static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs,
int64_t offset, size_t size,
QEMUIOVector *qiov)
{
ssize_t r;
size_t got;
char *buf, *end_of_vec;
struct iovec *i;
DPRINTF("offset=%" PRIi64 " size=%zu", offset, size);
ssh_seek(s, offset, SSH_SEEK_READ);
/* This keeps track of the current iovec element ('i'), where we
* will write to next ('buf'), and the end of the current iovec
* ('end_of_vec').
*/
i = &qiov->iov[0];
buf = i->iov_base;
end_of_vec = i->iov_base + i->iov_len;
/* libssh2 has a hard-coded limit of 2000 bytes per request,
* although it will also do readahead behind our backs. Therefore
* we may have to do repeated reads here until we have read 'size'
* bytes.
*/
for (got = 0; got < size; ) {
again:
DPRINTF("sftp_read buf=%p size=%zu", buf, end_of_vec - buf);
r = libssh2_sftp_read(s->sftp_handle, buf, end_of_vec - buf);
DPRINTF("sftp_read returned %zd", r);
if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
co_yield(s, bs);
goto again;
}
if (r < 0) {
sftp_error_report(s, "read failed");
s->offset = -1;
return -EIO;
}
if (r == 0) {
/* EOF: Short read so pad the buffer with zeroes and return it. */
qemu_iovec_memset(qiov, got, 0, size - got);
return 0;
}
got += r;
buf += r;
s->offset += r;
if (buf >= end_of_vec && got < size) {
i++;
buf = i->iov_base;
end_of_vec = i->iov_base + i->iov_len;
}
}
return 0;
}
static int ssh_create(const char *filename, QEMUOptionParameter *options)
{
int r, ret;
Error *local_err = NULL;
int64_t total_size = 0;
QDict *uri_options = NULL;
BDRVSSHState s;
ssize_t r2;
char c[1] = { '\0' };
ssh_state_init(&s);
/* Get desired file size. */
while (options && options->name) {
if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
total_size = options->value.n;
}
options++;
}
DPRINTF("total_size=%" PRIi64, total_size);
uri_options = qdict_new();
r = parse_uri(filename, uri_options, &local_err);
if (r < 0) {
qerror_report_err(local_err);
error_free(local_err);
ret = r;
goto out;
}
r = connect_to_ssh(&s, uri_options,
LIBSSH2_FXF_READ|LIBSSH2_FXF_WRITE|
LIBSSH2_FXF_CREAT|LIBSSH2_FXF_TRUNC, 0644);
if (r < 0) {
ret = r;
goto out;
}
if (total_size > 0) {
libssh2_sftp_seek64(s.sftp_handle, total_size-1);
r2 = libssh2_sftp_write(s.sftp_handle, c, 1);
if (r2 < 0) {
sftp_error_report(&s, "truncate failed");
ret = -EINVAL;
goto out;
}
s.attrs.filesize = total_size;
}
ret = 0;
out:
ssh_state_free(&s);
if (uri_options != NULL) {
QDECREF(uri_options);
}
return ret;
}
static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs)
{
int r;
DPRINTF("fsync");
again:
r = libssh2_sftp_fsync(s->sftp_handle);
if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
co_yield(s, bs);
goto again;
}
if (r == LIBSSH2_ERROR_SFTP_PROTOCOL &&
libssh2_sftp_last_error(s->sftp) == LIBSSH2_FX_OP_UNSUPPORTED) {
unsafe_flush_warning(s, "OpenSSH >= 6.3");
return 0;
}
if (r < 0) {
sftp_error_report(s, "fsync failed");
return -EIO;
}
return 0;
}
static int ssh_write(BDRVSSHState *s, BlockDriverState *bs,
int64_t offset, size_t size,
QEMUIOVector *qiov)
{
ssize_t r;
size_t written;
char *buf, *end_of_vec;
struct iovec *i;
DPRINTF("offset=%" PRIi64 " size=%zu", offset, size);
ssh_seek(s, offset, SSH_SEEK_WRITE);
/* This keeps track of the current iovec element ('i'), where we
* will read from next ('buf'), and the end of the current iovec
* ('end_of_vec').
*/
i = &qiov->iov[0];
buf = i->iov_base;
end_of_vec = i->iov_base + i->iov_len;
for (written = 0; written < size; ) {
again:
DPRINTF("sftp_write buf=%p size=%zu", buf, end_of_vec - buf);
r = libssh2_sftp_write(s->sftp_handle, buf, end_of_vec - buf);
DPRINTF("sftp_write returned %zd", r);
if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
co_yield(s, bs);
goto again;
}
if (r < 0) {
sftp_error_report(s, "write failed");
s->offset = -1;
return -EIO;
}
/* The libssh2 API is very unclear about this. A comment in
* the code says "nothing was acked, and no EAGAIN was
* received!" which apparently means that no data got sent
* out, and the underlying channel didn't return any EAGAIN
* indication. I think this is a bug in either libssh2 or
* OpenSSH (server-side). In any case, forcing a seek (to
* discard libssh2 internal buffers), and then trying again
* works for me.
*/
if (r == 0) {
ssh_seek(s, offset + written, SSH_SEEK_WRITE|SSH_SEEK_FORCE);
co_yield(s, bs);
goto again;
}
written += r;
buf += r;
s->offset += r;
if (buf >= end_of_vec && written < size) {
i++;
buf = i->iov_base;
end_of_vec = i->iov_base + i->iov_len;
}
if (offset + written > s->attrs.filesize)
s->attrs.filesize = offset + written;
}
return 0;
}
static int connect_to_ssh(BDRVSSHState *s, QDict *options,
int ssh_flags, int creat_mode)
{
int r, ret;
Error *err = NULL;
const char *host, *user, *path, *host_key_check;
int port;
host = qdict_get_str(options, "host");
if (qdict_haskey(options, "port")) {
port = qdict_get_int(options, "port");
} else {
port = 22;
}
path = qdict_get_str(options, "path");
if (qdict_haskey(options, "user")) {
user = qdict_get_str(options, "user");
} else {
user = g_get_user_name();
if (!user) {
ret = -errno;
goto err;
}
}
if (qdict_haskey(options, "host_key_check")) {
host_key_check = qdict_get_str(options, "host_key_check");
} else {
host_key_check = "yes";
}
/* Construct the host:port name for inet_connect. */
g_free(s->hostport);
s->hostport = g_strdup_printf("%s:%d", host, port);
/* Open the socket and connect. */
s->sock = inet_connect(s->hostport, &err);
if (err != NULL) {
ret = -errno;
qerror_report_err(err);
error_free(err);
goto err;
}
/* Create SSH session. */
s->session = libssh2_session_init();
if (!s->session) {
ret = -EINVAL;
session_error_report(s, "failed to initialize libssh2 session");
goto err;
}
#if TRACE_LIBSSH2 != 0
libssh2_trace(s->session, TRACE_LIBSSH2);
#endif
r = libssh2_session_handshake(s->session, s->sock);
if (r != 0) {
ret = -EINVAL;
session_error_report(s, "failed to establish SSH session");
goto err;
}
/* Check the remote host's key against known_hosts. */
ret = check_host_key(s, host, port, host_key_check);
if (ret < 0) {
goto err;
}
/* Authenticate. */
ret = authenticate(s, user);
if (ret < 0) {
goto err;
}
/* Start SFTP. */
s->sftp = libssh2_sftp_init(s->session);
if (!s->sftp) {
session_error_report(s, "failed to initialize sftp handle");
ret = -EINVAL;
goto err;
}
/* Open the remote file. */
DPRINTF("opening file %s flags=0x%x creat_mode=0%o",
path, ssh_flags, creat_mode);
s->sftp_handle = libssh2_sftp_open(s->sftp, path, ssh_flags, creat_mode);
if (!s->sftp_handle) {
session_error_report(s, "failed to open remote file '%s'", path);
ret = -EINVAL;
goto err;
}
r = libssh2_sftp_fstat(s->sftp_handle, &s->attrs);
if (r < 0) {
sftp_error_report(s, "failed to read file attributes");
return -EINVAL;
}
/* Delete the options we've used; any not deleted will cause the
* block layer to give an error about unused options.
*/
qdict_del(options, "host");
qdict_del(options, "port");
qdict_del(options, "user");
qdict_del(options, "path");
qdict_del(options, "host_key_check");
return 0;
err:
if (s->sftp_handle) {
libssh2_sftp_close(s->sftp_handle);
}
s->sftp_handle = NULL;
if (s->sftp) {
libssh2_sftp_shutdown(s->sftp);
}
s->sftp = NULL;
if (s->session) {
libssh2_session_disconnect(s->session,
"from qemu ssh client: "
"error opening connection");
libssh2_session_free(s->session);
}
s->session = NULL;
return ret;
}
