set_git_dir: handle feeding gitdir to itself
[git] / merge-blobs.c
1 #include "cache.h"
2 #include "run-command.h"
3 #include "xdiff-interface.h"
4 #include "ll-merge.h"
5 #include "blob.h"
6 #include "merge-blobs.h"
7
8 static int fill_mmfile_blob(mmfile_t *f, struct blob *obj)
9 {
10         void *buf;
11         unsigned long size;
12         enum object_type type;
13
14         buf = read_sha1_file(obj->object.oid.hash, &type, &size);
15         if (!buf)
16                 return -1;
17         if (type != OBJ_BLOB) {
18                 free(buf);
19                 return -1;
20         }
21         f->ptr = buf;
22         f->size = size;
23         return 0;
24 }
25
26 static void free_mmfile(mmfile_t *f)
27 {
28         free(f->ptr);
29 }
30
31 static void *three_way_filemerge(const char *path, mmfile_t *base, mmfile_t *our, mmfile_t *their, unsigned long *size)
32 {
33         int merge_status;
34         mmbuffer_t res;
35
36         /*
37          * This function is only used by cmd_merge_tree, which
38          * does not respect the merge.conflictstyle option.
39          * There is no need to worry about a label for the
40          * common ancestor.
41          */
42         merge_status = ll_merge(&res, path, base, NULL,
43                                 our, ".our", their, ".their", NULL);
44         if (merge_status < 0)
45                 return NULL;
46
47         *size = res.size;
48         return res.ptr;
49 }
50
51 void *merge_blobs(const char *path, struct blob *base, struct blob *our, struct blob *their, unsigned long *size)
52 {
53         void *res = NULL;
54         mmfile_t f1, f2, common;
55
56         /*
57          * Removed in either branch?
58          *
59          * NOTE! This depends on the caller having done the
60          * proper warning about removing a file that got
61          * modified in the other branch!
62          */
63         if (!our || !their) {
64                 enum object_type type;
65                 if (base)
66                         return NULL;
67                 if (!our)
68                         our = their;
69                 return read_sha1_file(our->object.oid.hash, &type, size);
70         }
71
72         if (fill_mmfile_blob(&f1, our) < 0)
73                 goto out_no_mmfile;
74         if (fill_mmfile_blob(&f2, their) < 0)
75                 goto out_free_f1;
76
77         if (base) {
78                 if (fill_mmfile_blob(&common, base) < 0)
79                         goto out_free_f2_f1;
80         } else {
81                 common.ptr = xstrdup("");
82                 common.size = 0;
83         }
84         res = three_way_filemerge(path, &common, &f1, &f2, size);
85         free_mmfile(&common);
86 out_free_f2_f1:
87         free_mmfile(&f2);
88 out_free_f1:
89         free_mmfile(&f1);
90 out_no_mmfile:
91         return res;
92 }