From bcaf5d75e5e4974dcc4b16e5e9966e2230cb8fd1 Mon Sep 17 00:00:00 2001
From: liuhaitao <liuhaitao@xiaomi.com>
Date: Fri, 19 Mar 2021 12:12:32 +0800
Subject: [PATCH] libc: update stream getoffset to handle write case

Change-Id: I80b01b446446d5a631d40822f220a0177a95e7e6
Signed-off-by: liuhaitao <liuhaitao@xiaomi.com>
---
 libs/libc/stdio/lib_ftell.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/libs/libc/stdio/lib_ftell.c b/libs/libc/stdio/lib_ftell.c
index ff93622fb4..2df6d78b85 100644
--- a/libs/libc/stdio/lib_ftell.c
+++ b/libs/libc/stdio/lib_ftell.c
@@ -37,7 +37,7 @@
  ****************************************************************************/
 
 /****************************************************************************
- * Name: lib_getrdoffset
+ * Name: lib_getoffset
  *
  * Description:
  *   It is insufficient to simply use the file offset; we must also account
@@ -50,9 +50,9 @@
  ****************************************************************************/
 
 #ifndef CONFIG_STDIO_DISABLE_BUFFERING
-static off_t lib_getrdoffset(FAR FILE *stream)
+static off_t lib_getoffset(FAR FILE *stream)
 {
-  off_t rdoffset = 0;
+  off_t offset = 0;
   lib_take_semaphore(stream);
 
   if (stream->fs_bufstart !=
@@ -60,18 +60,22 @@ static off_t lib_getrdoffset(FAR FILE *stream)
       stream->fs_bufstart)
     {
 #if CONFIG_NUNGET_CHARS > 0
-      rdoffset = stream->fs_bufread - stream->fs_bufpos +
+      offset = stream->fs_bufread - stream->fs_bufpos +
                  stream->fs_nungotten;
 #else
-      rdoffset = stream->fs_bufread - stream->fs_bufpos;
+      offset = stream->fs_bufread - stream->fs_bufpos;
 #endif
     }
+  else
+    {
+      offset = -(stream->fs_bufpos - stream->fs_bufstart);
+    }
 
   lib_give_semaphore(stream);
-  return rdoffset;
+  return offset;
 }
 #else
-#  define lib_getrdoffset(stream) (0)
+#  define lib_getoffset(stream) (0)
 #endif
 
 /****************************************************************************
@@ -109,7 +113,7 @@ long ftell(FAR FILE *stream)
   position = lseek(stream->fs_fd, 0, SEEK_CUR);
   if (position != (off_t)-1)
     {
-      return (long)(position - lib_getrdoffset(stream));
+      return (long)(position - lib_getoffset(stream));
     }
   else
     {