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Diffstat (limited to 'include/git2/sys/filter.h')
| -rw-r--r-- | include/git2/sys/filter.h | 292 |
1 files changed, 292 insertions, 0 deletions
diff --git a/include/git2/sys/filter.h b/include/git2/sys/filter.h new file mode 100644 index 000000000..94ad3aed4 --- /dev/null +++ b/include/git2/sys/filter.h @@ -0,0 +1,292 @@ +/* + * Copyright (C) the libgit2 contributors. All rights reserved. + * + * This file is part of libgit2, distributed under the GNU GPL v2 with + * a Linking Exception. For full terms see the included COPYING file. + */ +#ifndef INCLUDE_sys_git_filter_h__ +#define INCLUDE_sys_git_filter_h__ + +#include "git2/filter.h" + +/** + * @file git2/sys/filter.h + * @brief Git filter backend and plugin routines + * @defgroup git_backend Git custom backend APIs + * @ingroup Git + * @{ + */ +GIT_BEGIN_DECL + +/** + * Look up a filter by name + * + * @param name The name of the filter + * @return Pointer to the filter object or NULL if not found + */ +GIT_EXTERN(git_filter *) git_filter_lookup(const char *name); + +#define GIT_FILTER_CRLF "crlf" +#define GIT_FILTER_IDENT "ident" + +/** + * This is priority that the internal CRLF filter will be registered with + */ +#define GIT_FILTER_CRLF_PRIORITY 0 + +/** + * This is priority that the internal ident filter will be registered with + */ +#define GIT_FILTER_IDENT_PRIORITY 100 + +/** + * This is priority to use with a custom filter to imitate a core Git + * filter driver, so that it will be run last on checkout and first on + * checkin. You do not have to use this, but it helps compatibility. + */ +#define GIT_FILTER_DRIVER_PRIORITY 200 + +/** + * Create a new empty filter list + * + * Normally you won't use this because `git_filter_list_load` will create + * the filter list for you, but you can use this in combination with the + * `git_filter_lookup` and `git_filter_list_push` functions to assemble + * your own chains of filters. + */ +GIT_EXTERN(int) git_filter_list_new( + git_filter_list **out, git_repository *repo, git_filter_mode_t mode); + +/** + * Add a filter to a filter list with the given payload. + * + * Normally you won't have to do this because the filter list is created + * by calling the "check" function on registered filters when the filter + * attributes are set, but this does allow more direct manipulation of + * filter lists when desired. + * + * Note that normally the "check" function can set up a payload for the + * filter. Using this function, you can either pass in a payload if you + * know the expected payload format, or you can pass NULL. Some filters + * may fail with a NULL payload. Good luck! + */ +GIT_EXTERN(int) git_filter_list_push( + git_filter_list *fl, git_filter *filter, void *payload); + +/** + * Look up how many filters are in the list + * + * We will attempt to apply all of these filters to any data passed in, + * but note that the filter apply action still has the option of skipping + * data that is passed in (for example, the CRLF filter will skip data + * that appears to be binary). + * + * @param fl A filter list + * @return The number of filters in the list + */ +GIT_EXTERN(size_t) git_filter_list_length(const git_filter_list *fl); + +/** + * A filter source represents a file/blob to be processed + */ +typedef struct git_filter_source git_filter_source; + +/** + * Get the repository that the source data is coming from. + */ +GIT_EXTERN(git_repository *) git_filter_source_repo(const git_filter_source *src); + +/** + * Get the path that the source data is coming from. + */ +GIT_EXTERN(const char *) git_filter_source_path(const git_filter_source *src); + +/** + * Get the file mode of the source file + * If the mode is unknown, this will return 0 + */ +GIT_EXTERN(uint16_t) git_filter_source_filemode(const git_filter_source *src); + +/** + * Get the OID of the source + * If the OID is unknown (often the case with GIT_FILTER_CLEAN) then + * this will return NULL. + */ +GIT_EXTERN(const git_oid *) git_filter_source_id(const git_filter_source *src); + +/** + * Get the git_filter_mode_t to be applied + */ +GIT_EXTERN(git_filter_mode_t) git_filter_source_mode(const git_filter_source *src); + +/* + * struct git_filter + * + * The filter lifecycle: + * - initialize - first use of filter + * - shutdown - filter removed/unregistered from system + * - check - considering filter for file + * - apply - apply filter to file contents + * - cleanup - done with file + */ + +/** + * Initialize callback on filter + * + * Specified as `filter.initialize`, this is an optional callback invoked + * before a filter is first used. It will be called once at most. + * + * If non-NULL, the filter's `initialize` callback will be invoked right + * before the first use of the filter, so you can defer expensive + * initialization operations (in case libgit2 is being used in a way that + * doesn't need the filter). + */ +typedef int (*git_filter_init_fn)(git_filter *self); + +/** + * Shutdown callback on filter + * + * Specified as `filter.shutdown`, this is an optional callback invoked + * when the filter is unregistered or when libgit2 is shutting down. It + * will be called once at most and should release resources as needed. + * + * Typically this function will free the `git_filter` object itself. + */ +typedef void (*git_filter_shutdown_fn)(git_filter *self); + +/** + * Callback to decide if a given source needs this filter + * + * Specified as `filter.check`, this is an optional callback that checks + * if filtering is needed for a given source. + * + * It should return 0 if the filter should be applied (i.e. success), + * GIT_PASSTHROUGH if the filter should not be applied, or an error code + * to fail out of the filter processing pipeline and return to the caller. + * + * The `attr_values` will be set to the values of any attributes given in + * the filter definition. See `git_filter` below for more detail. + * + * The `payload` will be a pointer to a reference payload for the filter. + * This will start as NULL, but `check` can assign to this pointer for + * later use by the `apply` callback. Note that the value should be heap + * allocated (not stack), so that it doesn't go away before the `apply` + * callback can use it. If a filter allocates and assigns a value to the + * `payload`, it will need a `cleanup` callback to free the payload. + */ +typedef int (*git_filter_check_fn)( + git_filter *self, + void **payload, /* points to NULL ptr on entry, may be set */ + const git_filter_source *src, + const char **attr_values); + +/** + * Callback to actually perform the data filtering + * + * Specified as `filter.apply`, this is the callback that actually filters + * data. If it successfully writes the output, it should return 0. Like + * `check`, it can return GIT_PASSTHROUGH to indicate that the filter + * doesn't want to run. Other error codes will stop filter processing and + * return to the caller. + * + * The `payload` value will refer to any payload that was set by the + * `check` callback. It may be read from or written to as needed. + */ +typedef int (*git_filter_apply_fn)( + git_filter *self, + void **payload, /* may be read and/or set */ + git_buf *to, + const git_buf *from, + const git_filter_source *src); + +/** + * Callback to clean up after filtering has been applied + * + * Specified as `filter.cleanup`, this is an optional callback invoked + * after the filter has been applied. If the `check` or `apply` callbacks + * allocated a `payload` to keep per-source filter state, use this + * callback to free that payload and release resources as required. + */ +typedef void (*git_filter_cleanup_fn)( + git_filter *self, + void *payload); + +/** + * Filter structure used to register custom filters. + * + * To associate extra data with a filter, allocate extra data and put the + * `git_filter` struct at the start of your data buffer, then cast the + * `self` pointer to your larger structure when your callback is invoked. + * + * `version` should be set to GIT_FILTER_VERSION + * + * `attributes` is a whitespace-separated list of attribute names to check + * for this filter (e.g. "eol crlf text"). If the attribute name is bare, + * it will be simply loaded and passed to the `check` callback. If it has + * a value (i.e. "name=value"), the attribute must match that value for + * the filter to be applied. + * + * The `initialize`, `shutdown`, `check`, `apply`, and `cleanup` callbacks + * are all documented above with the respective function pointer typedefs. + */ +struct git_filter { + unsigned int version; + + const char *attributes; + + git_filter_init_fn initialize; + git_filter_shutdown_fn shutdown; + git_filter_check_fn check; + git_filter_apply_fn apply; + git_filter_cleanup_fn cleanup; +}; + +#define GIT_FILTER_VERSION 1 + +/** + * Register a filter under a given name with a given priority. + * + * As mentioned elsewhere, the initialize callback will not be invoked + * immediately. It is deferred until the filter is used in some way. + * + * A filter's attribute checks and `check` and `apply` callbacks will be + * issued in order of `priority` on smudge (to workdir), and in reverse + * order of `priority` on clean (to odb). + * + * Two filters are preregistered with libgit2: + * - GIT_FILTER_CRLF with priority 0 + * - GIT_FILTER_IDENT with priority 100 + * + * Currently the filter registry is not thread safe, so any registering or + * deregistering of filters must be done outside of any possible usage of + * the filters (i.e. during application setup or shutdown). + * + * @param name A name by which the filter can be referenced. Attempting + * to register with an in-use name will return GIT_EEXISTS. + * @param filter The filter definition. This pointer will be stored as is + * by libgit2 so it must be a durable allocation (either static + * or on the heap). + * @param priority The priority for filter application + * @return 0 on successful registry, error code <0 on failure + */ +GIT_EXTERN(int) git_filter_register( + const char *name, git_filter *filter, int priority); + +/** + * Remove the filter with the given name + * + * Attempting to remove the builtin libgit2 filters is not permitted and + * will return an error. + * + * Currently the filter registry is not thread safe, so any registering or + * deregistering of filters must be done outside of any possible usage of + * the filters (i.e. during application setup or shutdown). + * + * @param name The name under which the filter was registered + * @return 0 on success, error code <0 on failure + */ +GIT_EXTERN(int) git_filter_unregister(const char *name); + +/** @} */ +GIT_END_DECL +#endif |