Re: [Qemu-devel] [PATCH 1/3] block/ssh: Pull ssh_grow_file() from ssh_create()

[Eric Blake]

On 02/14/2018 02:49 PM, Max Reitz wrote:

If we ever want to offer even rudimentary truncation functionality for
ssh, we should put the respective code into a reusable function.

Signed-off-by: Max Reitz 
---
  block/ssh.c | 30 ++
  1 file changed, 22 insertions(+), 8 deletions(-)




+++ b/block/ssh.c
@@ -803,6 +803,26 @@ static int ssh_file_open(BlockDriverState *bs, QDict 
*options, int bdrv_flags,
  return ret;
  }
  
+static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp)

+{
+ssize_t ret;
+char c[1] = { '\0' };


Could spell this 'char c[1] = "";', but you just did code motion.

Reviewed-by: Eric Blake 

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.   +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

[Qemu-devel] [PATCH 1/3] block/ssh: Pull ssh_grow_file() from ssh_create()

[Max Reitz]

If we ever want to offer even rudimentary truncation functionality for
ssh, we should put the respective code into a reusable function.

Signed-off-by: Max Reitz 
---
 block/ssh.c | 30 ++
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/block/ssh.c b/block/ssh.c
index b63addcf94..964e55f7fe 100644
--- a/block/ssh.c
+++ b/block/ssh.c
@@ -803,6 +803,26 @@ static int ssh_file_open(BlockDriverState *bs, QDict 
*options, int bdrv_flags,
 return ret;
 }
 
+static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp)
+{
+ssize_t ret;
+char c[1] = { '\0' };
+
+/* offset must be strictly greater than the current size so we do
+ * not overwrite anything */
+assert(offset > 0 && offset > s->attrs.filesize);
+
+libssh2_sftp_seek64(s->sftp_handle, offset - 1);
+ret = libssh2_sftp_write(s->sftp_handle, c, 1);
+if (ret < 0) {
+sftp_error_setg(errp, s, "Failed to grow file");
+return -EIO;
+}
+
+s->attrs.filesize = offset;
+return 0;
+}
+
 static QemuOptsList ssh_create_opts = {
 .name = "ssh-create-opts",
 .head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head),
@@ -822,8 +842,6 @@ static int ssh_create(const char *filename, QemuOpts *opts, 
Error **errp)
 int64_t total_size = 0;
 QDict *uri_options = NULL;
 BDRVSSHState s;
-ssize_t r2;
-char c[1] = { '\0' };
 
 ssh_state_init(&s);
 
@@ -849,14 +867,10 @@ static int ssh_create(const char *filename, QemuOpts 
*opts, Error **errp)
 }
 
 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_setg(errp, &s, "truncate failed");
-ret = -EINVAL;
+ret = ssh_grow_file(&s, total_size, errp);
+if (ret < 0) {
 goto out;
 }
-s.attrs.filesize = total_size;
 }
 
 ret = 0;
-- 
2.14.3