From 6e0d757f24a45252c4cae9ea09732eda2562c767 Mon Sep 17 00:00:00 2001

From: "Richard W.M. Jones" <rjones@redhat.com>

Date: Tue, 9 Apr 2013 11:42:09 +0200

Subject: [PATCH 3/3] sftp: Add support for fsync (OpenSSH extension).

The new libssh2_sftp_fsync API causes data and metadata in the

currently open file to be committed to disk at the server.

This is an OpenSSH extension to the SFTP protocol.  See:

https://bugzilla.mindrot.org/show_bug.cgi?id=1798

---

 docs/Makefile.am          |  1 +

 docs/libssh2_sftp_fsync.3 | 39 +++++++++++++++++++

 include/libssh2_sftp.h    |  1 +

 src/sftp.c                | 97 +++++++++++++++++++++++++++++++++++++++++++++++

 src/sftp.h                |  5 +++

 5 files changed, 143 insertions(+)

 create mode 100644 docs/libssh2_sftp_fsync.3

diff --git a/docs/Makefile.am b/docs/Makefile.am

index e4cf487..e6ab394 100644

--- a/docs/Makefile.am

+++ b/docs/Makefile.am

@@ -120,6 +120,7 @@ dist_man_MANS = \

 	libssh2_sftp_fstat.3 \

 	libssh2_sftp_fstat_ex.3 \

 	libssh2_sftp_fstatvfs.3 \

+	libssh2_sftp_fsync.3 \

 	libssh2_sftp_get_channel.3 \

 	libssh2_sftp_init.3 \

 	libssh2_sftp_last_error.3 \

diff --git a/docs/libssh2_sftp_fsync.3 b/docs/libssh2_sftp_fsync.3

new file mode 100644

index 0000000..646760a

--- /dev/null

+++ b/docs/libssh2_sftp_fsync.3

@@ -0,0 +1,39 @@

+.TH libssh2_sftp_fsync 3 "8 Apr 2013" "libssh2 1.4.4" "libssh2 manual"

+.SH NAME

+libssh2_sftp_fsync - synchronize file to disk

+.SH SYNOPSIS

+.nf

+#include <libssh2.h>

+#include <libssh2_sftp.h>

+

+int

+libssh2_sftp_fsync(LIBSSH2_SFTP_HANDLE *handle)

+.fi

+.SH DESCRIPTION

+This function causes the remote server to synchronize the file

+data and metadata to disk (like fsync(2)).

+

+For this to work requires fsync@openssh.com support on the server.

+

+\fIhandle\fP - SFTP File Handle as returned by

+.BR libssh2_sftp_open_ex(3)

+

+.SH RETURN VALUE

+Returns 0 on success or negative on failure. If used in non-blocking mode, it

+returns LIBSSH2_ERROR_EAGAIN when it would otherwise block. While

+LIBSSH2_ERROR_EAGAIN is a negative number, it isn't really a failure per se.

+.SH ERRORS

+\fILIBSSH2_ERROR_ALLOC\fP -  An internal memory allocation call failed.

+

+\fILIBSSH2_ERROR_SOCKET_SEND\fP - Unable to send data on socket.

+

+\fILIBSSH2_ERROR_SFTP_PROTOCOL\fP - An invalid SFTP protocol response

+was received on the socket, or an SFTP operation caused an errorcode

+to be returned by the server.  In particular, this can be returned if

+the SSH server does not support the fsync operation: the SFTP subcode

+\fILIBSSH2_FX_OP_UNSUPPORTED\fP will be returned in this case.

+

+.SH AVAILABILITY

+Added in libssh2 1.4.4 and OpenSSH 6.3.

+.SH SEE ALSO

+.BR fsync(2)

diff --git a/include/libssh2_sftp.h b/include/libssh2_sftp.h

index 74884fb..677faf2 100644

--- a/include/libssh2_sftp.h

+++ b/include/libssh2_sftp.h

@@ -247,6 +247,7 @@ 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_fsync(LIBSSH2_SFTP_HANDLE *handle);

 LIBSSH2_API int libssh2_sftp_close_handle(LIBSSH2_SFTP_HANDLE *handle);

 #define libssh2_sftp_close(handle) libssh2_sftp_close_handle(handle)

diff --git a/src/sftp.c b/src/sftp.c

index 65fa77a..01017fd 100644

--- a/src/sftp.c

+++ b/src/sftp.c

@@ -986,6 +986,10 @@ sftp_shutdown(LIBSSH2_SFTP *sftp)

         LIBSSH2_FREE(session, sftp->symlink_packet);

         sftp->symlink_packet = NULL;

     }

+    if (sftp->fsync_packet) {

+        LIBSSH2_FREE(session, sftp->fsync_packet);

+        sftp->fsync_packet = NULL;

+    }

     sftp_packet_flush(sftp);

@@ -2014,6 +2018,99 @@ libssh2_sftp_write(LIBSSH2_SFTP_HANDLE *hnd, const char *buffer,

 }

+static int sftp_fsync(LIBSSH2_SFTP_HANDLE *handle)

+{

+    LIBSSH2_SFTP *sftp = handle->sftp;

+    LIBSSH2_CHANNEL *channel = sftp->channel;

+    LIBSSH2_SESSION *session = channel->session;

+    /* 34 = packet_len(4) + packet_type(1) + request_id(4) +

+       string_len(4) + strlen("fsync@openssh.com")(17) + handle_len(4) */

+    uint32_t packet_len = handle->handle_len + 34;

+    size_t data_len;

+    unsigned char *packet, *s, *data;

+    ssize_t rc;

+    uint32_t retcode;

+

+    if (sftp->fsync_state == libssh2_NB_state_idle) {

+        _libssh2_debug(session, LIBSSH2_TRACE_SFTP,

+                       "Issuing fsync 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->fsync_request_id = sftp->request_id++;

+        _libssh2_store_u32(&s, sftp->fsync_request_id);

+        _libssh2_store_str(&s, "fsync@openssh.com", 17);

+        _libssh2_store_str(&s, handle->handle, handle->handle_len);

+

+        sftp->fsync_state = libssh2_NB_state_created;

+    } else {

+        packet = sftp->fsync_packet;

+    }

+

+    if (sftp->fsync_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->fsync_packet = packet;

+            return LIBSSH2_ERROR_EAGAIN;

+        }

+

+        LIBSSH2_FREE(session, packet);

+        sftp->fsync_packet = NULL;

+

+        if (rc < 0) {

+            sftp->fsync_state = libssh2_NB_state_idle;

+            return _libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND,

+                                  "_libssh2_channel_write() failed");

+        }

+        sftp->fsync_state = libssh2_NB_state_sent;

+    }

+

+    rc = sftp_packet_require(sftp, SSH_FXP_STATUS,

+                             sftp->fsync_request_id, &data, &data_len);

+    if (rc == LIBSSH2_ERROR_EAGAIN) {

+        return rc;

+    } else if (rc) {

+        sftp->fsync_state = libssh2_NB_state_idle;

+        return _libssh2_error(session, rc,

+                              "Error waiting for FXP EXTENDED REPLY");

+    }

+

+    sftp->fsync_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,

+                              "fsync failed");

+    }

+

+    return 0;

+}

+

+/* libssh2_sftp_fsync

+ * Commit data on the handle to disk.

+ */

+LIBSSH2_API int

+libssh2_sftp_fsync(LIBSSH2_SFTP_HANDLE *hnd)

+{

+    int rc;

+    if(!hnd)

+        return LIBSSH2_ERROR_BAD_USE;

+    BLOCK_ADJUST(rc, hnd->sftp->channel->session,

+                 sftp_fsync(hnd));

+    return rc;

+}

+

+

 /*

  * sftp_fstat

  *

diff --git a/src/sftp.h b/src/sftp.h

index 55bdb46..63e8139 100644

--- a/src/sftp.h

+++ b/src/sftp.h

@@ -175,6 +175,11 @@ struct _LIBSSH2_SFTP

     /* State variable used in sftp_write() */

     libssh2_nonblocking_states write_state;

+    /* State variables used in sftp_fsync() */

+    libssh2_nonblocking_states fsync_state;

+    unsigned char *fsync_packet;

+    uint32_t fsync_request_id;

+

     /* State variables used in libssh2_sftp_readdir() */

     libssh2_nonblocking_states readdir_state;

     unsigned char *readdir_packet;

-- 

1.8.1.4