vasilito
cb424d7448
verify-patch-sanity.py validates every active recipe .patch has internally- consistent hunk line counts — catching the 'malformed patch at line N' failure at commit/CI/preflight time instead of hours into a cook. This cycle hit that class three times (qtwaylandscanner, sddm, xwayland), each only discovered when cookbook tried to apply the patch. Running it across the repo found 29 latent malformed patches (validated against GNU patch: e.g. relibc/P3-sysv-ipc reproduces 'malformed patch at line 22'). They were harmless only because they sit in vendored recipes (baked, not re- applied) — but would fail on any version-bump re-derivation. --fix recounts the hunk headers (body untouched) and repaired all 29. Wired into build-preflight.sh (Phase 1.0D) and redbear-ci.yml, with a unit test (test-patch-sanity.sh). Skips archived/legacy trees and unvalidatable formats (empty placeholders, bare-@@ git hunks).
134 lines
6.4 KiB
ReStructuredText
134 lines
6.4 KiB
ReStructuredText
Scripting Bridge API
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====================
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The SB APIs constitute the stable C++ API that lldb presents to external
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clients, and which get processed by SWIG to produce the Python bindings to
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lldb. As such it is important that they not suffer from the binary
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incompatibilities that C++ is so susceptible to. We've established a few rules
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to ensure that this happens.
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Extending the SB API
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--------------------
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The classes in the SB API's are all called SB<SomeName>, where SomeName is in
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CamelCase starting with an upper case letter. The method names are all
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CamelCase with initial capital letter as well.
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All the SB API classes are non-virtual, single inheritance classes. They should
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only include SBDefines.h or other SB headers as needed. There should be no
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inlined method implementations in the header files, they should all be in the
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implementation files. And there should be no direct ivar access.
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You also need to choose the ivars for the class with care, since you can't add
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or remove ivars without breaking binary compatibility. In some cases, the SB
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class is a thin wrapper around an internal lldb_private object. In that case,
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the class can have a single ivar, which is either a pointer, shared_ptr or
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unique_ptr to the object in the lldb_private API. All the lldb_private classes
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that get used this way are declared as opaque classes in lldb_forward.h, which
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is included in SBDefines.h. So if you need an SB class to wrap an lldb_private
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class that isn't in lldb_forward.h, add it there rather than making a direct
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opaque declaration in the SB classes .h file.
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If the SB Class needs some state of its own, as well as the backing object,
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don't include that as a direct ivar in the SB Class. Instead, make an Impl
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class in the SB's .cpp file, and then make the SB object hold a shared or
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unique pointer to the Impl object. The theory behind this is that if you need
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more state in the SB object, those needs are likely to change over time, and
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this way the Impl class can pick up members without changing the size of the
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object. An example of this is the SBValue class. Please note that you should
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not put this Impl class in the lldb namespace. Failure to do so leads to
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leakage of weak-linked symbols in the SBAPI.
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In order to fit into the Python API's, we need to be able to default construct
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all the SB objects. Since the ivars of the classes are all pointers of one sort
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or other, this can easily be done, but it means all the methods must be
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prepared to handle their opaque implementation pointer being empty, and doing
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something reasonable. We also always have an "IsValid" method on all the SB
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classes to report whether the object is empty or not.
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Another piece of the SB API infrastructure is the Python (or other script
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interpreter) customization. SWIG allows you to add property access, iterators
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and documentation to classes. We place the property accessors and iterators in
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a file dedicated to extensions to existing SB classes at
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"bindings/interface/SB<ClassName>Extensions.i". The documentation is similarly
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located at "bindings/interface/SB<ClassName>Docstrings.i". These two files, in
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addition to the actual header SB<ClassName>.h, forms the interface that lldb
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exposes to users through the scripting languages.
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There are some situations where you may want to add functionality to the SB API
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only for use in C++. To prevent SWIG from generating bindings to these
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functions, you can use a C macro guard, like so:
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::
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#ifndef SWIG
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int GetResourceCPPOnly() const;
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#endif
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In this case, ``GetResourceCPPOnly`` will not be generated for Python or other
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scripting languages. If you wanted to add a resource specifically only for the
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SWIG case, you can invert the condition and use ``#ifdef SWIG`` instead. When
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building the LLDB framework for macOS, the headers are processed with
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``unifdef`` prior to being copied into the framework bundle to remove macros
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involving SWIG.
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Another good principle when adding SB API methods is: if you find yourself
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implementing a significant algorithm in the SB API method, you should not do
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that, but instead look for and then add it - if not found - as a method in the
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underlying lldb_private class, and then call that from your SB API method.
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If it was a useful algorithm, it's very likely it already exists
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because the lldb_private code also needed to do it. And if it doesn't at
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present, if it was a useful thing to do, it's likely someone will later need
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it in lldb_private and then we end up with two implementations of the same
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algorithm. If we keep the SB API code to just what's needed to manage the SB
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objects and requests, we won't get into this situation.
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Lifetime
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--------
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Many SB API methods will return strings in the form of ``const char *`` values.
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Once created, these strings are guaranteed to live until the end of the
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debugging session. LLDB owns these strings, clients should not attempt to free
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them. Doing so may cause LLDB to crash.
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Note that this only affects the C++ API as scripting languages usually
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will usually create native string types from the ``const char *`` value.
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API Instrumentation
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-------------------
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The reproducer infrastructure requires API methods to be instrumented so that
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they can be captured and replayed. Instrumentation consists of two macros,
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``LLDB_REGISTER`` and ``LLDB_RECORD``. Both can be automatically generated with
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the ``lldb-instr`` utility.
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To add instrumentation for a given file, pass it to the ``lldb-instr`` tool.
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Like other clang-based tools it requires a compilation database
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(``compile_commands.json``) to be present in the current working directory.
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::
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$ ./bin/lldb-instr /path/to/lldb/source/API/SBDebugger.cpp
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The tool will automatically insert ``LLDB_RECORD`` macros inline, however you
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will need to run ``clang-format`` over the processed file, as the tool
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(intentionally) makes no attempt to get that right.
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The ``LLDB_REGISTER`` macros are printed to standard out between curly braces.
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You'll have to copy-paste those into the corresponding ``RegisterMethods``
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function in the implementation file. This function is fully specialized in the
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corresponding type.
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::
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template <> void RegisterMethods<SBDebugger>(Registry &R) {
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...
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}
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When adding a new class, you'll also have to add a call to ``RegisterMethods``
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in the ``SBRegistry`` constructor.
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The tool can be used incrementally. However, it will ignore existing macros
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even if their signature is wrong. It will only generate a ``LLDB_REGISTER`` if
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it emitted a corresponding ``LLDB_RECORD`` macro.
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