Merge branch 'tk/apply-dev-null-verify-name-fix'
[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 }