_IOBUF_DESC (or larger).
+ * Returns BUF as (const char *).
+ */
+static const char *
+iobuf_desc (iobuf_t a, byte *buf)
+{
+  size_t len = MAX_IOBUF_DESC;
+
+  if (! a || ! a->filter)
+    memcpy (buf, "?", 2);
+  else
+    a->filter (a->filter_ov, IOBUFCTRL_DESC, NULL, buf, &len);
+
+  return buf;
+}
+
+static void
+print_chain (iobuf_t a)
+{
+  if (!DBG_IOBUF)
+    return;
+  for (; a; a = a->chain)
+    {
+      byte desc[MAX_IOBUF_DESC];
+
+      log_debug ("iobuf chain: %d.%d '%s' filter_eof=%d start=%d len=%d\n",
+		 a->no, a->subno, iobuf_desc (a, desc), a->filter_eof,
+		 (int) a->d.start, (int) a->d.len);
+    }
+}
+
+int
+iobuf_print_chain (iobuf_t a)
+{
+  print_chain (a);
+  return 0;
+}
+
+iobuf_t
+iobuf_alloc (int use, size_t bufsize)
+{
+  iobuf_t a;
+  static int number = 0;
+
+  assert (use == IOBUF_INPUT || use == IOBUF_INPUT_TEMP
+	  || use == IOBUF_OUTPUT || use == IOBUF_OUTPUT_TEMP);
+  if (bufsize == 0)
+    {
+      log_bug ("iobuf_alloc() passed a bufsize of 0!\n");
+      bufsize = IOBUF_BUFFER_SIZE;
+    }
+
+  a = xcalloc (1, sizeof *a);
+  a->use = use;
+  a->d.buf = xmalloc (bufsize);
+  a->d.size = bufsize;
+  a->no = ++number;
+  a->subno = 0;
+  a->real_fname = NULL;
+  return a;
+}
+
+int
+iobuf_close (iobuf_t a)
+{
+  iobuf_t a_chain;
+  size_t dummy_len = 0;
+  int rc = 0;
+
+  for (; a; a = a_chain)
+    {
+      byte desc[MAX_IOBUF_DESC];
+      int rc2 = 0;
+
+      a_chain = a->chain;
+
+      if (a->use == IOBUF_OUTPUT && (rc = filter_flush (a)))
+	log_error ("filter_flush failed on close: %s\n", gpg_strerror (rc));
+
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: close '%s'\n",
+		   a->no, a->subno, iobuf_desc (a, desc));
+
+      if (a->filter && (rc2 = a->filter (a->filter_ov, IOBUFCTRL_FREE,
+					 a->chain, NULL, &dummy_len)))
+	log_error ("IOBUFCTRL_FREE failed on close: %s\n", gpg_strerror (rc));
+      if (! rc && rc2)
+	/* Whoops!  An error occurred.  Save it in RC if we haven't
+	   already recorded an error.  */
+	rc = rc2;
+
+      xfree (a->real_fname);
+      if (a->d.buf)
+	{
+	  memset (a->d.buf, 0, a->d.size);	/* erase the buffer */
+	  xfree (a->d.buf);
+	}
+      xfree (a);
+    }
+  return rc;
+}
+
+int
+iobuf_cancel (iobuf_t a)
+{
+  const char *s;
+  iobuf_t a2;
+  int rc;
+#if defined(HAVE_W32_SYSTEM) || defined(__riscos__)
+  char *remove_name = NULL;
+#endif
+
+  if (a && a->use == IOBUF_OUTPUT)
+    {
+      s = iobuf_get_real_fname (a);
+      if (s && *s)
+	{
+#if defined(HAVE_W32_SYSTEM) || defined(__riscos__)
+	  remove_name = xstrdup (s);
+#else
+	  remove (s);
+#endif
+	}
+    }
+
+  /* send a cancel message to all filters */
+  for (a2 = a; a2; a2 = a2->chain)
+    {
+      size_t dummy;
+      if (a2->filter)
+	a2->filter (a2->filter_ov, IOBUFCTRL_CANCEL, a2->chain, NULL, &dummy);
+    }
+
+  rc = iobuf_close (a);
+#if defined(HAVE_W32_SYSTEM) || defined(__riscos__)
+  if (remove_name)
+    {
+      /* Argg, MSDOS does not allow removing open files.  So
+       * we have to do it here */
+      gnupg_remove (remove_name);
+      xfree (remove_name);
+    }
+#endif
+  return rc;
+}
+
+
+iobuf_t
+iobuf_temp (void)
+{
+  return iobuf_alloc (IOBUF_OUTPUT_TEMP, IOBUF_BUFFER_SIZE);
+}
+
+iobuf_t
+iobuf_temp_with_content (const char *buffer, size_t length)
+{
+  iobuf_t a;
+  int i;
+
+  a = iobuf_alloc (IOBUF_INPUT_TEMP, length);
+  assert (length == a->d.size);
+  /* memcpy (a->d.buf, buffer, length); */
+  for (i=0; i < length; i++)
+    a->d.buf[i] = buffer[i];
+  a->d.len = length;
+
+  return a;
+}
+
+
+int
+iobuf_is_pipe_filename (const char *fname)
+{
+  if (!fname || (*fname=='-' && !fname[1]) )
+    return 1;
+  return check_special_filename (fname, 0, 1) != -1;
+}
+
+
+static iobuf_t
+do_open (const char *fname, int special_filenames,
+	 int use, const char *opentype, int mode700)
+{
+  iobuf_t a;
+  gnupg_fd_t fp;
+  file_filter_ctx_t *fcx;
+  size_t len = 0;
+  int print_only = 0;
+  int fd;
+  byte desc[MAX_IOBUF_DESC];
+
+  assert (use == IOBUF_INPUT || use == IOBUF_OUTPUT);
+
+  if (special_filenames
+      /* NULL or '-'.  */
+      && (!fname || (*fname == '-' && !fname[1])))
+    {
+      if (use == IOBUF_INPUT)
+	{
+	  fp = FD_FOR_STDIN;
+	  fname = "[stdin]";
+	}
+      else
+	{
+	  fp = FD_FOR_STDOUT;
+	  fname = "[stdout]";
+	}
+      print_only = 1;
+    }
+  else if (!fname)
+    return NULL;
+  else if (special_filenames
+           && (fd = check_special_filename (fname, 0, 1)) != -1)
+    return iobuf_fdopen (translate_file_handle (fd, use == IOBUF_INPUT ? 0 : 1),
+			 opentype);
+  else
+    {
+      if (use == IOBUF_INPUT)
+	fp = fd_cache_open (fname, opentype);
+      else
+	fp = direct_open (fname, opentype, mode700);
+      if (fp == GNUPG_INVALID_FD)
+	return NULL;
+    }
+
+  a = iobuf_alloc (use, IOBUF_BUFFER_SIZE);
+  fcx = xmalloc (sizeof *fcx + strlen (fname));
+  fcx->fp = fp;
+  fcx->print_only_name = print_only;
+  strcpy (fcx->fname, fname);
+  if (!print_only)
+    a->real_fname = xstrdup (fname);
+  a->filter = file_filter;
+  a->filter_ov = fcx;
+  file_filter (fcx, IOBUFCTRL_INIT, NULL, NULL, &len);
+  if (DBG_IOBUF)
+    log_debug ("iobuf-%d.%d: open '%s' desc=%s fd=%d\n",
+	       a->no, a->subno, fname, iobuf_desc (a, desc), FD2INT (fcx->fp));
+
+  return a;
+}
+
+iobuf_t
+iobuf_open (const char *fname)
+{
+  return do_open (fname, 1, IOBUF_INPUT, "rb", 0);
+}
+
+iobuf_t
+iobuf_create (const char *fname, int mode700)
+{
+  return do_open (fname, 1, IOBUF_OUTPUT, "wb", mode700);
+}
+
+iobuf_t
+iobuf_openrw (const char *fname)
+{
+  return do_open (fname, 0, IOBUF_OUTPUT, "r+b", 0);
+}
+
+
+static iobuf_t
+do_iobuf_fdopen (int fd, const char *mode, int keep_open)
+{
+  iobuf_t a;
+  gnupg_fd_t fp;
+  file_filter_ctx_t *fcx;
+  size_t len;
+
+  fp = INT2FD (fd);
+
+  a = iobuf_alloc (strchr (mode, 'w') ? IOBUF_OUTPUT : IOBUF_INPUT,
+		   IOBUF_BUFFER_SIZE);
+  fcx = xmalloc (sizeof *fcx + 20);
+  fcx->fp = fp;
+  fcx->print_only_name = 1;
+  fcx->keep_open = keep_open;
+  sprintf (fcx->fname, "[fd %d]", fd);
+  a->filter = file_filter;
+  a->filter_ov = fcx;
+  file_filter (fcx, IOBUFCTRL_INIT, NULL, NULL, &len);
+  if (DBG_IOBUF)
+    log_debug ("iobuf-%d.%d: fdopen%s '%s'\n",
+               a->no, a->subno, keep_open? "_nc":"", fcx->fname);
+  iobuf_ioctl (a, IOBUF_IOCTL_NO_CACHE, 1, NULL);
+  return a;
+}
+
+
+iobuf_t
+iobuf_fdopen (int fd, const char *mode)
+{
+  return do_iobuf_fdopen (fd, mode, 0);
+}
+
+iobuf_t
+iobuf_fdopen_nc (int fd, const char *mode)
+{
+  return do_iobuf_fdopen (fd, mode, 1);
+}
+
+
+iobuf_t
+iobuf_esopen (estream_t estream, const char *mode, int keep_open)
+{
+  iobuf_t a;
+  file_es_filter_ctx_t *fcx;
+  size_t len = 0;
+
+  a = iobuf_alloc (strchr (mode, 'w') ? IOBUF_OUTPUT : IOBUF_INPUT,
+		   IOBUF_BUFFER_SIZE);
+  fcx = xtrymalloc (sizeof *fcx + 30);
+  fcx->fp = estream;
+  fcx->print_only_name = 1;
+  fcx->keep_open = keep_open;
+  sprintf (fcx->fname, "[fd %p]", estream);
+  a->filter = file_es_filter;
+  a->filter_ov = fcx;
+  file_es_filter (fcx, IOBUFCTRL_INIT, NULL, NULL, &len);
+  if (DBG_IOBUF)
+    log_debug ("iobuf-%d.%d: esopen%s '%s'\n",
+               a->no, a->subno, keep_open? "_nc":"", fcx->fname);
+  return a;
+}
+
+
+iobuf_t
+iobuf_sockopen (int fd, const char *mode)
+{
+  iobuf_t a;
+#ifdef HAVE_W32_SYSTEM
+  sock_filter_ctx_t *scx;
+  size_t len;
+
+  a = iobuf_alloc (strchr (mode, 'w') ? IOBUF_OUTPUT : IOBUF_INPUT,
+		   IOBUF_BUFFER_SIZE);
+  scx = xmalloc (sizeof *scx + 25);
+  scx->sock = fd;
+  scx->print_only_name = 1;
+  sprintf (scx->fname, "[sock %d]", fd);
+  a->filter = sock_filter;
+  a->filter_ov = scx;
+  sock_filter (scx, IOBUFCTRL_INIT, NULL, NULL, &len);
+  if (DBG_IOBUF)
+    log_debug ("iobuf-%d.%d: sockopen '%s'\n", a->no, a->subno, scx->fname);
+  iobuf_ioctl (a, IOBUF_IOCTL_NO_CACHE, 1, NULL);
+#else
+  a = iobuf_fdopen (fd, mode);
+#endif
+  return a;
+}
+
+int
+iobuf_ioctl (iobuf_t a, iobuf_ioctl_t cmd, int intval, void *ptrval)
+{
+  byte desc[MAX_IOBUF_DESC];
+
+  if (cmd == IOBUF_IOCTL_KEEP_OPEN)
+    {
+      /* Keep system filepointer/descriptor open.  This was used in
+         the past by http.c; this ioctl is not directly used
+         anymore.  */
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: ioctl '%s' keep_open=%d\n",
+		   a ? a->no : -1, a ? a->subno : -1, iobuf_desc (a, desc),
+		   intval);
+      for (; a; a = a->chain)
+	if (!a->chain && a->filter == file_filter)
+	  {
+	    file_filter_ctx_t *b = a->filter_ov;
+	    b->keep_open = intval;
+	    return 0;
+	  }
+#ifdef HAVE_W32_SYSTEM
+	else if (!a->chain && a->filter == sock_filter)
+	  {
+	    sock_filter_ctx_t *b = a->filter_ov;
+	    b->keep_open = intval;
+	    return 0;
+	  }
+#endif
+    }
+  else if (cmd == IOBUF_IOCTL_INVALIDATE_CACHE)
+    {
+      if (DBG_IOBUF)
+	log_debug ("iobuf-*.*: ioctl '%s' invalidate\n",
+		   ptrval ? (char *) ptrval : "?");
+      if (!a && !intval && ptrval)
+	{
+	  if (fd_cache_invalidate (ptrval))
+            return -1;
+	  return 0;
+	}
+    }
+  else if (cmd == IOBUF_IOCTL_NO_CACHE)
+    {
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: ioctl '%s' no_cache=%d\n",
+		   a ? a->no : -1, a ? a->subno : -1, iobuf_desc (a, desc),
+		   intval);
+      for (; a; a = a->chain)
+	if (!a->chain && a->filter == file_filter)
+	  {
+	    file_filter_ctx_t *b = a->filter_ov;
+	    b->no_cache = intval;
+	    return 0;
+	  }
+#ifdef HAVE_W32_SYSTEM
+	else if (!a->chain && a->filter == sock_filter)
+	  {
+	    sock_filter_ctx_t *b = a->filter_ov;
+	    b->no_cache = intval;
+	    return 0;
+	  }
+#endif
+    }
+  else if (cmd == IOBUF_IOCTL_FSYNC)
+    {
+      /* Do a fsync on the open fd and return any errors to the caller
+         of iobuf_ioctl.  Note that we work on a file name here. */
+      if (DBG_IOBUF)
+        log_debug ("iobuf-*.*: ioctl '%s' fsync\n",
+                   ptrval? (const char*)ptrval:"<null>");
+
+      if (!a && !intval && ptrval)
+        {
+          return fd_cache_synchronize (ptrval);
+        }
+    }
+
+
+  return -1;
+}
+
+
+/****************
+ * Register an i/o filter.
+ */
+int
+iobuf_push_filter (iobuf_t a,
+		   int (*f) (void *opaque, int control,
+			     iobuf_t chain, byte * buf, size_t * len),
+                   void *ov)
+{
+  return iobuf_push_filter2 (a, f, ov, 0);
+}
+
+int
+iobuf_push_filter2 (iobuf_t a,
+		    int (*f) (void *opaque, int control,
+			      iobuf_t chain, byte * buf, size_t * len),
+		    void *ov, int rel_ov)
+{
+  iobuf_t b;
+  size_t dummy_len = 0;
+  int rc = 0;
+
+  if (a->use == IOBUF_OUTPUT && (rc = filter_flush (a)))
+    return rc;
+
+  if (a->subno >= MAX_NESTING_FILTER)
+    {
+      log_error ("i/o filter too deeply nested - corrupted data?\n");
+      return GPG_ERR_BAD_DATA;
+    }
+
+  /* We want to create a new filter and put it in front of A.  A
+     simple implementation would do:
+
+       b = iobuf_alloc (...);
+       b->chain = a;
+       return a;
+
+     This is a bit problematic: A is the head of the pipeline and
+     there are potentially many pointers to it.  Requiring the caller
+     to update all of these pointers is a burden.
+
+     An alternative implementation would add a level of indirection.
+     For instance, we could use a pipeline object, which contains a
+     pointer to the first filter in the pipeline.  This is not what we
+     do either.
+
+     Instead, we allocate a new buffer (B) and copy the first filter's
+     state into that and use the initial buffer (A) for the new
+     filter.  One limitation of this approach is that it is not
+     practical to maintain a pointer to a specific filter's state.
+
+     Before:
+
+           A
+           |
+           v 0x100               0x200
+           +----------+          +----------+
+           | filter x |--------->| filter y |---->....
+           +----------+          +----------+
+
+     After:           B
+                      |
+                      v 0x300
+                      +----------+
+           A          | filter x |
+           |          +----------+
+           v 0x100    ^          v 0x200
+           +----------+          +----------+
+           | filter w |          | filter y |---->....
+           +----------+          +----------+
+
+     Note: filter x's address changed from 0x100 to 0x300, but A still
+     points to the head of the pipeline.
+  */
+
+  b = xmalloc (sizeof *b);
+  memcpy (b, a, sizeof *b);
+  /* fixme: it is stupid to keep a copy of the name at every level
+   * but we need the name somewhere because the name known by file_filter
+   * may have been released when we need the name of the file */
+  b->real_fname = a->real_fname ? xstrdup (a->real_fname) : NULL;
+  /* remove the filter stuff from the new stream */
+  a->filter = NULL;
+  a->filter_ov = NULL;
+  a->filter_ov_owner = 0;
+  a->filter_eof = 0;
+  if (a->use == IOBUF_OUTPUT_TEMP)
+    /* A TEMP filter buffers any data sent to it; it does not forward
+       any data down the pipeline.  If we add a new filter to the
+       pipeline, it shouldn't also buffer data.  It should send it
+       downstream to be buffered.  Thus, the correct type for a filter
+       added in front of an IOBUF_OUTPUT_TEMP filter is IOBUF_OUPUT, not
+       IOBUF_OUTPUT_TEMP.  */
+    {
+      a->use = IOBUF_OUTPUT;
+
+      /* When pipeline is written to, the temp buffer's size is
+	 increased accordingly.  We don't need to allocate a 10 MB
+	 buffer for a non-terminal filter.  Just use the default
+	 size.  */
+      a->d.size = IOBUF_BUFFER_SIZE;
+    }
+  else if (a->use == IOBUF_INPUT_TEMP)
+    /* Same idea as above.  */
+    {
+      a->use = IOBUF_INPUT;
+      a->d.size = IOBUF_BUFFER_SIZE;
+    }
+
+  /* The new filter (A) gets a new buffer.
+
+     If the pipeline is an output or temp pipeline, then giving the
+     buffer to the new filter means that data that was written before
+     the filter was pushed gets sent to the filter.  That's clearly
+     wrong.
+
+     If the pipeline is an input pipeline, then giving the buffer to
+     the new filter (A) means that data that has read from (B), but
+     not yet read from the pipeline won't be processed by the new
+     filter (A)!  That's certainly not what we want.  */
+  a->d.buf = xmalloc (a->d.size);
+  a->d.len = 0;
+  a->d.start = 0;
+
+  /* disable nlimit for the new stream */
+  a->ntotal = b->ntotal + b->nbytes;
+  a->nlimit = a->nbytes = 0;
+  a->nofast = 0;
+  /* make a link from the new stream to the original stream */
+  a->chain = b;
+
+  /* setup the function on the new stream */
+  a->filter = f;
+  a->filter_ov = ov;
+  a->filter_ov_owner = rel_ov;
+
+  a->subno = b->subno + 1;
+
+  if (DBG_IOBUF)
+    {
+      byte desc[MAX_IOBUF_DESC];
+      log_debug ("iobuf-%d.%d: push '%s'\n",
+		 a->no, a->subno, iobuf_desc (a, desc));
+      print_chain (a);
+    }
+
+  /* now we can initialize the new function if we have one */
+  if (a->filter && (rc = a->filter (a->filter_ov, IOBUFCTRL_INIT, a->chain,
+				    NULL, &dummy_len)))
+    log_error ("IOBUFCTRL_INIT failed: %s\n", gpg_strerror (rc));
+  return rc;
+}
+
+/****************
+ * Remove an i/o filter.
+ */
+int
+iobuf_pop_filter (iobuf_t a, int (*f) (void *opaque, int control,
+                                       iobuf_t chain, byte * buf, size_t * len),
+                  void *ov)
+{
+  iobuf_t b;
+  size_t dummy_len = 0;
+  int rc = 0;
+  byte desc[MAX_IOBUF_DESC];
+
+  if (DBG_IOBUF)
+    log_debug ("iobuf-%d.%d: pop '%s'\n",
+	       a->no, a->subno, iobuf_desc (a, desc));
+  if (a->use == IOBUF_INPUT_TEMP || a->use == IOBUF_OUTPUT_TEMP)
+    {
+      /* This should be the last filter in the pipeline.  */
+      assert (! a->chain);
+      return 0;
+    }
+  if (!a->filter)
+    {				/* this is simple */
+      b = a->chain;
+      assert (b);
+      xfree (a->d.buf);
+      xfree (a->real_fname);
+      memcpy (a, b, sizeof *a);
+      xfree (b);
+      return 0;
+    }
+  for (b = a; b; b = b->chain)
+    if (b->filter == f && (!ov || b->filter_ov == ov))
+      break;
+  if (!b)
+    log_bug ("iobuf_pop_filter(): filter function not found\n");
+
+  /* flush this stream if it is an output stream */
+  if (a->use == IOBUF_OUTPUT && (rc = filter_flush (b)))
+    {
+      log_error ("filter_flush failed in iobuf_pop_filter: %s\n",
+                 gpg_strerror (rc));
+      return rc;
+    }
+  /* and tell the filter to free it self */
+  if (b->filter && (rc = b->filter (b->filter_ov, IOBUFCTRL_FREE, b->chain,
+				    NULL, &dummy_len)))
+    {
+      log_error ("IOBUFCTRL_FREE failed: %s\n", gpg_strerror (rc));
+      return rc;
+    }
+  if (b->filter_ov && b->filter_ov_owner)
+    {
+      xfree (b->filter_ov);
+      b->filter_ov = NULL;
+    }
+
+
+  /* and see how to remove it */
+  if (a == b && !b->chain)
+    log_bug ("can't remove the last filter from the chain\n");
+  else if (a == b)
+    {				/* remove the first iobuf from the chain */
+      /* everything from b is copied to a. This is save because
+       * a flush has been done on the to be removed entry
+       */
+      b = a->chain;
+      xfree (a->d.buf);
+      xfree (a->real_fname);
+      memcpy (a, b, sizeof *a);
+      xfree (b);
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: popped filter\n", a->no, a->subno);
+    }
+  else if (!b->chain)
+    {				/* remove the last iobuf from the chain */
+      log_bug ("Ohh jeee, trying to remove a head filter\n");
+    }
+  else
+    {				/* remove an intermediate iobuf from the chain */
+      log_bug ("Ohh jeee, trying to remove an intermediate filter\n");
+    }
+
+  return rc;
+}
+
+
+/****************
+ * read underflow: read at least one byte into the buffer and return
+ * the first byte or -1 on EOF.
+ */
+static int
+underflow (iobuf_t a, int clear_pending_eof)
+{
+  return underflow_target (a, clear_pending_eof, 1);
+}
+
+
+/****************
+ * read underflow: read TARGET bytes into the buffer and return
+ * the first byte or -1 on EOF.
+ */
+static int
+underflow_target (iobuf_t a, int clear_pending_eof, size_t target)
+{
+  size_t len;
+  int rc;
+
+  if (DBG_IOBUF)
+    log_debug ("iobuf-%d.%d: underflow: buffer size: %d; still buffered: %d => space for %d bytes\n",
+	       a->no, a->subno,
+	       (int) a->d.size, (int) (a->d.len - a->d.start),
+	       (int) (a->d.size - (a->d.len - a->d.start)));
+
+  if (a->use == IOBUF_INPUT_TEMP)
+    /* By definition, there isn't more data to read into the
+       buffer.  */
+    return -1;
+
+  assert (a->use == IOBUF_INPUT);
+
+  /* If there is still some buffered data, then move it to the start
+     of the buffer and try to fill the end of the buffer.  (This is
+     useful if we are called from iobuf_peek().)  */
+  assert (a->d.start <= a->d.len);
+  a->d.len -= a->d.start;
+  memmove (a->d.buf, &a->d.buf[a->d.start], a->d.len);
+  a->d.start = 0;
+
+  if (a->d.len < target && a->filter_eof)
+    /* The last time we tried to read from this filter, we got an EOF.
+       We couldn't return the EOF, because there was buffered data.
+       Since there is no longer any buffered data, return the
+       error.  */
+    {
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: underflow: eof (pending eof)\n",
+		   a->no, a->subno);
+      if (! clear_pending_eof)
+	return -1;
+
+      if (a->chain)
+	/* A filter follows this one.  Free this filter.  */
+	{
+	  iobuf_t b = a->chain;
+	  if (DBG_IOBUF)
+	    log_debug ("iobuf-%d.%d: filter popped (pending EOF returned)\n",
+		       a->no, a->subno);
+	  xfree (a->d.buf);
+	  xfree (a->real_fname);
+	  memcpy (a, b, sizeof *a);
+	  xfree (b);
+	  print_chain (a);
+	}
+      else
+	a->filter_eof = 0;	/* for the top level filter */
+      return -1;		/* return one(!) EOF */
+    }
+
+  if (a->d.len == 0 && a->error)
+    /* The last time we tried to read from this filter, we got an
+       error.  We couldn't return the error, because there was
+       buffered data.  Since there is no longer any buffered data,
+       return the error.  */
+    {
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: pending error (%s) returned\n",
+		   a->no, a->subno, gpg_strerror (a->error));
+      return -1;
+    }
+
+  if (a->filter && ! a->filter_eof && ! a->error)
+    /* We have a filter function and the last time we tried to read we
+       didn't get an EOF or an error.  Try to fill the buffer.  */
+    {
+      /* Be careful to account for any buffered data.  */
+      len = a->d.size - a->d.len;
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: underflow: A->FILTER (%lu bytes)\n",
+		   a->no, a->subno, (ulong) len);
+      if (len == 0)
+	/* There is no space for more data.  Don't bother calling
+	   A->FILTER.  */
+	rc = 0;
+      else
+	rc = a->filter (a->filter_ov, IOBUFCTRL_UNDERFLOW, a->chain,
+			&a->d.buf[a->d.len], &len);
+      a->d.len += len;
+
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: A->FILTER() returned rc=%d (%s), read %lu bytes\n",
+		   a->no, a->subno,
+		   rc, rc == 0 ? "ok" : rc == -1 ? "EOF" : gpg_strerror (rc),
+		   (ulong) len);
+/*  	    if( a->no == 1 ) */
+/*                   log_hexdump ("     data:", a->d.buf, len); */
+
+      if (rc == -1)
+	/* EOF.  */
+	{
+	  size_t dummy_len = 0;
+
+	  /* Tell the filter to free itself */
+	  if ((rc = a->filter (a->filter_ov, IOBUFCTRL_FREE, a->chain,
+			       NULL, &dummy_len)))
+	    log_error ("IOBUFCTRL_FREE failed: %s\n", gpg_strerror (rc));
+
+	  /* Free everything except for the internal buffer.  */
+	  if (a->filter_ov && a->filter_ov_owner)
+	    xfree (a->filter_ov);
+	  a->filter_ov = NULL;
+	  a->filter = NULL;
+	  a->filter_eof = 1;
+
+	  if (clear_pending_eof && a->d.len == 0 && a->chain)
+	    /* We don't need to keep this filter around at all:
+
+	         - we got an EOF
+		 - we have no buffered data
+		 - a filter follows this one.
+
+	      Unlink this filter.  */
+	    {
+	      iobuf_t b = a->chain;
+	      if (DBG_IOBUF)
+		log_debug ("iobuf-%d.%d: pop in underflow (nothing buffered, got EOF)\n",
+			   a->no, a->subno);
+	      xfree (a->d.buf);
+	      xfree (a->real_fname);
+	      memcpy (a, b, sizeof *a);
+	      xfree (b);
+
+	      print_chain (a);
+
+	      return -1;
+	    }
+	  else if (a->d.len == 0)
+	    /* We can't unlink this filter (it is the only one in the
+	       pipeline), but we can immediately return EOF.  */
+	    return -1;
+	}
+      else if (rc)
+	/* Record the error.  */
+	{
+	  a->error = rc;
+
+	  if (a->d.len == 0)
+	    /* There is no buffered data.  Immediately return EOF.  */
+	    return -1;
+	}
+    }
+
+  assert (a->d.start <= a->d.len);
+  if (a->d.start < a->d.len)
+    return a->d.buf[a->d.start++];
+
+  /* EOF.  */
+  return -1;
+}
+
+
+static int
+filter_flush (iobuf_t a)
+{
+  size_t len;
+  int rc;
+
+  if (a->use == IOBUF_OUTPUT_TEMP)
+    {				/* increase the temp buffer */
+      size_t newsize = a->d.size + IOBUF_BUFFER_SIZE;
+
+      if (DBG_IOBUF)
+	log_debug ("increasing temp iobuf from %lu to %lu\n",
+		   (ulong) a->d.size, (ulong) newsize);
+
+      a->d.buf = xrealloc (a->d.buf, newsize);
+      a->d.size = newsize;
+      return 0;
+    }
+  else if (a->use != IOBUF_OUTPUT)
+    log_bug ("flush on non-output iobuf\n");
+  else if (!a->filter)
+    log_bug ("filter_flush: no filter\n");
+  len = a->d.len;
+  rc = a->filter (a->filter_ov, IOBUFCTRL_FLUSH, a->chain, a->d.buf, &len);
+  if (!rc && len != a->d.len)
+    {
+      log_info ("filter_flush did not write all!\n");
+      rc = GPG_ERR_INTERNAL;
+    }
+  else if (rc)
+    a->error = rc;
+  a->d.len = 0;
+
+  return rc;
+}
+
+
+int
+iobuf_readbyte (iobuf_t a)
+{
+  int c;
+
+  if (a->use == IOBUF_OUTPUT || a->use == IOBUF_OUTPUT_TEMP)
+    {
+      log_bug ("iobuf_readbyte called on a non-INPUT pipeline!\n");
+      return -1;
+    }
+
+  assert (a->d.start <= a->d.len);
+
+  if (a->nlimit && a->nbytes >= a->nlimit)
+    return -1;			/* forced EOF */
+
+  if (a->d.start < a->d.len)
+    {
+      c = a->d.buf[a->d.start++];
+    }
+  else if ((c = underflow (a, 1)) == -1)
+    return -1;			/* EOF */
+
+  assert (a->d.start <= a->d.len);
+
+  /* Note: if underflow doesn't return EOF, then it returns the first
+     byte that was read and advances a->d.start appropriately.  */
+
+  a->nbytes++;
+  return c;
+}
+
+
+int
+iobuf_read (iobuf_t a, void *buffer, unsigned int buflen)
+{
+  unsigned char *buf = (unsigned char *)buffer;
+  int c, n;
+
+  if (a->use == IOBUF_OUTPUT || a->use == IOBUF_OUTPUT_TEMP)
+    {
+      log_bug ("iobuf_read called on a non-INPUT pipeline!\n");
+      return -1;
+    }
+
+  if (a->nlimit)
+    {
+      /* Handle special cases. */
+      for (n = 0; n < buflen; n++)
+	{
+	  if ((c = iobuf_readbyte (a)) == -1)
+	    {
+	      if (!n)
+		return -1;	/* eof */
+	      break;
+	    }
+
+	  if (buf)
+	    {
+	      *buf = c;
+	      buf++;
+	    }
+	}
+      return n;
+    }
+
+  n = 0;
+  do
+    {
+      if (n < buflen && a->d.start < a->d.len)
+	/* Drain the buffer.  */
+	{
+	  unsigned size = a->d.len - a->d.start;
+	  if (size > buflen - n)
+	    size = buflen - n;
+	  if (buf)
+	    memcpy (buf, a->d.buf + a->d.start, size);
+	  n += size;
+	  a->d.start += size;
+	  if (buf)
+	    buf += size;
+	}
+      if (n < buflen)
+	/* Draining the internal buffer didn't fill BUFFER.  Call
+	   underflow to read more data into the filter's internal
+	   buffer.  */
+	{
+	  if ((c = underflow (a, 1)) == -1)
+	    /* EOF.  If we managed to read something, don't return EOF
+	       now.  */
+	    {
+	      a->nbytes += n;
+	      return n ? n : -1 /*EOF*/;
+	    }
+	  if (buf)
+	    *buf++ = c;
+	  n++;
+	}
+    }
+  while (n < buflen);
+  a->nbytes += n;
+  return n;
+}
+
+
+
+int
+iobuf_peek (iobuf_t a, byte * buf, unsigned buflen)
+{
+  int n = 0;
+
+  assert (buflen > 0);
+  assert (a->use == IOBUF_INPUT || a->use == IOBUF_INPUT_TEMP);
+
+  if (buflen > a->d.size)
+    /* We can't peek more than we can buffer.  */
+    buflen = a->d.size;
+
+  /* Try to fill the internal buffer with enough data to satisfy the
+     request.  */
+  while (buflen > a->d.len - a->d.start)
+    {
+      if (underflow_target (a, 0, buflen) == -1)
+	/* EOF.  We can't read any more.  */
+	break;
+
+      /* Underflow consumes the first character (it's the return
+	 value).  unget() it by resetting the "file position".  */
+      assert (a->d.start == 1);
+      a->d.start = 0;
+    }
+
+  n = a->d.len - a->d.start;
+  if (n > buflen)
+    n = buflen;
+
+  if (n == 0)
+    /* EOF.  */
+    return -1;
+
+  memcpy (buf, &a->d.buf[a->d.start], n);
+
+  return n;
+}
+
+
+
+
+int
+iobuf_writebyte (iobuf_t a, unsigned int c)
+{
+  int rc;
+
+  if (a->use == IOBUF_INPUT || a->use == IOBUF_INPUT_TEMP)
+    {
+      log_bug ("iobuf_writebyte called on an input pipeline!\n");
+      return -1;
+    }
+
+  if (a->d.len == a->d.size)
+    if ((rc=filter_flush (a)))
+      return rc;
+
+  assert (a->d.len < a->d.size);
+  a->d.buf[a->d.len++] = c;
+  return 0;
+}
+
+
+int
+iobuf_write (iobuf_t a, const void *buffer, unsigned int buflen)
+{
+  const unsigned char *buf = (const unsigned char *)buffer;
+  int rc;
+
+  if (a->use == IOBUF_INPUT || a->use == IOBUF_INPUT_TEMP)
+    {
+      log_bug ("iobuf_write called on an input pipeline!\n");
+      return -1;
+    }
+
+  do
+    {
+      if (buflen && a->d.len < a->d.size)
+	{
+	  unsigned size = a->d.size - a->d.len;
+	  if (size > buflen)
+	    size = buflen;
+	  memcpy (a->d.buf + a->d.len, buf, size);
+	  buflen -= size;
+	  buf += size;
+	  a->d.len += size;
+	}
+      if (buflen)
+	{
+	  rc = filter_flush (a);
+          if (rc)
+	    return rc;
+	}
+    }
+  while (buflen);
+  return 0;
+}
+
+
+int
+iobuf_writestr (iobuf_t a, const char *buf)
+{
+  if (a->use == IOBUF_INPUT || a->use == IOBUF_INPUT_TEMP)
+    {
+      log_bug ("iobuf_writestr called on an input pipeline!\n");
+      return -1;
+    }
+
+  return iobuf_write (a, buf, strlen (buf));
+}
+
+
+
+int
+iobuf_write_temp (iobuf_t dest, iobuf_t source)
+{
+  assert (source->use == IOBUF_OUTPUT || source->use == IOBUF_OUTPUT_TEMP);
+  assert (dest->use == IOBUF_OUTPUT || dest->use == IOBUF_OUTPUT_TEMP);
+
+  iobuf_flush_temp (source);
+  return iobuf_write (dest, source->d.buf, source->d.len);
+}
+
+size_t
+iobuf_temp_to_buffer (iobuf_t a, byte * buffer, size_t buflen)
+{
+  byte desc[MAX_IOBUF_DESC];
+  size_t n;
+
+  while (1)
+    {
+      int rc = filter_flush (a);
+      if (rc)
+	log_bug ("Flushing iobuf %d.%d (%s) from iobuf_temp_to_buffer failed.  Ignoring.\n",
+		 a->no, a->subno, iobuf_desc (a, desc));
+      if (! a->chain)
+	break;
+      a = a->chain;
+    }
+
+  n = a->d.len;
+  if (n > buflen)
+    n = buflen;
+  memcpy (buffer, a->d.buf, n);
+  return n;
+}
+
+/* Copies the data from the input iobuf SOURCE to the output iobuf
+   DEST until either an error is encountered or EOF is reached.
+   Returns the number of bytes copies or (size_t)(-1) on error.  */
+size_t
+iobuf_copy (iobuf_t dest, iobuf_t source)
+{
+  char *temp;
+  /* Use a 32 KB buffer.  */
+  const size_t temp_size = 32 * 1024;
+
+  size_t nread;
+  size_t nwrote = 0;
+  size_t max_read = 0;
+  int err;
+
+  log_assert (source->use == IOBUF_INPUT || source->use == IOBUF_INPUT_TEMP);
+  log_assert (dest->use == IOBUF_OUTPUT || source->use == IOBUF_OUTPUT_TEMP);
+
+  if (iobuf_error (dest))
+    return (size_t)(-1);
+
+  temp = xmalloc (temp_size);
+  while (1)
+    {
+      nread = iobuf_read (source, temp, temp_size);
+      if (nread == -1)
+        /* EOF.  */
+        break;
+
+      if (nread > max_read)
+        max_read = nread;
+
+      err = iobuf_write (dest, temp, nread);
+      if (err)
+        break;
+      nwrote += nread;
+    }
+
+  /* Burn the buffer.  */
+  if (max_read)
+    wipememory (temp, max_read);
+  xfree (temp);
+
+  return nwrote;
+}
+
+
+void
+iobuf_flush_temp (iobuf_t temp)
+{
+  if (temp->use == IOBUF_INPUT || temp->use == IOBUF_INPUT_TEMP)
+    log_bug ("iobuf_flush_temp called on an input pipeline!\n");
+  while (temp->chain)
+    iobuf_pop_filter (temp, temp->filter, NULL);
+}
+
+
+void
+iobuf_set_limit (iobuf_t a, off_t nlimit)
+{
+  if (nlimit)
+    a->nofast = 1;
+  else
+    a->nofast = 0;
+  a->nlimit = nlimit;
+  a->ntotal += a->nbytes;
+  a->nbytes = 0;
+}
+
+
+
+off_t
+iobuf_get_filelength (iobuf_t a, int *overflow)
+{
+  if (overflow)
+    *overflow = 0;
+
+  /* Hmmm: file_filter may have already been removed */
+  for ( ; a->chain; a = a->chain )
+    ;
+
+  if (a->filter != file_filter)
+    return 0;
+
+  {
+    file_filter_ctx_t *b = a->filter_ov;
+    gnupg_fd_t fp = b->fp;
+
+#if defined(HAVE_W32_SYSTEM)
+    ulong size;
+    static int (* __stdcall get_file_size_ex) (void *handle,
+					       LARGE_INTEGER *r_size);
+    static int get_file_size_ex_initialized;
+
+    if (!get_file_size_ex_initialized)
+      {
+	void *handle;
+
+	handle = dlopen ("kernel32.dll", RTLD_LAZY);
+	if (handle)
+	  {
+	    get_file_size_ex = dlsym (handle, "GetFileSizeEx");
+	    if (!get_file_size_ex)
+	      dlclose (handle);
+	  }
+	get_file_size_ex_initialized = 1;
+      }
+
+    if (get_file_size_ex)
+      {
+	/* This is a newer system with GetFileSizeEx; we use this
+	   then because it seem that GetFileSize won't return a
+	   proper error in case a file is larger than 4GB. */
+	LARGE_INTEGER exsize;
+
+	if (get_file_size_ex (fp, &exsize))
+	  {
+	    if (!exsize.u.HighPart)
+	      return exsize.u.LowPart;
+	    if (overflow)
+	      *overflow = 1;
+	    return 0;
+	  }
+      }
+    else
+      {
+	if ((size=GetFileSize (fp, NULL)) != 0xffffffff)
+	  return size;
+      }
+    log_error ("GetFileSize for handle %p failed: %s\n",
+	       fp, w32_strerror (-1));
+#else /*!HAVE_W32_SYSTEM*/
+    {
+      struct stat st;
+
+      if ( !fstat (FD2INT (fp), &st) )
+        return st.st_size;
+      log_error("fstat() failed: %s\n", strerror(errno) );
+    }
+#endif /*!HAVE_W32_SYSTEM*/
+  }
+
+  return 0;
+}
+
+
+int
+iobuf_get_fd (iobuf_t a)
+{
+  for (; a->chain; a = a->chain)
+    ;
+
+  if (a->filter != file_filter)
+    return -1;
+
+  {
+    file_filter_ctx_t *b = a->filter_ov;
+    gnupg_fd_t fp = b->fp;
+
+    return FD2INT (fp);
+  }
+}
+
+
+off_t
+iobuf_tell (iobuf_t a)
+{
+  return a->ntotal + a->nbytes;
+}
+
+
+#if !defined(HAVE_FSEEKO) && !defined(fseeko)
+
+#ifdef HAVE_LIMITS_H
+# include <limits.h>
+#endif
+#ifndef LONG_MAX
+# define LONG_MAX ((long) ((unsigned long) -1 >> 1))
+#endif
+#ifndef LONG_MIN
+# define LONG_MIN (-1 - LONG_MAX)
+#endif
+
+/****************
+ * A substitute for fseeko, for hosts that don't have it.
+ */
+static int
+fseeko (FILE * stream, off_t newpos, int whence)
+{
+  while (newpos != (long) newpos)
+    {
+      long pos = newpos < 0 ? LONG_MIN : LONG_MAX;
+      if (fseek (stream, pos, whence) != 0)
+	return -1;
+      newpos -= pos;
+      whence = SEEK_CUR;
+    }
+  return fseek (stream, (long) newpos, whence);
+}
+#endif
+
+int
+iobuf_seek (iobuf_t a, off_t newpos)
+{
+  file_filter_ctx_t *b = NULL;
+
+  if (a->use == IOBUF_OUTPUT || a->use == IOBUF_INPUT)
+    {
+      /* Find the last filter in the pipeline.  */
+      for (; a->chain; a = a->chain)
+	;
+
+      if (a->filter != file_filter)
+	return -1;
+
+      b = a->filter_ov;
+
+#ifdef HAVE_W32_SYSTEM
+      if (SetFilePointer (b->fp, newpos, NULL, FILE_BEGIN) == 0xffffffff)
+	{
+	  log_error ("SetFilePointer failed on handle %p: ec=%d\n",
+		     b->fp, (int) GetLastError ());
+	  return -1;
+	}
+#else
+      if (lseek (b->fp, newpos, SEEK_SET) == (off_t) - 1)
+	{
+	  log_error ("can't lseek: %s\n", strerror (errno));
+	  return -1;
+	}
+#endif
+      /* Discard the buffer it is not a temp stream.  */
+      a->d.len = 0;
+    }
+  a->d.start = 0;
+  a->nbytes = 0;
+  a->nlimit = 0;
+  a->nofast = 0;
+  a->ntotal = newpos;
+  a->error = 0;
+
+  /* It is impossible for A->CHAIN to be non-NULL.  If A is an INPUT
+     or OUTPUT buffer, then we find the last filter, which is defined
+     as A->CHAIN being NULL.  If A is a TEMP filter, then A must be
+     the only filter in the pipe: when iobuf_push_filter adds a filter
+     to the front of a pipeline, it sets the new filter to be an
+     OUTPUT filter if the pipeline is an OUTPUT or TEMP pipeline and
+     to be an INPUT filter if the pipeline is an INPUT pipeline.
+     Thus, only the last filter in a TEMP pipeline can be a */
+
+  /* remove filters, but the last */
+  if (a->chain)
+    log_debug ("iobuf_pop_filter called in iobuf_seek - please report\n");
+  while (a->chain)
+    iobuf_pop_filter (a, a->filter, NULL);
+
+  return 0;
+}
+
+
+const char *
+iobuf_get_real_fname (iobuf_t a)
+{
+  if (a->real_fname)
+    return a->real_fname;
+
+  /* the old solution */
+  for (; a; a = a->chain)
+    if (!a->chain && a->filter == file_filter)
+      {
+	file_filter_ctx_t *b = a->filter_ov;
+	return b->print_only_name ? NULL : b->fname;
+      }
+
+  return NULL;
+}
+
+const char *
+iobuf_get_fname (iobuf_t a)
+{
+  for (; a; a = a->chain)
+    if (!a->chain && a->filter == file_filter)
+      {
+	file_filter_ctx_t *b = a->filter_ov;
+	return b->fname;
+      }
+  return NULL;
+}
+
+const char *
+iobuf_get_fname_nonnull (iobuf_t a)
+{
+  const char *fname;
+
+  fname = iobuf_get_fname (a);
+  return fname? fname : "[?]";
+}
+
+
+/****************
+ * Enable or disable partial body length mode (RFC 4880 4.2.2.4).
+ *
+ * If LEN is 0, this disables partial block mode by popping the
+ * partial body length filter, which must be the most recently
+ * added filter.
+ *
+ * If LEN is non-zero, it pushes a partial body length filter.  If
+ * this is a read filter, LEN must be the length byte from the first
+ * chunk and A should be position just after this first partial body
+ * length header.
+ */
+void
+iobuf_set_partial_body_length_mode (iobuf_t a, size_t len)
+{
+  if (!len)
+    /* Disable partial body length mode.  */
+    {
+      if (a->use == IOBUF_INPUT)
+	log_debug ("iobuf_pop_filter called in set_partial_block_mode"
+		   " - please report\n");
+
+      log_assert (a->filter == block_filter);
+      iobuf_pop_filter (a, block_filter, NULL);
+    }
+  else
+    /* Enabled partial body length mode.  */
+    {
+      block_filter_ctx_t *ctx = xcalloc (1, sizeof *ctx);
+      ctx->use = a->use;
+      ctx->partial = 1;
+      ctx->size = 0;
+      ctx->first_c = len;
+      iobuf_push_filter (a, block_filter, ctx);
+    }
+}
+
+
+
+unsigned int
+iobuf_read_line (iobuf_t a, byte ** addr_of_buffer,
+		 unsigned *length_of_buffer, unsigned *max_length)
+{
+  int c;
+  char *buffer = (char *)*addr_of_buffer;
+  unsigned length = *length_of_buffer;
+  unsigned nbytes = 0;
+  unsigned maxlen = *max_length;
+  char *p;
+
+  /* The code assumes that we have space for at least a newline and a
+     NUL character in the buffer.  This requires at least 2 bytes.  We
+     don't complicate the code by handling the stupid corner case, but
+     simply assert that it can't happen.  */
+  assert (!buffer || length >= 2 || maxlen >= 2);
+
+  if (!buffer || length <= 1)
+    /* must allocate a new buffer */
+    {
+      length = 256 <= maxlen ? 256 : maxlen;
+      buffer = xrealloc (buffer, length);
+      *addr_of_buffer = (unsigned char *)buffer;
+      *length_of_buffer = length;
+    }
+
+  p = buffer;
+  while ((c = iobuf_get (a)) != -1)
+    {
+      *p++ = c;
+      nbytes++;
+      if (c == '\n')
+	break;
+
+      if (nbytes == length - 1)
+	/* We don't have enough space to add a \n and a \0.  Increase
+	   the buffer size.  */
+	{
+	  if (length == maxlen)
+	    /* We reached the buffer's size limit!  */
+	    {
+	      /* Skip the rest of the line.  */
+	      while (c != '\n' && (c = iobuf_get (a)) != -1)
+		;
+
+	      /* p is pointing at the last byte in the buffer.  We
+		 always terminate the line with "\n\0" so overwrite
+		 the previous byte with a \n.  */
+	      assert (p > buffer);
+	      p[-1] = '\n';
+
+	      /* Indicate truncation.  */
+	      *max_length = 0;
+	      break;
+	    }
+
+	  length += length < 1024 ? 256 : 1024;
+	  if (length > maxlen)
+	    length = maxlen;
+
+	  buffer = xrealloc (buffer, length);
+	  *addr_of_buffer = (unsigned char *)buffer;
+	  *length_of_buffer = length;
+	  p = buffer + nbytes;
+	}
+    }
+  /* Add the terminating NUL.  */
+  *p = 0;
+
+  /* Return the number of characters written to the buffer including
+     the newline, but not including the terminating NUL.  */
+  return nbytes;
+}
+
+static int
+translate_file_handle (int fd, int for_write)
+{
+#if defined(HAVE_W32CE_SYSTEM)
+  /* This is called only with one of the special filenames.  Under
+     W32CE the FD here is not a file descriptor but a rendezvous id,
+     thus we need to finish the pipe first.  */
+  fd = _assuan_w32ce_finish_pipe (fd, for_write);
+#elif defined(HAVE_W32_SYSTEM)
+  {
+    int x;
+
+    (void)for_write;
+
+    if (fd == 0)
+      x = (int) GetStdHandle (STD_INPUT_HANDLE);
+    else if (fd == 1)
+      x = (int) GetStdHandle (STD_OUTPUT_HANDLE);
+    else if (fd == 2)
+      x = (int) GetStdHandle (STD_ERROR_HANDLE);
+    else
+      x = fd;
+
+    if (x == -1)
+      log_debug ("GetStdHandle(%d) failed: ec=%d\n",
+		 fd, (int) GetLastError ());
+
+    fd = x;
+  }
+#else
+  (void)for_write;
+#endif
+  return fd;
+}
+
+
+void
+iobuf_skip_rest (iobuf_t a, unsigned long n, int partial)
+{
+  if ( partial )
+    {
+      for (;;)
+        {
+          if (a->nofast || a->d.start >= a->d.len)
+            {
+              if (iobuf_readbyte (a) == -1)
+                {
+                  break;
+                }
+	    }
+          else
+            {
+              unsigned long count = a->d.len - a->d.start;
+              a->nbytes += count;
+              a->d.start = a->d.len;
+	    }
+	}
+    }
+  else
+    {
+      unsigned long remaining = n;
+      while (remaining > 0)
+        {
+          if (a->nofast || a->d.start >= a->d.len)
+            {
+              if (iobuf_readbyte (a) == -1)
+                {
+                  break;
+		}
+              --remaining;
+	    }
+          else
+            {
+              unsigned long count = a->d.len - a->d.start;
+              if (count > remaining)
+                {
+                  count = remaining;
+		}
+              a->nbytes += count;
+              a->d.start += count;
+              remaining -= count;
+	    }
+	}
+    }
+}