summaryrefslogtreecommitdiff
path: root/merge-file.c
blob: fc9b148993027d4064257d4df8e63a12e1afc5d4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
#include "cache.h"
#include "run-command.h"
#include "xdiff-interface.h"
#include "blob.h"

static void rm_temp_file(const char *filename)
{
	unlink(filename);
	free((void *)filename);
}

static const char *write_temp_file(mmfile_t *f)
{
	int fd;
	const char *tmp = getenv("TMPDIR");
	char *filename;

	if (!tmp)
		tmp = "/tmp";
	filename = mkpath("%s/%s", tmp, "git-tmp-XXXXXX");
	fd = mkstemp(filename);
	if (fd < 0)
		return NULL;
	filename = xstrdup(filename);
	if (f->size != xwrite(fd, f->ptr, f->size)) {
		rm_temp_file(filename);
		return NULL;
	}
	close(fd);
	return filename;
}

static void *read_temp_file(const char *filename, unsigned long *size)
{
	struct stat st;
	char *buf = NULL;
	int fd = open(filename, O_RDONLY);
	if (fd < 0)
		return NULL;
	if (!fstat(fd, &st)) {
		*size = st.st_size;
		buf = xmalloc(st.st_size);
		if (st.st_size != xread(fd, buf, st.st_size)) {
			free(buf);
			buf = NULL;
		}
	}
	close(fd);
	return buf;
}

static int fill_mmfile_blob(mmfile_t *f, struct blob *obj)
{
	void *buf;
	unsigned long size;
	char type[20];

	buf = read_sha1_file(obj->object.sha1, type, &size);
	if (!buf)
		return -1;
	if (strcmp(type, blob_type))
		return -1;
	f->ptr = buf;
	f->size = size;
	return 0;
}

static void free_mmfile(mmfile_t *f)
{
	free(f->ptr);
}

static void *three_way_filemerge(mmfile_t *base, mmfile_t *our, mmfile_t *their, unsigned long *size)
{
	void *res;
	const char *t1, *t2, *t3;

	t1 = write_temp_file(base);
	t2 = write_temp_file(our);
	t3 = write_temp_file(their);
	res = NULL;
	if (t1 && t2 && t3) {
		int code = run_command("merge", t2, t1, t3, NULL);
		if (!code || code == -1)
			res = read_temp_file(t2, size);
	}
	rm_temp_file(t1);
	rm_temp_file(t2);
	rm_temp_file(t3);
	return res;
}

static int common_outf(void *priv_, mmbuffer_t *mb, int nbuf)
{
	int i;
	mmfile_t *dst = priv_;

	for (i = 0; i < nbuf; i++) {
		memcpy(dst->ptr + dst->size, mb[i].ptr, mb[i].size);
		dst->size += mb[i].size;
	}
	return 0;
}

static int generate_common_file(mmfile_t *res, mmfile_t *f1, mmfile_t *f2)
{
	unsigned long size = f1->size < f2->size ? f1->size : f2->size;
	void *ptr = xmalloc(size);
	xpparam_t xpp;
	xdemitconf_t xecfg;
	xdemitcb_t ecb;

	xpp.flags = XDF_NEED_MINIMAL;
	xecfg.ctxlen = 3;
	xecfg.flags = XDL_EMIT_COMMON;
	ecb.outf = common_outf;

	res->ptr = ptr;
	res->size = 0;

	ecb.priv = res;
	return xdl_diff(f1, f2, &xpp, &xecfg, &ecb);
}

void *merge_file(struct blob *base, struct blob *our, struct blob *their, unsigned long *size)
{
	void *res = NULL;
	mmfile_t f1, f2, common;

	/*
	 * Removed in either branch?
	 *
	 * NOTE! This depends on the caller having done the
	 * proper warning about removing a file that got
	 * modified in the other branch!
	 */
	if (!our || !their) {
		char type[20];
		if (base)
			return NULL;
		if (!our)
			our = their;
		return read_sha1_file(our->object.sha1, type, size);
	}

	if (fill_mmfile_blob(&f1, our) < 0)
		goto out_no_mmfile;
	if (fill_mmfile_blob(&f2, their) < 0)
		goto out_free_f1;

	if (base) {
		if (fill_mmfile_blob(&common, base) < 0)
			goto out_free_f2_f1;
	} else {
		if (generate_common_file(&common, &f1, &f2) < 0)
			goto out_free_f2_f1;
	}
	res = three_way_filemerge(&common, &f1, &f2, size);
	free_mmfile(&common);
out_free_f2_f1:
	free_mmfile(&f2);
out_free_f1:
	free_mmfile(&f1);
out_no_mmfile:
	return res;
}