add support to libssh2 for hole punching...

libssh2/include/libssh2_sftp.h

@@ -251,6 +251,8 @@ LIBSSH2_API int libssh2_sftp_readdir_ex(LIBSSH2_SFTP_HANDLE *handle, \
 
 LIBSSH2_API ssize_t libssh2_sftp_write(LIBSSH2_SFTP_HANDLE *handle,
                                        const char *buffer, size_t count);
+LIBSSH2_API int libssh2_sftp_punchhole(LIBSSH2_SFTP_HANDLE *handle,
+                                       off_t off, off_t len);
 LIBSSH2_API int libssh2_sftp_fsync(LIBSSH2_SFTP_HANDLE *handle);
 
 LIBSSH2_API int libssh2_sftp_close_handle(LIBSSH2_SFTP_HANDLE *handle);

libssh2/src/sftp.c

@@ -2336,6 +2336,111 @@ libssh2_sftp_fsync(LIBSSH2_SFTP_HANDLE *hnd)
 }
 
 
+static int sftp_punchhole(LIBSSH2_SFTP_HANDLE *handle, off_t off, off_t len)
+{
+    LIBSSH2_SFTP *sftp = handle->sftp;
+    LIBSSH2_CHANNEL *channel = sftp->channel;
+    LIBSSH2_SESSION *session = channel->session;
+    /* 55 = packet_len(4) + packet_type(1) + request_id(4) +
+       string_len(4) + strlen("punchhole@funkthat.com")(22) + handle_len(4) +
+       off_len(8) + len_len(8) */
+    uint32_t packet_len = handle->handle_len + 55;
+    size_t data_len;
+    unsigned char *packet, *s, *data;
+    ssize_t rc;
+    uint32_t retcode;
+
+    if(sftp->punchhole_state == libssh2_NB_state_idle) {
+        _libssh2_debug(session, LIBSSH2_TRACE_SFTP,
+                       "Issuing punchhole command");
+        s = packet = LIBSSH2_ALLOC(session, packet_len);
+        if(!packet) {
+            return _libssh2_error(session, LIBSSH2_ERROR_ALLOC,
+                                  "Unable to allocate memory for FXP_EXTENDED "
+                                  "packet");
+        }
+
+        _libssh2_store_u32(&s, packet_len - 4);
+        *(s++) = SSH_FXP_EXTENDED;
+        sftp->punchhole_request_id = sftp->request_id++;
+        _libssh2_store_u32(&s, sftp->punchhole_request_id);
+        _libssh2_store_str(&s, "punchhole@funkthat.com", 22);
+        _libssh2_store_str(&s, handle->handle, handle->handle_len);
+        _libssh2_store_u64(&s, off);
+        _libssh2_store_u64(&s, len);
+
+        sftp->punchhole_state = libssh2_NB_state_created;
+    }
+    else {
+        packet = sftp->punchhole_packet;
+    }
+
+    if(sftp->punchhole_state == libssh2_NB_state_created) {
+        rc = _libssh2_channel_write(channel, 0, packet, packet_len);
+        if(rc == LIBSSH2_ERROR_EAGAIN ||
+            (0 <= rc && rc < (ssize_t)packet_len)) {
+            sftp->punchhole_packet = packet;
+            return LIBSSH2_ERROR_EAGAIN;
+        }
+
+        LIBSSH2_FREE(session, packet);
+        sftp->punchhole_packet = NULL;
+
+        if(rc < 0) {
+            sftp->punchhole_state = libssh2_NB_state_idle;
+            return _libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND,
+                                  "_libssh2_channel_write() failed");
+        }
+        sftp->punchhole_state = libssh2_NB_state_sent;
+    }
+
+    rc = sftp_packet_require(sftp, SSH_FXP_STATUS,
+                             sftp->punchhole_request_id, &data, &data_len, 9);
+    if(rc == LIBSSH2_ERROR_EAGAIN) {
+        return rc;
+    }
+    else if(rc == LIBSSH2_ERROR_BUFFER_TOO_SMALL) {
+        if(data_len > 0) {
+            LIBSSH2_FREE(session, data);
+        }
+        return _libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL,
+                              "SFTP punchhole packet too short");
+    }
+    else if(rc) {
+        sftp->punchhole_state = libssh2_NB_state_idle;
+        return _libssh2_error(session, rc,
+                              "Error waiting for FXP EXTENDED REPLY");
+    }
+
+    sftp->punchhole_state = libssh2_NB_state_idle;
+
+    retcode = _libssh2_ntohu32(data + 5);
+    LIBSSH2_FREE(session, data);
+
+    if(retcode != LIBSSH2_FX_OK) {
+        sftp->last_errno = retcode;
+        return _libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL,
+                              "punchhole failed");
+    }
+
+    return 0;
+}
+
+/* libssh2_sftp_punchhole
+ * Punch hole in remote file.
+ */
+LIBSSH2_API int
+libssh2_sftp_punchhole(LIBSSH2_SFTP_HANDLE *hnd, off_t off, off_t len)
+{
+    int rc;
+    if(!hnd)
+        return LIBSSH2_ERROR_BAD_USE;
+    BLOCK_ADJUST(rc, hnd->sftp->channel->session,
+                 sftp_punchhole(hnd, off, len));
+    return rc;
+}
+
+
 /*
  * sftp_fstat
  *

libssh2/src/sftp.h

@@ -183,6 +183,11 @@ struct _LIBSSH2_SFTP
     unsigned char *fsync_packet;
     uint32_t fsync_request_id;
 
+    /* State variables used in sftp_punchhole() */
+    libssh2_nonblocking_states punchhole_state;
+    unsigned char *punchhole_packet;
+    uint32_t punchhole_request_id;
+
     /* State variables used in libssh2_sftp_readdir() */
     libssh2_nonblocking_states readdir_state;
     unsigned char *readdir_packet;