haiku/docs/user/storage/PathFinder.dox
Ingo Weinhold 556e8b250a Update BPathFinder API docs
* Update FindPath() wrt. B_FIND_PATH_PACKAGE_PATH handling.
* Add documentation for BResolvableExpression version of constructor and
  SetTo().
2013-11-21 13:29:21 +01:00

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/*
* Copyright 2013, Haiku, Inc. All rights reserved.
* Distributed under the terms of the MIT License.
*
* Documentation by:
* Ingo Weinhold, ingo_weinhold@gmx.de
*
* Corresponds to:
* headers/os/storage/PathFinder.h hrev46390
* src/kits/storage/PathFinder.cpp hrev46390
*/
/*!
\file PathFinder.h
\ingroup storage
\ingroup libbe
\brief Provides the BPathFinder class interface.
*/
/*!
\class BPathFinder
\ingroup storage
\ingroup libbe
\brief Helper class to retrieve paths in the file system layout.
The BPathFinder provides two sets of methods for retrieving paths:
FindPath() for getting a single path in an installation location specified
via a constructor or a SetTo() invocation, and the static FindPaths() for
getting a list of paths for all installation locations.
*/
/*!
\fn BPathFinder::BPathFinder(const void* codePointer,
const char* dependency)
\brief Creates an object referring to an installation location based on a
loaded image file.
When initialized with this constructor a FindPath() method called afterward
determines the path of the image (i.e. executable, library, or add-on) file
associated with \a codePointer, a pointer to a location in the code or
static data of an image loaded in the caller's team. Based on that path the
path constant passed to FindPath() will be evaluated. In most cases that
means first determining the path of the installation location from the path.
If \a dependency is specified, instead of determining the installation
location path from the image path, the installation location path of the
dependency \a dependency of the package containing the image file is used.
If the initialization fails, e.g. due to insufficient memory or invalid
arguments, subsequent calls to FindPath() will return an error.
\param codePointer A pointer to code or static data belonging to the image
based on which FindPath() shall compute the path. The special value
\c B_APP_IMAGE_SYMBOL (the default) can be used to refer to the program
image, and \c B_CURRENT_IMAGE_SYMBOL for the caller's image.
\param dependency The name of the package's "requires" entry to be used for
resolving the installation location. Can be \c NULL (the default).
*/
/*!
\fn BPathFinder::BPathFinder(const char* path, const char* dependency)
\brief Creates an object referring to an installation location based on a
given path.
When initialized with this constructor a FindPath() method called afterward
evaluates the path constant passed to it based on \a path. In most cases
that means first determining the path of the installation location from the
given path.
If \a dependency is specified, instead of determining the installation
location path from the given path, the installation location path of the
dependency \a dependency of the package containing the file referred to by
\a path is used.
If the initialization fails, e.g. due to insufficient memory or invalid
arguments, subsequent calls to FindPath() will return an error.
\param path A path based on which FindPath() shall compute the path.
\param dependency The name of the package's "requires" entry to be used for
resolving the installation location. Can be \c NULL.
*/
/*!
\fn BPathFinder::BPathFinder(const entry_ref& ref, const char* dependency)
\brief Creates an object referring to an installation location based on a
given entry_ref.
The constructor converts the given entry_ref \a ref to a path and then
initializes the object like
BPathFinder::BPathFinder(const char*, const char*).
\param ref A reference to be resolved to a path based on which FindPath()
shall compute the path.
\param dependency The name of the package's "requires" entry to be used for
resolving the installation location. Can be \c NULL.
\see BPathFinder::BPathFinder(const char*, const char*)
*/
/*!
\fn BPathFinder::BPathFinder(const BResolvableExpression& expression,
const char* dependency)
\brief Creates an object referring to an installation location based on the
path of a package satisfying the given resolvable expression.
The constructor finds the latest package that satisfies the resolvable
expression \a expression and then uses its path to initialize the object
like BPathFinder::BPathFinder(const char*, const char*).
\note When using this constructor linking against libpackage.so is required.
\param expression A resolvable expression to be resolved to the path of the
latest package satisfying it, based on which FindPath() shall compute
the path.
\param dependency The name of the package's "requires" entry to be used for
resolving the installation location. Can be \c NULL.
\see BPathFinder::BPathFinder(const char*, const char*)
*/
/*!
\fn status_t BPathFinder::SetTo(const void* codePointer,
const char* dependency)
\brief Reinitializes the object to refer to an installation location based
on a loaded image file.
When reinitialized with this method a FindPath() method called afterward
determines the path of the image (i.e. executable, library, or add-on) file
associated with \a codePointer, a pointer to a location in the code or
static data of an image loaded in the caller's team. Based on that path the
path constant passed to FindPath() will be evaluated. In most cases that
means first determining the path of the installation location from the path.
If \a dependency is specified, instead of determining the installation
location path from the image path, the installation location path of the
dependency \a dependency of the package containing the image file is used.
If the initialization fails, e.g. due to insufficient memory or invalid
arguments, this method and subsequent calls to FindPath() will return an
error.
\param codePointer A pointer to code or static data belonging to the image
based on which FindPath() shall compute the path. The special value
\c B_APP_IMAGE_SYMBOL (the default) can be used to refer to the program
image, and \c B_CURRENT_IMAGE_SYMBOL for the caller's image.
\param dependency The name of the package's "requires" entry to be used for
resolving the installation location. Can be \c NULL (the default).
\return A status code.
\retval B_OK Everything went fine.
*/
/*!
\fn status_t BPathFinder::SetTo(const char* path, const char* dependency)
\brief Reinitializes the object to refer to an installation location based
on a given path.
When reinitialized with this method a FindPath() method called afterward
evaluates the path constant passed to it based on \a path. In most cases
that means first determining the path of the installation location from the
given path.
If \a dependency is specified, instead of determining the installation
location path from the given path, the installation location path of the
dependency \a dependency of the package containing the file referred to by
\a path is used.
If the initialization fails, e.g. due to insufficient memory or invalid
arguments, this method and subsequent calls to FindPath() will return an
error.
\param path A path based on which FindPath() shall compute the path.
\param dependency The name of the package's "requires" entry to be used for
resolving the installation location. Can be \c NULL.
\return A status code.
\retval B_OK Everything went fine.
*/
/*!
\fn status_t BPathFinder::SetTo(const entry_ref& ref,
const char* dependency)
\brief Reinitializes the object to refer to an installation location based
on a given entry_ref.
This method converts the given entry_ref \a ref to a path and then calls
calls BPathFinder::SetTo(const char*, const char*).
\param ref A reference to be resolved to a path based on which FindPath()
shall compute the path.
\param dependency The name of the package's "requires" entry to be used for
resolving the installation location. Can be \c NULL.
\see status_t BPathFinder::SetTo(const char*, const char*)
*/
/*!
\fn status_t BPathFinder::SetTo(const BResolvableExpression& expression,
const char* dependency)
\brief Reinitializes the object to refer to an installation location based
on a given resolvable expression.
This method finds the latest package that satisfies the resolvable
expression \a expression and then passes its path to
BPathFinder::SetTo(const char*, const char*).
\note When using this method linking against libpackage.so is required.
\param expression A resolvable expression to be resolved to the path of the
latest package satisfying it, based on which FindPath() shall compute
the path.
\param dependency The name of the package's "requires" entry to be used for
resolving the installation location. Can be \c NULL.
\see status_t BPathFinder::SetTo(const char*, const char*)
*/
/*!
\fn status_t BPathFinder::FindPath(const char* architecture,
path_base_directory baseDirectory, const char* subPath, uint32 flags,
BPath& _path)
\brief Retrieves a path in the file system layout based.
Depending on how the object was initialized this method starts with a path
(from an image file or as given) and based on it evaluates \a baseDirectory.
In most cases that means first determining the path of the installation
location from the path, then appending the relative path corresponding to
the given \a baseDirectory constant, and finally appending \a subPath, if
given.
If a dependency string was passed to the previous constructor or SetTo()
method, instead of determining the installation location path from the
initial path, the installation location path of the dependency of the
package containing the file the initial path refers to is used.
If \a baseDirectory specifies a path that is architecture dependent,
\a architecture is used for constructing the path. If \a architecture is
\c NULL, the architecture associated with the initial path (as returned by
guess_architecture_for_path()) is used. Note that if an image was specified,
this is the same as the caller's architecture (as returned by
get_architecture()).
If \c B_FIND_PATH_IMAGE_PATH or \c B_FIND_PATH_PACKAGE_PATH are
specified, \a subPath is ignored. In the former case, which is only valid,
if an image was specified for initialization, \a dependency is ignored as
well and the path of the image file is returned. In the latter case the path
of the package containing the file the initial path refers to, respectively,
if \a dependency was specified, that of the package \a dependency was
resolved to is returned.
\param architecture The name of the architecture to be used for resolving
architecture dependent paths. Can be \c NULL, in which case the
architecture associated with the initial path is used.
\param baseDirectory Constant indicating which path to retrieve.
\param subPath Relative subpath that shall be appended. Can be \c NULL.
\param flags Bitwise OR of any of the following flags:
- \c B_FIND_PATH_CREATE_DIRECTORY: If the resulting path doesn't exist,
create it as a directory (including all missing ancestors).
- \c B_FIND_PATH_CREATE_PARENT_DIRECTORY: If the resulting path's parent
doesn't exist, create the parent directory (including all missing
ancestors).
- \c B_FIND_PATH_EXISTING_ONLY: If the resulting path doesn't exist,
fail with \c B_ENTRY_NOT_FOUND.
\param _path The variable to be set to the resulting path on success.
\return A status code.
\retval B_OK Everything went fine.
\retval B_ENTRY_NOT_FOUND A file system entry required for retrieving the
path doesn't exist. E.g. \c B_FIND_PATH_PACKAGE_PATH was specified
and the image file doesn't belong to a package, or \c dependency was
specified, but isn't a "requires" entry of the package, or
\c B_FIND_PATH_EXISTING_ONLY was specified and the resulting path
doesn't exist.
*/
/*!
\fn status_t BPathFinder::FindPath(path_base_directory baseDirectory,
const char* subPath, uint32 flags, BPath& _path)
\brief Retrieves a path in the file system layout based.
Equivalent to a call to BPathFinder::FindPath(const char*,
path_base_directory, const char*, uint32, BPath&) with a \c NULL
architecture.
\param baseDirectory Constant indicating which path to retrieve.
\param subPath Relative subpath that shall be appended. Can be \c NULL.
\param flags Bitwise OR of any of the following flags:
- \c B_FIND_PATH_CREATE_DIRECTORY: If the resulting path doesn't exist,
create it as a directory (including all missing ancestors).
- \c B_FIND_PATH_CREATE_PARENT_DIRECTORY: If the resulting path's parent
doesn't exist, create the parent directory (including all missing
ancestors).
- \c B_FIND_PATH_EXISTING_ONLY: If the resulting path doesn't exist,
fail with \c B_ENTRY_NOT_FOUND.
\param _path The variable to be set to the resulting path on success.
\return A status code.
\retval B_OK Everything went fine.
\retval B_ENTRY_NOT_FOUND A file system entry required for retrieving the
path doesn't exist. E.g. \c B_FIND_PATH_PACKAGE_PATH was specified
and the image file doesn't belong to a package, or \c dependency was
specified, but isn't a "requires" entry of the package, or
\c B_FIND_PATH_EXISTING_ONLY was specified and the resulting path
doesn't exist.
*/
/*!
\fn status_t BPathFinder::FindPath(path_base_directory baseDirectory,
const char* subPath, BPath& _path)
\brief Retrieves a path in the file system layout based.
Equivalent to a call to BPathFinder::FindPath(const char*,
path_base_directory, const char*, uint32, BPath&) with a \c NULL
architecture and 0 flags.
\param baseDirectory Constant indicating which path to retrieve.
\param subPath Relative subpath that shall be appended. Can be \c NULL.
\param _path The variable to be set to the resulting path on success.
\return A status code.
\retval B_OK Everything went fine.
\retval B_ENTRY_NOT_FOUND A file system entry required for retrieving the
path doesn't exist. E.g. \c B_FIND_PATH_PACKAGE_PATH was specified
and the image file doesn't belong to a package, or \c dependency was
specified, but isn't a "requires" entry of the package.
*/
/*!
\fn status_t BPathFinder::FindPath(path_base_directory baseDirectory,
BPath& _path)
\brief Retrieves a path in the file system layout based.
Equivalent to a call to BPathFinder::FindPath(const char*,
path_base_directory, const char*, uint32, BPath&) with a \c NULL
architecture, 0 flags, and \c NULL subpath.
\param baseDirectory Constant indicating which path to retrieve.
\param _path The variable to be set to the resulting path on success.
\return A status code.
\retval B_OK Everything went fine.
\retval B_ENTRY_NOT_FOUND A file system entry required for retrieving the
path doesn't exist. E.g. \c B_FIND_PATH_PACKAGE_PATH was specified
and the image file doesn't belong to a package, or \c dependency was
specified, but isn't a "requires" entry of the package.
*/
/*!
\fn status_t BPathFinder::FindPaths(const char* architecture,
path_base_directory baseDirectory, const char* subPath, uint32 flags,
BStringList& _paths)
\brief Retrieves a list of paths in the file system layout.
For each installation location -- in the order most specific to most
generic, non-packaged before packaged -- the function evaluates
\a baseDirectory to a path and appends \a subPath, if given.
If \a baseDirectory specifies a path that is architecture dependent,
\a architecture is used for constructing each path. If \a architecture is
\c NULL, the caller's architecture (as returned by get_architecture()) is
used.
\c B_FIND_PATH_PACKAGE_PATH and \c B_FIND_PATH_IMAGE_PATH are not
valid arguments for this function.
\param architecture The name of the architecture to be used for resolving
architecture dependent paths. Can be \c NULL, in which case the caller's
architecture is used.
\param baseDirectory Constant indicating which paths to retrieve.
\param subPath Relative subpath that shall be appended. Can be \c NULL.
\param flags Bitwise OR of any of the following flags:
- \c B_FIND_PATH_CREATE_DIRECTORY: If a resulting path doesn't exist,
create it as a directory (including all missing ancestors).
- \c B_FIND_PATH_CREATE_PARENT_DIRECTORY: If a resulting path's parent
doesn't exist, create the parent directory (including all missing
ancestors).
- \c B_FIND_PATH_EXISTING_ONLY: If a resulting path doesn't exist, skip
it. If none of the paths exist, fail with \c B_ENTRY_NOT_FOUND.
\param _paths The BStringList variable where the retrieved paths shall be
stored. The list is emptied before adding the paths. It is also emptied
on error.
\return A status code.
\retval B_OK Everything went fine.
\retval B_ENTRY_NOT_FOUND A file system entry required for retrieving the
paths doesn't exist. E.g. \c B_FIND_PATH_EXISTING_ONLY was specified and
none of the resulting paths do exist.
*/
/*!
\fn status_t BPathFinder::FindPaths(path_base_directory baseDirectory,
const char* subPath, uint32 flags, BStringList& _paths)
\brief Retrieves a list of paths in the file system layout.
Equivalent to a call to BPathFinder::FindPaths(const char*,
path_base_directory, const char*, uint32, BStringList&) with a \c NULL
architecture.
\param baseDirectory Constant indicating which paths to retrieve.
\param subPath Relative subpath that shall be appended. Can be \c NULL.
\param flags Bitwise OR of any of the following flags:
- \c B_FIND_PATH_CREATE_DIRECTORY: If a resulting path doesn't exist,
create it as a directory (including all missing ancestors).
- \c B_FIND_PATH_CREATE_PARENT_DIRECTORY: If a resulting path's parent
doesn't exist, create the parent directory (including all missing
ancestors).
- \c B_FIND_PATH_EXISTING_ONLY: If a resulting path doesn't exist, skip
it. If none of the paths exist, fail with \c B_ENTRY_NOT_FOUND.
\param _paths The BStringList variable where the retrieved paths shall be
stored. The list is emptied before adding the paths. It is also emptied
on error.
\return A status code.
\retval B_OK Everything went fine.
\retval B_ENTRY_NOT_FOUND A file system entry required for retrieving the
paths doesn't exist. E.g. \c B_FIND_PATH_EXISTING_ONLY was specified and
none of the resulting paths do exist.
*/
/*!
\fn status_t BPathFinder::FindPaths(path_base_directory baseDirectory,
const char* subPath, BStringList& _paths)
\brief Retrieves a list of paths in the file system layout.
Equivalent to a call to BPathFinder::FindPaths(const char*,
path_base_directory, const char*, uint32, BStringList&) with a \c NULL
architecture and 0 flags.
\param baseDirectory Constant indicating which paths to retrieve.
\param subPath Relative subpath that shall be appended. Can be \c NULL.
\param _paths The BStringList variable where the retrieved paths shall be
stored. The list is emptied before adding the paths. It is also emptied
on error.
\return A status code.
\retval B_OK Everything went fine.
\retval B_ENTRY_NOT_FOUND A file system entry required for retrieving the
paths doesn't exist. E.g. \c B_FIND_PATH_EXISTING_ONLY was specified and
none of the resulting paths do exist.
*/
/*!
\fn status_t BPathFinder::FindPaths(path_base_directory baseDirectory,
BStringList& _paths)
\brief Retrieves a list of paths in the file system layout.
Equivalent to a call to BPathFinder::FindPaths(const char*,
path_base_directory, const char*, uint32, BStringList&) with a \c NULL
architecture, 0 flags, and \c NULL subpath.
\param baseDirectory Constant indicating which paths to retrieve.
\param _paths The BStringList variable where the retrieved paths shall be
stored. The list is emptied before adding the paths. It is also emptied
on error.
\return A status code.
\retval B_OK Everything went fine.
\retval B_ENTRY_NOT_FOUND A file system entry required for retrieving the
paths doesn't exist. E.g. \c B_FIND_PATH_EXISTING_ONLY was specified and
none of the resulting paths do exist.
*/