revision: do not include sibling history in --ancestry-path output
[git] / replace_object.c
1 #include "cache.h"
2 #include "sha1-lookup.h"
3 #include "refs.h"
4
5 static struct replace_object {
6         unsigned char sha1[2][20];
7 } **replace_object;
8
9 static int replace_object_alloc, replace_object_nr;
10
11 static const unsigned char *replace_sha1_access(size_t index, void *table)
12 {
13         struct replace_object **replace = table;
14         return replace[index]->sha1[0];
15 }
16
17 static int replace_object_pos(const unsigned char *sha1)
18 {
19         return sha1_pos(sha1, replace_object, replace_object_nr,
20                         replace_sha1_access);
21 }
22
23 static int register_replace_object(struct replace_object *replace,
24                                    int ignore_dups)
25 {
26         int pos = replace_object_pos(replace->sha1[0]);
27
28         if (0 <= pos) {
29                 if (ignore_dups)
30                         free(replace);
31                 else {
32                         free(replace_object[pos]);
33                         replace_object[pos] = replace;
34                 }
35                 return 1;
36         }
37         pos = -pos - 1;
38         if (replace_object_alloc <= ++replace_object_nr) {
39                 replace_object_alloc = alloc_nr(replace_object_alloc);
40                 replace_object = xrealloc(replace_object,
41                                           sizeof(*replace_object) *
42                                           replace_object_alloc);
43         }
44         if (pos < replace_object_nr)
45                 memmove(replace_object + pos + 1,
46                         replace_object + pos,
47                         (replace_object_nr - pos - 1) *
48                         sizeof(*replace_object));
49         replace_object[pos] = replace;
50         return 0;
51 }
52
53 static int register_replace_ref(const char *refname,
54                                 const unsigned char *sha1,
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->sha1[0])) {
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->sha1[1], sha1);
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 }
88
89 /* We allow "recursive" replacement. Only within reason, though */
90 #define MAXREPLACEDEPTH 5
91
92 const unsigned char *lookup_replace_object(const unsigned char *sha1)
93 {
94         int pos, depth = MAXREPLACEDEPTH;
95         const unsigned char *cur = sha1;
96
97         if (!read_replace_refs)
98                 return sha1;
99
100         prepare_replace_object();
101
102         /* Try to recursively replace the object */
103         do {
104                 if (--depth < 0)
105                         die("replace depth too high for object %s",
106                             sha1_to_hex(sha1));
107
108                 pos = replace_object_pos(cur);
109                 if (0 <= pos)
110                         cur = replace_object[pos]->sha1[1];
111         } while (0 <= pos);
112
113         return cur;
114 }