sftp: Added lsetstat extension

Signed-off-by: Abdelrahman Youssef <abdelrahmanyossef12@gmail.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>

include/libssh/sftp.h

@@ -948,6 +948,29 @@ LIBSSH_API int sftp_rename(sftp_session sftp, const char *original, const  char
  */
 LIBSSH_API int sftp_setstat(sftp_session sftp, const char *file, sftp_attributes attr);
 
+/**
+ * @brief This request is like setstat (excluding mode and size) but sets file
+ * attributes on symlinks themselves.
+ *
+ * Note, that this function can only set time values using 32 bit values due to
+ * the restrictions in the SFTP protocol version 3 implemented by libssh.
+ * The support for 64 bit time values was introduced in SFTP version 5, which is
+ * not implemented by libssh nor any major SFTP servers.
+ *
+ * @param sftp          The sftp session handle.
+ *
+ * @param file          The symbolic link which attributes should be changed.
+ *
+ * @param attr          The file attributes structure with the attributes set
+ *                      which should be changed.
+ *
+ * @return              0 on success, < 0 on error with ssh and sftp error set.
+ *
+ * @see sftp_get_error()
+ */
+LIBSSH_API int
+sftp_lsetstat(sftp_session sftp, const char *file, sftp_attributes attr);
+
 /**
  * @brief Change the file owner and group
  *

src/sftp.c

@@ -1893,6 +1893,10 @@ int sftp_setstat(sftp_session sftp, const char *file, sftp_attributes attr)
     sftp_status_message status = NULL;
     int rc;
 
+    if (sftp == NULL || file == NULL || attr == NULL) {
+        return -1;
+    }
+
     buffer = ssh_buffer_new();
     if (buffer == NULL) {
         ssh_set_error_oom(sftp->session);
@@ -1967,6 +1971,95 @@ int sftp_setstat(sftp_session sftp, const char *file, sftp_attributes attr)
     return -1;
 }
 
+int
+sftp_lsetstat(sftp_session sftp, const char *file, sftp_attributes attr)
+{
+    uint32_t id;
+    ssh_buffer buffer = NULL;
+    sftp_message msg = NULL;
+    sftp_status_message status = NULL;
+    const char *extension_name = "lsetstat@openssh.com";
+    int rc;
+
+    if (sftp == NULL || file == NULL || attr == NULL) {
+        return -1;
+    }
+
+    buffer = ssh_buffer_new();
+    if (buffer == NULL) {
+        ssh_set_error_oom(sftp->session);
+        sftp_set_error(sftp, SSH_FX_FAILURE);
+        return -1;
+    }
+
+    id = sftp_get_new_id(sftp);
+
+    rc = ssh_buffer_pack(buffer, "dss", id, extension_name, file);
+    if (rc != SSH_OK) {
+        ssh_set_error_oom(sftp->session);
+        SSH_BUFFER_FREE(buffer);
+        sftp_set_error(sftp, SSH_FX_FAILURE);
+        return -1;
+    }
+
+    rc = buffer_add_attributes(buffer, attr);
+    if (rc != 0) {
+        ssh_set_error_oom(sftp->session);
+        SSH_BUFFER_FREE(buffer);
+        sftp_set_error(sftp, SSH_FX_FAILURE);
+        return -1;
+    }
+
+    rc = sftp_packet_write(sftp, SSH_FXP_EXTENDED, buffer);
+    SSH_BUFFER_FREE(buffer);
+    if (rc < 0) {
+        return -1;
+    }
+
+    while (msg == NULL) {
+        if (sftp_read_and_dispatch(sftp) < 0) {
+            return -1;
+        }
+        msg = sftp_dequeue(sftp, id);
+    }
+
+    /* By specification, this command only returns SSH_FXP_STATUS */
+    if (msg->packet_type == SSH_FXP_STATUS) {
+        status = parse_status_msg(msg);
+        sftp_message_free(msg);
+        if (status == NULL) {
+            return -1;
+        }
+        sftp_set_error(sftp, status->status);
+        switch (status->status) {
+        case SSH_FX_OK:
+            status_msg_free(status);
+            return 0;
+        default:
+            break;
+        }
+        /*
+         * The status should be SSH_FX_OK if the command was successful, if it
+         * didn't, then there was an error
+         */
+        ssh_set_error(sftp->session,
+                      SSH_REQUEST_DENIED,
+                      "SFTP server: %s",
+                      status->errormsg);
+        status_msg_free(status);
+        return -1;
+    } else {
+        ssh_set_error(sftp->session,
+                      SSH_FATAL,
+                      "Received message %d when attempting to lsetstat",
+                      msg->packet_type);
+        sftp_message_free(msg);
+        sftp_set_error(sftp, SSH_FX_BAD_MESSAGE);
+    }
+
+    return -1;
+}
+
 /* Change the file owner and group */
 int sftp_chown(sftp_session sftp, const char *file, uid_t owner, gid_t group) {
 	struct sftp_attributes_struct attr;