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
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
|
#include "cache.h"
#include "diff.h"
static const char merge_tree_usage[] = "git-merge-tree <base-tree> <branch1> <branch2>";
static int resolve_directories = 1;
static void merge_trees(struct tree_desc t[3], const char *base);
static void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1)
{
unsigned long size = 0;
void *buf = NULL;
if (sha1) {
buf = read_object_with_reference(sha1, "tree", &size, NULL);
if (!buf)
die("unable to read tree %s", sha1_to_hex(sha1));
}
desc->size = size;
desc->buf = buf;
return buf;
}
struct name_entry {
const unsigned char *sha1;
const char *path;
unsigned int mode;
int pathlen;
};
static void entry_clear(struct name_entry *a)
{
memset(a, 0, sizeof(*a));
}
static int entry_compare(struct name_entry *a, struct name_entry *b)
{
return base_name_compare(
a->path, a->pathlen, a->mode,
b->path, b->pathlen, b->mode);
}
static void entry_extract(struct tree_desc *t, struct name_entry *a)
{
a->sha1 = tree_entry_extract(t, &a->path, &a->mode);
a->pathlen = strlen(a->path);
}
/* An empty entry never compares same, not even to another empty entry */
static int same_entry(struct name_entry *a, struct name_entry *b)
{
return a->sha1 &&
b->sha1 &&
!memcmp(a->sha1, b->sha1, 20) &&
a->mode == b->mode;
}
static void resolve(const char *base, struct name_entry *result)
{
printf("0 %06o %s %s%s\n", result->mode, sha1_to_hex(result->sha1), base, result->path);
}
static int unresolved_directory(const char *base, struct name_entry n[3])
{
int baselen;
char *newbase;
struct name_entry *p;
struct tree_desc t[3];
void *buf0, *buf1, *buf2;
if (!resolve_directories)
return 0;
p = n;
if (!p->mode) {
p++;
if (!p->mode)
p++;
}
if (!S_ISDIR(p->mode))
return 0;
baselen = strlen(base);
newbase = xmalloc(baselen + p->pathlen + 2);
memcpy(newbase, base, baselen);
memcpy(newbase + baselen, p->path, p->pathlen);
memcpy(newbase + baselen + p->pathlen, "/", 2);
buf0 = fill_tree_descriptor(t+0, n[0].sha1);
buf1 = fill_tree_descriptor(t+1, n[1].sha1);
buf2 = fill_tree_descriptor(t+2, n[2].sha1);
merge_trees(t, newbase);
free(buf0);
free(buf1);
free(buf2);
free(newbase);
return 1;
}
static void unresolved(const char *base, struct name_entry n[3])
{
if (unresolved_directory(base, n))
return;
printf("1 %06o %s %s%s\n", n[0].mode, sha1_to_hex(n[0].sha1), base, n[0].path);
printf("2 %06o %s %s%s\n", n[1].mode, sha1_to_hex(n[1].sha1), base, n[1].path);
printf("3 %06o %s %s%s\n", n[2].mode, sha1_to_hex(n[2].sha1), base, n[2].path);
}
/*
* Merge two trees together (t[1] and t[2]), using a common base (t[0])
* as the origin.
*
* This walks the (sorted) trees in lock-step, checking every possible
* name. Note that directories automatically sort differently from other
* files (see "base_name_compare"), so you'll never see file/directory
* conflicts, because they won't ever compare the same.
*
* IOW, if a directory changes to a filename, it will automatically be
* seen as the directory going away, and the filename being created.
*
* Think of this as a three-way diff.
*
* The output will be either:
* - successful merge
* "0 mode sha1 filename"
* NOTE NOTE NOTE! FIXME! We really really need to walk the index
* in parallel with this too!
*
* - conflict:
* "1 mode sha1 filename"
* "2 mode sha1 filename"
* "3 mode sha1 filename"
* where not all of the 1/2/3 lines may exist, of course.
*
* The successful merge rules are the same as for the three-way merge
* in git-read-tree.
*/
static void merge_trees(struct tree_desc t[3], const char *base)
{
for (;;) {
struct name_entry entry[3];
unsigned int mask = 0;
int i, last;
last = -1;
for (i = 0; i < 3; i++) {
if (!t[i].size)
continue;
entry_extract(t+i, entry+i);
if (last >= 0) {
int cmp = entry_compare(entry+i, entry+last);
/*
* Is the new name bigger than the old one?
* Ignore it
*/
if (cmp > 0)
continue;
/*
* Is the new name smaller than the old one?
* Ignore all old ones
*/
if (cmp < 0)
mask = 0;
}
mask |= 1u << i;
last = i;
}
if (!mask)
break;
/*
* Update the tree entries we've walked, and clear
* all the unused name-entries.
*/
for (i = 0; i < 3; i++) {
if (mask & (1u << i)) {
update_tree_entry(t+i);
continue;
}
entry_clear(entry + i);
}
/* Same in both? */
if (same_entry(entry+1, entry+2)) {
if (entry[0].sha1) {
resolve(base, entry+1);
continue;
}
}
if (same_entry(entry+0, entry+1)) {
if (entry[2].sha1) {
resolve(base, entry+2);
continue;
}
}
if (same_entry(entry+0, entry+2)) {
if (entry[1].sha1) {
resolve(base, entry+1);
continue;
}
}
unresolved(base, entry);
}
}
static void *get_tree_descriptor(struct tree_desc *desc, const char *rev)
{
unsigned char sha1[20];
void *buf;
if (get_sha1(rev, sha1) < 0)
die("unknown rev %s", rev);
buf = fill_tree_descriptor(desc, sha1);
if (!buf)
die("%s is not a tree", rev);
return buf;
}
int main(int argc, char **argv)
{
struct tree_desc t[3];
void *buf1, *buf2, *buf3;
if (argc < 4)
usage(merge_tree_usage);
buf1 = get_tree_descriptor(t+0, argv[1]);
buf2 = get_tree_descriptor(t+1, argv[2]);
buf3 = get_tree_descriptor(t+2, argv[3]);
merge_trees(t, "");
free(buf1);
free(buf2);
free(buf3);
return 0;
}
|
