[gvfs] sftp: Implement try_query_fs_info using the OpenSSH statvfs extension

[Ross Lagerwall <rossl src gnome org>]

commit da8daebe5cf91c2a02a6adf0b8ccd4c56af5029d
Author: Ross Lagerwall <rosslagerwall gmail com>
Date:   Wed Oct 23 12:21:34 2013 +0200

    sftp: Implement try_query_fs_info using the OpenSSH statvfs extension
    
    Use the statvfs command from OpenSSH to fill in the filesystem size,
    free and used attributes as well as whether the filesystem is readonly
    or not.
    
    The extension is defined at http://api.libssh.org/rfc/PROTOCOL.
    The extension is signified by the name "statvfs openssh com" with a
    version of "2".
    
    Based on a patch Alban Browaeys.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=549207

 daemon/gvfsbackendsftp.c |  130 +++++++++++++++++++++++++++++++++++++++++++++-
 daemon/sftp.h            |    6 ++-
 2 files changed, 134 insertions(+), 2 deletions(-)
---
diff --git a/daemon/gvfsbackendsftp.c b/daemon/gvfsbackendsftp.c
index a95d908..abfd8e4 100644
--- a/daemon/gvfsbackendsftp.c
+++ b/daemon/gvfsbackendsftp.c
@@ -84,6 +84,10 @@
 static GQuark id_q;
 
 typedef enum {
+  SFTP_EXT_OPENSSH_STATVFS,
+} SFTPServerExtensions;
+
+typedef enum {
   SFTP_VENDOR_INVALID = 0,
   SFTP_VENDOR_OPENSSH,
   SFTP_VENDOR_SSH
@@ -162,6 +166,7 @@ struct _GVfsBackendSftp
   guint32 my_gid;
   
   int protocol_version;
+  SFTPServerExtensions extensions;
   
   GOutputStream *command_stream;
   GInputStream *reply_stream;
@@ -246,6 +251,12 @@ get_sftp_client_vendor (void)
   return res;
 }
 
+static gboolean
+has_extension (GVfsBackendSftp *backend, SFTPServerExtensions extension)
+{
+  return (backend->extensions & (1 << extension)) != 0;
+}
+
 static void
 g_vfs_backend_sftp_finalize (GObject *object)
 {
@@ -1561,6 +1572,14 @@ do_mount (GVfsBackend *backend,
           GMountSource *mount_source,
           gboolean is_automount)
 {
+  const struct {
+    const char *name;               /* extension_name field */
+    const char *data;               /* extension_data field */
+    SFTPServerExtensions enable;    /* flag to enable this extension */
+  } extensions[] = {
+    { "statvfs openssh com", "2", SFTP_EXT_OPENSSH_STATVFS },
+  };
+
   GVfsBackendSftp *op_backend = G_VFS_BACKEND_SFTP (backend);
   gchar **args; /* Enough for now, extend if you add more args */
   pid_t pid;
@@ -1573,6 +1592,7 @@ do_mount (GVfsBackend *backend,
   GMountSpec *sftp_mount_spec;
   char *extension_name, *extension_data;
   char *display_name;
+  int i;
 
   args = setup_ssh_commandline (backend);
 
@@ -1653,7 +1673,12 @@ do_mount (GVfsBackend *backend,
       extension_data = read_string (reply, NULL);
       if (extension_data)
         {
-          /* TODO: Do something with this */
+          for (i = 0; i < G_N_ELEMENTS (extensions); i++)
+            {
+              if (!strcmp (extension_name, extensions[i].name) &&
+                  !strcmp (extension_data, extensions[i].data))
+                op_backend->extensions |= 1 << extensions[i].enable;
+            }
         }
       g_free (extension_name);
       g_free (extension_data);
@@ -4131,6 +4156,108 @@ try_query_info (GVfsBackend *backend,
   return TRUE;
 }
 
+static void
+query_fs_info_reply (GVfsBackendSftp *backend,
+                     int reply_type,
+                     GDataInputStream *reply,
+                     guint32 len,
+                     GVfsJob *job,
+                     gpointer user_data)
+{
+  GFileInfo *info = user_data;
+  guint64 frsize, blocks, bfree, bavail, flags;
+
+  if (reply_type == SSH_FXP_STATUS)
+    {
+      guint32 code = read_status_code (reply);
+
+      if (code == SSH_FX_NO_SUCH_FILE)
+        not_dir_or_not_exist_error (backend, job, G_VFS_JOB_QUERY_FS_INFO (job)->filename);
+      else
+        result_from_status_code (job, code, -1, -1);
+      return;
+    }
+  else if (reply_type != SSH_FXP_EXTENDED_REPLY)
+    {
+      g_vfs_job_failed (job,
+                        G_IO_ERROR, G_IO_ERROR_FAILED,
+                        "%s", _("Invalid reply received"));
+      return;
+    }
+
+  g_data_input_stream_read_uint64 (reply, NULL, NULL); /* bsize */
+  frsize = g_data_input_stream_read_uint64 (reply, NULL, NULL);
+  blocks = g_data_input_stream_read_uint64 (reply, NULL, NULL);
+  bfree = g_data_input_stream_read_uint64 (reply, NULL, NULL);
+  bavail = g_data_input_stream_read_uint64 (reply, NULL, NULL);
+  g_data_input_stream_read_uint64 (reply, NULL, NULL); /* files */
+  g_data_input_stream_read_uint64 (reply, NULL, NULL); /* ffree */
+  g_data_input_stream_read_uint64 (reply, NULL, NULL); /* favail */
+  g_data_input_stream_read_uint64 (reply, NULL, NULL); /* fsid */
+  flags = g_data_input_stream_read_uint64 (reply, NULL, NULL);
+  g_data_input_stream_read_uint64 (reply, NULL, NULL); /* namemax */
+
+  /* If free and available are both 0, treat it like the size information is
+   * missing.
+   * */
+  if (bfree || bavail)
+    {
+      g_file_info_set_attribute_uint64 (info,
+                                        G_FILE_ATTRIBUTE_FILESYSTEM_FREE,
+                                        frsize * bavail);
+
+      g_file_info_set_attribute_uint64 (info,
+                                        G_FILE_ATTRIBUTE_FILESYSTEM_SIZE,
+                                        frsize * blocks);
+
+      g_file_info_set_attribute_uint64 (info,
+                                        G_FILE_ATTRIBUTE_FILESYSTEM_USED,
+                                        frsize * (blocks - bfree));
+    }
+
+  g_file_info_set_attribute_boolean (info,
+                                     G_FILE_ATTRIBUTE_FILESYSTEM_READONLY,
+                                     flags & SSH_FXE_STATVFS_ST_RDONLY);
+
+  g_vfs_job_succeeded (job);
+}
+
+static gboolean
+try_query_fs_info (GVfsBackend *backend,
+                   GVfsJobQueryFsInfo *job,
+                   const char *filename,
+                   GFileInfo *info,
+                   GFileAttributeMatcher *matcher)
+{
+  GVfsBackendSftp *op_backend = G_VFS_BACKEND_SFTP (backend);
+  GDataOutputStream *command;
+
+  g_file_info_set_attribute_string (info,
+                                    G_FILE_ATTRIBUTE_FILESYSTEM_TYPE, "sftp");
+
+  if (has_extension (op_backend, SFTP_EXT_OPENSSH_STATVFS) &&
+      (g_file_attribute_matcher_matches (matcher,
+                                         G_FILE_ATTRIBUTE_FILESYSTEM_SIZE) ||
+       g_file_attribute_matcher_matches (matcher,
+                                         G_FILE_ATTRIBUTE_FILESYSTEM_FREE) ||
+       g_file_attribute_matcher_matches (matcher,
+                                         G_FILE_ATTRIBUTE_FILESYSTEM_USED) ||
+       g_file_attribute_matcher_matches (matcher,
+                                         G_FILE_ATTRIBUTE_FILESYSTEM_READONLY)))
+    {
+      command = new_command_stream (op_backend, SSH_FXP_EXTENDED);
+      put_string (command, "statvfs openssh com");
+      put_string (command, filename);
+
+      queue_command_stream_and_free (op_backend, command, query_fs_info_reply,
+                                     G_VFS_JOB (job), info);
+    }
+  else
+    g_vfs_job_succeeded (G_VFS_JOB (job));
+
+  return TRUE;
+}
+
 typedef struct {
    GFileInfo *info;
    GFileAttributeMatcher *attribute_matcher;
@@ -5940,6 +6067,7 @@ g_vfs_backend_sftp_class_init (GVfsBackendSftpClass *klass)
   backend_class->try_close_read = try_close_read;
   backend_class->try_close_write = try_close_write;
   backend_class->try_query_info = try_query_info;
+  backend_class->try_query_fs_info = try_query_fs_info;
   backend_class->try_query_info_on_read = (gpointer) try_query_info_fstat;
   backend_class->try_query_info_on_write = (gpointer) try_query_info_fstat;
   backend_class->try_enumerate = try_enumerate;
diff --git a/daemon/sftp.h b/daemon/sftp.h
index 6b7fc3e..dc1ed4f 100644
--- a/daemon/sftp.h
+++ b/daemon/sftp.h
@@ -20,7 +20,8 @@
  * Author: Alexander Larsson <alexl redhat com>
  */
 
-/* From draft-ietf-secsh-filexfer-02.txt */
+/* From draft-ietf-secsh-filexfer-02.txt
+ * OpenSSH extensions from: http://api.libssh.org/rfc/PROTOCOL */
 
 /* version */
 #define        SSH_FILEXFER_VERSION            3
@@ -85,3 +86,6 @@
 #define SSH_FX_OP_UNSUPPORTED          8
 #define SSH_FX_MAX                     8
 
+/* OpenSSH extension flags */
+#define SSH_FXE_STATVFS_ST_RDONLY      0x1 /* read-only */
+#define SSH_FXE_STATVFS_ST_NOSUID      0x2 /* no setuid */