reftable/reftable-record.h

   1 /*
   2 Copyright 2020 Google LLC
   3
   4 Use of this source code is governed by a BSD-style
   5 license that can be found in the LICENSE file or at
   6 https://developers.google.com/open-source/licenses/bsd
   7 */
   8
   9 #ifndef REFTABLE_RECORD_H
  10 #define REFTABLE_RECORD_H
  11
  12 #include "hash.h"
  13 #include <stdint.h>
  14
  15 /*
  16  * Basic data types
  17  *
  18  * Reftables store the state of each ref in struct reftable_ref_record, and they
  19  * store a sequence of reflog updates in struct reftable_log_record.
  20  */
  21
  22 /* reftable_ref_record holds a ref database entry target_value */
  23 struct reftable_ref_record {
  24         char *refname; /* Name of the ref, malloced. */
  25         size_t refname_cap;
  26         uint64_t update_index; /* Logical timestamp at which this value is
  27                                 * written */
  28
  29         enum {
  30                 /* tombstone to hide deletions from earlier tables */
  31                 REFTABLE_REF_DELETION = 0x0,
  32
  33                 /* a simple ref */
  34                 REFTABLE_REF_VAL1 = 0x1,
  35                 /* a tag, plus its peeled hash */
  36                 REFTABLE_REF_VAL2 = 0x2,
  37
  38                 /* a symbolic reference */
  39                 REFTABLE_REF_SYMREF = 0x3,
  40 #define REFTABLE_NR_REF_VALUETYPES 4
  41         } value_type;
  42         union {
  43                 unsigned char val1[GIT_MAX_RAWSZ];
  44                 struct {
  45                         unsigned char value[GIT_MAX_RAWSZ]; /* first hash  */
  46                         unsigned char target_value[GIT_MAX_RAWSZ]; /* second hash */
  47                 } val2;
  48                 char *symref; /* referent, malloced 0-terminated string */
  49         } value;
  50 };
  51
  52 /* Returns the first hash, or NULL if `rec` is not of type
  53  * REFTABLE_REF_VAL1 or REFTABLE_REF_VAL2. */
  54 const unsigned char *reftable_ref_record_val1(const struct reftable_ref_record *rec);
  55
  56 /* Returns the second hash, or NULL if `rec` is not of type
  57  * REFTABLE_REF_VAL2. */
  58 const unsigned char *reftable_ref_record_val2(const struct reftable_ref_record *rec);
  59
  60 /* returns whether 'ref' represents a deletion */
  61 int reftable_ref_record_is_deletion(const struct reftable_ref_record *ref);
  62
  63 /* prints a reftable_ref_record onto stdout. Useful for debugging. */
  64 void reftable_ref_record_print(const struct reftable_ref_record *ref,
  65                                uint32_t hash_id);
  66
  67 /* frees and nulls all pointer values inside `ref`. */
  68 void reftable_ref_record_release(struct reftable_ref_record *ref);
  69
  70 /* returns whether two reftable_ref_records are the same. Useful for testing. */
  71 int reftable_ref_record_equal(const struct reftable_ref_record *a,
  72                               const struct reftable_ref_record *b, int hash_size);
  73
  74 /* reftable_log_record holds a reflog entry */
  75 struct reftable_log_record {
  76         char *refname;
  77         size_t refname_cap;
  78         uint64_t update_index; /* logical timestamp of a transactional update.
  79                                 */
  80
  81         enum {
  82                 /* tombstone to hide deletions from earlier tables */
  83                 REFTABLE_LOG_DELETION = 0x0,
  84
  85                 /* a simple update */
  86                 REFTABLE_LOG_UPDATE = 0x1,
  87 #define REFTABLE_NR_LOG_VALUETYPES 2
  88         } value_type;
  89
  90         union {
  91                 struct {
  92                         unsigned char new_hash[GIT_MAX_RAWSZ];
  93                         unsigned char old_hash[GIT_MAX_RAWSZ];
  94                         char *name;
  95                         char *email;
  96                         uint64_t time;
  97                         int16_t tz_offset;
  98                         char *message;
  99                         size_t message_cap;
 100                 } update;
 101         } value;
 102 };
 103
 104 /* returns whether 'ref' represents the deletion of a log record. */
 105 int reftable_log_record_is_deletion(const struct reftable_log_record *log);
 106
 107 /* frees and nulls all pointer values. */
 108 void reftable_log_record_release(struct reftable_log_record *log);
 109
 110 /* returns whether two records are equal. Useful for testing. */
 111 int reftable_log_record_equal(const struct reftable_log_record *a,
 112                               const struct reftable_log_record *b, int hash_size);
 113
 114 /* dumps a reftable_log_record on stdout, for debugging/testing. */
 115 void reftable_log_record_print(struct reftable_log_record *log,
 116                                uint32_t hash_id);
 117
 118 #endif