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Cygwin: set buffer size for pipes created by non-Cygwin processes 

Rename fhandler_pipe_and_fifo::max_atomic_write to pipe_buf_size.
This reflect its actual meaning better.  The fhandler_pipe_and_fifo
constructor initializes it to DEFAULT_PIPEBUFSIZE (== 64K), which is
the buffer size for the windows pipes created by fhandler_pipe and
fhandler_fifo.  But if we inherit a stdio pipe handle from a
non-Cygwin process, the buffer size could be different.

To remedy this, add a method fhandler_pipe::set_pipe_buf_size that
queries the OS for the pipe buffer size, and use it in
dtable::init_std_file_from_handle.
This commit is contained in:
Ken Brown 2021-09-07 17:40:21 -04:00 committed by Corinna Vinschen
parent 27b24069d1
commit 99be238347
3 changed files with 27 additions and 6 deletions
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5
winsup/cygwin/dtable.cc
View File

@ -406,6 +406,11 @@ dtable::init_std_file_from_handle (int fd, HANDLE handle)
}
if (!fh->init (handle, access, bin))
api_fatal ("couldn't initialize fd %d for %s", fd, fh->get_name ());
if (fh->ispipe ())
{
fhandler_pipe *fhp = (fhandler_pipe *) fh;
fhp->set_pipe_buf_size ();
}
fh->open_setup (openflags);
fh->usecount = 0;

3
winsup/cygwin/fhandler.h
View File

@ -1172,7 +1172,7 @@ class fhandler_socket_unix : public fhandler_socket
class fhandler_pipe_fifo: public fhandler_base
{
protected:
size_t max_atomic_write;
size_t pipe_buf_size;
public:
fhandler_pipe_fifo ();
@ -1192,6 +1192,7 @@ public:
bool ispipe() const { return true; }
void set_read_mutex (HANDLE mtx) { read_mtx = mtx; }
void set_pipe_buf_size ();
void set_popen_pid (pid_t pid) {popen_pid = pid;}
pid_t get_popen_pid () const {return popen_pid;}

25
winsup/cygwin/fhandler_pipe.cc
View File

@ -29,7 +29,7 @@ STATUS_PIPE_EMPTY simply means there's no data to be read. */
|| _s == STATUS_PIPE_EMPTY; })
fhandler_pipe_fifo::fhandler_pipe_fifo ()
: fhandler_base (), max_atomic_write (DEFAULT_PIPEBUFSIZE)
: fhandler_base (), pipe_buf_size (DEFAULT_PIPEBUFSIZE)
{
}
@ -269,7 +269,7 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
buffer size - 1. Pending read lowers WriteQuotaAvailable on
the write side and thus affects select's ability to return
more or less reliable info whether a write succeeds or not. */
ULONG chunk = max_atomic_write - 1;
ULONG chunk = pipe_buf_size - 1;
status = NtQueryInformationFile (get_handle (), &io,
&fpli, sizeof (fpli),
FilePipeLocalInformation);
@ -391,12 +391,12 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
if (!len)
return 0;
if (len <= max_atomic_write)
if (len <= pipe_buf_size)
chunk = len;
else if (is_nonblocking ())
chunk = len = max_atomic_write;
chunk = len = pipe_buf_size;
else
chunk = max_atomic_write;
chunk = pipe_buf_size;
/* Create a wait event if the pipe or fifo is in blocking mode. */
if (!is_nonblocking () && !(evt = CreateEvent (NULL, false, false, NULL)))
@ -894,6 +894,21 @@ nt_create (LPSECURITY_ATTRIBUTES sa_ptr, HANDLE &r, HANDLE &w,
return 0;
}
/* Called by dtable::init_std_file_from_handle for stdio handles
inherited from non-Cygwin processes. */
void
fhandler_pipe::set_pipe_buf_size ()
{
NTSTATUS status;
IO_STATUS_BLOCK io;
FILE_PIPE_LOCAL_INFORMATION fpli;
status = NtQueryInformationFile (get_handle (), &io, &fpli, sizeof fpli,
FilePipeLocalInformation);
if (NT_SUCCESS (status))
pipe_buf_size = fpli.InboundQuota;
}
int
fhandler_pipe::ioctl (unsigned int cmd, void *p)
{