Add data and methods to the shared memory that keep track of the
number of open readers.
Increment this number in open, dup, fork, and exec. Decrement it in
close. Reset read_ready if there are no readers left.
Even though we currently allow a FIFO to be opened for reading only
once, we can still have more than one reader open because of dup and
fork. Add a named shared memory section accessible to all readers of
a given FIFO. In future commits we will add information needed by all
readers to this section
Add a class fifo_shmem_t that lets us access this information.
Add a method create_shmem that is called when a reader opens, and add
a method reopen_shmem that is called by dup, fork, and exec. (Each
new reader needs its own view of the shared memory.)
This will simplify future work.
Rename the thread from "listen_client_thread" to "fifo_reader_thread"
because it will be used for more than just listening.
Remove the fixup_before stuff, which won't be needed after future
changes to fixup_after_fork and fixup_after_exec.
- Make read_ready a manual-reset event.
- Signal read_ready in open instead of in the listen_client_thread.
- Don't reset read_ready when the listen_client thread terminates;
instead do it in close().
- Rearrange open and change its error handling.
- Add a wait_open_pipe method that waits for a pipe instance to be
available and then calls open_pipe. Use it when opening a writer if
we can't connect immediately. This can happen if the system is
heavily loaded and/or if many writers are trying to open
simultaneously.
According to Posix, a FIFO open for reading is at EOF if it is empty
and there are no writers open.
The only way to test this is to poll the fifo_client_handlers as in
raw_read and select.cc:peek_fifo. The current hit_eof instead relies
on the value of nconnected, which can be out of date. On the one
hand, it doesn't take into account writers that were connected but
have since closed. On the other hand, it doesn't take into account
writers that are in the process of opening but haven't yet connected.
Fix this by introducing a maybe_eof method that tentatively assumes
EOF if there are no connected writers after polling. Then check for
writers currently opening (via a new 'writer_opening' event), and wait
for the fifo_reader_thread to record any new connection that was made
while we were polling.
To handle the needs of peek_fifo, replace the get_fc_handle method
by a get_fc_handler method, and add a fifo_client_handler::get_state
method.
Remove the is_connected method, which was used only in peek_fifo and
is no longer needed.
Remove the nconnected data member, which was used only for the flawed
hit_eof.
Add some comments about events to fhandler.h.
Always return 0; no one is doing anything with the return value
anyway.
Remove the return value from stop_listen_client.
Make the connection event auto-reset, so that we don't have to reset
it later.
Simplify the process of connecting a bogus client when thread
termination is signaled.
Make some failures fatal.
Remove the unnecessary extra check for thread termination near the end
of listen_client_thread.
Make the values correspond to the possible return values of
fifo_client_handler::pipe_state().
When cleaning up the fc_handler list in listen_client_thread(), don't
delete handlers in the fc_closing state. I think the pipe might still
have input to be read in that case.
Set the state to fc_closing later in the same function if a connection
is made and the status returned by NtFsControlFile is
STATUS_PIPE_CLOSING.
In raw_read, don't error out if NtReadFile returns an unexpected
status; just set the state of that handler to fc_error. One writer in
a bad state doesn't justify giving up on reading.
Replace the 'fhandler_base *' member by a HANDLE to the server side of
the Windows named pipe instance. Make the corresponding
simplifications throughout.
When `cygwin-console-helper.exe` is either missing, or corresponds to a
different Cygwin runtime, we currently wait forever while setting up
access to the pseudo console, even long after the process is gone that
was supposed to signal that it set up access to the pseudo console.
Let's handle that more gracefully: if the process exited without
signaling, we cannot use the pseudo console. In that case, let's just
fall back to not using it.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The workaround to access the full disk required since Vista
and described in http://support.microsoft.com/kb/942448
(NOT ACCESSIBLE at the time of writing this commit message)
is required on floppy drives as well.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
The cast to generate the return value uses a DWORD variable
as test and set value. The error case is the constant -1.
Given the type of the other half of the conditioal expression,
-1 is cast to DWORD as well.
On 64 bit, this results in the error case returning a 32 bit
-1 value which is equivalent to (ssize_t) 4294967295 rather
than (ssize_t) -1.
Add a fixing cast.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
The return type of fhandler write methods is ssize_t. Don't
use an int to store the return value, use ssize_t. Use ptrdiff_t
for the buffer size.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
The implicit assumption seemed to be that any subsequent occurence of
the same setting in nsswitch.conf is supposed to rewrite the previous
ones completely. This was not the case if the third or any further
schema was previously defined and the last line defined less than that
(but at least 2), for example:
```
db_home: windows cygwin /myhome/%U
db_home: cygwin desc
```
Let's document this behavior as well.
Signed-off-by: David Macek <david.macek.0@gmail.com>
If the cygdrive prefix is /, then the following happens right now:
$ ln -s /tmp/foo .
$ ls -l foo
lrwxrwxrwx 1 user group 12 Apr 15 23:44 foo -> /mnt/tmp/foo
Fix this by skipping cygdrive prefix conversion to WSL drive
prefix "/mnt", if the cygdrive prefix is just "/". There's no
satisfying way to do the right thing all the time in this case
anyway. For a description and the alternatives, see
https://cygwin.com/pipermail/cygwin-developers/2020-April/011859.html
Also, fix a typo in a comment.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
If the first scheme in db_* was invalid, the code would think there
were no schemes specified and replace the second scheme with
NSS_SCHEME_DESC.
Signed-off-by: David Macek <david.macek.0@gmail.com>
So far Cygwin was jumping through hoops to restrict memory
allocation to specific regions. With the advent of VirtualAlloc2
and MapViewOfFile3 (and it's NT counterpart NtMapViewOfSectionEx),
we can skip searching for free space in the specific regions
and just call these functions and let the OS do the job more
efficiently and less racy.
Use VirtualAlloc2 on W10 1803 and later in thread stack allocation.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
So far Cygwin was jumping through hoops to restrict memory
allocation to specific regions. With the advent of VirtualAlloc2
and MapViewOfFile3 (and it's NT counterpart NtMapViewOfSectionEx),
we can skip searching for free space in the specific regions
and just call these functions and let the OS do the job more
efficiently and less racy.
Use the new functions on W10 1803 and later in mmap.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Windows 10 1803 introduced an extended memory API allowing
to specify memory regions allocations are to be taken off.
In preparation of using this API, define the struct
MEM_EXTENDED_PARAMETER and friends. Declare and allow to
autoload the functions VirtualAlloc2 and NtMapViewOfSectionEx.
Introduce a wincap flag has_extended_mem_api.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Otherwise big stacks have a higher probability to collide with
randomized PEBs and TEBs after fork.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Unfortunately Windows doesn't understand WSL symlinks,
despite being a really easy job. NT functions trying
to access paths traversing WSL symlinks return the status
code STATUS_IO_REPARSE_TAG_NOT_HANDLED. Handle this
status code same as STATUS_OBJECT_PATH_NOT_FOUND in
symlink_info::check to align behaviour to traversing
paths with other non-NTFS type symlinks.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
WSL symlinks are reparse points containing a POSIX path in UTF-8.
On filesystems supporting reparse points, use this symlink type.
On other filesystems, or in case of error, fall back to the good
old plain SYSTEM file.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Commit 4a36897af3 allowed to convert /mnt/<drive> path
prefixes to Cygwin cygdrive prefixes on the fly. However,
the patch neglected WSL symlinks pointing to the /mnt
directory. Rearrange path conversion so /mnt is converted
to the cygdrive prefix path itself.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Treat WSL symlinks just like other symlinks. Convert
absolute paths pointing to Windows drives via
/mnt/<driveletter> to Windows-style paths <driveletter>:
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This reverts commit 082f2513c7.
Turns out, Linux as well as BSD really only wait for the smaller
number, MIN or # of requested bytes.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Ken Brown
Corinna Vinschen
Johannes Schindelin
David Macek via Cygwin-patches
Brian Inglis
Biswapriyo Nath