git notes merge: Initial implementation handling trivial merges only
[git/git.git] / notes-merge.c
CommitLineData
75ef3f4a
JH
1#include "cache.h"
2#include "commit.h"
3#include "refs.h"
4#include "notes-merge.h"
5
6void init_notes_merge_options(struct notes_merge_options *o)
7{
8 memset(o, 0, sizeof(struct notes_merge_options));
9 o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
10}
11
12#define OUTPUT(o, v, ...) \
13 do { \
14 if ((o)->verbosity >= (v)) { \
15 printf(__VA_ARGS__); \
16 puts(""); \
17 } \
18 } while (0)
19
20int notes_merge(struct notes_merge_options *o,
21 unsigned char *result_sha1)
22{
23 unsigned char local_sha1[20], remote_sha1[20];
24 struct commit *local, *remote;
25 struct commit_list *bases = NULL;
26 const unsigned char *base_sha1;
27 int result = 0;
28
29 assert(o->local_ref && o->remote_ref);
30 hashclr(result_sha1);
31
32 trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
33 o->local_ref, o->remote_ref);
34
35 /* Dereference o->local_ref into local_sha1 */
36 if (!resolve_ref(o->local_ref, local_sha1, 0, NULL))
37 die("Failed to resolve local notes ref '%s'", o->local_ref);
38 else if (!check_ref_format(o->local_ref) && is_null_sha1(local_sha1))
39 local = NULL; /* local_sha1 == null_sha1 indicates unborn ref */
40 else if (!(local = lookup_commit_reference(local_sha1)))
41 die("Could not parse local commit %s (%s)",
42 sha1_to_hex(local_sha1), o->local_ref);
43 trace_printf("\tlocal commit: %.7s\n", sha1_to_hex(local_sha1));
44
45 /* Dereference o->remote_ref into remote_sha1 */
46 if (get_sha1(o->remote_ref, remote_sha1)) {
47 /*
48 * Failed to get remote_sha1. If o->remote_ref looks like an
49 * unborn ref, perform the merge using an empty notes tree.
50 */
51 if (!check_ref_format(o->remote_ref)) {
52 hashclr(remote_sha1);
53 remote = NULL;
54 } else {
55 die("Failed to resolve remote notes ref '%s'",
56 o->remote_ref);
57 }
58 } else if (!(remote = lookup_commit_reference(remote_sha1))) {
59 die("Could not parse remote commit %s (%s)",
60 sha1_to_hex(remote_sha1), o->remote_ref);
61 }
62 trace_printf("\tremote commit: %.7s\n", sha1_to_hex(remote_sha1));
63
64 if (!local && !remote)
65 die("Cannot merge empty notes ref (%s) into empty notes ref "
66 "(%s)", o->remote_ref, o->local_ref);
67 if (!local) {
68 /* result == remote commit */
69 hashcpy(result_sha1, remote_sha1);
70 goto found_result;
71 }
72 if (!remote) {
73 /* result == local commit */
74 hashcpy(result_sha1, local_sha1);
75 goto found_result;
76 }
77 assert(local && remote);
78
79 /* Find merge bases */
80 bases = get_merge_bases(local, remote, 1);
81 if (!bases) {
82 base_sha1 = null_sha1;
83 OUTPUT(o, 4, "No merge base found; doing history-less merge");
84 } else if (!bases->next) {
85 base_sha1 = bases->item->object.sha1;
86 OUTPUT(o, 4, "One merge base found (%.7s)",
87 sha1_to_hex(base_sha1));
88 } else {
89 /* TODO: How to handle multiple merge-bases? */
90 base_sha1 = bases->item->object.sha1;
91 OUTPUT(o, 3, "Multiple merge bases found. Using the first "
92 "(%.7s)", sha1_to_hex(base_sha1));
93 }
94
95 OUTPUT(o, 4, "Merging remote commit %.7s into local commit %.7s with "
96 "merge-base %.7s", sha1_to_hex(remote->object.sha1),
97 sha1_to_hex(local->object.sha1), sha1_to_hex(base_sha1));
98
99 if (!hashcmp(remote->object.sha1, base_sha1)) {
100 /* Already merged; result == local commit */
101 OUTPUT(o, 2, "Already up-to-date!");
102 hashcpy(result_sha1, local->object.sha1);
103 goto found_result;
104 }
105 if (!hashcmp(local->object.sha1, base_sha1)) {
106 /* Fast-forward; result == remote commit */
107 OUTPUT(o, 2, "Fast-forward");
108 hashcpy(result_sha1, remote->object.sha1);
109 goto found_result;
110 }
111
112 /* TODO: */
113 result = error("notes_merge() cannot yet handle real merges.");
114
115found_result:
116 free_commit_list(bases);
117 trace_printf("notes_merge(): result = %i, result_sha1 = %.7s\n",
118 result, sha1_to_hex(result_sha1));
119 return result;
120}