On Tue, Sep 8, 2015 at 11:21 AM, Ivan Zhakov <i...@visualsvn.com> wrote:
> On 7 September 2015 at 18:06, <kot...@apache.org> wrote: > > Author: kotkov > > Date: Mon Sep 7 15:06:57 2015 > > New Revision: 1701633 > > > > URL: http://svn.apache.org/r1701633 > > Log: > > Fix svn_stream_for_stdin() and related functions for STDOUT and STDERR > > that were returning streams with mark() and seek() capabilities. > > > > STDIN, STDOUT and STDERR don't provide general support for positioning > > requests. This behavior is implementation-specific and depends on what's > > passed as the corresponding handle. For example, on Linux, > apr_file_seek() > > that calls lseek() internally fails with ESPIPE [1] when the descriptor > is > > associated with a terminal device. As we cannot safely advertise mark() > > and seek() support for these streams, don't do that. > Good find! > > [1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/lseek.html > > > > * subversion/libsvn_subr/stream.c > > (svn_stream_for_stdin, svn_stream_for_stdout, svn_stream_for_stderr): > > Don't install mark and seek handlers. > > > It may be worth to introduce local helper like > 'make_stream_from_apr_file(svn_boolean_t supports_seek)' and use it in > svn_stream_from_apr_file2() and svn_stream_for_stdin() instead of > clearing mark/seek handlers after calling svn_stream_from_apr_file2(). > > Another problem that currently svn_stream_t for stdin/stderr/stdout > pretends to support native svn_stream_skip(), while I'm not sure that > all platforms support seek for stdin. > One more thing we could do is not adding mark & seek on stream based on write-only files. I haven't tried but that's something we should be able to do generically in svn_stream_from_apr_file already. -- Stefan^2.
