libc: Implement ttyname and ttyname_r

Note: this patch can get file path from root pseudo file handle,
but a general infrastructure is setup for other file system too.

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
Change-Id: I86cd79ebb741f2f43fdd398bb7498c40687d949b

fs/inode/Make.defs

@@ -19,8 +19,8 @@
 ############################################################################
 
 CSRCS += fs_files.c fs_foreachinode.c fs_inode.c fs_inodeaddref.c
-CSRCS += fs_inodebasename.c fs_inodefind.c fs_inodefree.c fs_inoderelease.c
-CSRCS += fs_inoderemove.c fs_inodereserve.c fs_inodesearch.c
+CSRCS += fs_inodebasename.c fs_inodefind.c fs_inodefree.c fs_inodegetpath.c
+CSRCS += fs_inoderelease.c fs_inoderemove.c fs_inodereserve.c fs_inodesearch.c
 
 # Include inode/utils build support
 

fs/inode/fs_inodegetpath.c

@@ -0,0 +1,72 @@
+/****************************************************************************
+ * fs/inode/fs_inodegetpath.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <errno.h>
+#include <string.h>
+#include <nuttx/fs/fs.h>
+
+#include "inode/inode.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: inode_getpath
+ *
+ * Description:
+ *   Given the full path from inode.
+ *
+ ****************************************************************************/
+
+int inode_getpath(FAR struct inode *node, FAR char *path)
+{
+  if (path == NULL)
+    {
+      return -EINVAL;
+    }
+  else if (node == NULL)
+    {
+      path[0] = '\0';
+      return OK;
+    }
+  else if (node->i_parent != NULL)
+    {
+      int ret = inode_getpath(node->i_parent, path);
+      if (ret < 0)
+        {
+          return ret;
+        }
+    }
+
+  strcat(path, node->i_name);
+  if (node->i_child)
+    {
+      strcat(path, "/");
+    }
+
+  return OK;
+}

fs/inode/inode.h

@@ -245,6 +245,16 @@ int inode_find(FAR struct inode_search_s *desc);
 struct stat;  /* Forward reference */
 int inode_stat(FAR struct inode *inode, FAR struct stat *buf, int resolve);
 
+/****************************************************************************
+ * Name: inode_getpath
+ *
+ * Description:
+ *   Given the full path from inode.
+ *
+ ****************************************************************************/
+
+int inode_getpath(FAR struct inode *node, FAR char *path);
+
 /****************************************************************************
  * Name: inode_free
  *

fs/vfs/fs_fcntl.c

@@ -28,6 +28,7 @@
 #include <fcntl.h>
 #include <errno.h>
 #include <assert.h>
+#include <sys/ioctl.h>
 
 #include <nuttx/sched.h>
 #include <nuttx/cancelpt.h>
@@ -206,6 +207,15 @@ static int file_vfcntl(FAR struct file *filep, int cmd, va_list ap)
         ret = -ENOSYS; /* Not implemented */
         break;
 
+      case F_GETPATH:
+        /* Get the path of the file descriptor. The argument must be a buffer
+         * of size PATH_MAX or greater.
+         */
+
+        {
+          ret = file_ioctl(filep, FIOC_FILEPATH, va_arg(ap, FAR char *));
+        }
+
       default:
         break;
     }

fs/vfs/fs_ioctl.c

@@ -103,6 +103,13 @@ int file_vioctl(FAR struct file *filep, int req, va_list ap)
         ret = file_fcntl(filep, F_SETFD,
                          file_fcntl(filep, F_GETFD) & ~FD_CLOEXEC);
         break;
+
+      case FIOC_FILEPATH:
+        if (!INODE_IS_MOUNTPT(inode))
+          {
+            ret = inode_getpath(inode, (FAR char *)(uintptr_t)arg);
+          }
+        break;
     }
 
   return ret;