https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=555afcb2f3a6638084912ce1011bd6acef59ea79
commit 555afcb2f3a6638084912ce1011bd6acef59ea79 Author: Corinna Vinschen <[email protected]> AuthorDate: Sun Aug 18 21:55:52 2024 +0200 Commit: Corinna Vinschen <[email protected]> CommitDate: Thu Aug 22 19:58:49 2024 +0200 Cygwin: select: set pipe writable only if PIPE_BUF bytes left 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 <[email protected]> Diff: --- winsup/cygwin/select.cc | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/winsup/cygwin/select.cc b/winsup/cygwin/select.cc index 725aab90c7a6..db52ffcccf8e 100644 --- a/winsup/cygwin/select.cc +++ b/winsup/cygwin/select.cc @@ -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; }
