This commit was manufactured by cvs2svn to create branch

'GNUPG-1-9-BRANCH'.

1 files changed, 2415 insertions, 0 deletions

diff --git a/common/iobuf.c b/common/iobuf.c
new file mode 100644
index 000000000..773e2993b
--- /dev/null
+++ b/common/iobuf.c
@@ -0,0 +1,2415 @@
+/* iobuf.c  -  file handling
+ * Copyright (C) 1998, 1999, 2000, 2001, 2003 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#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_DOSISH_SYSTEM
+#include <windows.h>
+#endif
+#ifdef __riscos__
+#include <kernel.h>
+#include <swis.h>
+#endif /* __riscos__ */
+
+#include "memory.h"
+#include "util.h"
+#include "iobuf.h"
+
+#undef FILE_FILTER_USES_STDIO
+
+#ifdef HAVE_DOSISH_SYSTEM
+#define USE_SETMODE 1
+#endif
+
+#ifdef FILE_FILTER_USES_STDIO
+#define my_fileno(a)  fileno ((a))
+#define my_fopen_ro(a,b) fopen ((a),(b))
+#define my_fopen(a,b)    fopen ((a),(b))
+typedef FILE *FILEP_OR_FD;
+#define INVALID_FP    NULL
+#define FILEP_OR_FD_FOR_STDIN  (stdin)
+#define FILEP_OR_FD_FOR_STDOUT  (stdout)
+typedef struct
+{
+  FILE *fp;			/* open file handle */
+  int keep_open;
+  int no_cache;
+  int print_only_name;		/* flags indicating that fname is not a real file */
+  char fname[1];		/* name of the file */
+}
+file_filter_ctx_t;
+#else
+#define my_fileno(a)  (a)
+#define my_fopen_ro(a,b) fd_cache_open ((a),(b))
+#define my_fopen(a,b) direct_open ((a),(b))
+#ifdef HAVE_DOSISH_SYSTEM
+typedef HANDLE FILEP_OR_FD;
+#define INVALID_FP  ((HANDLE)-1)
+#define FILEP_OR_FD_FOR_STDIN  (GetStdHandle (STD_INPUT_HANDLE))
+#define FILEP_OR_FD_FOR_STDOUT (GetStdHandle (STD_OUTPUT_HANDLE))
+#undef USE_SETMODE
+#else
+typedef int FILEP_OR_FD;
+#define INVALID_FP  (-1)
+#define FILEP_OR_FD_FOR_STDIN  (0)
+#define FILEP_OR_FD_FOR_STDOUT (1)
+#endif
+typedef struct
+{
+  FILEP_OR_FD fp;		/* open file 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;
+
+struct close_cache_s
+{
+  struct close_cache_s *next;
+  FILEP_OR_FD fp;
+  char fname[1];
+};
+typedef struct close_cache_s *CLOSE_CACHE;
+static CLOSE_CACHE close_cache;
+#endif
+
+#ifdef __MINGW32__
+typedef struct
+{
+  int sock;
+  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 */
+}
+sock_filter_ctx_t;
+#endif /*__MINGW32__*/
+
+/* The first partial length header block must be of size 512
+ * to make it easier (and efficienter) 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
+
+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;			/* of partial header (which is > 0) */
+  int eof;
+}
+block_filter_ctx_t;
+
+static int special_names_enabled;
+
+static int underflow (iobuf_t a);
+static int translate_file_handle (int fd, int for_write);
+
+#ifndef FILE_FILTER_USES_STDIO
+
+/*
+ * Invalidate (i.e. close) a cached iobuf
+ */
+static void
+fd_cache_invalidate (const char *fname)
+{
+  CLOSE_CACHE cc;
+
+  assert (fname);
+  if (DBG_IOBUF)
+    log_debug ("fd_cache_invalidate (%s)\n", fname);
+
+  for (cc = close_cache; cc; cc = cc->next)
+    {
+      if (cc->fp != INVALID_FP && !strcmp (cc->fname, fname))
+	{
+	  if (DBG_IOBUF)
+	    log_debug ("                did (%s)\n", cc->fname);
+#ifdef HAVE_DOSISH_SYSTEM
+	  CloseHandle (cc->fp);
+#else
+	  close (cc->fp);
+#endif
+	  cc->fp = INVALID_FP;
+	}
+    }
+}
+
+
+
+static FILEP_OR_FD
+direct_open (const char *fname, const char *mode)
+{
+#ifdef HAVE_DOSISH_SYSTEM
+  unsigned long da, cd, sm;
+  HANDLE hfile;
+
+  /* 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 share mode which is
+   * something new for MS applications ;-)
+   */
+  if (strchr (mode, '+'))
+    {
+      fd_cache_invalidate (fname);
+      da = GENERIC_READ | GENERIC_WRITE;
+      cd = OPEN_EXISTING;
+      sm = FILE_SHARE_READ | FILE_SHARE_WRITE;
+    }
+  else if (strchr (mode, 'w'))
+    {
+      fd_cache_invalidate (fname);
+      da = GENERIC_WRITE;
+      cd = CREATE_ALWAYS;
+      sm = FILE_SHARE_WRITE;
+    }
+  else
+    {
+      da = GENERIC_READ;
+      cd = OPEN_EXISTING;
+      sm = FILE_SHARE_READ;
+    }
+
+  hfile = CreateFile (fname, da, sm, NULL, cd, FILE_ATTRIBUTE_NORMAL, NULL);
+  return hfile;
+#else
+  int oflag;
+  int cflag = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
+
+  /* Note, that we do not handle all mode combinations */
+  if (strchr (mode, '+'))
+    {
+      fd_cache_invalidate (fname);
+      oflag = O_RDWR;
+    }
+  else if (strchr (mode, 'w'))
+    {
+      fd_cache_invalidate (fname);
+      oflag = O_WRONLY | O_CREAT | O_TRUNC;
+    }
+  else
+    {
+      oflag = O_RDONLY;
+    }
+#ifdef O_BINARY
+  if (strchr (mode, 'b'))
+    oflag |= O_BINARY;
+#endif
+#ifndef __riscos__
+  return open (fname, oflag, cflag);
+#else
+  {
+    struct stat buf;
+    int rc = stat (fname, &buf);
+
+    /* Don't allow iobufs on directories */
+    if (!rc && S_ISDIR (buf.st_mode) && !S_ISREG (buf.st_mode))
+      return __set_errno (EISDIR);
+    else
+      return open (fname, oflag, cflag);
+  }
+#endif
+#endif
+}
+
+
+/*
+ * 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, FILEP_OR_FD fp)
+{
+  CLOSE_CACHE cc;
+
+  assert (fp);
+  if (!fname || !*fname)
+    {
+#ifdef HAVE_DOSISH_SYSTEM
+      CloseHandle (fp);
+#else
+      close (fp);
+#endif
+      if (DBG_IOBUF)
+	log_debug ("fd_cache_close (%p) real\n", (void *) fp);
+      return;
+    }
+  /* try to reuse a slot */
+  for (cc = close_cache; cc; cc = cc->next)
+    {
+      if (cc->fp == INVALID_FP && !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 an direct_open on FNAME but first try to reuse one from the fd_cache
+ */
+static FILEP_OR_FD
+fd_cache_open (const char *fname, const char *mode)
+{
+  CLOSE_CACHE cc;
+
+  assert (fname);
+  for (cc = close_cache; cc; cc = cc->next)
+    {
+      if (cc->fp != INVALID_FP && !strcmp (cc->fname, fname))
+	{
+	  FILEP_OR_FD fp = cc->fp;
+	  cc->fp = INVALID_FP;
+	  if (DBG_IOBUF)
+	    log_debug ("fd_cache_open (%s) using cached fp\n", fname);
+#ifdef HAVE_DOSISH_SYSTEM
+	  if (SetFilePointer (fp, 0, NULL, FILE_BEGIN) == 0xffffffff)
+	    {
+	      log_error ("rewind file failed on handle %p: ec=%d\n",
+			 fp, (int) GetLastError ());
+	      fp = INVALID_FP;
+	    }
+#else
+	  if (lseek (fp, 0, SEEK_SET) == (off_t) - 1)
+	    {
+	      log_error ("can't rewind fd %d: %s\n", fp, strerror (errno));
+	      fp = INVALID_FP;
+	    }
+#endif
+	  return fp;
+	}
+    }
+  if (DBG_IOBUF)
+    log_debug ("fd_cache_open (%s) not cached\n", fname);
+  return direct_open (fname, mode);
+}
+
+
+#endif /*FILE_FILTER_USES_STDIO */
+
+
+/****************
+ * Read data from a file into buf which has an allocated length of *LEN.
+ * return the number of read bytes in *LEN. OPAQUE is the FILE * of
+ * the stream. A is not used.
+ * control may be:
+ * IOBUFCTRL_INIT: called just before the function is linked into the
+ *		   list of function. This can be used to prepare internal
+ *		   data structures of the function.
+ * IOBUFCTRL_FREE: called just before the function is removed from the
+ *		    list of functions and can be used to release internal
+ *		    data structures or close a file etc.
+ * IOBUFCTRL_UNDERFLOW: called by iobuf_underflow to fill the buffer
+ *		    with new stuff. *RET_LEN is the available size of the
+ *		    buffer, and should be set to the number of bytes
+ *		    which were put into the buffer. The function
+ *		    returns 0 to indicate success, -1 on EOF and
+ *		    GPG_ERR_xxxxx for other errors.
+ *
+ * IOBUFCTRL_FLUSH: called by iobuf_flush() to write out the collected stuff.
+ *		    *RET_LAN is the number of bytes in BUF.
+ *
+ * IOBUFCTRL_CANCEL: send to all filters on behalf of iobuf_cancel.  The
+ *		    filter may take appropriate action on this message.
+ */
+static int
+file_filter (void *opaque, int control, iobuf_t chain, byte * buf,
+	     size_t * ret_len)
+{
+  file_filter_ctx_t *a = opaque;
+  FILEP_OR_FD f = a->fp;
+  size_t size = *ret_len;
+  size_t nbytes = 0;
+  int rc = 0;
+
+#ifdef FILE_FILTER_USES_STDIO
+  if (control == IOBUFCTRL_UNDERFLOW)
+    {
+      assert (size);		/* need a buffer */
+      if (feof (f))
+	{			/* On terminals you could easiely read as many EOFs as you call         */
+	  rc = -1;		/* fread() or fgetc() repeatly. Every call will block until you press   */
+	  *ret_len = 0;		/* CTRL-D. So we catch this case before we call fread() again.          */
+	}
+      else
+	{
+	  clearerr (f);
+	  nbytes = fread (buf, 1, size, f);
+	  if (feof (f) && !nbytes)
+	    {
+	      rc = -1;		/* okay: we can return EOF now. */
+	    }
+	  else if (ferror (f) && errno != EPIPE)
+	    {
+	      rc = gpg_error_from_errno (errno);
+	      log_error ("%s: read error: %s\n", a->fname, strerror (errno));
+	    }
+	  *ret_len = nbytes;
+	}
+    }
+  else if (control == IOBUFCTRL_FLUSH)
+    {
+      if (size)
+	{
+	  clearerr (f);
+	  nbytes = fwrite (buf, 1, size, f);
+	  if (ferror (f))
+	    {
+	      rc = gpg_error_from_errno (errno);
+	      log_error ("%s: write error: %s\n", a->fname, strerror (errno));
+	    }
+	}
+      *ret_len = nbytes;
+    }
+  else if (control == IOBUFCTRL_INIT)
+    {
+      a->keep_open = a->no_cache = 0;
+    }
+  else if (control == IOBUFCTRL_DESC)
+    {
+      *(char **) buf = "file_filter";
+    }
+  else if (control == IOBUFCTRL_FREE)
+    {
+      if (f != stdin && f != stdout)
+	{
+	  if (DBG_IOBUF)
+	    log_debug ("%s: close fd %d\n", a->fname, fileno (f));
+	  if (!a->keep_open)
+	    fclose (f);
+	}
+      f = NULL;
+      xfree (a);		/* we can free our context now */
+    }
+#else /* !stdio implementation */
+
+  if (control == IOBUFCTRL_UNDERFLOW)
+    {
+      assert (size);		/* need a buffer */
+      if (a->eof_seen)
+	{
+	  rc = -1;
+	  *ret_len = 0;
+	}
+      else
+	{
+#ifdef HAVE_DOSISH_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_errno (errno);
+		  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_DOSISH_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_errno (errno);
+	      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)
+    {
+      *(char **) buf = "file_filter(fd)";
+    }
+  else if (control == IOBUFCTRL_FREE)
+    {
+#ifdef HAVE_DOSISH_SYSTEM
+      if (f != FILEP_OR_FD_FOR_STDIN && f != FILEP_OR_FD_FOR_STDOUT)
+	{
+	  if (DBG_IOBUF)
+	    log_debug ("%s: close handle %p\n", a->fname, f);
+	  if (!a->keep_open)
+	    fd_cache_close (a->no_cache ? NULL : a->fname, f);
+	}
+#else
+      if ((int) f != 0 && (int) f != 1)
+	{
+	  if (DBG_IOBUF)
+	    log_debug ("%s: close fd %d\n", a->fname, f);
+	  if (!a->keep_open)
+	    fd_cache_close (a->no_cache ? NULL : a->fname, f);
+	}
+      f = INVALID_FP;
+#endif
+      xfree (a);		/* we can free our context now */
+    }
+#endif /* !stdio implementation */
+  return rc;
+}
+
+#ifdef __MINGW32__
+/* Becuase sockets are an special object under Lose32 we have to
+ * use a special filter */
+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;
+
+  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)
+    {
+      *(char **) buf = "sock_filter";
+    }
+  else if (control == IOBUFCTRL_FREE)
+    {
+      if (!a->keep_open)
+	closesocket (a->sock);
+      xfree (a);		/* we can free our context now */
+    }
+  return rc;
+}
+#endif /*__MINGW32__*/
+
+/****************
+ * 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 * buf,
+	      size_t * ret_len)
+{
+  block_filter_ctx_t *a = opaque;
+  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 (chain) << 24;
+		      a->size |= iobuf_get (chain) << 16;
+		      a->size |= iobuf_get (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;
+		    }
+		  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
+		{		/* the gnupg partial length scheme - much better :-) */
+		  c = iobuf_get (chain);
+		  a->size = c << 8;
+		  c = iobuf_get (chain);
+		  a->size |= c;
+		  if (c == -1)
+		    {
+		      log_error ("block_filter: error reading length info\n");
+		      rc = GPG_ERR_BAD_DATA;
+		    }
+		  if (!a->size)
+		    {
+		      a->eof = 1;
+		      if (!n)
+			rc = -1;
+		      break;
+		    }
+		}
+	    }
+
+	  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_errno (errno);
+		      a->buflen = 0;
+		      nbytes -= n;
+		    }
+		  if ((n = nbytes) > blen)
+		    n = blen;
+		  if (n && iobuf_write (chain, p, n))
+		    rc = gpg_error_from_errno (errno);
+		  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
+	{			/* the gnupg scheme (which is not openpgp compliant) */
+	  size_t avail, n;
+
+	  for (p = buf; !rc && size;)
+	    {
+	      n = size;
+	      avail = a->size - a->count;
+	      if (!avail)
+		{
+		  if (n > a->size)
+		    {
+		      iobuf_put (chain, (a->size >> 8) & 0xff);
+		      iobuf_put (chain, a->size & 0xff);
+		      avail = a->size;
+		      a->count = 0;
+		    }
+		  else
+		    {
+		      iobuf_put (chain, (n >> 8) & 0xff);
+		      iobuf_put (chain, n & 0xff);
+		      avail = n;
+		      a->count = a->size - n;
+		    }
+		}
+	      if (n > avail)
+		n = avail;
+	      if (iobuf_write (chain, p, n))
+		rc = gpg_error_from_errno (errno);
+	      a->count += n;
+	      p += n;
+	      size -= n;
+	    }
+	}
+    }
+  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 == 1)
+	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)
+    {
+      *(char **) buf = "block_filter";
+    }
+  else if (control == IOBUFCTRL_FREE)
+    {
+      if (a->use == 2)
+	{			/* 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_errno (errno);
+		}
+	      xfree (a->buffer);
+	      a->buffer = NULL;
+	      a->buflen = 0;
+	    }
+	  else
+	    {
+	      iobuf_writebyte (chain, 0);
+	      iobuf_writebyte (chain, 0);
+	    }
+	}
+      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;
+}
+
+
+static void
+print_chain (iobuf_t a)
+{
+  if (!DBG_IOBUF)
+    return;
+  for (; a; a = a->chain)
+    {
+      size_t dummy_len = 0;
+      const char *desc = "[none]";
+
+      if (a->filter)
+	a->filter (a->filter_ov, IOBUFCTRL_DESC, NULL,
+		   (byte *) & desc, &dummy_len);
+
+      log_debug ("iobuf chain: %d.%d `%s' filter_eof=%d start=%d len=%d\n",
+		 a->no, a->subno, desc, a->filter_eof,
+		 (int) a->d.start, (int) a->d.len);
+    }
+}
+
+int
+iobuf_print_chain (iobuf_t a)
+{
+  print_chain (a);
+  return 0;
+}
+
+/****************
+ * Allocate a new io buffer, with no function assigned.
+ * Use is the desired usage: 1 for input, 2 for output, 3 for temp buffer
+ * BUFSIZE is a suggested buffer size.
+ */
+iobuf_t
+iobuf_alloc (int use, size_t bufsize)
+{
+  iobuf_t a;
+  static int number = 0;
+
+  a = xcalloc (1, sizeof *a);
+  a->use = use;
+  a->d.buf = xmalloc (bufsize);
+  a->d.size = bufsize;
+  a->no = ++number;
+  a->subno = 0;
+  a->opaque = NULL;
+  a->real_fname = NULL;
+  return a;
+}
+
+int
+iobuf_close (iobuf_t a)
+{
+  iobuf_t a2;
+  size_t dummy_len = 0;
+  int rc = 0;
+
+  if (a && a->directfp)
+    {
+      fclose (a->directfp);
+      xfree (a->real_fname);
+      if (DBG_IOBUF)
+	log_debug ("iobuf_close -> %p\n", a->directfp);
+      return 0;
+    }
+
+  for (; a && !rc; a = a2)
+    {
+      a2 = a->chain;
+      if (a->use == 2 && (rc = iobuf_flush (a)))
+	log_error ("iobuf_flush failed on close: %s\n", gpg_strerror (rc));
+
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: close `%s'\n", a->no, a->subno, a->desc);
+      if (a->filter && (rc = a->filter (a->filter_ov, IOBUFCTRL_FREE,
+					a->chain, NULL, &dummy_len)))
+	log_error ("IOBUFCTRL_FREE failed on close: %s\n", gpg_strerror (rc));
+      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_DOSISH_SYSTEM) || defined(__riscos__)
+  char *remove_name = NULL;
+#endif
+
+  if (a && a->use == 2)
+    {
+      s = iobuf_get_real_fname (a);
+      if (s && *s)
+	{
+#if defined(HAVE_DOSISH_SYSTEM) || defined(__riscos__)
+	  remove_name = m_strdup (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_DOSISH_SYSTEM) || defined(__riscos__)
+  if (remove_name)
+    {
+      /* Argg, MSDOS does not allow to remove open files.  So
+       * we have to do it here */
+      remove (remove_name);
+      xfree (remove_name);
+    }
+#endif
+  return rc;
+}
+
+
+/****************
+ * create a temporary iobuf, which can be used to collect stuff
+ * in an iobuf and later be written by iobuf_write_temp() to another
+ * iobuf.
+ */
+iobuf_t
+iobuf_temp ()
+{
+  iobuf_t a;
+
+  a = iobuf_alloc (3, 8192);
+
+  return a;
+}
+
+iobuf_t
+iobuf_temp_with_content (const char *buffer, size_t length)
+{
+  iobuf_t a;
+
+  a = iobuf_alloc (3, length);
+  memcpy (a->d.buf, buffer, length);
+  a->d.len = length;
+
+  return a;
+}
+
+void
+iobuf_enable_special_filenames (int yes)
+{
+  special_names_enabled = yes;
+}
+
+/*
+ * see whether the filename has the for "-&nnnn", where n is a
+ * non-zero number.
+ * Returns this number or -1 if it is not the case.
+ */
+static int
+check_special_filename (const char *fname)
+{
+  if (special_names_enabled && fname && *fname == '-' && fname[1] == '&')
+    {
+      int i;
+
+      fname += 2;
+      for (i = 0; isdigit (fname[i]); i++)
+	;
+      if (!fname[i])
+	return atoi (fname);
+    }
+  return -1;
+}
+
+/****************
+ * Create a head iobuf for reading from a file
+ * returns: NULL if an error occures and sets errno
+ */
+iobuf_t
+iobuf_open (const char *fname)
+{
+  iobuf_t a;
+  FILEP_OR_FD fp;
+  file_filter_ctx_t *fcx;
+  size_t len;
+  int print_only = 0;
+  int fd;
+
+  if (!fname || (*fname == '-' && !fname[1]))
+    {
+      fp = FILEP_OR_FD_FOR_STDIN;
+#ifdef USE_SETMODE
+      setmode (my_fileno (fp), O_BINARY);
+#endif
+      fname = "[stdin]";
+      print_only = 1;
+    }
+  else if ((fd = check_special_filename (fname)) != -1)
+    return iobuf_fdopen (translate_file_handle (fd, 0), "rb");
+  else if ((fp = my_fopen_ro (fname, "rb")) == INVALID_FP)
+    return NULL;
+  a = iobuf_alloc (1, 8192);
+  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_DESC, NULL, (byte *) & a->desc, &len);
+  file_filter (fcx, IOBUFCTRL_INIT, NULL, NULL, &len);
+  if (DBG_IOBUF)
+    log_debug ("iobuf-%d.%d: open `%s' fd=%d\n",
+	       a->no, a->subno, fname, (int) my_fileno (fcx->fp));
+
+  return a;
+}
+
+/****************
+ * Create a head iobuf for reading from a file
+ * returns: NULL if an error occures and sets errno
+ */
+iobuf_t
+iobuf_fdopen (int fd, const char *mode)
+{
+  iobuf_t a;
+  FILEP_OR_FD fp;
+  file_filter_ctx_t *fcx;
+  size_t len;
+
+#ifdef FILE_FILTER_USES_STDIO
+  if (!(fp = fdopen (fd, mode)))
+    return NULL;
+#else
+  fp = (FILEP_OR_FD) fd;
+#endif
+  a = iobuf_alloc (strchr (mode, 'w') ? 2 : 1, 8192);
+  fcx = xmalloc (sizeof *fcx + 20);
+  fcx->fp = fp;
+  fcx->print_only_name = 1;
+  sprintf (fcx->fname, "[fd %d]", fd);
+  a->filter = file_filter;
+  a->filter_ov = fcx;
+  file_filter (fcx, IOBUFCTRL_DESC, NULL, (byte *) & a->desc, &len);
+  file_filter (fcx, IOBUFCTRL_INIT, NULL, NULL, &len);
+  if (DBG_IOBUF)
+    log_debug ("iobuf-%d.%d: fdopen `%s'\n", a->no, a->subno, fcx->fname);
+  iobuf_ioctl (a, 3, 1, NULL);	/* disable fd caching */
+  return a;
+}
+
+
+iobuf_t
+iobuf_sockopen (int fd, const char *mode)
+{
+  iobuf_t a;
+#ifdef __MINGW32__
+  sock_filter_ctx_t *scx;
+  size_t len;
+
+  a = iobuf_alloc (strchr (mode, 'w') ? 2 : 1, 8192);
+  scx = m_alloc (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_DESC, NULL, (byte *) & a->desc, &len);
+  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, 3, 1, NULL);	/* disable fd caching */
+#else
+  a = iobuf_fdopen (fd, mode);
+#endif
+  return a;
+}
+
+/****************
+ * create an iobuf for writing to a file; the file will be created.
+ */
+iobuf_t
+iobuf_create (const char *fname)
+{
+  iobuf_t a;
+  FILEP_OR_FD fp;
+  file_filter_ctx_t *fcx;
+  size_t len;
+  int print_only = 0;
+  int fd;
+
+  if (!fname || (*fname == '-' && !fname[1]))
+    {
+      fp = FILEP_OR_FD_FOR_STDOUT;
+#ifdef USE_SETMODE
+      setmode (my_fileno (fp), O_BINARY);
+#endif
+      fname = "[stdout]";
+      print_only = 1;
+    }
+  else if ((fd = check_special_filename (fname)) != -1)
+    return iobuf_fdopen (translate_file_handle (fd, 1), "wb");
+  else if ((fp = my_fopen (fname, "wb")) == INVALID_FP)
+    return NULL;
+  a = iobuf_alloc (2, 8192);
+  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_DESC, NULL, (byte *) & a->desc, &len);
+  file_filter (fcx, IOBUFCTRL_INIT, NULL, NULL, &len);
+  if (DBG_IOBUF)
+    log_debug ("iobuf-%d.%d: create `%s'\n", a->no, a->subno, a->desc);
+
+  return a;
+}
+
+/****************
+ * append to an iobuf; if the file does not exist, create it.
+ * cannot be used for stdout.
+ * Note: This is not used.
+ */
+#if 0				/* not used */
+iobuf_t
+iobuf_append (const char *fname)
+{
+  iobuf_t a;
+  FILE *fp;
+  file_filter_ctx_t *fcx;
+  size_t len;
+
+  if (!fname)
+    return NULL;
+  else if (!(fp = my_fopen (fname, "ab")))
+    return NULL;
+  a = iobuf_alloc (2, 8192);
+  fcx = m_alloc (sizeof *fcx + strlen (fname));
+  fcx->fp = fp;
+  strcpy (fcx->fname, fname);
+  a->real_fname = m_strdup (fname);
+  a->filter = file_filter;
+  a->filter_ov = fcx;
+  file_filter (fcx, IOBUFCTRL_DESC, NULL, (byte *) & a->desc, &len);
+  file_filter (fcx, IOBUFCTRL_INIT, NULL, NULL, &len);
+  if (DBG_IOBUF)
+    log_debug ("iobuf-%d.%d: append `%s'\n", a->no, a->subno, a->desc);
+
+  return a;
+}
+#endif
+
+iobuf_t
+iobuf_openrw (const char *fname)
+{
+  iobuf_t a;
+  FILEP_OR_FD fp;
+  file_filter_ctx_t *fcx;
+  size_t len;
+
+  if (!fname)
+    return NULL;
+  else if ((fp = my_fopen (fname, "r+b")) == INVALID_FP)
+    return NULL;
+  a = iobuf_alloc (2, 8192);
+  fcx = xmalloc (sizeof *fcx + strlen (fname));
+  fcx->fp = fp;
+  strcpy (fcx->fname, fname);
+  a->real_fname = xstrdup (fname);
+  a->filter = file_filter;
+  a->filter_ov = fcx;
+  file_filter (fcx, IOBUFCTRL_DESC, NULL, (byte *) & a->desc, &len);
+  file_filter (fcx, IOBUFCTRL_INIT, NULL, NULL, &len);
+  if (DBG_IOBUF)
+    log_debug ("iobuf-%d.%d: openrw `%s'\n", a->no, a->subno, a->desc);
+
+  return a;
+}
+
+
+int
+iobuf_ioctl (iobuf_t a, int cmd, int intval, void *ptrval)
+{
+  if (cmd == 1)
+    {				/* keep system filepointer/descriptor open */
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: ioctl `%s' keep=%d\n",
+		   a ? a->no : -1, a ? a->subno : -1, a ? 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 __MINGW32__
+	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 == 2)
+    {				/* invalidate cache */
+      if (DBG_IOBUF)
+	log_debug ("iobuf-*.*: ioctl `%s' invalidate\n",
+		   ptrval ? (char *) ptrval : "?");
+      if (!a && !intval && ptrval)
+	{
+#ifndef FILE_FILTER_USES_STDIO
+	  fd_cache_invalidate (ptrval);
+#endif
+	  return 0;
+	}
+    }
+  else if (cmd == 3)
+    {				/* disallow/allow caching */
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: ioctl `%s' no_cache=%d\n",
+		   a ? a->no : -1, a ? a->subno : -1, a ? 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 __MINGW32__
+	else if (!a->chain && a->filter == sock_filter)
+	  {
+	    sock_filter_ctx_t *b = a->filter_ov;
+	    b->no_cache = intval;
+	    return 0;
+	  }
+#endif
+    }
+
+  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->directfp)
+    BUG ();
+
+  if (a->use == 2 && (rc = iobuf_flush (a)))
+    return rc;
+  /* make a copy of the current stream, so that
+   * A is the new stream and B the original one.
+   * The contents of the buffers are transferred to the
+   * new stream.
+   */
+  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 == 3)
+    a->use = 2;			/* make a write stream from a temp stream */
+
+  if (a->use == 2)
+    {				/* allocate a fresh buffer for the
+                                   original stream */
+      b->d.buf = xmalloc (a->d.size);
+      b->d.len = 0;
+      b->d.start = 0;
+    }
+  else
+    {				/* allocate a fresh buffer for the new
+                                   stream */
+      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 &= ~1;
+  /* make a link from the new stream to the original stream */
+  a->chain = b;
+  a->opaque = b->opaque;
+
+  /* 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;
+  f (ov, IOBUFCTRL_DESC, NULL, (byte *) & a->desc, &dummy_len);
+
+  if (DBG_IOBUF)
+    {
+      log_debug ("iobuf-%d.%d: push `%s'\n", a->no, a->subno, 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
+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;
+
+  if (a->directfp)
+    BUG ();
+
+  if (DBG_IOBUF)
+    log_debug ("iobuf-%d.%d: pop `%s'\n", a->no, a->subno, a->desc);
+  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 ("pop_filter(): filter function not found\n");
+
+  /* flush this stream if it is an output stream */
+  if (a->use == 2 && (rc = iobuf_flush (b)))
+    {
+      log_error ("iobuf_flush failed in 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 more bytes into the buffer and return
+ * the first byte or -1 on EOF.
+ */
+static int
+underflow (iobuf_t a)
+{
+  size_t len;
+  int rc;
+
+  assert (a->d.start == a->d.len);
+  if (a->use == 3)
+    return -1;			/* EOF because a temp buffer can't do an underflow */
+
+  if (a->filter_eof)
+    {
+      if (a->chain)
+	{
+	  iobuf_t b = a->chain;
+	  if (DBG_IOBUF)
+	    log_debug ("iobuf-%d.%d: pop `%s' in underflow\n",
+		       a->no, a->subno, a->desc);
+	  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 */
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: underflow: eof (due to filter eof)\n",
+		   a->no, a->subno);
+      return -1;		/* return one(!) EOF */
+    }
+  if (a->error)
+    {
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: error\n", a->no, a->subno);
+      return -1;
+    }
+
+  if (a->directfp)
+    {
+      FILE *fp = a->directfp;
+
+      len = fread (a->d.buf, 1, a->d.size, fp);
+      if (len < a->d.size)
+	{
+	  if (ferror (fp))
+	    a->error = gpg_error_from_errno (errno);
+	}
+      a->d.len = len;
+      a->d.start = 0;
+      return len ? a->d.buf[a->d.start++] : -1;
+    }
+
+
+  if (a->filter)
+    {
+      len = a->d.size;
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: underflow: req=%lu\n",
+		   a->no, a->subno, (ulong) len);
+      rc = a->filter (a->filter_ov, IOBUFCTRL_UNDERFLOW, a->chain,
+		      a->d.buf, &len);
+      if (DBG_IOBUF)
+	{
+	  log_debug ("iobuf-%d.%d: underflow: got=%lu rc=%d\n",
+		     a->no, a->subno, (ulong) len, rc);
+/*  	    if( a->no == 1 ) */
+/*                   log_hexdump ("     data:", a->d.buf, len); */
+	}
+      if (a->use == 1 && rc == -1)
+	{			/* EOF: we can remove the filter */
+	  size_t dummy_len = 0;
+
+	  /* and 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));
+	  if (a->filter_ov && a->filter_ov_owner)
+	    {
+	      xfree (a->filter_ov);
+	      a->filter_ov = NULL;
+	    }
+	  a->filter = NULL;
+	  a->desc = NULL;
+	  a->filter_ov = NULL;
+	  a->filter_eof = 1;
+	  if (!len && a->chain)
+	    {
+	      iobuf_t b = a->chain;
+	      if (DBG_IOBUF)
+		log_debug ("iobuf-%d.%d: pop `%s' in underflow (!len)\n",
+			   a->no, a->subno, a->desc);
+	      xfree (a->d.buf);
+	      xfree (a->real_fname);
+	      memcpy (a, b, sizeof *a);
+	      xfree (b);
+	      print_chain (a);
+	    }
+	}
+      else if (rc)
+	a->error = rc;
+
+      if (!len)
+	{
+	  if (DBG_IOBUF)
+	    log_debug ("iobuf-%d.%d: underflow: eof\n", a->no, a->subno);
+	  return -1;
+	}
+      a->d.len = len;
+      a->d.start = 0;
+      return a->d.buf[a->d.start++];
+    }
+  else
+    {
+      if (DBG_IOBUF)
+	log_debug ("iobuf-%d.%d: underflow: eof (no filter)\n",
+		   a->no, a->subno);
+      return -1;		/* no filter; return EOF */
+    }
+}
+
+
+int
+iobuf_flush (iobuf_t a)
+{
+  size_t len;
+  int rc;
+
+  if (a->directfp)
+    return 0;
+
+  if (a->use == 3)
+    {				/* increase the temp buffer */
+      char *newbuf;
+      size_t newsize = a->d.size + 8192;
+
+      if (DBG_IOBUF)
+	log_debug ("increasing temp iobuf from %lu to %lu\n",
+		   (ulong) a->d.size, (ulong) newsize);
+      newbuf = xmalloc (newsize);
+      memcpy (newbuf, a->d.buf, a->d.len);
+      xfree (a->d.buf);
+      a->d.buf = newbuf;
+      a->d.size = newsize;
+      return 0;
+    }
+  else if (a->use != 2)
+    log_bug ("flush on non-output iobuf\n");
+  else if (!a->filter)
+    log_bug ("iobuf_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 ("iobuf_flush did not write all!\n");
+      rc = GPG_ERR_INTERNAL;
+    }
+  else if (rc)
+    a->error = rc;
+  a->d.len = 0;
+
+  return rc;
+}
+
+
+/****************
+ * Read a byte from the iobuf; returns -1 on EOF
+ */
+int
+iobuf_readbyte (iobuf_t a)
+{
+  int c;
+
+  /* nlimit does not work together with unget */
+  /* nbytes is also not valid! */
+  if (a->unget.buf)
+    {
+      if (a->unget.start < a->unget.len)
+	return a->unget.buf[a->unget.start++];
+      xfree (a->unget.buf);
+      a->unget.buf = NULL;
+      a->nofast &= ~2;
+    }
+
+  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)
+    return -1;			/* EOF */
+
+  a->nbytes++;
+  return c;
+}
+
+
+int
+iobuf_read (iobuf_t a, byte * buf, unsigned buflen)
+{
+  int c, n;
+
+  if (a->unget.buf || a->nlimit)
+    {
+      /* handle special cases */
+      for (n = 0; n < buflen; n++)
+	{
+	  if ((c = iobuf_readbyte (a)) == -1)
+	    {
+	      if (!n)
+		return -1;	/* eof */
+	      break;
+	    }
+	  else if (buf)
+	    *buf = c;
+	  if (buf)
+	    buf++;
+	}
+      return n;
+    }
+
+  n = 0;
+  do
+    {
+      if (n < buflen && a->d.start < a->d.len)
+	{
+	  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)
+	{
+	  if ((c = underflow (a)) == -1)
+	    {
+	      a->nbytes += n;
+	      return n ? n : -1 /*EOF*/;
+	    }
+	  if (buf)
+	    *buf++ = c;
+	  n++;
+	}
+    }
+  while (n < buflen);
+  a->nbytes += n;
+  return n;
+}
+
+
+/****************
+ * Have a look at the iobuf.
+ * NOTE: This only works in special cases.
+ */
+int
+iobuf_peek (iobuf_t a, byte * buf, unsigned buflen)
+{
+  int n = 0;
+
+  if (a->filter_eof)
+    return -1;
+
+  if (!(a->d.start < a->d.len))
+    {
+      if (underflow (a) == -1)
+	return -1;
+      /* and unget this character */
+      assert (a->d.start == 1);
+      a->d.start = 0;
+    }
+
+  for (n = 0; n < buflen && (a->d.start + n) < a->d.len; n++, buf++)
+    *buf = a->d.buf[n];
+  return n;
+}
+
+
+
+
+int
+iobuf_writebyte (iobuf_t a, unsigned c)
+{
+  int rc;
+
+  if (a->directfp)
+    BUG ();
+
+  if (a->d.len == a->d.size)
+    if ((rc=iobuf_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, byte * buf, unsigned buflen)
+{
+  int rc;
+
+  if (a->directfp)
+    BUG ();
+
+  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 = iobuf_flush (a);
+          if (rc)
+	    return rc;
+	}
+    }
+  while (buflen);
+  return 0;
+}
+
+
+int
+iobuf_writestr (iobuf_t a, const char *buf)
+{
+  int rc;
+
+  for (; *buf; buf++)
+    if ((rc=iobuf_writebyte (a, *buf)))
+      return rc;
+  return 0;
+}
+
+
+
+/****************
+ * copy the contents of TEMP to A.
+ */
+int
+iobuf_write_temp (iobuf_t a, iobuf_t temp)
+{
+  while (temp->chain)
+    pop_filter (temp, temp->filter, NULL);
+  return iobuf_write (a, temp->d.buf, temp->d.len);
+}
+
+/****************
+ * copy the contents of the temp io stream to BUFFER.
+ */
+size_t
+iobuf_temp_to_buffer (iobuf_t a, byte * buffer, size_t buflen)
+{
+  size_t n = a->d.len;
+
+  if (n > buflen)
+    n = buflen;
+  memcpy (buffer, a->d.buf, n);
+  return n;
+}
+
+
+/****************
+ * Call this function to terminate processing of the temp stream
+ * without closing it.	This removes all filters from the stream
+ * makes sure that iobuf_get_temp_{buffer,length}() returns correct
+ * values.
+ */
+void
+iobuf_flush_temp (iobuf_t temp)
+{
+  while (temp->chain)
+    pop_filter (temp, temp->filter, NULL);
+}
+
+
+/****************
+ * Set a limit on how many bytes may be read from the input stream A.
+ * Setting the limit to 0 disables this feature.
+ */
+void
+iobuf_set_limit (iobuf_t a, off_t nlimit)
+{
+  if (nlimit)
+    a->nofast |= 1;
+  else
+    a->nofast &= ~1;
+  a->nlimit = nlimit;
+  a->ntotal += a->nbytes;
+  a->nbytes = 0;
+}
+
+
+
+/****************
+ * Return the length of an open file
+ */
+off_t
+iobuf_get_filelength (iobuf_t a)
+{
+  struct stat st;
+
+  if (a->directfp)
+    {
+      FILE *fp = a->directfp;
+
+      if (!fstat (fileno (fp), &st))
+	return st.st_size;
+      log_error ("fstat() failed: %s\n", strerror (errno));
+      return 0;
+    }
+
+  /* Hmmm: file_filter may have already been removed */
+  for (; a; a = a->chain)
+    if (!a->chain && a->filter == file_filter)
+      {
+	file_filter_ctx_t *b = a->filter_ov;
+	FILEP_OR_FD fp = b->fp;
+
+#if defined(HAVE_DOSISH_SYSTEM) && !defined(FILE_FILTER_USES_STDIO)
+	ulong size;
+
+	if ((size = GetFileSize (fp, NULL)) != 0xffffffff)
+	  return size;
+	log_error ("GetFileSize for handle %p failed: ec=%d\n",
+		   fp, (int) GetLastError ());
+#else
+	if (!fstat (my_fileno (fp), &st))
+	  return st.st_size;
+	log_error ("fstat() failed: %s\n", strerror (errno));
+#endif
+	break;
+      }
+
+  return 0;
+}
+
+/****************
+ * Tell the file position, where the next read will take place
+ */
+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
+
+/****************
+ * This is a very limited implementation. It simply discards all internal
+ * buffering and removes all filters but the first one.
+ */
+int
+iobuf_seek (iobuf_t a, off_t newpos)
+{
+  file_filter_ctx_t *b = NULL;
+
+  if (a->directfp)
+    {
+      FILE *fp = a->directfp;
+      if (fseeko (fp, newpos, SEEK_SET))
+	{
+	  log_error ("can't seek: %s\n", strerror (errno));
+	  return -1;
+	}
+      clearerr (fp);
+    }
+  else
+    {
+      for (; a; a = a->chain)
+	{
+	  if (!a->chain && a->filter == file_filter)
+	    {
+	      b = a->filter_ov;
+	      break;
+	    }
+	}
+      if (!a)
+	return -1;
+#ifdef FILE_FILTER_USES_STDIO
+      if (fseeko (b->fp, newpos, SEEK_SET))
+	{
+	  log_error ("can't fseek: %s\n", strerror (errno));
+	  return -1;
+	}
+#else
+#ifdef HAVE_DOSISH_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
+#endif
+    }
+  a->d.len = 0;			/* discard buffer */
+  a->d.start = 0;
+  a->nbytes = 0;
+  a->nlimit = 0;
+  a->nofast &= ~1;
+  a->ntotal = newpos;
+  a->error = 0;
+  /* remove filters, but the last */
+  if (a->chain)
+    log_debug ("pop_filter called in iobuf_seek - please report\n");
+  while (a->chain)
+    pop_filter (a, a->filter, NULL);
+
+  return 0;
+}
+
+
+
+
+
+
+/****************
+ * Retrieve the real filename
+ */
+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;
+}
+
+
+/****************
+ * Retrieve the filename
+ */
+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;
+}
+
+/****************
+ * Start the block write mode, see rfc1991.new for details.
+ * A value of 0 for N stops this mode (flushes and writes
+ * the end marker)
+ */
+void
+iobuf_set_block_mode (iobuf_t a, size_t n)
+{
+  block_filter_ctx_t *ctx = xcalloc (1, sizeof *ctx);
+
+  assert (a->use == 1 || a->use == 2);
+  ctx->use = a->use;
+  if (!n)
+    {
+      if (a->use == 1)
+	log_debug ("pop_filter called in set_block_mode - please report\n");
+      pop_filter (a, block_filter, NULL);
+    }
+  else
+    {
+      ctx->size = n;		/* only needed for use 2 */
+      iobuf_push_filter (a, block_filter, ctx);
+    }
+}
+
+/****************
+ * enable partial block mode as described in the OpenPGP draft.
+ * LEN is the first length byte on read, but ignored on writes.
+ */
+void
+iobuf_set_partial_block_mode (iobuf_t a, size_t len)
+{
+  block_filter_ctx_t *ctx = xcalloc (1, sizeof *ctx);
+
+  assert (a->use == 1 || a->use == 2);
+  ctx->use = a->use;
+  if (!len)
+    {
+      if (a->use == 1)
+	log_debug ("pop_filter called in set_partial_block_mode"
+		   " - please report\n");
+      pop_filter (a, block_filter, NULL);
+    }
+  else
+    {
+      ctx->partial = 1;
+      ctx->size = 0;
+      ctx->first_c = len;
+      iobuf_push_filter (a, block_filter, ctx);
+    }
+}
+
+
+/****************
+ * Checks whether the stream is in block mode
+ * Note: This does not work if other filters are pushed on the stream.
+ */
+int
+iobuf_in_block_mode (iobuf_t a)
+{
+  if (a && a->filter == block_filter)
+    return 1;			/* yes */
+  return 0;			/* no */
+}
+
+
+/****************
+ * Same as fgets() but if the buffer is too short a larger one will
+ * be allocated up to some limit *max_length.
+ * A line is considered a byte stream ending in a LF.
+ * Returns the length of the line. EOF is indicated by a line of
+ * length zero. The last LF may be missing due to an EOF.
+ * is max_length is zero on return, the line has been truncated.
+ *
+ * Note: The buffer is allocated with enough space to append a CR,LF,EOL
+ */
+unsigned int
+iobuf_read_line (iobuf_t a, byte ** addr_of_buffer,
+		 unsigned *length_of_buffer, unsigned *max_length)
+{
+  int c;
+  char *buffer = *addr_of_buffer;
+  unsigned length = *length_of_buffer;
+  unsigned nbytes = 0;
+  unsigned maxlen = *max_length;
+  char *p;
+
+  if (!buffer)
+    {				/* must allocate a new buffer */
+      length = 256;
+      buffer = xmalloc (length);
+      *addr_of_buffer = buffer;
+      *length_of_buffer = length;
+    }
+
+  length -= 3;			/* reserve 3 bytes (cr,lf,eol) */
+  p = buffer;
+  while ((c = iobuf_get (a)) != -1)
+    {
+      if (nbytes == length)
+	{			/* increase the buffer */
+	  if (length > maxlen)
+	    {			/* this is out limit */
+	      /* skip the rest of the line */
+	      while (c != '\n' && (c = iobuf_get (a)) != -1)
+		;
+	      *p++ = '\n';	/* always append a LF (we have reserved space) */
+	      nbytes++;
+	      *max_length = 0;	/* indicate truncation */
+	      break;
+	    }
+	  length += 3;		/* correct for the reserved byte */
+	  length += length < 1024 ? 256 : 1024;
+	  buffer = xrealloc (buffer, length);
+	  *addr_of_buffer = buffer;
+	  *length_of_buffer = length;
+	  length -= 3;		/* and reserve again */
+	  p = buffer + nbytes;
+	}
+      *p++ = c;
+      nbytes++;
+      if (c == '\n')
+	break;
+    }
+  *p = 0;			/* make sure the line is a string */
+
+  return nbytes;
+}
+
+/* This is the non iobuf specific function */
+int
+iobuf_translate_file_handle (int fd, int for_write)
+{
+#ifdef __MINGW32__
+  {
+    int x;
+
+    if (fd <= 2)
+      return fd;		/* do not do this for error, stdin, stdout, stderr */
+
+    x = _open_osfhandle (fd, for_write ? 1 : 0);
+    if (x == -1)
+      log_error ("failed to translate osfhandle %p\n", (void *) fd);
+    else
+      {
+	/*log_info ("_open_osfhandle %p yields %d%s\n",
+	   (void*)fd, x, for_write? " for writing":"" ); */
+	fd = x;
+      }
+  }
+#endif
+  return fd;
+}
+
+static int
+translate_file_handle (int fd, int for_write)
+{
+#ifdef __MINGW32__
+#ifdef FILE_FILTER_USES_STDIO
+  fd = iobuf_translate_file_handle (fd, for_write);
+#else
+  {
+    int x;
+
+    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;
+  }
+#endif
+#endif
+  return fd;
+}