diff options
Diffstat (limited to 'winsup/cygwin/select.cc')
| -rw-r--r-- | winsup/cygwin/select.cc | 44 |
1 files changed, 30 insertions, 14 deletions
diff --git a/winsup/cygwin/select.cc b/winsup/cygwin/select.cc index db52ffc..bc02c3f 100644 --- a/winsup/cygwin/select.cc +++ b/winsup/cygwin/select.cc @@ -584,13 +584,14 @@ no_verify (select_record *, fd_set *, fd_set *, fd_set *) return 0; } -static int -pipe_data_available (int fd, fhandler_base *fh, HANDLE h, bool writing) +ssize_t +pipe_data_available (int fd, fhandler_base *fh, HANDLE h, int flags) { if (fh->get_device () == FH_PIPER) { DWORD nbytes_in_pipe; - if (!writing && PeekNamedPipe (h, NULL, 0, NULL, &nbytes_in_pipe, NULL)) + if (!(flags & PDA_WRITE) + && PeekNamedPipe (h, NULL, 0, NULL, &nbytes_in_pipe, NULL)) return nbytes_in_pipe; return -1; } @@ -609,9 +610,17 @@ 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 ? PIPE_BUF : -1; + switch (flags) + { + case PDA_WRITE: + return 1; + case PDA_SELECT | PDA_WRITE: + return PIPE_BUF; + default: + return -1; + } } - if (writing) + if (flags & PDA_WRITE) { /* If there is anything available in the pipe buffer then signal that. This means that a pipe could still block since you could @@ -638,20 +647,26 @@ pipe_data_available (int fd, fhandler_base *fh, HANDLE h, bool writing) /* Note: Do not use NtQueryInformationFile() for query_hdl because NtQueryInformationFile() seems to interfere with reading pipes in non-cygwin apps. Instead, use PeekNamedPipe() here. */ + /* Note 2: we return the number of available bytes. Select for writing + returns writable *only* if at least PIPE_BUF bytes are left in the + buffer. If we can't fetch the real number of available bytes, the + number of bytes returned depends on the caller. For select we return + PIPE_BUF to fake writability, for writing we return 1 to allow + handling this fact. */ if (fh->get_device () == FH_PIPEW && fpli.WriteQuotaAvailable == 0) { HANDLE query_hdl = ((fhandler_pipe *) fh)->get_query_handle (); if (!query_hdl) query_hdl = ((fhandler_pipe *) fh)->temporary_query_hdl (); - if (!query_hdl) - return PIPE_BUF; /* We cannot know actual write pipe space. */ + if (!query_hdl) /* We cannot know actual write pipe space. */ + return (flags & PDA_SELECT) ? PIPE_BUF : 1; 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 PIPE_BUF; /* We cannot know actual write pipe space. */ + if (!res) /* We cannot know actual write pipe space. */ + return (flags & PDA_SELECT) ? PIPE_BUF : 1; fpli.WriteQuotaAvailable = fpli.InboundQuota - nbytes_in_pipe; } if (fpli.WriteQuotaAvailable > 0) @@ -715,10 +730,10 @@ peek_pipe (select_record *s, bool from_select) gotone = s->read_ready = true; goto out; } - int n = pipe_data_available (s->fd, fh, h, false); + ssize_t n = pipe_data_available (s->fd, fh, h, PDA_SELECT); /* On PTY masters, check if input from the echo pipe is available. */ if (n == 0 && fh->get_echo_handle ()) - n = pipe_data_available (s->fd, fh, fh->get_echo_handle (), false); + n = pipe_data_available (s->fd, fh, fh->get_echo_handle (), PDA_SELECT); if (n < 0) { @@ -759,7 +774,7 @@ out: gotone += s->except_ready = true; return gotone; } - int n = pipe_data_available (s->fd, fh, h, true); + ssize_t n = pipe_data_available (s->fd, fh, h, PDA_SELECT | PDA_WRITE); select_printf ("write: %s, n %d", fh->get_name (), n); gotone += s->write_ready = (n >= PIPE_BUF); if (n < 0 && s->except_selected) @@ -972,7 +987,8 @@ peek_fifo (select_record *s, bool from_select) out: if (s->write_selected) { - int n = pipe_data_available (s->fd, fh, fh->get_handle (), true); + ssize_t n = pipe_data_available (s->fd, fh, fh->get_handle (), + PDA_SELECT | PDA_WRITE); select_printf ("write: %s, n %d", fh->get_name (), n); gotone += s->write_ready = (n >= PIPE_BUF); if (n < 0 && s->except_selected) @@ -1398,7 +1414,7 @@ out: HANDLE h = ptys->get_output_handle (); if (s->write_selected) { - int n = pipe_data_available (s->fd, fh, h, true); + ssize_t n = pipe_data_available (s->fd, fh, h, PDA_SELECT | PDA_WRITE); select_printf ("write: %s, n %d", fh->get_name (), n); gotone += s->write_ready = (n >= PIPE_BUF); if (n < 0 && s->except_selected) |