354 lines
12 KiB
C
354 lines
12 KiB
C
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/*
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* Copyright (C) the libgit2 contributors. All rights reserved.
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*
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* This file is part of libgit2, distributed under the GNU GPL v2 with
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* a Linking Exception. For full terms see the included COPYING file.
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*/
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#ifndef INCLUDE_sys_git_filter_h__
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#define INCLUDE_sys_git_filter_h__
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#include "git2/filter.h"
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/**
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* @file git2/sys/filter.h
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* @brief Git filter backend and plugin routines
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* @defgroup git_backend Git custom backend APIs
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* @ingroup Git
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* @{
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*/
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GIT_BEGIN_DECL
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/**
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* Look up a filter by name
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*
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* @param name The name of the filter
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* @return Pointer to the filter object or NULL if not found
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*/
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GIT_EXTERN(git_filter *) git_filter_lookup(const char *name);
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#define GIT_FILTER_CRLF "crlf"
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#define GIT_FILTER_IDENT "ident"
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/**
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* This is priority that the internal CRLF filter will be registered with
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*/
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#define GIT_FILTER_CRLF_PRIORITY 0
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/**
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* This is priority that the internal ident filter will be registered with
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*/
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#define GIT_FILTER_IDENT_PRIORITY 100
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/**
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* This is priority to use with a custom filter to imitate a core Git
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* filter driver, so that it will be run last on checkout and first on
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* checkin. You do not have to use this, but it helps compatibility.
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*/
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#define GIT_FILTER_DRIVER_PRIORITY 200
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/**
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* Create a new empty filter list
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*
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* Normally you won't use this because `git_filter_list_load` will create
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* the filter list for you, but you can use this in combination with the
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* `git_filter_lookup` and `git_filter_list_push` functions to assemble
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* your own chains of filters.
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*/
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GIT_EXTERN(int) git_filter_list_new(
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git_filter_list **out,
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git_repository *repo,
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git_filter_mode_t mode,
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uint32_t options);
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/**
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* Add a filter to a filter list with the given payload.
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*
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* Normally you won't have to do this because the filter list is created
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* by calling the "check" function on registered filters when the filter
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* attributes are set, but this does allow more direct manipulation of
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* filter lists when desired.
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*
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* Note that normally the "check" function can set up a payload for the
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* filter. Using this function, you can either pass in a payload if you
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* know the expected payload format, or you can pass NULL. Some filters
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* may fail with a NULL payload. Good luck!
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*/
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GIT_EXTERN(int) git_filter_list_push(
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git_filter_list *fl, git_filter *filter, void *payload);
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/**
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* Look up how many filters are in the list
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*
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* We will attempt to apply all of these filters to any data passed in,
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* but note that the filter apply action still has the option of skipping
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* data that is passed in (for example, the CRLF filter will skip data
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* that appears to be binary).
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*
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* @param fl A filter list
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* @return The number of filters in the list
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*/
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GIT_EXTERN(size_t) git_filter_list_length(const git_filter_list *fl);
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/**
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* A filter source represents a file/blob to be processed
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*/
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typedef struct git_filter_source git_filter_source;
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/**
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* Get the repository that the source data is coming from.
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*/
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GIT_EXTERN(git_repository *) git_filter_source_repo(const git_filter_source *src);
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/**
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* Get the path that the source data is coming from.
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*/
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GIT_EXTERN(const char *) git_filter_source_path(const git_filter_source *src);
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/**
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* Get the file mode of the source file
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* If the mode is unknown, this will return 0
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*/
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GIT_EXTERN(uint16_t) git_filter_source_filemode(const git_filter_source *src);
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/**
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* Get the OID of the source
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* If the OID is unknown (often the case with GIT_FILTER_CLEAN) then
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* this will return NULL.
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*/
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GIT_EXTERN(const git_oid *) git_filter_source_id(const git_filter_source *src);
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/**
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* Get the git_filter_mode_t to be used
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*/
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GIT_EXTERN(git_filter_mode_t) git_filter_source_mode(const git_filter_source *src);
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/**
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* Get the combination git_filter_flag_t options to be applied
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*/
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GIT_EXTERN(uint32_t) git_filter_source_flags(const git_filter_source *src);
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/**
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* Initialize callback on filter
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*
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* Specified as `filter.initialize`, this is an optional callback invoked
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* before a filter is first used. It will be called once at most.
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*
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* If non-NULL, the filter's `initialize` callback will be invoked right
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* before the first use of the filter, so you can defer expensive
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* initialization operations (in case libgit2 is being used in a way that
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* doesn't need the filter).
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*/
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typedef int GIT_CALLBACK(git_filter_init_fn)(git_filter *self);
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/**
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* Shutdown callback on filter
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*
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* Specified as `filter.shutdown`, this is an optional callback invoked
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* when the filter is unregistered or when libgit2 is shutting down. It
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* will be called once at most and should release resources as needed.
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* This may be called even if the `initialize` callback was not made.
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*
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* Typically this function will free the `git_filter` object itself.
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*/
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typedef void GIT_CALLBACK(git_filter_shutdown_fn)(git_filter *self);
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/**
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* Callback to decide if a given source needs this filter
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*
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* Specified as `filter.check`, this is an optional callback that checks
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* if filtering is needed for a given source.
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*
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* It should return 0 if the filter should be applied (i.e. success),
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* GIT_PASSTHROUGH if the filter should not be applied, or an error code
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* to fail out of the filter processing pipeline and return to the caller.
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*
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* The `attr_values` will be set to the values of any attributes given in
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* the filter definition. See `git_filter` below for more detail.
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*
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* The `payload` will be a pointer to a reference payload for the filter.
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* This will start as NULL, but `check` can assign to this pointer for
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* later use by the `stream` callback. Note that the value should be heap
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* allocated (not stack), so that it doesn't go away before the `stream`
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* callback can use it. If a filter allocates and assigns a value to the
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* `payload`, it will need a `cleanup` callback to free the payload.
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*/
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typedef int GIT_CALLBACK(git_filter_check_fn)(
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git_filter *self,
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void **payload, /* NULL on entry, may be set */
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const git_filter_source *src,
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const char **attr_values);
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#ifndef GIT_DEPRECATE_HARD
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/**
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* Callback to actually perform the data filtering
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*
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* Specified as `filter.apply`, this is the callback that actually filters
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* data. If it successfully writes the output, it should return 0. Like
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* `check`, it can return GIT_PASSTHROUGH to indicate that the filter
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* doesn't want to run. Other error codes will stop filter processing and
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* return to the caller.
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*
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* The `payload` value will refer to any payload that was set by the
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* `check` callback. It may be read from or written to as needed.
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*
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* @deprecated use git_filter_stream_fn
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*/
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typedef int GIT_CALLBACK(git_filter_apply_fn)(
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git_filter *self,
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void **payload, /* may be read and/or set */
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git_buf *to,
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const git_buf *from,
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const git_filter_source *src);
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#endif
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/**
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* Callback to perform the data filtering.
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*
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* Specified as `filter.stream`, this is a callback that filters data
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* in a streaming manner. This function will provide a
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* `git_writestream` that will the original data will be written to;
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* with that data, the `git_writestream` will then perform the filter
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* translation and stream the filtered data out to the `next` location.
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*/
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typedef int GIT_CALLBACK(git_filter_stream_fn)(
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git_writestream **out,
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git_filter *self,
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void **payload,
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const git_filter_source *src,
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git_writestream *next);
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/**
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* Callback to clean up after filtering has been applied
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*
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* Specified as `filter.cleanup`, this is an optional callback invoked
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* after the filter has been applied. If the `check`, `apply`, or
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* `stream` callbacks allocated a `payload` to keep per-source filter
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* state, use this callback to free that payload and release resources
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* as required.
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*/
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typedef void GIT_CALLBACK(git_filter_cleanup_fn)(
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git_filter *self,
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void *payload);
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/**
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* Filter structure used to register custom filters.
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*
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* To associate extra data with a filter, allocate extra data and put the
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* `git_filter` struct at the start of your data buffer, then cast the
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* `self` pointer to your larger structure when your callback is invoked.
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*/
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struct git_filter {
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/** The `version` field should be set to `GIT_FILTER_VERSION`. */
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unsigned int version;
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/**
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* A whitespace-separated list of attribute names to check for this
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* filter (e.g. "eol crlf text"). If the attribute name is bare, it
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* will be simply loaded and passed to the `check` callback. If it
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* has a value (i.e. "name=value"), the attribute must match that
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* value for the filter to be applied. The value may be a wildcard
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* (eg, "name=*"), in which case the filter will be invoked for any
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* value for the given attribute name. See the attribute parameter
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* of the `check` callback for the attribute value that was specified.
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*/
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const char *attributes;
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/** Called when the filter is first used for any file. */
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git_filter_init_fn initialize;
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/** Called when the filter is removed or unregistered from the system. */
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git_filter_shutdown_fn shutdown;
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/**
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* Called to determine whether the filter should be invoked for a
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* given file. If this function returns `GIT_PASSTHROUGH` then the
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* `stream` or `apply` functions will not be invoked and the
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* contents will be passed through unmodified.
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*/
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git_filter_check_fn check;
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#ifdef GIT_DEPRECATE_HARD
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void *reserved;
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#else
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/**
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* Provided for backward compatibility; this will apply the
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* filter to the given contents in a `git_buf`. Callers should
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* provide a `stream` function instead.
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*/
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git_filter_apply_fn apply;
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#endif
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/**
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* Called to apply the filter, this function will provide a
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* `git_writestream` that will the original data will be
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* written to; with that data, the `git_writestream` will then
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* perform the filter translation and stream the filtered data
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* out to the `next` location.
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*/
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git_filter_stream_fn stream;
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/** Called when the system is done filtering for a file. */
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git_filter_cleanup_fn cleanup;
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};
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#define GIT_FILTER_VERSION 1
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#define GIT_FILTER_INIT {GIT_FILTER_VERSION}
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/**
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* Initializes a `git_filter` with default values. Equivalent to
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* creating an instance with GIT_FILTER_INIT.
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*
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* @param filter the `git_filter` struct to initialize.
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* @param version Version the struct; pass `GIT_FILTER_VERSION`
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* @return Zero on success; -1 on failure.
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*/
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GIT_EXTERN(int) git_filter_init(git_filter *filter, unsigned int version);
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/**
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* Register a filter under a given name with a given priority.
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*
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* As mentioned elsewhere, the initialize callback will not be invoked
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* immediately. It is deferred until the filter is used in some way.
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*
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* A filter's attribute checks and `check` and `stream` (or `apply`)
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* callbacks will be issued in order of `priority` on smudge (to
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* workdir), and in reverse order of `priority` on clean (to odb).
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*
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* Two filters are preregistered with libgit2:
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* - GIT_FILTER_CRLF with priority 0
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* - GIT_FILTER_IDENT with priority 100
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*
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* Currently the filter registry is not thread safe, so any registering or
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* deregistering of filters must be done outside of any possible usage of
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* the filters (i.e. during application setup or shutdown).
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*
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* @param name A name by which the filter can be referenced. Attempting
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* to register with an in-use name will return GIT_EEXISTS.
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* @param filter The filter definition. This pointer will be stored as is
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* by libgit2 so it must be a durable allocation (either static
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* or on the heap).
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* @param priority The priority for filter application
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* @return 0 on successful registry, error code <0 on failure
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*/
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GIT_EXTERN(int) git_filter_register(
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const char *name, git_filter *filter, int priority);
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/**
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* Remove the filter with the given name
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*
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* Attempting to remove the builtin libgit2 filters is not permitted and
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* will return an error.
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*
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* Currently the filter registry is not thread safe, so any registering or
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* deregistering of filters must be done outside of any possible usage of
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* the filters (i.e. during application setup or shutdown).
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*
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* @param name The name under which the filter was registered
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* @return 0 on success, error code <0 on failure
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*/
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GIT_EXTERN(int) git_filter_unregister(const char *name);
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/** @} */
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GIT_END_DECL
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#endif
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