Make definition of off_t robust against misbehaving w32 toolchains.

* configure.ac (NEED__FILE_OFFSET_BITS): Change to define gpgme_off_t
and gpgme_ssize_t.
(API__OFF_T, API__SSIZE_T): New ac_subst.
* src/gpgme.h.in: Replace all ssize_t and off_t by ac_subst macros.
* src/assuan-support.c, src/ath-pthread.c, src/ath.c, src/ath.h
* src/data-compat.c, src/data-fd.c, src/data-mem.c, src/data-stream.c
* src/data-user.c, src/data.c, src/data.h, src/engine-gpgsm.c
* src/engine-uiserver.c, src/gpgme-tool.c, src/gpgme.c: Replace off_t
by gpgme_off_t and sszie_t by gpgme_ssize_t.
* src/ath-pthread.c, src/ath.h: Include gpgme.h.
--

For a detailed description, see the gpgme.texi diff.

16 files changed, 77 insertions, 72 deletions

diff --git a/src/assuan-support.c b/src/assuan-support.c
index 6ff0679d..d06518a1 100644
--- a/src/assuan-support.c
+++ b/src/assuan-support.c
@@ -68,14 +68,14 @@ my_close (assuan_context_t ctx, assuan_fd_t fd)
 }
 
 
-static ssize_t
+static gpgme_ssize_t
 my_read (assuan_context_t ctx, assuan_fd_t fd, void *buffer, size_t size)
 {
   return _gpgme_io_read ((int) fd, buffer, size);
 }
 
 
-static ssize_t
+static gpgme_ssize_t
 my_write (assuan_context_t ctx, assuan_fd_t fd, const void *buffer, size_t size)
 {
   return _gpgme_io_write ((int) fd, buffer, size);
diff --git a/src/ath-pthread.c b/src/ath-pthread.c
index dfbdac2a..47b38ee0 100644
--- a/src/ath-pthread.c
+++ b/src/ath-pthread.c
@@ -39,6 +39,8 @@
 
 #include <pthread.h>
 
+#include "gpgme.h"
+
 #include "ath.h"
 
 
@@ -130,21 +132,21 @@ ath_mutex_unlock (ath_mutex_t *lock)
 }
 
 
-ssize_t
+gpgme_ssize_t
 ath_read (int fd, void *buf, size_t nbytes)
 {
   return read (fd, buf, nbytes);
 }
 
 
-ssize_t
+gpgme_ssize_t
 ath_write (int fd, const void *buf, size_t nbytes)
 {
   return write (fd, buf, nbytes);
 }
 
 
-ssize_t
+gpgme_ssize_t
 ath_select (int nfd, fd_set *rset, fd_set *wset, fd_set *eset,
 	    struct timeval *timeout)
 {
@@ -152,7 +154,7 @@ ath_select (int nfd, fd_set *rset, fd_set *wset, fd_set *eset,
 }
 
 
-ssize_t
+gpgme_ssize_t
 ath_waitpid (pid_t pid, int *status, int options)
 {
   return waitpid (pid, status, options);
diff --git a/src/ath.c b/src/ath.c
index 52cee458..ddd8a872 100644
--- a/src/ath.c
+++ b/src/ath.c
@@ -40,8 +40,9 @@
 #include <sys/wait.h>
 #endif
 
+#include "gpgme.h"
+
 #ifdef _MSC_VER
-  typedef long ssize_t;
   typedef int  pid_t;
 #endif
 
@@ -125,7 +126,7 @@ ath_mutex_unlock (ath_mutex_t *lock)
 }
 
 
-ssize_t
+gpgme_ssize_t
 ath_read (int fd, void *buf, size_t nbytes)
 {
 #if defined(HAVE_W32CE_SYSTEM) && defined(_MSC_VER)
@@ -136,7 +137,7 @@ ath_read (int fd, void *buf, size_t nbytes)
 }
 
 
-ssize_t
+gpgme_ssize_t
 ath_write (int fd, const void *buf, size_t nbytes)
 {
 #if defined(HAVE_W32CE_SYSTEM) && defined(_MSC_VER)
@@ -147,7 +148,7 @@ ath_write (int fd, const void *buf, size_t nbytes)
 }
 
 
-ssize_t
+gpgme_ssize_t
 ath_select (int nfd, fd_set *rset, fd_set *wset, fd_set *eset,
 	    struct timeval *timeout)
 {
@@ -159,7 +160,7 @@ ath_select (int nfd, fd_set *rset, fd_set *wset, fd_set *eset,
 }
 
 
-ssize_t
+gpgme_ssize_t
 ath_waitpid (pid_t pid, int *status, int options)
 {
 #ifdef HAVE_W32_SYSTEM
diff --git a/src/ath.h b/src/ath.h
index eecf8d10..8eb9eb95 100644
--- a/src/ath.h
+++ b/src/ath.h
@@ -88,11 +88,11 @@ int ath_mutex_unlock (ath_mutex_t *mutex);
 
 /* Replacement for the POSIX functions, which can be used to allow
    other (user-level) threads to run.  */
-ssize_t ath_read (int fd, void *buf, size_t nbytes);
-ssize_t ath_write (int fd, const void *buf, size_t nbytes);
-ssize_t ath_select (int nfd, fd_set *rset, fd_set *wset, fd_set *eset,
-		    struct timeval *timeout);
-ssize_t ath_waitpid (pid_t pid, int *status, int options);
+gpgme_ssize_t ath_read (int fd, void *buf, size_t nbytes);
+gpgme_ssize_t ath_write (int fd, const void *buf, size_t nbytes);
+gpgme_ssize_t ath_select (int nfd, fd_set *rset, fd_set *wset, fd_set *eset,
+                           struct timeval *timeout);
+gpgme_ssize_t ath_waitpid (pid_t pid, int *status, int options);
 int ath_accept (int s, struct sockaddr *addr, socklen_t *length_ptr);
 int ath_connect (int s, const struct sockaddr *addr, socklen_t length);
 int ath_sendmsg (int s, const struct msghdr *msg, int flags);
diff --git a/src/data-compat.c b/src/data-compat.c
index e9ca90a9..99827f16 100644
--- a/src/data-compat.c
+++ b/src/data-compat.c
@@ -41,7 +41,7 @@
    non-zero).  */
 gpgme_error_t
 gpgme_data_new_from_filepart (gpgme_data_t *r_dh, const char *fname,
-			      FILE *stream, off_t offset, size_t length)
+			      FILE *stream, gpgme_off_t offset, size_t length)
 {
 #if defined (HAVE_W32CE_SYSTEM) && defined (_MSC_VER)
   return gpgme_error (GPG_ERR_NOT_IMPLEMENTED);
@@ -175,7 +175,7 @@ gpgme_error_to_errno (gpgme_error_t err)
 }
 
 
-static ssize_t
+static gpgme_ssize_t
 old_user_read (gpgme_data_t dh, void *buffer, size_t size)
 {
   gpgme_error_t err;
@@ -191,8 +191,8 @@ old_user_read (gpgme_data_t dh, void *buffer, size_t size)
 }
 
 
-static off_t
-old_user_seek (gpgme_data_t dh, off_t offset, int whence)
+static gpgme_off_t
+old_user_seek (gpgme_data_t dh, gpgme_off_t offset, int whence)
 {
   gpgme_error_t err;
   TRACE_BEG2 (DEBUG_DATA, "gpgme:old_user_seek", dh,
diff --git a/src/data-fd.c b/src/data-fd.c
index 4b75e942..42d6a0d2 100644
--- a/src/data-fd.c
+++ b/src/data-fd.c
@@ -89,22 +89,22 @@ lseek (int fildes, long offset, int whence)
 
 
 
-static ssize_t
+static gpgme_ssize_t
 fd_read (gpgme_data_t dh, void *buffer, size_t size)
 {
   return read (dh->data.fd, buffer, size);
 }
 
 
-static ssize_t
+static gpgme_ssize_t
 fd_write (gpgme_data_t dh, const void *buffer, size_t size)
 {
   return write (dh->data.fd, buffer, size);
 }
 
 
-static off_t
-fd_seek (gpgme_data_t dh, off_t offset, int whence)
+static gpgme_off_t
+fd_seek (gpgme_data_t dh, gpgme_off_t offset, int whence)
 {
   return lseek (dh->data.fd, offset, whence);
 }
diff --git a/src/data-mem.c b/src/data-mem.c
index fc7694d2..e06a920c 100644
--- a/src/data-mem.c
+++ b/src/data-mem.c
@@ -35,7 +35,7 @@
 #include "debug.h"
 
 
-static ssize_t
+static gpgme_ssize_t
 mem_read (gpgme_data_t dh, void *buffer, size_t size)
 {
   size_t amt = dh->data.mem.length - dh->data.mem.offset;
@@ -54,7 +54,7 @@ mem_read (gpgme_data_t dh, void *buffer, size_t size)
 }
 
 
-static ssize_t
+static gpgme_ssize_t
 mem_write (gpgme_data_t dh, const void *buffer, size_t size)
 {
   size_t unused;
@@ -109,8 +109,8 @@ mem_write (gpgme_data_t dh, const void *buffer, size_t size)
 }
 
 
-static off_t
-mem_seek (gpgme_data_t dh, off_t offset, int whence)
+static gpgme_off_t
+mem_seek (gpgme_data_t dh, gpgme_off_t offset, int whence)
 {
   switch (whence)
     {
diff --git a/src/data-stream.c b/src/data-stream.c
index a9bb815b..f358a0e0 100644
--- a/src/data-stream.c
+++ b/src/data-stream.c
@@ -31,7 +31,7 @@
 #include "data.h"
 
 
-static ssize_t
+static gpgme_ssize_t
 stream_read (gpgme_data_t dh, void *buffer, size_t size)
 {
   size_t amt = fread (buffer, 1, size, dh->data.stream);
@@ -41,7 +41,7 @@ stream_read (gpgme_data_t dh, void *buffer, size_t size)
 }
 
 
-static ssize_t
+static gpgme_ssize_t
 stream_write (gpgme_data_t dh, const void *buffer, size_t size)
 {
   size_t amt = fwrite (buffer, 1, size, dh->data.stream);
@@ -51,8 +51,8 @@ stream_write (gpgme_data_t dh, const void *buffer, size_t size)
 }
 
 
-static off_t
-stream_seek (gpgme_data_t dh, off_t offset, int whence)
+static gpgme_off_t
+stream_seek (gpgme_data_t dh, gpgme_off_t offset, int whence)
 {
   int err;
 
diff --git a/src/data-user.c b/src/data-user.c
index 52046148..816ad7db 100644
--- a/src/data-user.c
+++ b/src/data-user.c
@@ -31,7 +31,7 @@
 #include "data.h"
 
 
-static ssize_t
+static gpgme_ssize_t
 user_read (gpgme_data_t dh, void *buffer, size_t size)
 {
   if (!dh->data.user.cbs->read)
@@ -44,7 +44,7 @@ user_read (gpgme_data_t dh, void *buffer, size_t size)
 }
 
 
-static ssize_t
+static gpgme_ssize_t
 user_write (gpgme_data_t dh, const void *buffer, size_t size)
 {
   if (!dh->data.user.cbs->write)
@@ -57,8 +57,8 @@ user_write (gpgme_data_t dh, const void *buffer, size_t size)
 }
 
 
-static off_t
-user_seek (gpgme_data_t dh, off_t offset, int whence)
+static gpgme_off_t
+user_seek (gpgme_data_t dh, gpgme_off_t offset, int whence)
 {
   if (!dh->data.user.cbs->seek)
     {
diff --git a/src/data.c b/src/data.c
index 0657081c..7123a82b 100644
--- a/src/data.c
+++ b/src/data.c
@@ -72,10 +72,10 @@ _gpgme_data_release (gpgme_data_t dh)
 /* Read up to SIZE bytes into buffer BUFFER from the data object with
    the handle DH.  Return the number of characters read, 0 on EOF and
    -1 on error.  If an error occurs, errno is set.  */
-ssize_t
+gpgme_ssize_t
 gpgme_data_read (gpgme_data_t dh, void *buffer, size_t size)
 {
-  ssize_t res;
+  gpgme_ssize_t res;
   TRACE_BEG2 (DEBUG_DATA, "gpgme_data_read", dh,
 	      "buffer=%p, size=%u", buffer, size);
 
@@ -100,10 +100,10 @@ gpgme_data_read (gpgme_data_t dh, void *buffer, size_t size)
 /* Write up to SIZE bytes from buffer BUFFER to the data object with
    the handle DH.  Return the number of characters written, or -1 on
    error.  If an error occurs, errno is set.  */
-ssize_t
+gpgme_ssize_t
 gpgme_data_write (gpgme_data_t dh, const void *buffer, size_t size)
 {
-  ssize_t res;
+  gpgme_ssize_t res;
   TRACE_BEG2 (DEBUG_DATA, "gpgme_data_write", dh,
 	      "buffer=%p, size=%u", buffer, size);
 
@@ -128,8 +128,8 @@ gpgme_data_write (gpgme_data_t dh, const void *buffer, size_t size)
 /* Set the current position from where the next read or write starts
    in the data object with the handle DH to OFFSET, relativ to
    WHENCE.  */
-off_t
-gpgme_data_seek (gpgme_data_t dh, off_t offset, int whence)
+gpgme_off_t
+gpgme_data_seek (gpgme_data_t dh, gpgme_off_t offset, int whence)
 {
   TRACE_BEG2 (DEBUG_DATA, "gpgme_data_seek", dh,
 	      "offset=%lli, whence=%i", offset, whence);
@@ -253,7 +253,7 @@ _gpgme_data_inbound_handler (void *opaque, int fd)
   gpgme_data_t dh = (gpgme_data_t) data->handler_value;
   char buffer[BUFFER_SIZE];
   char *bufp = buffer;
-  ssize_t buflen;
+  gpgme_ssize_t buflen;
   TRACE_BEG1 (DEBUG_CTX, "_gpgme_data_inbound_handler", dh,
 	      "fd=0x%x", fd);
 
@@ -268,7 +268,7 @@ _gpgme_data_inbound_handler (void *opaque, int fd)
 
   do
     {
-      ssize_t amt = gpgme_data_write (dh, bufp, buflen);
+      gpgme_ssize_t amt = gpgme_data_write (dh, bufp, buflen);
       if (amt == 0 || (amt < 0 && errno != EINTR))
 	return TRACE_ERR (gpg_error_from_syserror ());
       bufp += amt;
@@ -284,13 +284,13 @@ _gpgme_data_outbound_handler (void *opaque, int fd)
 {
   struct io_cb_data *data = (struct io_cb_data *) opaque;
   gpgme_data_t dh = (gpgme_data_t) data->handler_value;
-  ssize_t nwritten;
+  gpgme_ssize_t nwritten;
   TRACE_BEG1 (DEBUG_CTX, "_gpgme_data_outbound_handler", dh,
 	      "fd=0x%x", fd);
 
   if (!dh->pending_len)
     {
-      ssize_t amt = gpgme_data_read (dh, dh->pending, BUFFER_SIZE);
+      gpgme_ssize_t amt = gpgme_data_read (dh, dh->pending, BUFFER_SIZE);
       if (amt < 0)
 	return TRACE_ERR (gpg_error_from_syserror ());
       if (amt == 0)
diff --git a/src/data.h b/src/data.h
index 5076619b..3d404af8 100644
--- a/src/data.h
+++ b/src/data.h
@@ -36,20 +36,23 @@
 /* Read up to SIZE bytes into buffer BUFFER from the data object with
    the handle DH.  Return the number of characters read, 0 on EOF and
    -1 on error.  If an error occurs, errno is set.  */
-typedef ssize_t (*gpgme_data_read_cb) (gpgme_data_t dh, void *buffer,
-				       size_t size);
+typedef gpgme_ssize_t (*gpgme_data_read_cb) (gpgme_data_t dh,
+                                             void *buffer,
+                                             size_t size);
 
 /* Write up to SIZE bytes from buffer BUFFER to the data object with
    the handle DH.  Return the number of characters written, or -1 on
    error.  If an error occurs, errno is set.  */
-typedef ssize_t (*gpgme_data_write_cb) (gpgme_data_t dh, const void *buffer,
-					size_t size);
+typedef gpgme_ssize_t (*gpgme_data_write_cb) (gpgme_data_t dh,
+                                              const void *buffer,
+                                              size_t size);
 
 /* Set the current position from where the next read or write starts
    in the data object with the handle DH to OFFSET, relativ to
    WHENCE.  */
-typedef off_t (*gpgme_data_seek_cb) (gpgme_data_t dh, off_t offset,
-				     int whence);
+typedef gpgme_off_t (*gpgme_data_seek_cb) (gpgme_data_t dh,
+                                            gpgme_off_t offset,
+                                            int whence);
 
 /* Release the data object with the handle DH.  */
 typedef void (*gpgme_data_release_cb) (gpgme_data_t dh);
@@ -109,7 +112,7 @@ struct gpgme_data
       /* Allocated size of BUFFER.  */
       size_t size;
       size_t length;
-      off_t offset;
+      gpgme_off_t offset;
     } mem;
 
     /* For gpgme_data_new_from_read_cb.  */
diff --git a/src/engine-gpgsm.c b/src/engine-gpgsm.c
index 79adde2c..391b632d 100644
--- a/src/engine-gpgsm.c
+++ b/src/engine-gpgsm.c
@@ -891,7 +891,7 @@ status_handler (void *opaque, int fd)
           char *src = line + 2;
 	  char *end = line + linelen;
 	  char *dst = src;
-          ssize_t nwritten;
+          gpgme_ssize_t nwritten;
 
           linelen = 0;
           while (src < end)
diff --git a/src/engine-uiserver.c b/src/engine-uiserver.c
index a68915a5..a0008e41 100644
--- a/src/engine-uiserver.c
+++ b/src/engine-uiserver.c
@@ -754,7 +754,7 @@ status_handler (void *opaque, int fd)
           char *src = line + 2;
 	  char *end = line + linelen;
 	  char *dst = src;
-          ssize_t nwritten;
+          gpgme_ssize_t nwritten;
 
           linelen = 0;
           while (src < end)
diff --git a/src/gpgme-tool.c b/src/gpgme-tool.c
index 978c387d..bce52b82 100644
--- a/src/gpgme-tool.c
+++ b/src/gpgme-tool.c
@@ -3056,7 +3056,7 @@ _cmd_genkey_write (gpgme_data_t data, const void *buf, size_t size)
 {
   while (size > 0)
     {
-      ssize_t writen = gpgme_data_write (data, buf, size);
+      gpgme_ssize_t writen = gpgme_data_write (data, buf, size);
       if (writen < 0 && errno != EAGAIN)
 	return gpg_error_from_syserror ();
       else if (writen > 0)
@@ -3112,7 +3112,7 @@ cmd_genkey (assuan_context_t ctx, char *line)
   do
     {
       char buf[512];
-      ssize_t readn = gpgme_data_read (inp_data, buf, sizeof (buf));
+      gpgme_ssize_t readn = gpgme_data_read (inp_data, buf, sizeof (buf));
       if (readn < 0)
 	{
 	  err = gpg_error_from_syserror ();
diff --git a/src/gpgme.c b/src/gpgme.c
index 281ba9cf..a8de64b4 100644
--- a/src/gpgme.c
+++ b/src/gpgme.c
@@ -643,7 +643,7 @@ gpgme_set_io_cbs (gpgme_ctx_t ctx, gpgme_io_cbs_t io_cbs)
 
 /* This function provides access to the internal read function; it is
    normally not used.  */
-ssize_t
+gpgme_ssize_t
 gpgme_io_read (int fd, void *buffer, size_t count)
 {
   int ret;
@@ -659,7 +659,7 @@ gpgme_io_read (int fd, void *buffer, size_t count)
 /* This function provides access to the internal write function.  It
    is to be used by user callbacks to return data to gpgme.  See
    gpgme_passphrase_cb_t and gpgme_edit_cb_t.  */
-ssize_t
+gpgme_ssize_t
 gpgme_io_write (int fd, const void *buffer, size_t count)
 {
   int ret;
diff --git a/src/gpgme.h.in b/src/gpgme.h.in
index 12bd4ac7..caf64d4c 100644
--- a/src/gpgme.h.in
+++ b/src/gpgme.h.in
@@ -18,7 +18,7 @@
    You should have received a copy of the GNU Lesser General Public
    License along with this program; if not, see <http://www.gnu.org/licenses/>.
 
-   File: @configure_input@  */
+   Generated from gpgme.h.in for @GPGME_CONFIG_HOST@.  */
 
 #ifndef GPGME_H
 #define GPGME_H
@@ -33,10 +33,8 @@
 
 /* Include stdio.h for the FILE type definition.  */
 #include <stdio.h>
-
-@INSERT__TYPEDEFS_FOR_GPGME_H@
-
 #include <time.h>
+@INSERT__TYPEDEFS_FOR_GPGME_H@
 
 #include <gpg-error.h>
 
@@ -1043,8 +1041,8 @@ void gpgme_get_io_cbs (gpgme_ctx_t ctx, gpgme_io_cbs_t io_cbs);
 
 /* Wrappers around the internal I/O functions for use with
    gpgme_passphrase_cb_t and gpgme_edit_cb_t.  */
-ssize_t gpgme_io_read (int fd, void *buffer, size_t count);
-ssize_t gpgme_io_write (int fd, const void *buffer, size_t count);
+@API__SSIZE_T@ gpgme_io_read (int fd, void *buffer, size_t count);
+@API__SSIZE_T@ gpgme_io_write (int fd, const void *buffer, size_t count);
 int     gpgme_io_writen (int fd, const void *buffer, size_t count);
 
 /* Process the pending operation and, if HANG is non-zero, wait for
@@ -1060,19 +1058,20 @@ gpgme_ctx_t gpgme_wait_ext (gpgme_ctx_t ctx, gpgme_error_t *status,
 /* Read up to SIZE bytes into buffer BUFFER from the data object with
    the handle HANDLE.  Return the number of characters read, 0 on EOF
    and -1 on error.  If an error occurs, errno is set.  */
-typedef ssize_t (*gpgme_data_read_cb_t) (void *handle, void *buffer,
+typedef @API__SSIZE_T@ (*gpgme_data_read_cb_t) (void *handle, void *buffer,
 					 size_t size);
 
 /* Write up to SIZE bytes from buffer BUFFER to the data object with
    the handle HANDLE.  Return the number of characters written, or -1
    on error.  If an error occurs, errno is set.  */
-typedef ssize_t (*gpgme_data_write_cb_t) (void *handle, const void *buffer,
+typedef @API__SSIZE_T@ (*gpgme_data_write_cb_t) (void *handle, const void *buffer,
 					  size_t size);
 
 /* Set the current position from where the next read or write starts
    in the data object with the handle HANDLE to OFFSET, relativ to
    WHENCE.  */
-typedef off_t (*gpgme_data_seek_cb_t) (void *handle, off_t offset, int whence);
+typedef @API__OFF_T@ (*gpgme_data_seek_cb_t) (void *handle,
+                                       @API__OFF_T@ offset, int whence);
 
 /* Close the data object with the handle DL.  */
 typedef void (*gpgme_data_release_cb_t) (void *handle);
@@ -1089,17 +1088,17 @@ typedef struct gpgme_data_cbs *gpgme_data_cbs_t;
 /* Read up to SIZE bytes into buffer BUFFER from the data object with
    the handle DH.  Return the number of characters read, 0 on EOF and
    -1 on error.  If an error occurs, errno is set.  */
-ssize_t gpgme_data_read (gpgme_data_t dh, void *buffer, size_t size);
+@API__SSIZE_T@ gpgme_data_read (gpgme_data_t dh, void *buffer, size_t size);
 
 /* Write up to SIZE bytes from buffer BUFFER to the data object with
    the handle DH.  Return the number of characters written, or -1 on
    error.  If an error occurs, errno is set.  */
-ssize_t gpgme_data_write (gpgme_data_t dh, const void *buffer, size_t size);
+@API__SSIZE_T@ gpgme_data_write (gpgme_data_t dh, const void *buffer, size_t size);
 
 /* Set the current position from where the next read or write starts
    in the data object with the handle DH to OFFSET, relativ to
    WHENCE.  */
-off_t gpgme_data_seek (gpgme_data_t dh, off_t offset, int whence);
+@API__OFF_T@ gpgme_data_seek (gpgme_data_t dh, @API__OFF_T@ offset, int whence);
 
 /* Create a new data buffer and return it in R_DH.  */
 gpgme_error_t gpgme_data_new (gpgme_data_t *r_dh);
@@ -1168,7 +1167,7 @@ gpgme_error_t gpgme_data_new_from_file (gpgme_data_t *r_dh,
    non-zero).  */
 gpgme_error_t gpgme_data_new_from_filepart (gpgme_data_t *r_dh,
 					    const char *fname, FILE *fp,
-					    off_t offset, size_t length);
+					    @API__OFF_T@ offset, size_t length);
 
 /* Reset the read pointer in DH.  Deprecated, please use
    gpgme_data_seek instead.  */