t7201.24: Add refspec to keep --track working
[git] / replace_object.c
1 #include "cache.h"
2 #include "sha1-lookup.h"
3 #include "refs.h"
4 #include "commit.h"
5
6 static struct replace_object {
7         unsigned char sha1[2][20];
8 } **replace_object;
9
10 static int replace_object_alloc, replace_object_nr;
11
12 static const unsigned char *replace_sha1_access(size_t index, void *table)
13 {
14         struct replace_object **replace = table;
15         return replace[index]->sha1[0];
16 }
17
18 static int replace_object_pos(const unsigned char *sha1)
19 {
20         return sha1_pos(sha1, replace_object, replace_object_nr,
21                         replace_sha1_access);
22 }
23
24 static int register_replace_object(struct replace_object *replace,
25                                    int ignore_dups)
26 {
27         int pos = replace_object_pos(replace->sha1[0]);
28
29         if (0 <= pos) {
30                 if (ignore_dups)
31                         free(replace);
32                 else {
33                         free(replace_object[pos]);
34                         replace_object[pos] = replace;
35                 }
36                 return 1;
37         }
38         pos = -pos - 1;
39         if (replace_object_alloc <= ++replace_object_nr) {
40                 replace_object_alloc = alloc_nr(replace_object_alloc);
41                 replace_object = xrealloc(replace_object,
42                                           sizeof(*replace_object) *
43                                           replace_object_alloc);
44         }
45         if (pos < replace_object_nr)
46                 memmove(replace_object + pos + 1,
47                         replace_object + pos,
48                         (replace_object_nr - pos - 1) *
49                         sizeof(*replace_object));
50         replace_object[pos] = replace;
51         return 0;
52 }
53
54 static int register_replace_ref(const char *refname,
55                                 const unsigned char *sha1,
56                                 int flag, void *cb_data)
57 {
58         /* Get sha1 from refname */
59         const char *slash = strrchr(refname, '/');
60         const char *hash = slash ? slash + 1 : refname;
61         struct replace_object *repl_obj = xmalloc(sizeof(*repl_obj));
62
63         if (strlen(hash) != 40 || get_sha1_hex(hash, repl_obj->sha1[0])) {
64                 free(repl_obj);
65                 warning("bad replace ref name: %s", refname);
66                 return 0;
67         }
68
69         /* Copy sha1 from the read ref */
70         hashcpy(repl_obj->sha1[1], sha1);
71
72         /* Register new object */
73         if (register_replace_object(repl_obj, 1))
74                 die("duplicate replace ref: %s", refname);
75
76         return 0;
77 }
78
79 static void prepare_replace_object(void)
80 {
81         static int replace_object_prepared;
82
83         if (replace_object_prepared)
84                 return;
85
86         for_each_replace_ref(register_replace_ref, NULL);
87         replace_object_prepared = 1;
88         if (!replace_object_nr)
89                 read_replace_refs = 0;
90 }
91
92 /* We allow "recursive" replacement. Only within reason, though */
93 #define MAXREPLACEDEPTH 5
94
95 const unsigned char *do_lookup_replace_object(const unsigned char *sha1)
96 {
97         int pos, depth = MAXREPLACEDEPTH;
98         const unsigned char *cur = sha1;
99
100         if (!read_replace_refs)
101                 return sha1;
102
103         prepare_replace_object();
104
105         /* Try to recursively replace the object */
106         do {
107                 if (--depth < 0)
108                         die("replace depth too high for object %s",
109                             sha1_to_hex(sha1));
110
111                 pos = replace_object_pos(cur);
112                 if (0 <= pos)
113                         cur = replace_object[pos]->sha1[1];
114         } while (0 <= pos);
115
116         return cur;
117 }