My normal habit these days, in new code, is to treat int and bool as
_almost_ completely separate types. I'm still willing to use C's
implicit test for zero on an integer (e.g. 'if (!blob.len)' is fine,
no need to spell it out as blob.len != 0), but generally, if a
variable is going to be conceptually a boolean, I like to declare it
bool and assign to it using 'true' or 'false' rather than 0 or 1.
PuTTY is an exception, because it predates the C99 bool, and I've
stuck to its existing coding style even when adding new code to it.
But it's been annoying me more and more, so now that I've decided C99
bool is an acceptable thing to require from our toolchain in the first
place, here's a quite thorough trawl through the source doing
'boolification'. Many variables and function parameters are now typed
as bool rather than int; many assignments of 0 or 1 to those variables
are now spelled 'true' or 'false'.
I managed this thorough conversion with the help of a custom clang
plugin that I wrote to trawl the AST and apply heuristics to point out
where things might want changing. So I've even managed to do a decent
job on parts of the code I haven't looked at in years!
To make the plugin's work easier, I pushed platform front ends
generally in the direction of using standard 'bool' in preference to
platform-specific boolean types like Windows BOOL or GTK's gboolean;
I've left the platform booleans in places they _have_ to be for the
platform APIs to work right, but variables only used by my own code
have been converted wherever I found them.
In a few places there are int values that look very like booleans in
_most_ of the places they're used, but have a rarely-used third value,
or a distinction between different nonzero values that most users
don't care about. In these cases, I've _removed_ uses of 'true' and
'false' for the return values, to emphasise that there's something
more subtle going on than a simple boolean answer:
- the 'multisel' field in dialog.h's list box structure, for which
the GTK front end in particular recognises a difference between 1
and 2 but nearly everything else treats as boolean
- the 'urgent' parameter to plug_receive, where 1 vs 2 tells you
something about the specific location of the urgent pointer, but
most clients only care about 0 vs 'something nonzero'
- the return value of wc_match, where -1 indicates a syntax error in
the wildcard.
- the return values from SSH-1 RSA-key loading functions, which use
-1 for 'wrong passphrase' and 0 for all other failures (so any
caller which already knows it's not loading an _encrypted private_
key can treat them as boolean)
- term->esc_query, and the 'query' parameter in toggle_mode in
terminal.c, which _usually_ hold 0 for ESC[123h or 1 for ESC[?123h,
but can also hold -1 for some other intervening character that we
don't support.
In a few places there's an integer that I haven't turned into a bool
even though it really _can_ only take values 0 or 1 (and, as above,
tried to make the call sites consistent in not calling those values
true and false), on the grounds that I thought it would make it more
confusing to imply that the 0 value was in some sense 'negative' or
bad and the 1 positive or good:
- the return value of plug_accepting uses the POSIXish convention of
0=success and nonzero=error; I think if I made it bool then I'd
also want to reverse its sense, and that's a job for a separate
piece of work.
- the 'screen' parameter to lineptr() in terminal.c, where 0 and 1
represent the default and alternate screens. There's no obvious
reason why one of those should be considered 'true' or 'positive'
or 'success' - they're just indices - so I've left it as int.
ssh_scp_recv had particularly confusing semantics for its previous int
return value: its call sites used '<= 0' to check for error, but it
never actually returned a negative number, just 0 or 1. Now the
function and its call sites agree that it's a bool.
In a couple of places I've renamed variables called 'ret', because I
don't like that name any more - it's unclear whether it means the
return value (in preparation) for the _containing_ function or the
return value received from a subroutine call, and occasionally I've
accidentally used the same variable for both and introduced a bug. So
where one of those got in my way, I've renamed it to 'toret' or 'retd'
(the latter short for 'returned') in line with my usual modern
practice, but I haven't done a thorough job of finding all of them.
Finally, one amusing side effect of doing this is that I've had to
separate quite a few chained assignments. It used to be perfectly fine
to write 'a = b = c = TRUE' when a,b,c were int and TRUE was just a
the 'true' defined by stdbool.h, that idiom provokes a warning from
gcc: 'suggest parentheses around assignment used as truth value'!
This commit includes <stdbool.h> from defs.h and deletes my
traditional definitions of TRUE and FALSE, but other than that, it's a
100% mechanical search-and-replace transforming all uses of TRUE and
FALSE into the C99-standardised lowercase spellings.
No actual types are changed in this commit; that will come next. This
is just getting the noise out of the way, so that subsequent commits
can have a higher proportion of signal.
I was having a play with clang's MSVC compatibility mode, just to see
how much of PuTTY it could compile, and one of its warnings pointed
out this error which must have crept in when I was changing the EOF
flags in winhandl.c from booleans to three-state enums - I left the !
on the front of what was previously an if (!thing) and needed to turn
into if (thing == EOF_NO).
Handles managed by winhandl.c have a 'busy' flag, which is used to
mean two things: (a) is a subthread currently blocked on this handle
so various operations in the main thread have to be deferred until it
finishes? And (b) is this handle currently one that should be returned
to the main loop to be waited for?
For HT_INPUT and HT_OUTPUT, those things are either both true or both
false, so a single flag covering both of them is fine. But HT_FOREIGN
handles have the property that they should always be waited for in the
main loop, but no subthread is blocked on them. The latter means that
operations done on them in the main thread should not be deferred; the
only such operation is cleaning them up in handle_free().
handle_free() was failing to spot this, and was deferring freeing
HT_FOREIGN handles until their subthread terminated - which of course
never happened. As a result, when a named pipe server was closed, its
actual Windows event object got destroyed, but winhandl.c still kept
passing it back to the main thread, leading to a tight loop because
MsgWaitForMultipleObjects would return ERROR_INVALID_HANDLE and never
block.
When a winhandl.c input thread returns EOF to the main thread, the
latter might immediately delete the input thread's context. I
carefully wrote in a comment that in that case we had to not touch ctx
ever again after signalling to the main thread - but the test for
whether that was true, which also touched ctx, itself came _after_ the
SetEvent which sent that signal. Ahem.
Spotted by Minefield, which it looks as if I haven't run for a while.
To understand the handle leak bug that I fixed in git commit
7549f2da40, I had to think fairly hard
to remind myself what all this code was doing, which means the
comments weren't good enough. Expanded and rewritten some of them in
the hope that things will be clearer next time.
If (say) a read handle returns EOF, and its gotdata function responds
by calling handle_free(), then we want the handle to have already had
its defunct flag set so that the handle can be destroyed. Otherwise
handle_free will set the 'done' flag to ask the subthread to
terminate, and then sit and wait for it to say it's done so -
forgetting that it signalled termination already by returning EOF, and
hence will not be responding to that signal.
Ditto for write errors on write handles, though that should happen
less often.
The code for cleaning up handle structures works by the main thread
asking the per-handle subthread to shut down by means of setting its
'done' flag, and then once the subthread signals back through its
event object that it's done so, the main thread frees all its
resources and removes the event object from the list of things being
checked in the program's event loop.
But read threads were not sending back that final event acknowledging
a request to shut down, so their event objects were never being
cleaned up.
Bug spotted by Ronald Weiss.
Mike Edenfield points out that modern versions of the Windows SDK have
decided that 'INPUT' is a sensible name for an OS data structure
(sigh), and provided a patch to add a disambiguating prefix to
winhandl.c's enum values INPUT, OUTPUT and FOREIGN.
[originally from svn r10109]
This commit adds two new support modules, winnpc.c and winnps.c, which
deal respectively with being a client and server of a Windows named
pipe (which, in spite of what Unix programmers will infer from that
name, is actually closer to Windows's analogue of a Unix-domain
socket). Each one provides a fully featured Socket wrapper around the
hairy Windows named pipe API, so that the rest of the code base should
be able to use these interchangeably with ordinary sockets and hardly
notice the difference.
As part of this work, I've introduced a mechanism in winhandl.c to
permit it to store handles of event objects on behalf of other Windows
support modules and deal with passing them to applications' main event
loops as necessary. (Perhaps it would have been cleaner to split
winhandl.c into an event-object tracking layer analogous to uxsel, and
the handle management which is winhandl.c's proper job, but this is
less disruptive for the present.)
[originally from svn r10069]
data channels. Should comprehensively fix 'half-closed', in principle,
though it's a big and complicated change and so there's a good chance
I've made at least one mistake somewhere.
All connections should now be rigorous about propagating end-of-file
(or end-of-data-stream, or socket shutdown, or whatever) independently
in both directions, except in frontends with no mechanism for sending
explicit EOF (e.g. interactive terminal windows) or backends which are
basically always used for interactive sessions so it's unlikely that
an application would be depending on independent EOF (telnet, rlogin).
EOF should now never accidentally be sent while there's still buffered
data to go out before it. (May help fix 'portfwd-corrupt', and also I
noticed recently that the ssh main session channel can accidentally
have MSG_EOF sent before the output bufchain is clear, leading to
embarrassment when it subsequently does send the output).
[originally from svn r9279]
OVERLAPPED structure in output threads, as we already do for input
threads. This apparently sorts out a hanging issue with serial ports
when trying to do simultaneous read and write, because (GJV says,
and it sounds plausible to me) in the absence of that event object
Windows signals the file handle itself to notify GetOverlappedResult
that it can return - and since the file handle might be being
signalled by a read operation instead, that leads to ambiguity.
Using an explicit event object in both directions means Windows
always knows which way the data is going.
Also a trivial fix in handle_output_new(), which was referencing the
wrong element of a union due to a copy and paste error. (Since the
result was address-taken and cast to void *, this wasn't a
functional error, but it was conceptually wrong.)
[originally from svn r8410]
Instead of passing -1 to its gotdata and sentdata callbacks on
error, winhandl.c will now pass the negation of the Windows error
number; and the Plink front end will now format that into an error
message and pass it on to the user.
[originally from svn r7416]
[r7415 == 702a92ceb8]
from is closed normally from the writing end. This is ludicrous; if
that situation isn't a natural EOF, _nothing_ is. So if we get that
particular error, we pretend it's EOF.
[originally from svn r7415]
which have been broken since r6797.
(At least some versions of Win9x are gratuitously picky about the arguments to
CreateThread(), requiring lpThreadId not to be NULL.)
[originally from svn r7132]
[r6797 == 291533d3f9]
required. (I just tried getting rid of them; it worked fine for
serial ports, but not for anything else. The Windows I/O API sucks.)
[originally from svn r6843]
unfriendly in an interactive session, because at 19200 baud it takes
nearly two seconds to receive that much data, and as long as the
data is flowing continuously Windows waits until it has a full
buffer. So here's another annoying flag in the winhandl API, which
restricts reads to length 1 so that serial output shows up as it
appears.
(I tried this yesterday, but without the OVERLAPPED fix in r6826 it
behaved very erratically. It now seems solid.)
[originally from svn r6827]
[r6826 == 2aedc83f8d]
a serial port backend:
- In order to do simultaneous reading and writing on the same
HANDLE, you must enable overlapped access and pass an OVERLAPPED
structure to each ReadFile and WriteFile call. This would make
sense if it were an optional thing I could do if I wanted to do
the reading and writing in the same thread, but making it
mandatory even if I'm doing them in _different_ threads is just
annoying and arbitrary.
- Serial ports occasionally return length 0 from ReadFile, for no
particularly good reason. Fortunately serial ports also don't
have a real EOF condition to speak of, so ignoring EOFs is
actually a viable response in spite of sounding utterly gross.
Hence, handle_{input,output}_new() now accept a flags parameter,
which includes a flag to enable the OVERLAPPED bureaucracy and a
flag to cause EOFs to be ignored on input handles. The current
clients of winhandl.c do not use either of these.
[originally from svn r6813]
to do something, otherwise handle_get_events will forget to tell the
front end to check for that subthread finishing. This applies even
when we're only setting `busy' to tell the subthread to terminate!
[originally from svn r6805]
thread-based approach to stdin and stdout, wraps it in a halfway
sensible API, and makes it a globally available service across all
network tools.
There is no direct functionality enhancement from this checkin:
winplink.c now talks to the new API instead of doing it all
internally, but does nothing different as a result.
However, this should lay the groundwork for several diverse pieces
of work in future: pipe-based ProxyCommand on Windows, a serial port
back end, and (hopefully) a pipe-based means of communicating with
Pageant, which should have sensible blocking behaviour and hence
permit asynchronous agent requests and decrypt-on-demand.
[originally from svn r6797]
