aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
Diffstat
-rw-r--r--winsup/cygwin/fhandler/pipe.cc44
-rw-r--r--winsup/cygwin/local_includes/select.h5
-rw-r--r--winsup/cygwin/select.cc44
3 files changed, 75 insertions, 18 deletions
diff --git a/winsup/cygwin/fhandler/pipe.cc b/winsup/cygwin/fhandler/pipe.cc
index ce6099d..33ab117 100644
--- a/winsup/cygwin/fhandler/pipe.cc
+++ b/winsup/cygwin/fhandler/pipe.cc
@@ -13,6 +13,7 @@ details. */
#include "security.h"
#include "path.h"
#include "fhandler.h"
+#include "select.h"
#include "dtable.h"
#include "cygheap.h"
#include "pinfo.h"
@@ -433,6 +434,7 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
NTSTATUS status = STATUS_SUCCESS;
IO_STATUS_BLOCK io;
HANDLE evt;
+ bool short_write_once = false;
if (!len)
return 0;
@@ -471,6 +473,7 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
len1 = chunk;
else
len1 = (ULONG) left;
+
/* NtWriteFile returns success with # of bytes written == 0 if writing
on a non-blocking pipe fails because the pipe buffer doesn't have
sufficient space.
@@ -517,6 +520,13 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
}
else
cygwait (select_sem, 10, cw_cancel);
+ /* If we got a timeout in the blocking case, and we already
+ did a short write, we got a signal in the previous loop. */
+ if (waitret == WAIT_TIMEOUT && short_write_once)
+ {
+ waitret = WAIT_SIGNALED;
+ break;
+ }
}
/* Loop in case of blocking write or SA_RESTART */
while (waitret == WAIT_TIMEOUT || waitret == WAIT_SIGNALED);
@@ -533,13 +543,39 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
status = STATUS_THREAD_CANCELED;
else if (waitret == WAIT_SIGNALED)
status = STATUS_THREAD_SIGNALED;
+ else if (waitret == WAIT_TIMEOUT && io.Status == STATUS_CANCELLED)
+ status = STATUS_SUCCESS;
else
status = io.Status;
}
- if (!is_nonblocking () || !NT_SUCCESS (status) || io.Information > 0
- || len <= PIPE_BUF)
+ if (status != STATUS_THREAD_SIGNALED && !NT_SUCCESS (status))
break;
- len1 >>= 1;
+ if (io.Information > 0 || len <= PIPE_BUF || short_write_once)
+ break;
+ /* Independent of being blocking or non-blocking, if we're here,
+ the pipe has less space than requested. If the pipe is a
+ non-Cygwin pipe, just try the old strategy of trying a half
+ write. If the pipe has at
+ least PIPE_BUF bytes available, try to write all matching
+ PIPE_BUF sized blocks. If it's less than PIPE_BUF, try
+ the next less power of 2 bytes. This is not really the Linux
+ strategy because Linux is filling the pages of a pipe buffer
+ in a very implementation-defined way we can't emulate, but it
+ resembles it closely enough to get useful results. */
+ ssize_t avail = pipe_data_available (-1, this, get_handle (),
+ PDA_WRITE);
+ if (avail < 1) /* error or pipe closed */
+ break;
+ if (avail >= len1) /* somebody read from the pipe */
+ avail = len1;
+ if (avail == 1) /* 1 byte left or non-Cygwin pipe */
+ len1 >>= 1;
+ else if (avail >= PIPE_BUF)
+ len1 = avail & ~(PIPE_BUF - 1);
+ else
+ len1 = 1 << (31 - __builtin_clzl (avail));
+ if (!is_nonblocking ())
+ short_write_once = true;
}
if (isclosed ()) /* A signal handler might have closed the fd. */
{
@@ -569,7 +605,7 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
else
__seterrno_from_nt_status (status);
- if (nbytes_now == 0)
+ if (nbytes_now == 0 || short_write_once)
break;
}
out:
diff --git a/winsup/cygwin/local_includes/select.h b/winsup/cygwin/local_includes/select.h
index 4e20212..dea0233 100644
--- a/winsup/cygwin/local_includes/select.h
+++ b/winsup/cygwin/local_includes/select.h
@@ -139,4 +139,9 @@ public:
extern "C" int cygwin_select (int , fd_set *, fd_set *, fd_set *,
struct timeval *to);
+ssize_t pipe_data_available (int, fhandler_base *, HANDLE, int);
+
+#define PDA_WRITE 0x01
+#define PDA_SELECT 0x02
+
#endif /* _SELECT_H_ */
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)
generated by cgit v1.1 at 2024-09-27 05:15:27 +0000