/*
* Copyright (C) 2009-2011 the libgit2 contributors
*
* 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_git_odb_h__
#define INCLUDE_git_odb_h__
#include "common.h"
#include "types.h"
#include "oid.h"
#include "odb_backend.h"
/**
* @file git2/odb.h
* @brief Git object database routines
* @defgroup git_odb Git object database routines
* @ingroup Git
* @{
*/
GIT_BEGIN_DECL
/**
* Create a new object database with no backends.
*
* Before the ODB can be used for read/writing, a custom database
* backend must be manually added using `git_odb_add_backend()`
*
* @param out location to store the database pointer, if opened.
* Set to NULL if the open failed.
* @return GIT_SUCCESS or an error code
*/
GIT_EXTERN(int) git_odb_new(git_odb **out);
/**
* Create a new object database and automatically add
* the two default backends:
*
* - git_odb_backend_loose: read and write loose object files
* from disk, assuming `objects_dir` as the Objects folder
*
* - git_odb_backend_pack: read objects from packfiles,
* assuming `objects_dir` as the Objects folder which
* contains a 'pack/' folder with the corresponding data
*
* @param out location to store the database pointer, if opened.
* Set to NULL if the open failed.
* @param objects_dir path of the backends' "objects" directory.
* @return GIT_SUCCESS or an error code
*/
GIT_EXTERN(int) git_odb_open(git_odb **out, const char *objects_dir);
/**
* Add a custom backend to an existing Object DB
*
* The backends are checked in relative ordering, based on the
* value of the `priority` parameter.
*
* Read <odb_backends.h> for more information.
*
* @param odb database to add the backend to
* @param backend pointer to a git_odb_backend instance
* @param priority Value for ordering the backends queue
* @return 0 on sucess; error code otherwise
*/
GIT_EXTERN(int) git_odb_add_backend(git_odb *odb, git_odb_backend *backend, int priority);
/**
* Add a custom backend to an existing Object DB; this
* backend will work as an alternate.
*
* Alternate backends are always checked for objects *after*
* all the main backends have been exhausted.
*
* The backends are checked in relative ordering, based on the
* value of the `priority` parameter.
*
* Writing is disabled on alternate backends.
*
* Read <odb_backends.h> for more information.
*
* @param odb database to add the backend to
* @param backend pointer to a git_odb_backend instance
* @param priority Value for ordering the backends queue
* @return 0 on sucess; error code otherwise
*/
GIT_EXTERN(int) git_odb_add_alternate(git_odb *odb, git_odb_backend *backend, int priority);
/**
* Close an open object database.
*
* @param db database pointer to close. If NULL no action is taken.
*/
GIT_EXTERN(void) git_odb_free(git_odb *db);
/**
* Read an object from the database.
*
* This method queries all available ODB backends
* trying to read the given OID.
*
* The returned object is reference counted and
* internally cached, so it should be closed
* by the user once it's no longer in use.
*
* @param out pointer where to store the read object
* @param db database to search for the object in.
* @param id identity of the object to read.
* @return
* - GIT_SUCCESS if the object was read;
* - GIT_ENOTFOUND if the object is not in the database.
*/
GIT_EXTERN(int) git_odb_read(git_odb_object **out, git_odb *db, const git_oid *id);
/**
* Read an object from the database, given a prefix
* of its identifier.
*
* This method queries all available ODB backends
* trying to match the 'len' first hexadecimal
* characters of the 'short_id'.
* The remaining (GIT_OID_HEXSZ-len)*4 bits of
* 'short_id' must be 0s.
* 'len' must be at least GIT_OID_MINPREFIXLEN,
* and the prefix must be long enough to identify
* a unique object in all the backends; the
* method will fail otherwise.
*
* The returned object is reference counted and
* internally cached, so it should be closed
* by the user once it's no longer in use.
*
* @param out pointer where to store the read object
* @param db database to search for the object in.
* @param short_id a prefix of the id of the object to read.
* @param len the length of the prefix
* @return GIT_SUCCESS if the object was read;
* GIT_ENOTFOUND if the object is not in the database.
* GIT_EAMBIGUOUS if the prefix is ambiguous (several objects match the prefix)
*/
GIT_EXTERN(int) git_odb_read_prefix(git_odb_object **out, git_odb *db, const git_oid *short_id, unsigned int len);
/**
* Read the header of an object from the database, without
* reading its full contents.
*
* The header includes the length and the type of an object.
*
* Note that most backends do not support reading only the header
* of an object, so the whole object will be read and then the
* header will be returned.
*
* @param len_p pointer where to store the length
* @param type_p pointer where to store the type
* @param db database to search for the object in.
* @param id identity of the object to read.
* @return
* - GIT_SUCCESS if the object was read;
* - GIT_ENOTFOUND if the object is not in the database.
*/
GIT_EXTERN(int) git_odb_read_header(size_t *len_p, git_otype *type_p, git_odb *db, const git_oid *id);
/**
* Determine if the given object can be found in the object database.
*
* @param db database to be searched for the given object.
* @param id the object to search for.
* @return
* - 1, if the object was found
* - 0, otherwise
*/
GIT_EXTERN(int) git_odb_exists(git_odb *db, const git_oid *id);
/**
* Write an object directly into the ODB
*
* This method writes a full object straight into the ODB.
* For most cases, it is preferred to write objects through a write
* stream, which is both faster and less memory intensive, specially
* for big objects.
*
* This method is provided for compatibility with custom backends
* which are not able to support streaming writes
*
* @param oid pointer to store the OID result of the write
* @param odb object database where to store the object
* @param data buffer with the data to storr
* @param len size of the buffer
* @param type type of the data to store
* @return GIT_SUCCESS or an error code
*/
GIT_EXTERN(int) git_odb_write(git_oid *oid, git_odb *odb, const void *data, size_t len, git_otype type);
/**
* Open a stream to write an object into the ODB
*
* The type and final length of the object must be specified
* when opening the stream.
*
* The returned stream will be of type `GIT_STREAM_WRONLY` and
* will have the following methods:
*
* - stream->write: write `n` bytes into the stream
* - stream->finalize_write: close the stream and store the object in
* the odb
* - stream->free: free the stream
*
* The streaming write won't be effective until `stream->finalize_write`
* is called and returns without an error
*
* The stream must always be free'd or will leak memory.
*
* @see git_odb_stream
*
* @param stream pointer where to store the stream
* @param db object database where the stream will write
* @param size final size of the object that will be written
* @param type type of the object that will be written
* @return 0 if the stream was created; error code otherwise
*/
GIT_EXTERN(int) git_odb_open_wstream(git_odb_stream **stream, git_odb *db, size_t size, git_otype type);
/**
* Open a stream to read an object from the ODB
*
* Note that most backends do *not* support streaming reads
* because they store their objects as compressed/delta'ed blobs.
*
* It's recommended to use `git_odb_read` instead, which is
* assured to work on all backends.
*
* The returned stream will be of type `GIT_STREAM_RDONLY` and
* will have the following methods:
*
* - stream->read: read `n` bytes from the stream
* - stream->free: free the stream
*
* The stream must always be free'd or will leak memory.
*
* @see git_odb_stream
*
* @param stream pointer where to store the stream
* @param db object database where the stream will read from
* @param oid oid of the object the stream will read from
* @return 0 if the stream was created; error code otherwise
*/
GIT_EXTERN(int) git_odb_open_rstream(git_odb_stream **stream, git_odb *db, const git_oid *oid);
/**
* Determine the object-ID (sha1 hash) of a data buffer
*
* The resulting SHA-1 OID will the itentifier for the data
* buffer as if the data buffer it were to written to the ODB.
*
* @param id the resulting object-ID.
* @param data data to hash
* @param len size of the data
* @param type of the data to hash
* @return GIT_SUCCESS or an error code
*/
GIT_EXTERN(int) git_odb_hash(git_oid *id, const void *data, size_t len, git_otype type);
/**
* Read a file from disk and fill a git_oid with the object id
* that the file would have if it were written to the Object
* Database as an object of the given type. Similar functionality
* to git.git's `git hash-object` without the `-w` flag.
*
* @param out oid structure the result is written into.
* @param path file to read and determine object id for
* @param type the type of the object that will be hashed
* @return GIT_SUCCESS or an error code
*/
GIT_EXTERN(int) git_odb_hashfile(git_oid *out, const char *path, git_otype type);
/**
* Close an ODB object
*
* This method must always be called once a `git_odb_object` is no
* longer needed, otherwise memory will leak.
*
* @param object object to close
*/
GIT_EXTERN(void) git_odb_object_free(git_odb_object *object);
/**
* Return the OID of an ODB object
*
* This is the OID from which the object was read from
*
* @param object the object
* @return a pointer to the OID
*/
GIT_EXTERN(const git_oid *) git_odb_object_id(git_odb_object *object);
/**
* Return the data of an ODB object
*
* This is the uncompressed, raw data as read from the ODB,
* without the leading header.
*
* This pointer is owned by the object and shall not be free'd.
*
* @param object the object
* @return a pointer to the data
*/
GIT_EXTERN(const void *) git_odb_object_data(git_odb_object *object);
/**
* Return the size of an ODB object
*
* This is the real size of the `data` buffer, not the
* actual size of the object.
*
* @param object the object
* @return the size
*/
GIT_EXTERN(size_t) git_odb_object_size(git_odb_object *object);
/**
* Return the type of an ODB object
*
* @param object the object
* @return the type
*/
GIT_EXTERN(git_otype) git_odb_object_type(git_odb_object *object);
/** @} */
GIT_END_DECL
#endif