diff options
Diffstat (limited to 'libio/fileops.c')
| -rw-r--r-- | libio/fileops.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/libio/fileops.c b/libio/fileops.c index cf68dbfe52..204cfeaa35 100644 --- a/libio/fileops.c +++ b/libio/fileops.c @@ -91,7 +91,9 @@ extern struct __gconv_trans_data __libio_translit attribute_hidden; The position in the buffer that corresponds to the position in external file system is normally _IO_read_end, except in putback - mode, when it is _IO_save_end. + mode, when it is _IO_save_end and also when the file is in append mode, + since switching from read to write mode automatically sends the position in + the external file system to the end of file. If the field _fb._offset is >= 0, it gives the offset in the file as a whole corresponding to eGptr(). (?) @@ -966,6 +968,14 @@ do_ftell (_IO_FILE *fp) /* Adjust for unflushed data. */ if (!was_writing) offset -= fp->_IO_read_end - fp->_IO_read_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. */ + else 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; } |