/*
* This file is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2,
* as published by the Free Software Foundation.
*
* In addition to the permissions in the GNU General Public License,
* the authors give you unlimited permission to link the compiled
* version of this file into combinations with other programs,
* and to distribute those combinations without any restriction
* coming from the use of this file. (The General Public License
* restrictions do apply in other respects; for example, they cover
* modification of the file, and distribution when not linked into
* a combined executable.)
*
* This file is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#ifndef INCLUDE_git_oid_h__
#define INCLUDE_git_oid_h__
#include "common.h"
#include "types.h"
/**
* @file git2/oid.h
* @brief Git object id routines
* @defgroup git_oid Git object id routines
* @ingroup Git
* @{
*/
GIT_BEGIN_DECL
/** Size (in bytes) of a raw/binary oid */
#define GIT_OID_RAWSZ 20
/** Size (in bytes) of a hex formatted oid */
#define GIT_OID_HEXSZ (GIT_OID_RAWSZ * 2)
/** Minimum length (in number of hex characters,
* i.e. packets of 4 bits) of an oid prefix */
#define GIT_OID_MINPREFIXLEN 4
/** Unique identity of any object (commit, tree, blob, tag). */
typedef struct {
/** raw binary formatted id */
unsigned char id[GIT_OID_RAWSZ];
} git_oid;
/**
* Parse a hex formatted object id into a git_oid.
* @param out oid structure the result is written into.
* @param str input hex string; must be pointing at the start of
* the hex sequence and have at least the number of bytes
* needed for an oid encoded in hex (40 bytes).
* @return GIT_SUCCESS if valid; GIT_ENOTOID on failure.
*/
GIT_EXTERN(int) git_oid_mkstr(git_oid *out, const char *str);
/**
* Copy an already raw oid into a git_oid structure.
* @param out oid structure the result is written into.
* @param raw the raw input bytes to be copied.
*/
GIT_EXTERN(void) git_oid_mkraw(git_oid *out, const unsigned char *raw);
/**
* Format a git_oid into a hex string.
* @param str output hex string; must be pointing at the start of
* the hex sequence and have at least the number of bytes
* needed for an oid encoded in hex (40 bytes). Only the
* oid digits are written; a '\\0' terminator must be added
* by the caller if it is required.
* @param oid oid structure to format.
*/
GIT_EXTERN(void) git_oid_fmt(char *str, const git_oid *oid);
/**
* Format a git_oid into a loose-object path string.
* <p>
* The resulting string is "aa/...", where "aa" is the first two
* hex digitis of the oid and "..." is the remaining 38 digits.
*
* @param str output hex string; must be pointing at the start of
* the hex sequence and have at least the number of bytes
* needed for an oid encoded in hex (41 bytes). Only the
* oid digits are written; a '\\0' terminator must be added
* by the caller if it is required.
* @param oid oid structure to format.
*/
GIT_EXTERN(void) git_oid_pathfmt(char *str, const git_oid *oid);
/**
* Format a git_oid into a newly allocated c-string.
* @param oid the oid structure to format
* @return the c-string; NULL if memory is exhausted. Caller must
* deallocate the string with free().
*/
GIT_EXTERN(char *) git_oid_allocfmt(const git_oid *oid);
/**
* Format a git_oid into a buffer as a hex format c-string.
* <p>
* If the buffer is smaller than GIT_OID_HEXSZ+1, then the resulting
* oid c-string will be truncated to n-1 characters. If there are
* any input parameter errors (out == NULL, n == 0, oid == NULL),
* then a pointer to an empty string is returned, so that the return
* value can always be printed.
*
* @param out the buffer into which the oid string is output.
* @param n the size of the out buffer.
* @param oid the oid structure to format.
* @return the out buffer pointer, assuming no input parameter
* errors, otherwise a pointer to an empty string.
*/
GIT_EXTERN(char *) git_oid_to_string(char *out, size_t n, const git_oid *oid);
/**
* Copy an oid from one structure to another.
* @param out oid structure the result is written into.
* @param src oid structure to copy from.
*/
GIT_EXTERN(void) git_oid_cpy(git_oid *out, const git_oid *src);
/**
* Compare two oid structures.
* @param a first oid structure.
* @param b second oid structure.
* @return <0, 0, >0 if a < b, a == b, a > b.
*/
GIT_EXTERN(int) git_oid_cmp(const git_oid *a, const git_oid *b);
/**
* Compare the first 'len' hexadecimal characters (packets of 4 bits)
* of two oid structures.
* @param len the number of hex chars to compare
* @param a first oid structure.
* @param b second oid structure.
* @return 0 in case of a match
*/
GIT_EXTERN(int) git_oid_ncmp(unsigned int len, git_oid *a, git_oid *b);
/**
* OID Shortener object
*/
typedef struct git_oid_shorten git_oid_shorten;
/**
* Create a new OID shortener.
*
* The OID shortener is used to process a list of OIDs
* in text form and return the shortest length that would
* uniquely identify all of them.
*
* E.g. look at the result of `git log --abbrev`.
*
* @param min_length The minimal length for all identifiers,
* which will be used even if shorter OIDs would still
* be unique.
* @return a `git_oid_shorten` instance, NULL if OOM
*/
git_oid_shorten *git_oid_shorten_new(size_t min_length);
/**
* Add a new OID to set of shortened OIDs and calculate
* the minimal length to uniquely identify all the OIDs in
* the set.
*
* The OID is expected to be a 40-char hexadecimal string.
* The OID is owned by the user and will not be modified
* or freed.
*
* For performance reasons, there is a hard-limit of how many
* OIDs can be added to a single set (around ~22000, assuming
* a mostly randomized distribution), which should be enough
* for any kind of program, and keeps the algorithm fast and
* memory-efficient.
*
* Attempting to add more than those OIDs will result in a
* GIT_ENOMEM error
*
* @param os a `git_oid_shorten` instance
* @param text_oid an OID in text form
* @return the minimal length to uniquely identify all OIDs
* added so far to the set; or an error code (<0) if an
* error occurs.
*/
int git_oid_shorten_add(git_oid_shorten *os, const char *text_oid);
/**
* Free an OID shortener instance
*
* @param os a `git_oid_shorten` instance
*/
void git_oid_shorten_free(git_oid_shorten *os);
/** @} */
GIT_END_DECL
#endif
