drgn/libdrgn/lazy_object.h
Omar Sandoval 87b7292aa5 Relicense drgn from GPLv3+ to LGPLv2.1+
drgn is currently licensed as GPLv3+. Part of the long term vision for
drgn is that other projects can use it as a library providing
programmatic interfaces for debugger functionality. A more permissive
license is better suited to this goal. We decided on LGPLv2.1+ as a good
balance between software freedom and permissiveness.

All contributors not employed by Meta were contacted via email and
consented to the license change. The only exception was the author of
commit c4fbf7e589 ("libdrgn: fix for compilation error"), who did not
respond. That commit reverted a single line of code to one originally
written by me in commit 640b1c011d ("libdrgn: embed DWARF index in
DWARF info cache").

Signed-off-by: Omar Sandoval <osandov@osandov.com>
2022-11-01 17:05:16 -07:00

86 lines
2.1 KiB
C

// Copyright (c) Meta Platforms, Inc. and affiliates.
// SPDX-License-Identifier: LGPL-2.1-or-later
/**
* @file
*
* Lazy objects.
*
* See @ref LazyObjects.
*/
#ifndef DRGN_LAZY_OBJECT_H
#define DRGN_LAZY_OBJECT_H
#include "drgn.h"
/**
* @ingroup Internals
*
* @defgroup LazyObjects Lazy objects
*
* Lazily-evaluated objects.
*
* The graph of objects and types in a program can be very deep (and often
* cyclical), so drgn lazily evaluates objects in some cases.
*
* @{
*/
/**
* Initialize an unevaluated @ref drgn_lazy_object.
*
* @param[out] lazy_obj Lazy object to initialize.
* @param[in] prog Program owning the lazy object.
* @param[in] fn Thunk callback.
* @param[in] arg Argument to pass to @p fn.
*/
static inline void
drgn_lazy_object_init_thunk(union drgn_lazy_object *lazy_obj,
struct drgn_program *prog, drgn_object_thunk_fn *fn,
void *arg)
{
lazy_obj->thunk.dummy_type = NULL;
lazy_obj->thunk.prog = prog;
lazy_obj->thunk.fn = fn;
lazy_obj->thunk.arg = arg;
}
/** Return whether a @ref drgn_lazy_object has been evaluated. */
static inline bool
drgn_lazy_object_is_evaluated(const union drgn_lazy_object *lazy_obj)
{
return lazy_obj->obj.type != NULL;
}
/**
* Evaluate a @ref drgn_lazy_object.
*
* If this success, then the lazy object is considered evaluated and future
* calls will always succeed. If this fails, then the lazy object remains in a
* valid, unevaluated state.
*/
struct drgn_error *drgn_lazy_object_evaluate(union drgn_lazy_object *lazy_obj);
/**
* Free a @ref drgn_lazy_object.
*
* If the object has been evaluated, then this deinitializes @ref
* drgn_lazy_object::obj. Otherwise, this calls @ref drgn_lazy_object::fn to
* free @ref drgn_lazy_object::arg.
*/
void drgn_lazy_object_deinit(union drgn_lazy_object *lazy_obj);
/**
* Check whether a @ref drgn_lazy_object belongs to a given @ref drgn_program.
*
* @return @c NULL if the program matches, non-@c NULL if not.
*/
struct drgn_error *
drgn_lazy_object_check_prog(const union drgn_lazy_object *lazy_obj,
struct drgn_program *prog);
/** @} */
#endif /* DRGN_LAZY_OBJECT_H */