Fix fseek/ftell; add fsetpos/fgetpos

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@862 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 24 insertions, 4 deletions

diff --git a/nuttx/lib/lib_fseek.c b/nuttx/lib/lib_fseek.c
index 18781b6e3..379e5c322 100644
--- a/nuttx/lib/lib_fseek.c
+++ b/nuttx/lib/lib_fseek.c
@@ -89,11 +89,25 @@
 
 /****************************************************************************
  * Name: fseek
+ *
+ * Description:
+ *   The fseek() function sets the file position indicator for the stream
+ *   pointed to by stream. The new position, measured in bytes, is obtained
+ *   by adding offset bytes to the position specified by whence. If whence is
+ *   set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset is relative to the
+ *   start of the file, the current position indicator, or end-of-file,
+ *   respectively. A successful call to the fseek() function clears the
+ *   end-of-file indicator for the stream and undoes any effects of the ungetc(3)
+ *   function on the same stream.
+ *
+ * Returned Value:
+ *   Zero on succes; -1 on failure with errno set appropriately. 
+ *
  ****************************************************************************/
 
-int fseek(FILE *stream, long int offset, int whence)
+int fseek(FAR FILE *stream, long int offset, int whence)
 {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+ #if CONFIG_STDIO_BUFFER_SIZE > 0
   /* Flush any valid read/write data in the buffer (also verifies stream) */
 
   if (lib_rdflush(stream) < 0 || lib_wrflush(stream) < 0)
@@ -105,14 +119,20 @@ int fseek(FILE *stream, long int offset, int whence)
 
   if (!stream)
     {
-      *get_errno_ptr() = EBADF;
+      errno = EBADF;
       return ERROR;
     }
 #endif
 
+  /* On success or failure, discard any characters saved by ungetc() */
+
+#if CONFIG_NUNGET_CHARS > 0
+  stream->fs_nungotten = 0;
+#endif
+
   /* Perform the fseek on the underlying file descriptor */
 
-  return lseek(stream->fs_filedes, offset, whence) >= 0 ? OK : ERROR;
+  return lseek(stream->fs_filedes, offset, whence) == (off_t)-1 ? ERROR : OK;
 }