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Cygwin: select: set pipe writable only if PIPE_BUF bytes left

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Linux select(2) returns the pipe as writable if at least one
free page (4K onl most systems) is left in a page-oriented buffer
handling. This is the same as PIPE_BUF.

Emulate this behaviour by only returning the pipe as writable
if at least 4K space is left in the buffer.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2024-08-18 21:55:52 +02:00
parent 3d9eb1b2c5
commit 555afcb2f3
1 changed files with 9 additions and 9 deletions
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18
winsup/cygwin/select.cc
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@ -591,7 +591,7 @@ pipe_data_available (int fd, fhandler_base *fh, HANDLE h, bool writing)
{
DWORD nbytes_in_pipe;
if (!writing && PeekNamedPipe (h, NULL, 0, NULL, &nbytes_in_pipe, NULL))
return nbytes_in_pipe > 0;
return nbytes_in_pipe;
return -1;
}
@ -609,7 +609,7 @@ pipe_data_available (int fd, fhandler_base *fh, HANDLE h, bool writing)
access on the write end. */
select_printf ("fd %d, %s, NtQueryInformationFile failed, status %y",
fd, fh->get_name (), status);
return writing ? 1 : -1;
return writing ? PIPE_BUF : -1;
}
if (writing)
{
@ -644,14 +644,14 @@ pipe_data_available (int fd, fhandler_base *fh, HANDLE h, bool writing)
if (!query_hdl)
query_hdl = ((fhandler_pipe *) fh)->temporary_query_hdl ();
if (!query_hdl)
return 1; /* We cannot know actual write pipe space. */
return PIPE_BUF; /* We cannot know actual write pipe space. */
DWORD nbytes_in_pipe;
BOOL res =
PeekNamedPipe (query_hdl, NULL, 0, NULL, &nbytes_in_pipe, NULL);
if (!((fhandler_pipe *) fh)->get_query_handle ())
CloseHandle (query_hdl); /* Close temporary query_hdl */
if (!res)
return 1;
return PIPE_BUF; /* We cannot know actual write pipe space. */
fpli.WriteQuotaAvailable = fpli.InboundQuota - nbytes_in_pipe;
}
if (fpli.WriteQuotaAvailable > 0)
@ -659,7 +659,7 @@ pipe_data_available (int fd, fhandler_base *fh, HANDLE h, bool writing)
paranoid_printf ("fd %d, %s, write: size %u, avail %u", fd,
fh->get_name (), fpli.InboundQuota,
fpli.WriteQuotaAvailable);
return 1;
return fpli.WriteQuotaAvailable;
}
/* TODO: Buffer really full or non-Cygwin reader? */
}
@ -667,7 +667,7 @@ pipe_data_available (int fd, fhandler_base *fh, HANDLE h, bool writing)
{
paranoid_printf ("fd %d, %s, read avail %u", fd, fh->get_name (),
fpli.ReadDataAvailable);
return 1;
return fpli.ReadDataAvailable;
}
if (fpli.NamedPipeState & FILE_PIPE_CLOSING_STATE)
return -1;
@ -761,7 +761,7 @@ out:
}
int n = pipe_data_available (s->fd, fh, h, true);
select_printf ("write: %s, n %d", fh->get_name (), n);
gotone += s->write_ready = n;
gotone += s->write_ready = (n >= PIPE_BUF);
if (n < 0 && s->except_selected)
gotone += s->except_ready = true;
}
@ -974,7 +974,7 @@ out:
{
int n = pipe_data_available (s->fd, fh, fh->get_handle (), true);
select_printf ("write: %s, n %d", fh->get_name (), n);
gotone += s->write_ready = n;
gotone += s->write_ready = (n >= PIPE_BUF);
if (n < 0 && s->except_selected)
gotone += s->except_ready = true;
}
@ -1400,7 +1400,7 @@ out:
{
int n = pipe_data_available (s->fd, fh, h, true);
select_printf ("write: %s, n %d", fh->get_name (), n);
gotone += s->write_ready = n;
gotone += s->write_ready = (n >= PIPE_BUF);
if (n < 0 && s->except_selected)
gotone += s->except_ready = true;
}