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Author SHA1 Message Date
Dimitri Papadopoulos Orfanos
71c75561e5 Fix typos found by codespell (#12475)
<!-- Enter a brief description/summary of your PR here. What does it fix/what does it change/how was it tested (even manually, if necessary)? -->
## Summary of the Pull Request

Fix typos found by codespell. Some of it in documentation and user-visible text, mostly in code comments. While I understand you might not be interested in fixing code comments, one of the reasons being extra noise in git history, kindly note that most spell checking tools do not discriminate between documentation and code comments. So it's easier to fix everything for long maintenance.

<!-- Other than the issue solved, is this relevant to any other issues/existing PRs? --> 
## References

<!-- Please review the items on the PR checklist before submitting-->
## PR Checklist
* [ ] Closes #xxx
* [X] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [x] Tests added/passed
* [X] Documentation updated. If checked, please file a pull request on [our docs repo](https://github.com/MicrosoftDocs/terminal) and link it here: [#501](https://github.com/MicrosoftDocs/terminal/pull/501)
* [ ] Schema updated.
* [ ] I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #xxx

<!-- Provide a more detailed description of the PR, other things fixed or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

<!-- Describe how you validated the behavior. Add automated tests wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

I have checked and re-checked all changes.
2022-02-17 17:58:31 +00:00
James Holderness
d79cf254be Simplify the IStateMachineEngine interface (#12277)
There were a number of methods in the `IStateMachineEngine` interface
which controlled how the `StateMachine` interpreted escape sequences.
But essentially what it came down to was a bunch of a properties that
were always true for the `InputStateMachineEngine`, and always false for
the `OutputStateMachine` engine. To simplify the implementation, and
make things a little more efficient, I've now replaced all of those
virtual calls with a single boolean field in the `StateMachine` that is
initialised in the constructor. 

I started by adding an `isEngineForInput` parameter to the constructor
to indicate the the type of engine being passed in. But to keep things
simple for callers, and I also then added a constructor without that
parameter, which could derive the value automatically based on the type
of the engine pointer.

Then in the `StateMachine` implementation, anywhere we were previously
calling `ParseControlSequenceAfterSs3`, `FlushAtEndOfString`,
`DispatchControlCharsFromEscape`, or `DispatchIntermediatesFromEscape`,
we now just reference `_isEngineForInput`. But I've also copied across
some of the original comments from those methods, to make it clear at
the point of usage why we have a difference in behavior for input and
output.

To make sure the unit tests would catch any problems, I hardcoded the
`_isEngineForInput` field to `false`, and confirmed that it broke a
bunch of input engine tests. Then I hardcoded it to `true`, and
confirmed that it broke a bunch of state machine and output engine
tests. With the `_isEngineForInput` set correctly, everything passed.

I also manually tested the various output edge cases that would be
effected by this code - C0 controls within an escape sequence, time
delays in the middle of an escape sequence, `SCS` character set
selection which requires intermediates following an escape, and a G3
single shift select which depends on `SS3`.

Closes #12254
2022-01-28 21:03:26 +00:00
James Holderness
2559ed6efa Introduce a mechanism for passing through DCS data strings (#9307)
This PR introduces a mechanism via which DCS data strings can be passed
through directly to the dispatch method that will be handling them, so
the data can be processed as it is received, rather than being buffered
in the state machine. This also simplifies the way string termination is
handled, so it now more closely matches the behaviour of the original
DEC terminals.

* Initial support for DCS sequences was introduced in PR #6328.
* Handling of DCS (and other) C1 controls was added in PR #7340.
* This is a prerequisite for Sixel (#448) and Soft Font (#9164) support.

The way this now works, a `DCS` sequence is dispatched as soon as the
final character of the `VTID` is received. Based on that ID, the
`OutputStateMachineEngine` should forward the call to the corresponding
dispatch method, and its the responsibility of that method to return an
appropriate handler function for the sequence.

From then on, the `StateMachine` will pass on all of the remaining bytes
in the data string to the handler function. When a data string is
terminated (with `CAN`, `SUB`, or `ESC`), the `StateMachine` will pass
on one final `ESC` character to let the handler know that the sequence
is finished. The handler can also end a sequence prematurely by
returning false, and then all remaining data bytes will be ignored.

Note that once a `DCS` sequence has been dispatched, it's not possible
to abort the data string. Both `CAN` and `SUB` are considered valid
forms of termination, and an `ESC` doesn't necessarily have to be
followed by a `\` for the string terminator. This is because the data
string is typically processed as it's received. For example, when
outputting a Sixel image, you wouldn't erase the parts that had already
been displayed if the data string is terminated early.

With this new way of handling the string termination, I was also able to
simplify some of the `StateMachine` processing, and get rid of a few
states that are no longer necessary. These changes don't apply to the
`OSC` sequences, though, since we're more likely to want to match the
XTerm behavior for those cases (which requires a valid `ST` control for
the sequence to be accepted).

## Validation Steps Performed

For the unit tests, I've had to make a few changes to some of the
`OutputEngineTests` to account for the updated `StateMachine`
processing. I've also added a new `StateMachineTest` to confirm that the
data strings are correctly passed through to the string handler under
all forms of termination.

To test whether the framework is actually usable, I've been working on
DRCS Soft Font support branched off of this PR, and haven't encountered
any problems. To test the throughput speed, I also hacked together a
basic Sixel parser, and that seemed to perform reasonably well.

Closes #7316
2021-04-30 19:17:30 +00:00
James Holderness
55151a4a04 Refactor VT parameter handling (#7799)
This PR introduces a pair of classes for managing VT parameters that
automatically handle range checking and default fallback values, so the
individual operations don't have to do that validation themselves. In
addition to simplifying the code, this fixes a few cases where we were
mishandling missing or extraneous parameters, and adds support for
parameter sequences on commands that couldn't previously handle them.
This PR also sets a limit on the number of parameters allowed, to help
thwart DoS memory consumption attacks.

## References

* The new parameter class also introduces the concept of an
  omitted/default parameter which is not necessarily zero, which is a
  prerequisite for addressing issue #4417.

## Detailed Description of the Pull Request / Additional comments

There are two new classes provide by this PR: a `VTParameter` class,
similar in function to a `std::optional<size_t>`, which holds an
individual parameter (which may be an omitted/default value); and a
`VTParameters` class, similar in function to `gsl:span<VTParameter>`,
which holds a sequence of those parameters.

Where `VTParameter` differs from `std::optional` is with the inclusion
of two cast operators. There is a `size_t` cast that interprets omitted
and zero values as 1 (the expected behaviour for most numeric
parameters). And there is a generic cast, for use with the enum
parameter types, which interprets omitted values as 0 (the expected
behaviour for most selective parameters).

The advantage of `VTParameters` class is that it has an `at` method that
can never fail - out of range values simply return the a default
`VTParameter` instance (this is standard behaviour in VT terminals). It
also has a `size` method that will always return a minimum count of 1,
since an empty parameter list is typically the equivalent of a single
"default" parameter, so this guarantees you'll get at least one value
when iterating over the list with `size()`.

For cases where we just need to call the same dispatch method for every
parameter, there is a helper `for_each` method, which repeatedly calls a
given predicate function with each value in the sequence. It also
collates the returned success values to determine the overall result of
the sequence. As with the `size` method, this will always make at least
one call, so it correctly handles empty sequences.

With those two classes in place, we could get rid of all the parameter
validation and default handling code in the `OutputStateMachineEngine`.
We now just use the `VTParameters::at` method to grab a parameter and
typically pass it straight to the appropriate dispatch method, letting
the cast operators automatically handle the assignment of default
values. Occasionally we might need a `value_or` call to specify a
non-standard default value, but those cases are fairly rare.

In some case the `OutputStateMachineEngine` was also checking whether
parameters values were in range, but for the most part this shouldn't
have been necessary, since that is something the dispatch classes would
already have been doing themselves (in the few cases that they weren't,
I've now updated them to do so).

I've also updated the `InputStateMachineEngine` in a similar way to the
`OutputStateMachineEngine`, getting rid of a few of the parameter
extraction methods, and simplifying other parts of the implementation.
It's not as clean a replacement as the output engine, but there are
still benefits in using the new classes.

## Validation Steps Performed

For the most part I haven't had to alter existing tests other than
accounting for changes to the API. There were a couple of tests I needed
to drop because they were checking for failure cases which shouldn't
have been failing (unexpected parameters should never be an error), or
testing output engine validation that is no longer handled at that
level.

I've added a few new tests to cover operations that take sequences of
selective parameters (`ED`, `EL`, `TBC`, `SM`, and `RM`). And I've
extended the cursor movement tests to make sure those operations can
handle extraneous parameters that weren't expected. I've also added a
test to verify that the state machine will correctly ignore parameters
beyond the maximum 32 parameter count limit.

I've also manual confirmed that the various test cases given in issues
#2101 are now working as expected.

Closes #2101
2020-10-15 16:12:52 +00:00
James Holderness
7fcff4d33a Refactor VT control sequence identification (#7304)
This PR changes the way VT control sequences are identified and
dispatched, to be more efficient and easier to extend. Instead of
parsing the intermediate characters into a vector, and then having to
identify a sequence using both that vector and the final char, we now
use just a single `uint64_t` value as the identifier.

The way the identifier is constructed is by taking the private parameter
prefix, each of the intermediate characters, and then the final
character, and shifting them into a 64-bit integer one byte at a time,
in reverse order. For example, the `DECTLTC` control has a private
parameter prefix of `?`, one intermediate of `'`, and a final character
of `s`. The ASCII values of those characters are `0x3F`, `0x27`, and
`0x73` respectively, and reversing them gets you 0x73273F, so that would
then be the identifier for the control.

The reason for storing them in reverse order, is because sometimes we
need to look at the first intermediate to determine the operation, and
treat the rest of the sequence as a kind of sub-identifier (the
character set designation sequences are one example of this). When in
reverse order, this can easily be achieved by masking off the low byte
to get the first intermediate, and then shifting the value right by 8
bits to get a new identifier with the rest of the sequence.

With 64 bits we have enough space for a private prefix, six
intermediates, and the final char, which is way more than we should ever
need (the _DEC STD 070_ specification recommends supporting at least
three intermediates, but in practice we're unlikely to see more than
two).

With this new way of identifying controls, it should now be possible for
every action code to be unique (for the most part). So I've also used
this PR to clean up the action codes a bit, splitting the codes for the
escape sequences from the control sequences, and sorting them into
alphabetical order (which also does a reasonable job of clustering
associated controls).

## Validation Steps Performed

I think the existing unit tests should be good enough to confirm that
all sequences are still being dispatched correctly. However, I've also
manually tested a number of sequences to make sure they were still
working as expected, in particular those that used intermediates, since
they were the most affected by the dispatch code refactoring.

Since these changes also affected the input state machine, I've done
some manual testing of the conpty keyboard handling (both with and
without the new Win32 input mode enabled) to make sure the keyboard VT
sequences were processed correctly. I've also manually tested the
various VT mouse modes in Vttest to confirm that they were still working
correctly too.

Closes #7276
2020-08-18 18:57:52 +00:00
Dustin L. Howett
80da24ecf8 Replace basic_string_view<T> with span<const T> (#6921)
We were using std::basic_string_view as a stand-in for std::span so that
we could change over all at once when C++20 dropped with full span
support. That day's not here yet, but as of 54a7fce3e we're using GSL 3,
whose span is C++20-compliant.

This commit replaces every instance of basic_string_view that was not
referring to an actual string with a span of the appropriate type.

I moved the `const` qualifier into span's `T` because while
`basic_string_view.at()` returns `const T&`, `span.at()` returns `T&`
(without the const). I wanted to maintain the invariant that members of
the span were immutable.

* Mechanical Changes
   * `sv.at(x)` -> `gsl::at(sp, x)`
   * `sv.c{begin,end}` -> `sp.{begin,end}` (span's iterators are const)

I had to replace a `std::basic_string<>` with a `std::vector<>` in
ConImeInfo, and I chose to replace a manual array walk in
ScreenInfoUiaProviderBase with a ranged-for. Please review those
specifically.

This will almost certainly cause a code size regression in Windows
because I'm blowing out all the PGO counts. Whoops.

Related: #3956, #975.
2020-07-15 16:40:42 +00:00
James Holderness
96a77cb74b Improve support for VT character sets (#4496)
This PR improves our VT character set support, enabling the [`SCS`]
escape sequences to designate into all four G-sets with both 94- and
96-character sets, and supports invoking those G-sets into both the GL
and GR areas of the code table, with [locking shifts] and [single
shifts]. It also adds [`DOCS`] sequences to switch between UTF-8 and the
ISO-2022 coding system (which is what the VT character sets require),
and adds support for a lot more characters sets, up to around the level
of a VT510.

[`SCS`]: https://vt100.net/docs/vt510-rm/SCS.html
[locking shifts]: https://vt100.net/docs/vt510-rm/LS.html
[single shifts]: https://vt100.net/docs/vt510-rm/SS.html
[`DOCS`]: https://en.wikipedia.org/wiki/ISO/IEC_2022#Interaction_with_other_coding_systems

## Detailed Description of the Pull Request / Additional comments

To make it easier for us to declare a bunch of character sets, I've made
a little `constexpr` class that can build up a mapping table from a base
character set (ASCII or Latin1), along with a collection of mappings for
the characters the deviate from the base set. Many of the character sets
are simple variations of ASCII, so they're easy to define this way.

This class then casts directly to a `wstring_view` which is how the
translation tables are represented in most of the code. We have an array
of four of these tables representing the four G-sets, two instances for
the active left and right tables, and one instance for the single shift
table.

Initially we had just one `DesignateCharset` method, which could select
the active character set. We now have two designate methods (for 94- and
96- character sets), and each takes a G-set number specifying the target
of the designation, and a pair of characters identifying the character
set that will be designated (at the higher VT levels, character sets are
often identified by more than one character).

There are then two new `LockingShift` methods to invoke these G-sets
into either the GL or GR area of the code table, and a `SingleShift`
method which invokes a G-set temporarily (for just the next character
that is output).

I should mention here that I had to make some changes to the state
machine to make these single shift sequences work. The problem is that
the input state machine treats `SS3` as the start of a control sequence,
while the output state machine needs it to be dispatched immediately
(it's literally the _Single Shift 3_ escape sequence). To make that
work, I've added a `ParseControlSequenceAfterSs3` callback in the
`IStateMachineEngine` interface to decide which behavior is appropriate.

When it comes to mapping a character, it's simply an array reference
into the appropriate `wstring_view` table. If the single shift table is
set, that takes preference. Otherwise the GL table is used for
characters in the range 0x20 to 0x7F, and the GR table for characters
0xA0 to 0xFF (technically some character sets will only map up to 0x7E
and 0xFE, but that's easily controlled by the length of the
`wstring_view`).

The `DEL` character is a bit of a special case. By default it's meant to
be ignored like the `NUL` character (it's essentially a time-fill
character). However, it's possible that it could be remapped to a
printable character in a 96-character set, so we need to check for that
after the translation. This is handled in the `AdaptDispatch::Print`
method, so it doesn't interfere with the primary `PrintString` code
path.

The biggest problem with this whole process, though, is that the GR
mappings only really make sense if you have access to the raw output,
but by the time the output gets to us, it would already have been
translated to Unicode by the active code page. And in the case of UTF-8,
the characters we eventually receive may originally have been composed
from two or more code points.

The way I've dealt with this was to disable the GR translations by
default, and then added support for a pair of ISO-2022 `DOCS` sequences,
which can switch the code page between UTF-8 and ISO-8859-1. When the
code page is ISO-8859-1, we're essentially receiving the raw output
bytes, so it's safe to enable the GR translations. This is not strictly
correct ISO-2022 behavior, and there are edge cases where it's not going
to work, but it's the best solution I could come up with.

## Validation Steps Performed

As a result of the `SS3` changes in the state machine engine, I've had
to move the existing `SS3` tests from the `OutputEngineTest` to the
`InputEngineTest`, otherwise they would now fail (technically they
should never have been output tests).

I've added no additional unit tests, but I have done a lot of manual
testing, and made sure we passed all the character set tests in Vttest
(at least for the character sets we currently support). Note that this
required a slightly hacked version of the app, since by default it
doesn't expose a lot of the test to low-level terminals, and we
currently identify as a VT100.

Closes #3377
Closes #3487
2020-06-04 19:40:15 +00:00
James Holderness
d92c8293ce Add support for VT52 emulation (#4789)
## Summary of the Pull Request

This PR adds support for the core VT52 commands, and implements the `DECANM` private mode sequence, which switches the terminal between ANSI mode and VT52-compatible mode.

## References

PR #2017 defined the initial specification for VT52 support.
PR #4044 removed the original VT52 cursor ops that conflicted with VT100 sequences.

## PR Checklist
* [x] Closes #976
* [x] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [x] Tests added/passed
* [ ] Requires documentation to be updated
* [x] I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #2017

## Detailed Description of the Pull Request / Additional comments

Most of the work involves updates to the parsing state machine, which behaves differently in VT52 mode. `CSI`, `OSC`, and `SS3` sequences are not applicable, and there is one special-case escape sequence (_Direct Cursor Address_), which requires an additional state to handle parameters that come _after_ the final character.

Once the parsing is handled though, it's mostly just a matter of dispatching the commands to existing methods in the `ITermDispatch` interface. Only one new method was required in the interface to handle the _Identify_ command.

The only real new functionality is in the `TerminalInput` class, which needs to generate different escape sequences for certain keys in VT52 mode. This does not yet support _all_ of the VT52 key sequences, because the VT100 support is itself not yet complete. But the basics are in place, and I think the rest is best left for a follow-up issue, and potentially a refactor of the `TerminalInput` class.

I should point out that the original spec called for a new _Graphic Mode_ character set, but I've since discovered that the VT terminals that _emulate_ VT52 just use the existing VT100 _Special Graphics_ set, so that is really what we should be doing too. We can always consider adding the VT52 graphic set as a option later, if there is demand for strict VT52 compatibility. 

## Validation Steps Performed

I've added state machine and adapter tests to confirm that the `DECANM` mode changing sequences are correctly dispatched and forwarded to the `ConGetSet` handler. I've also added state machine tests that confirm the VT52 escape sequences are dispatched correctly when the ANSI mode is reset.

For fuzzing support, I've extended the VT command fuzzer to generate the different kinds of VT52 sequences, as well as mode change sequences to switch between the ANSI and VT52 modes.

In terms of manual testing, I've confirmed that the _Test of VT52 mode_ in Vttest now works as expected.
2020-06-01 21:20:40 +00:00
Dustin L. Howett (MSFT)
64ac0d25e0 vt: make sure to Flush the entire parsed sequence (#4870)
When we had to flush unknown sequences to the terminal, we were only
taking the _most recent run_ with us; therefore, if we received `\e[?12`
and `34h` in separate packets we would _only_ send out `34h`.

This change fixes that issue by ensuring that we cache partial bits of
sequences we haven't yet completed, just in case we need to flush them.

Fixes #3080.
Fixes #3081.
2020-03-11 16:44:52 -07:00
Michael Niksa
913c5ec744 Correct passthrough sequences after refactor (#4125)
## Summary of the Pull Request
When refactoring the `StateMachine::ProcessString` algorithm to use safer structures, I made an off-by-one error when attempting to simplify the loop. 

## References
- Introduced in #3956 

## PR Checklist
* [x] Closes #4116
* [x] I work here.
* [x] Tests added/passed
* [x] No documentation
* [x] I'm a core contributor.

## Detailed Description of the Pull Request / Additional comments
The algorithm in use exploited holding onto some pointers and sizes as it rotated around the loop to call back as member variables in the pass-through function `FlushToTerminal`. 

As a part of the refactor, I adjusted to persisting a `std::wstring_view` of the currently processing string instead of pointer/size. I also attempted to simplify the loop at the same time as both the individual and group branches were performing some redundant operations in respect to updating the "run" length. 

Turns out, I made a mistake here. I wrote it so it worked correctly for the bottom half where we transition from bulk printing to an escape but then I messed up the top case.

## Validation Steps Performed
- [x] Manual validation of the exact command given in the bug report.
- [x] Wrote automated tests to validate both paths through the `ProcessString` loop that work with the `_run` variable.
2020-01-08 19:16:49 +00:00
Michael Niksa
6f667f48ae Make the terminal parser/adapter and related classes use modern… (#3956)
## Summary of the Pull Request
Refactors parsing/adapting libraries and consumers to use safer and/or more consistent mechanisms for passing information.

## PR Checklist
* [x] I work here
* [x] Tests still pass
* [x] Am a core contributor.

## Detailed Description of the Pull Request / Additional comments
This is in support of hopefully turning audit mode on to more projects. If I turned it on, it would immediately complain about certain classes of issues like pointer and size, pointer math, etc. The changes in this refactoring will eliminate those off the top.

Additionally, this has caught a bunch of comments all over the VT classes that weren't updated to match the parameters lists.

Additionally, this has caught a handful of member variables on classes that were completely unused (and now gone).

Additionally, I'm killing almost all hungarian and shortening variable names. I'm only really leaving 'p' for pointers.

Additionally, this is vaguely in support of a future where we can have "infinite scrollback" in that I'm moving things to size_t across the board. I know it's a bit of a memory cost, but all the casting and moving between types is error prone and unfun to save a couple bytes.

## Validation Steps Performed
- [x] build it
- [x] run all the tests
- [x] everyone looked real hard at it
2019-12-19 14:12:53 -08:00
Dustin L. Howett (MSFT)
dd2fbef39d Move the VT parser's parse state into instanced storage (#3110)
The VT parser used to be keeping a boolean used to determine whether it
was in bulk or single-character parse mode in a function-level static.
That turned out to not be great.

Fixes #3108; fixes #3073.
2019-10-09 11:01:15 -07:00