Improved three-way blob merging code
[git/git.git] / merge-file.c
CommitLineData
0c799383
LT
1#include "cache.h"
2#include "run-command.h"
3#include "xdiff-interface.h"
4#include "blob.h"
5
6static void rm_temp_file(const char *filename)
7{
8 unlink(filename);
9 free((void *)filename);
10}
11
12static const char *write_temp_file(mmfile_t *f)
13{
14 int fd;
15 const char *tmp = getenv("TMPDIR");
16 char *filename;
17
18 if (!tmp)
19 tmp = "/tmp";
20 filename = mkpath("%s/%s", tmp, "git-tmp-XXXXXX");
21 fd = mkstemp(filename);
22 if (fd < 0)
23 return NULL;
24 filename = strdup(filename);
25 if (f->size != xwrite(fd, f->ptr, f->size)) {
26 rm_temp_file(filename);
27 return NULL;
28 }
29 close(fd);
30 return filename;
31}
32
33static void *read_temp_file(const char *filename, unsigned long *size)
34{
35 struct stat st;
36 char *buf = NULL;
37 int fd = open(filename, O_RDONLY);
38 if (fd < 0)
39 return NULL;
40 if (!fstat(fd, &st)) {
41 *size = st.st_size;
42 buf = xmalloc(st.st_size);
43 if (st.st_size != xread(fd, buf, st.st_size)) {
44 free(buf);
45 buf = NULL;
46 }
47 }
48 close(fd);
49 return buf;
50}
51
52static int fill_mmfile_blob(mmfile_t *f, struct blob *obj)
53{
54 void *buf;
55 unsigned long size;
56 char type[20];
57
58 buf = read_sha1_file(obj->object.sha1, type, &size);
59 if (!buf)
60 return -1;
61 if (strcmp(type, blob_type))
62 return -1;
63 f->ptr = buf;
64 f->size = size;
65 return 0;
66}
67
68static void free_mmfile(mmfile_t *f)
69{
70 free(f->ptr);
71}
72
73static void *three_way_filemerge(mmfile_t *base, mmfile_t *our, mmfile_t *their, unsigned long *size)
74{
75 void *res;
76 const char *t1, *t2, *t3;
77
78 t1 = write_temp_file(base);
79 t2 = write_temp_file(our);
80 t3 = write_temp_file(their);
81 res = NULL;
82 if (t1 && t2 && t3) {
83 int code = run_command("merge", t2, t1, t3, NULL);
84 if (!code || code == -1)
85 res = read_temp_file(t2, size);
86 }
87 rm_temp_file(t1);
88 rm_temp_file(t2);
89 rm_temp_file(t3);
90 return res;
91}
92
93static int common_outf(void *priv_, mmbuffer_t *mb, int nbuf)
94{
95 int i;
96 mmfile_t *dst = priv_;
97
98 for (i = 0; i < nbuf; i++) {
99 memcpy(dst->ptr + dst->size, mb[i].ptr, mb[i].size);
100 dst->size += mb[i].size;
101 }
102 return 0;
103}
104
105static int generate_common_file(mmfile_t *res, mmfile_t *f1, mmfile_t *f2)
106{
107 unsigned long size = f1->size < f2->size ? f1->size : f2->size;
108 void *ptr = xmalloc(size);
109 xpparam_t xpp;
110 xdemitconf_t xecfg;
111 xdemitcb_t ecb;
112
113 xpp.flags = XDF_NEED_MINIMAL;
114 xecfg.ctxlen = 3;
115 xecfg.flags = XDL_EMIT_COMMON;
116 ecb.outf = common_outf;
117
118 res->ptr = ptr;
119 res->size = 0;
120
121 ecb.priv = res;
122 return xdl_diff(f1, f2, &xpp, &xecfg, &ecb);
123}
124
125void *merge_file(struct blob *base, struct blob *our, struct blob *their, unsigned long *size)
126{
127 void *res = NULL;
128 mmfile_t f1, f2, common;
129
130 /*
131 * Removed in either branch?
132 *
133 * NOTE! This depends on the caller having done the
134 * proper warning about removing a file that got
135 * modified in the other branch!
136 */
137 if (!our || !their) {
138 char type[20];
139 if (base)
140 return NULL;
141 if (!our)
142 our = their;
143 return read_sha1_file(our->object.sha1, type, size);
144 }
145
146 if (fill_mmfile_blob(&f1, our) < 0)
147 goto out_no_mmfile;
148 if (fill_mmfile_blob(&f2, their) < 0)
149 goto out_free_f1;
150
151 if (base) {
152 if (fill_mmfile_blob(&common, base) < 0)
153 goto out_free_f2_f1;
154 } else {
155 if (generate_common_file(&common, &f1, &f2) < 0)
156 goto out_free_f2_f1;
157 }
158 res = three_way_filemerge(&common, &f1, &f2, size);
159 free_mmfile(&common);
160out_free_f2_f1:
161 free_mmfile(&f2);
162out_free_f1:
163 free_mmfile(&f1);
164out_no_mmfile:
165 return res;
166}