summaryrefslogtreecommitdiff
path: root/notes-merge.c
blob: ab9885039ee00c8f847bb9cc9ab26e103cfd1cca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
#include "cache.h"
#include "commit.h"
#include "refs.h"
#include "notes-merge.h"
 
void init_notes_merge_options(struct notes_merge_options *o)
{
	memset(o, 0, sizeof(struct notes_merge_options));
	o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
}
 
#define OUTPUT(o, v, ...) \
	do { \
		if ((o)->verbosity >= (v)) { \
			printf(__VA_ARGS__); \
			puts(""); \
		} \
	} while (0)
 
int notes_merge(struct notes_merge_options *o,
		unsigned char *result_sha1)
{
	unsigned char local_sha1[20], remote_sha1[20];
	struct commit *local, *remote;
	struct commit_list *bases = NULL;
	const unsigned char *base_sha1;
	int result = 0;
 
	assert(o->local_ref && o->remote_ref);
	hashclr(result_sha1);
 
	trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
	       o->local_ref, o->remote_ref);
 
	/* Dereference o->local_ref into local_sha1 */
	if (!resolve_ref(o->local_ref, local_sha1, 0, NULL))
		die("Failed to resolve local notes ref '%s'", o->local_ref);
	else if (!check_ref_format(o->local_ref) && is_null_sha1(local_sha1))
		local = NULL; /* local_sha1 == null_sha1 indicates unborn ref */
	else if (!(local = lookup_commit_reference(local_sha1)))
		die("Could not parse local commit %s (%s)",
		    sha1_to_hex(local_sha1), o->local_ref);
	trace_printf("\tlocal commit: %.7s\n", sha1_to_hex(local_sha1));
 
	/* Dereference o->remote_ref into remote_sha1 */
	if (get_sha1(o->remote_ref, remote_sha1)) {
		/*
		 * Failed to get remote_sha1. If o->remote_ref looks like an
		 * unborn ref, perform the merge using an empty notes tree.
		 */
		if (!check_ref_format(o->remote_ref)) {
			hashclr(remote_sha1);
			remote = NULL;
		} else {
			die("Failed to resolve remote notes ref '%s'",
			    o->remote_ref);
		}
	} else if (!(remote = lookup_commit_reference(remote_sha1))) {
		die("Could not parse remote commit %s (%s)",
		    sha1_to_hex(remote_sha1), o->remote_ref);
	}
	trace_printf("\tremote commit: %.7s\n", sha1_to_hex(remote_sha1));
 
	if (!local && !remote)
		die("Cannot merge empty notes ref (%s) into empty notes ref "
		    "(%s)", o->remote_ref, o->local_ref);
	if (!local) {
		/* result == remote commit */
		hashcpy(result_sha1, remote_sha1);
		goto found_result;
	}
	if (!remote) {
		/* result == local commit */
		hashcpy(result_sha1, local_sha1);
		goto found_result;
	}
	assert(local && remote);
 
	/* Find merge bases */
	bases = get_merge_bases(local, remote, 1);
	if (!bases) {
		base_sha1 = null_sha1;
		OUTPUT(o, 4, "No merge base found; doing history-less merge");
	} else if (!bases->next) {
		base_sha1 = bases->item->object.sha1;
		OUTPUT(o, 4, "One merge base found (%.7s)",
		       sha1_to_hex(base_sha1));
	} else {
		/* TODO: How to handle multiple merge-bases? */
		base_sha1 = bases->item->object.sha1;
		OUTPUT(o, 3, "Multiple merge bases found. Using the first "
		       "(%.7s)", sha1_to_hex(base_sha1));
	}
 
	OUTPUT(o, 4, "Merging remote commit %.7s into local commit %.7s with "
	       "merge-base %.7s", sha1_to_hex(remote->object.sha1),
	       sha1_to_hex(local->object.sha1), sha1_to_hex(base_sha1));
 
	if (!hashcmp(remote->object.sha1, base_sha1)) {
		/* Already merged; result == local commit */
		OUTPUT(o, 2, "Already up-to-date!");
		hashcpy(result_sha1, local->object.sha1);
		goto found_result;
	}
	if (!hashcmp(local->object.sha1, base_sha1)) {
		/* Fast-forward; result == remote commit */
		OUTPUT(o, 2, "Fast-forward");
		hashcpy(result_sha1, remote->object.sha1);
		goto found_result;
	}
 
	/* TODO: */
	result = error("notes_merge() cannot yet handle real merges.");
 
found_result:
	free_commit_list(bases);
	trace_printf("notes_merge(): result = %i, result_sha1 = %.7s\n",
	       result, sha1_to_hex(result_sha1));
	return result;
}