374 lines
11 KiB
C
374 lines
11 KiB
C
/*
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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_git_oid_h__
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#define INCLUDE_git_oid_h__
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#include "common.h"
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#include "types.h"
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#include "experimental.h"
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/**
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* @file git2/oid.h
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* @brief Git object id routines
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* @defgroup git_oid Git object id routines
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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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/** The type of object id. */
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typedef enum {
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#ifdef GIT_EXPERIMENTAL_SHA256
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GIT_OID_SHA1 = 1, /**< SHA1 */
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GIT_OID_SHA256 = 2 /**< SHA256 */
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#else
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GIT_OID_SHA1 = 1 /**< SHA1 */
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#endif
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} git_oid_t;
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/*
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* SHA1 is currently the only supported object ID type.
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*/
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/** SHA1 is currently libgit2's default oid type. */
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#define GIT_OID_DEFAULT GIT_OID_SHA1
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/** Size (in bytes) of a raw/binary sha1 oid */
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#define GIT_OID_SHA1_SIZE 20
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/** Size (in bytes) of a hex formatted sha1 oid */
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#define GIT_OID_SHA1_HEXSIZE (GIT_OID_SHA1_SIZE * 2)
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/**
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* The binary representation of the null sha1 object ID.
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*/
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#ifndef GIT_EXPERIMENTAL_SHA256
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# define GIT_OID_SHA1_ZERO { { 0 } }
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#else
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# define GIT_OID_SHA1_ZERO { GIT_OID_SHA1, { 0 } }
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#endif
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/**
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* The string representation of the null sha1 object ID.
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*/
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#define GIT_OID_SHA1_HEXZERO "0000000000000000000000000000000000000000"
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/*
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* Experimental SHA256 support is a breaking change to the API.
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* This exists for application compatibility testing.
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*/
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#ifdef GIT_EXPERIMENTAL_SHA256
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/** Size (in bytes) of a raw/binary sha256 oid */
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# define GIT_OID_SHA256_SIZE 32
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/** Size (in bytes) of a hex formatted sha256 oid */
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# define GIT_OID_SHA256_HEXSIZE (GIT_OID_SHA256_SIZE * 2)
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/**
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* The binary representation of the null sha256 object ID.
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*/
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# define GIT_OID_SHA256_ZERO { GIT_OID_SHA256, { 0 } }
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/**
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* The string representation of the null sha256 object ID.
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*/
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# define GIT_OID_SHA256_HEXZERO "0000000000000000000000000000000000000000000000000000000000000000"
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#endif
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/* Maximum possible object ID size in raw / hex string format. */
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#ifndef GIT_EXPERIMENTAL_SHA256
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# define GIT_OID_MAX_SIZE GIT_OID_SHA1_SIZE
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# define GIT_OID_MAX_HEXSIZE GIT_OID_SHA1_HEXSIZE
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#else
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# define GIT_OID_MAX_SIZE GIT_OID_SHA256_SIZE
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# define GIT_OID_MAX_HEXSIZE GIT_OID_SHA256_HEXSIZE
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#endif
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/** Minimum length (in number of hex characters,
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* i.e. packets of 4 bits) of an oid prefix */
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#define GIT_OID_MINPREFIXLEN 4
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/** Unique identity of any object (commit, tree, blob, tag). */
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typedef struct git_oid {
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#ifdef GIT_EXPERIMENTAL_SHA256
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/** type of object id */
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unsigned char type;
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#endif
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/** raw binary formatted id */
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unsigned char id[GIT_OID_MAX_SIZE];
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} git_oid;
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/**
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* Parse a hex formatted object id into a git_oid.
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*
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* The appropriate number of bytes for the given object ID type will
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* be read from the string - 40 bytes for SHA1, 64 bytes for SHA256.
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* The given string need not be NUL terminated.
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*
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* @param out oid structure the result is written into.
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* @param str input hex string; must be pointing at the start of
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* the hex sequence and have at least the number of bytes
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* needed for an oid encoded in hex (40 bytes for sha1,
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* 256 bytes for sha256).
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* @param type the type of object id
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* @return 0 or an error code
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*/
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#ifdef GIT_EXPERIMENTAL_SHA256
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GIT_EXTERN(int) git_oid_fromstr(git_oid *out, const char *str, git_oid_t type);
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#else
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GIT_EXTERN(int) git_oid_fromstr(git_oid *out, const char *str);
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#endif
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/**
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* Parse a hex formatted NUL-terminated string into a git_oid.
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*
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* @param out oid structure the result is written into.
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* @param str input hex string; must be null-terminated.
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* @param type the type of object id
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* @return 0 or an error code
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*/
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#ifdef GIT_EXPERIMENTAL_SHA256
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GIT_EXTERN(int) git_oid_fromstrp(git_oid *out, const char *str, git_oid_t type);
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#else
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GIT_EXTERN(int) git_oid_fromstrp(git_oid *out, const char *str);
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#endif
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/**
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* Parse N characters of a hex formatted object id into a git_oid.
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*
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* If N is odd, the last byte's high nibble will be read in and the
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* low nibble set to zero.
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*
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* @param out oid structure the result is written into.
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* @param str input hex string of at least size `length`
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* @param length length of the input string
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* @param type the type of object id
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* @return 0 or an error code
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*/
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#ifdef GIT_EXPERIMENTAL_SHA256
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GIT_EXTERN(int) git_oid_fromstrn(git_oid *out, const char *str, size_t length, git_oid_t type);
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#else
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GIT_EXTERN(int) git_oid_fromstrn(git_oid *out, const char *str, size_t length);
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#endif
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/**
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* Copy an already raw oid into a git_oid structure.
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*
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* @param out oid structure the result is written into.
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* @param raw the raw input bytes to be copied.
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* @return 0 on success or error code
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*/
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#ifdef GIT_EXPERIMENTAL_SHA256
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GIT_EXTERN(int) git_oid_fromraw(git_oid *out, const unsigned char *raw, git_oid_t type);
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#else
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GIT_EXTERN(int) git_oid_fromraw(git_oid *out, const unsigned char *raw);
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#endif
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/**
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* Format a git_oid into a hex string.
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*
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* @param out output hex string; must be pointing at the start of
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* the hex sequence and have at least the number of bytes
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* needed for an oid encoded in hex (40 bytes for SHA1,
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* 64 bytes for SHA256). Only the oid digits are written;
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* a '\\0' terminator must be added by the caller if it is
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* required.
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* @param id oid structure to format.
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* @return 0 on success or error code
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*/
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GIT_EXTERN(int) git_oid_fmt(char *out, const git_oid *id);
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/**
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* Format a git_oid into a partial hex string.
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*
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* @param out output hex string; you say how many bytes to write.
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* If the number of bytes is > GIT_OID_SHA1_HEXSIZE, extra bytes
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* will be zeroed; if not, a '\0' terminator is NOT added.
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* @param n number of characters to write into out string
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* @param id oid structure to format.
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* @return 0 on success or error code
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*/
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GIT_EXTERN(int) git_oid_nfmt(char *out, size_t n, const git_oid *id);
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/**
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* Format a git_oid into a loose-object path string.
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*
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* The resulting string is "aa/...", where "aa" is the first two
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* hex digits of the oid and "..." is the remaining 38 digits.
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*
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* @param out output hex string; must be pointing at the start of
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* the hex sequence and have at least the number of bytes
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* needed for an oid encoded in hex (41 bytes for SHA1,
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* 65 bytes for SHA256). Only the oid digits are written;
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* a '\\0' terminator must be added by the caller if it
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* is required.
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* @param id oid structure to format.
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* @return 0 on success, non-zero callback return value, or error code
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*/
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GIT_EXTERN(int) git_oid_pathfmt(char *out, const git_oid *id);
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/**
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* Format a git_oid into a statically allocated c-string.
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*
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* The c-string is owned by the library and should not be freed
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* by the user. If libgit2 is built with thread support, the string
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* will be stored in TLS (i.e. one buffer per thread) to allow for
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* concurrent calls of the function.
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*
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* @param oid The oid structure to format
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* @return the c-string or NULL on failure
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*/
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GIT_EXTERN(char *) git_oid_tostr_s(const git_oid *oid);
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/**
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* Format a git_oid into a buffer as a hex format c-string.
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*
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* If the buffer is smaller than the size of a hex-formatted oid string
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* plus an additional byte (GIT_OID_SHA_HEXSIZE + 1 for SHA1 or
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* GIT_OID_SHA256_HEXSIZE + 1 for SHA256), then the resulting
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* oid c-string will be truncated to n-1 characters (but will still be
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* NUL-byte terminated).
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*
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* If there are any input parameter errors (out == NULL, n == 0, oid ==
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* NULL), then a pointer to an empty string is returned, so that the
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* return value can always be printed.
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*
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* @param out the buffer into which the oid string is output.
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* @param n the size of the out buffer.
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* @param id the oid structure to format.
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* @return the out buffer pointer, assuming no input parameter
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* errors, otherwise a pointer to an empty string.
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*/
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GIT_EXTERN(char *) git_oid_tostr(char *out, size_t n, const git_oid *id);
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/**
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* Copy an oid from one structure to another.
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*
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* @param out oid structure the result is written into.
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* @param src oid structure to copy from.
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* @return 0 on success or error code
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*/
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GIT_EXTERN(int) git_oid_cpy(git_oid *out, const git_oid *src);
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/**
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* Compare two oid structures.
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*
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* @param a first oid structure.
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* @param b second oid structure.
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* @return <0, 0, >0 if a < b, a == b, a > b.
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*/
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GIT_EXTERN(int) git_oid_cmp(const git_oid *a, const git_oid *b);
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/**
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* Compare two oid structures for equality
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*
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* @param a first oid structure.
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* @param b second oid structure.
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* @return true if equal, false otherwise
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*/
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GIT_EXTERN(int) git_oid_equal(const git_oid *a, const git_oid *b);
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/**
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* Compare the first 'len' hexadecimal characters (packets of 4 bits)
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* of two oid structures.
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*
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* @param a first oid structure.
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* @param b second oid structure.
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* @param len the number of hex chars to compare
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* @return 0 in case of a match
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*/
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GIT_EXTERN(int) git_oid_ncmp(const git_oid *a, const git_oid *b, size_t len);
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/**
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* Check if an oid equals an hex formatted object id.
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*
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* @param id oid structure.
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* @param str input hex string of an object id.
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* @return 0 in case of a match, -1 otherwise.
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*/
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GIT_EXTERN(int) git_oid_streq(const git_oid *id, const char *str);
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/**
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* Compare an oid to an hex formatted object id.
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*
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* @param id oid structure.
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* @param str input hex string of an object id.
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* @return -1 if str is not valid, <0 if id sorts before str,
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* 0 if id matches str, >0 if id sorts after str.
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*/
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GIT_EXTERN(int) git_oid_strcmp(const git_oid *id, const char *str);
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/**
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* Check is an oid is all zeros.
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*
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* @return 1 if all zeros, 0 otherwise.
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*/
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GIT_EXTERN(int) git_oid_is_zero(const git_oid *id);
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/**
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* OID Shortener object
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*/
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typedef struct git_oid_shorten git_oid_shorten;
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/**
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* Create a new OID shortener.
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*
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* The OID shortener is used to process a list of OIDs
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* in text form and return the shortest length that would
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* uniquely identify all of them.
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*
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* E.g. look at the result of `git log --abbrev`.
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*
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* @param min_length The minimal length for all identifiers,
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* which will be used even if shorter OIDs would still
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* be unique.
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* @return a `git_oid_shorten` instance, NULL if OOM
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*/
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GIT_EXTERN(git_oid_shorten *) git_oid_shorten_new(size_t min_length);
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/**
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* Add a new OID to set of shortened OIDs and calculate
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* the minimal length to uniquely identify all the OIDs in
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* the set.
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*
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* The OID is expected to be a 40-char hexadecimal string.
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* The OID is owned by the user and will not be modified
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* or freed.
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*
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* For performance reasons, there is a hard-limit of how many
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* OIDs can be added to a single set (around ~32000, assuming
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* a mostly randomized distribution), which should be enough
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* for any kind of program, and keeps the algorithm fast and
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* memory-efficient.
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*
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* Attempting to add more than those OIDs will result in a
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* GIT_ERROR_INVALID error
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*
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* @param os a `git_oid_shorten` instance
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* @param text_id an OID in text form
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* @return the minimal length to uniquely identify all OIDs
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* added so far to the set; or an error code (<0) if an
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* error occurs.
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*/
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GIT_EXTERN(int) git_oid_shorten_add(git_oid_shorten *os, const char *text_id);
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/**
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* Free an OID shortener instance
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*
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* @param os a `git_oid_shorten` instance
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*/
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GIT_EXTERN(void) git_oid_shorten_free(git_oid_shorten *os);
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/** @} */
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GIT_END_DECL
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#endif
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