Merge branch 'ot/ref-filter-cleanup'
[git/git.git] / replace_object.c
1 #include "cache.h"
2 #include "sha1-lookup.h"
3 #include "refs.h"
4 #include "commit.h"
5
6 /*
7 * An array of replacements. The array is kept sorted by the original
8 * sha1.
9 */
10 static struct replace_object {
11 unsigned char original[20];
12 unsigned char replacement[20];
13 } **replace_object;
14
15 static int replace_object_alloc, replace_object_nr;
16
17 static const unsigned char *replace_sha1_access(size_t index, void *table)
18 {
19 struct replace_object **replace = table;
20 return replace[index]->original;
21 }
22
23 static int replace_object_pos(const unsigned char *sha1)
24 {
25 return sha1_pos(sha1, replace_object, replace_object_nr,
26 replace_sha1_access);
27 }
28
29 static int register_replace_object(struct replace_object *replace,
30 int ignore_dups)
31 {
32 int pos = replace_object_pos(replace->original);
33
34 if (0 <= pos) {
35 if (ignore_dups)
36 free(replace);
37 else {
38 free(replace_object[pos]);
39 replace_object[pos] = replace;
40 }
41 return 1;
42 }
43 pos = -pos - 1;
44 ALLOC_GROW(replace_object, replace_object_nr + 1, replace_object_alloc);
45 replace_object_nr++;
46 if (pos < replace_object_nr)
47 MOVE_ARRAY(replace_object + pos + 1, replace_object + pos,
48 replace_object_nr - pos - 1);
49 replace_object[pos] = replace;
50 return 0;
51 }
52
53 static int register_replace_ref(const char *refname,
54 const struct object_id *oid,
55 int flag, void *cb_data)
56 {
57 /* Get sha1 from refname */
58 const char *slash = strrchr(refname, '/');
59 const char *hash = slash ? slash + 1 : refname;
60 struct replace_object *repl_obj = xmalloc(sizeof(*repl_obj));
61
62 if (strlen(hash) != 40 || get_sha1_hex(hash, repl_obj->original)) {
63 free(repl_obj);
64 warning("bad replace ref name: %s", refname);
65 return 0;
66 }
67
68 /* Copy sha1 from the read ref */
69 hashcpy(repl_obj->replacement, oid->hash);
70
71 /* Register new object */
72 if (register_replace_object(repl_obj, 1))
73 die("duplicate replace ref: %s", refname);
74
75 return 0;
76 }
77
78 static void prepare_replace_object(void)
79 {
80 static int replace_object_prepared;
81
82 if (replace_object_prepared)
83 return;
84
85 for_each_replace_ref(register_replace_ref, NULL);
86 replace_object_prepared = 1;
87 if (!replace_object_nr)
88 check_replace_refs = 0;
89 }
90
91 /* We allow "recursive" replacement. Only within reason, though */
92 #define MAXREPLACEDEPTH 5
93
94 /*
95 * If a replacement for object sha1 has been set up, return the
96 * replacement object's name (replaced recursively, if necessary).
97 * The return value is either sha1 or a pointer to a
98 * permanently-allocated value. This function always respects replace
99 * references, regardless of the value of check_replace_refs.
100 */
101 const unsigned char *do_lookup_replace_object(const unsigned char *sha1)
102 {
103 int pos, depth = MAXREPLACEDEPTH;
104 const unsigned char *cur = sha1;
105
106 prepare_replace_object();
107
108 /* Try to recursively replace the object */
109 do {
110 if (--depth < 0)
111 die("replace depth too high for object %s",
112 sha1_to_hex(sha1));
113
114 pos = replace_object_pos(cur);
115 if (0 <= pos)
116 cur = replace_object[pos]->replacement;
117 } while (0 <= pos);
118
119 return cur;
120 }