diff options
Diffstat (limited to 'libio/wfileops.c')
| -rw-r--r-- | libio/wfileops.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/libio/wfileops.c b/libio/wfileops.c index 3199861b4d..f123add354 100644 --- a/libio/wfileops.c +++ b/libio/wfileops.c @@ -713,9 +713,16 @@ do_ftell_wide (_IO_FILE *fp) offset += outstop - out; } - /* _IO_read_end coincides with fp._offset, so the actual file - position is fp._offset - (_IO_read_end - new_write_ptr). */ - offset -= fp->_IO_read_end - fp->_IO_write_ptr; + /* We don't trust _IO_read_end to represent the current file offset + when writing in append mode because the value would have to be + shifted to the end of the file during a flush. Use the write base + instead, along with the new offset we got above when we did a seek + to the end of the file. */ + if (append_mode) + offset += fp->_IO_write_ptr - fp->_IO_write_base; + /* For all other modes, _IO_read_end represents the file offset. */ + else + offset += fp->_IO_write_ptr - fp->_IO_read_end; } } |