[lldb] Change the implementation of Status to store an llvm::Error (NFC) (#106774)

(based on a conversation I had with @labath yesterday in
https://github.com/llvm/llvm-project/pull/106442)

Most AP

[lldb] Change the implementation of Status to store an llvm::Error (NFC) (#106774)

(based on a conversation I had with @labath yesterday in
https://github.com/llvm/llvm-project/pull/106442)

Most APIs that currently vend a Status would be better served by
returning llvm::Expected<> instead. If possibles APIs should be
refactored to avoid Status. The only legitimate long-term uses of Status
are objects that need to store an error for a long time (which should be
questioned as a design decision, too).

This patch makes the transition to llvm::Error easier by making the
places that cannot switch to llvm::Error explicit: They are marked with
a call to Status::clone(). Every other API can and should be refactored
to use llvm::Expected. In the end Status should only be used in very few
places.

Whenever an unchecked Error is dropped by Status it logs this to the
verbose API channel.

Implementation notes:

This patch introduces two new kinds of error_category as well as new
llvm::Error types. Here is the mapping of lldb::ErrorType to
llvm::Errors:
```
(eErrorTypeInvalid)
eErrorTypeGeneric llvm::StringError
eErrorTypePOSIX llvm::ECError
eErrorTypeMachKernel MachKernelError
eErrorTypeExpression llvm::ErrorList<ExpressionError>
eErrorTypeWin32 Win32Error
```

Relanding with built-in cloning support for llvm::ECError, and support
for initializing a Windows error with a NO_ERROR error code, and
modifying TestGDBRemotePlatformFile.py to support different renderings
of ENOSYS.

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[lldb][Windows] Fixed the test gdb_remote_client/TestGDBRemotePlatformFile (#92088)

The tests `test_file_permissions` and `test_file_permissions_fallback`
are disabled for Windows target. These tes

[lldb][Windows] Fixed the test gdb_remote_client/TestGDBRemotePlatformFile (#92088)

The tests `test_file_permissions` and `test_file_permissions_fallback`
are disabled for Windows target. These tests use MockGDBServerResponder
and do not depend on the real target. These tests failed in case of
Windows host and Linux target. Disable them for Windows host too.

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[NFC][Py Reformat] Reformat python files in lldb

This is an ongoing series of commits that are reformatting our Python
code. Reformatting is done with `black` (23.1.0).

If you end up having problem

[NFC][Py Reformat] Reformat python files in lldb

This is an ongoing series of commits that are reformatting our Python
code. Reformatting is done with `black` (23.1.0).

If you end up having problems merging this commit because you have made
changes to a python file, the best way to handle that is to run `git
checkout --ours <yourfile>` and then reformat it with black.

RFC: https://discourse.llvm.org/t/rfc-document-and-standardize-python-code-style

Differential revision: https://reviews.llvm.org/D151460

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[lldb][tests] Automatically call compute_mydir (NFC)

Eliminate boilerplate of having each test manually assign to `mydir` by calling
`compute_mydir` in lldbtest.py.

Differential Revision: https://r

[lldb][tests] Automatically call compute_mydir (NFC)

Eliminate boilerplate of having each test manually assign to `mydir` by calling
`compute_mydir` in lldbtest.py.

Differential Revision: https://reviews.llvm.org/D128077

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[lldb/platform-gdb] Clear cached protocol state upon disconnection

Previously we would persist the flags indicating whether the remote side
supports a particular feature across reconnects, which is

[lldb/platform-gdb] Clear cached protocol state upon disconnection

Previously we would persist the flags indicating whether the remote side
supports a particular feature across reconnects, which is obviously not
a good idea.

I implement the clearing by nuking (its the only way to be sure :) the
entire GDBRemoteCommunication object in the disconnect operation and
creating a new one upon connection. This allows us to maintain a nice
invariant that the GDBRemoteCommunication object (which is now a
pointer) exists only if it is connected. The downside to that is that a
lot of functions now needs to check the validity of the pointer instead
of blindly accessing the object.

The process communication does not suffer from the same issue because we
always destroy the entire Process object for a relaunch.

Differential Revision: https://reviews.llvm.org/D116539

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[lldb/test] Move gdb client utils into the packages tree

This infrastructure has proven proven its worth, so give it a more
prominent place.

My immediate motivation for this is the desire to reuse

[lldb/test] Move gdb client utils into the packages tree

This infrastructure has proven proven its worth, so give it a more
prominent place.

My immediate motivation for this is the desire to reuse this
infrastructure for qemu platform testing, but I believe this move makes
sense independently of that. Moving this code to the packages tree will
allow as to add more structure to the gdb client tests -- currently they
are all crammed into the same test folder as that was the only way they
could access this code.

I'm splitting the code into two parts while moving it. The first once
contains just the generic gdb protocol wrappers, while the other one
contains the unit test glue. The reason for that is that for qemu
testing, I need to run the gdb code in a separate process, so I will
only be using the first part there.

Differential Revision: https://reviews.llvm.org/D113893

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[lldb] [test] Skip file permission tests on Windows

[lldb] [gdb-remote] Use standardized GDB errno values

GDB uses normalized errno values for vFile errors. Implement
the translation between them and system errno values in the gdb-remote
plugin.

Di

[lldb] [gdb-remote] Use standardized GDB errno values

GDB uses normalized errno values for vFile errors. Implement
the translation between them and system errno values in the gdb-remote
plugin.

Differential Revision: https://reviews.llvm.org/D108148

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[lldb] [gdb-remote] Add fallbacks for vFile:mode and vFile:exists

Add a GDB-compatible fallback to vFile:fstat for vFile:mode, and to
vFile:open for vFile:exists. Note that this is only partial fal

[lldb] [gdb-remote] Add fallbacks for vFile:mode and vFile:exists

Add a GDB-compatible fallback to vFile:fstat for vFile:mode, and to
vFile:open for vFile:exists. Note that this is only partial fallback,
as it fails if the file cannot be opened.

Differential Revision: https://reviews.llvm.org/D107811

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[lldb] Add new commands and tests for getting file perms & exists

Add two new commands 'platform get-file-permissions' and 'platform
file-exists' for the respective bits of LLDB protocol. Add tests

[lldb] Add new commands and tests for getting file perms & exists

Add two new commands 'platform get-file-permissions' and 'platform
file-exists' for the respective bits of LLDB protocol. Add tests for
them. Fix error handling in GetFilePermissions().

Differential Revision: https://reviews.llvm.org/D107809

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[lldb] [test] Move "platform connect" logic into a common class

Create a common GDBPlatformClientTestBase class and move the platform
select/connect logic there to reduce duplication.

Differential

[lldb] [test] Move "platform connect" logic into a common class

Create a common GDBPlatformClientTestBase class and move the platform
select/connect logic there to reduce duplication.

Differential Revision: https://reviews.llvm.org/D109585

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[lldb] [gdb-remote] Implement fallback to vFile:stat for GetFileSize()

Implement a fallback to getting the file size via vFile:stat packet
when the remote server does not implement vFile:size. This

[lldb] [gdb-remote] Implement fallback to vFile:stat for GetFileSize()

Implement a fallback to getting the file size via vFile:stat packet
when the remote server does not implement vFile:size. This makes it
possible to query file sizes from remote gdbserver.

Note that unlike vFile:size, the fallback will not work if the server is
unable to open the file.

While at it, add a few tests for the 'platform get-size' command.

Differential Revision: https://reviews.llvm.org/D107780

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[lldb] [Commands] Remove 'append' from 'platform file open' mode

Remove File::eOpenOptionAppend from the mode used by 'platform file
open' command. According to POSIX, O_APPEND causes all successiv

[lldb] [Commands] Remove 'append' from 'platform file open' mode

Remove File::eOpenOptionAppend from the mode used by 'platform file
open' command. According to POSIX, O_APPEND causes all successive
writes to be done at the end of the file. This effectively makes
the offset argument to 'platform file write' meaningless.

Furthermore, apparently O_APPEND is not implemented reliably everywhere.
The Linux manpage for pwrite(2) suggests that Linux does respect
O_APPEND there while according to POSIX it should not, so the actual
behavior would be dependent on how the vFile:pwrite packet is
implemented on the server.

Ideally, the mode used for opening flags would be provided via options.
However, changing the default mode seems to be a reasonable intermediate
solution.

Differential Revision: https://reviews.llvm.org/D107664

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[lldb] [Commands] Fix reporting errors in 'platform file read/write'

Fix 'platform file read' and 'platform file write' commands to correctly
detect erraneous return and report it as such. Currentl

[lldb] [Commands] Fix reporting errors in 'platform file read/write'

Fix 'platform file read' and 'platform file write' commands to correctly
detect erraneous return and report it as such. Currently, errors were
implicitly printed as a return value of -1, and the commands were
assumed to be successful.

Differential Revision: https://reviews.llvm.org/D107665

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[lldb] [gdb-remote] Use hexadecimal numbers in vFile packats for GDB compliance

Use hexadecimal numbers rather than decimal in various vFile packets
in order to fix compatibility with gdbserver. Th

[lldb] [gdb-remote] Use hexadecimal numbers in vFile packats for GDB compliance

Use hexadecimal numbers rather than decimal in various vFile packets
in order to fix compatibility with gdbserver. This also changes the few
custom LLDB packets -- while technically they do not have to be changed,
it is easier to use the same syntax consistently across LLDB.

Differential Revision: https://reviews.llvm.org/D107475

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[lldb] [gdb-remote] Sync vFile:open mode constants with GDB

Sync the mode constants used to drive vFile:open requests with these
used by GDB and defined for the gdb remote protocol. This makes it
p

[lldb] [gdb-remote] Sync vFile:open mode constants with GDB

Sync the mode constants used to drive vFile:open requests with these
used by GDB and defined for the gdb remote protocol. This makes it
possible to use 'platform file open' after connecting to gdbremote
server (and to some degree to operate on the open file modulo other
incompatibilities).

Differential Revision: https://reviews.llvm.org/D106985

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