do not depend on signed integer overflow
[git] / builtin / merge-file.c
1 #include "builtin.h"
2 #include "cache.h"
3 #include "xdiff/xdiff.h"
4 #include "xdiff-interface.h"
5 #include "parse-options.h"
6
7 static const char *const merge_file_usage[] = {
8         "git merge-file [options] [-L name1 [-L orig [-L name2]]] file1 orig_file file2",
9         NULL
10 };
11
12 static int label_cb(const struct option *opt, const char *arg, int unset)
13 {
14         static int label_count = 0;
15         const char **names = (const char **)opt->value;
16
17         if (label_count >= 3)
18                 return error("too many labels on the command line");
19         names[label_count++] = arg;
20         return 0;
21 }
22
23 int cmd_merge_file(int argc, const char **argv, const char *prefix)
24 {
25         const char *names[3] = { NULL, NULL, NULL };
26         mmfile_t mmfs[3];
27         mmbuffer_t result = {NULL, 0};
28         xmparam_t xmp = {{0}};
29         int ret = 0, i = 0, to_stdout = 0;
30         int quiet = 0;
31         struct option options[] = {
32                 OPT_BOOLEAN('p', "stdout", &to_stdout, "send results to standard output"),
33                 OPT_SET_INT(0, "diff3", &xmp.style, "use a diff3 based merge", XDL_MERGE_DIFF3),
34                 OPT_SET_INT(0, "ours", &xmp.favor, "for conflicts, use our version",
35                             XDL_MERGE_FAVOR_OURS),
36                 OPT_SET_INT(0, "theirs", &xmp.favor, "for conflicts, use their version",
37                             XDL_MERGE_FAVOR_THEIRS),
38                 OPT_SET_INT(0, "union", &xmp.favor, "for conflicts, use a union version",
39                             XDL_MERGE_FAVOR_UNION),
40                 OPT_INTEGER(0, "marker-size", &xmp.marker_size,
41                             "for conflicts, use this marker size"),
42                 OPT__QUIET(&quiet),
43                 OPT_CALLBACK('L', NULL, names, "name",
44                              "set labels for file1/orig_file/file2", &label_cb),
45                 OPT_END(),
46         };
47
48         xmp.level = XDL_MERGE_ZEALOUS_ALNUM;
49         xmp.style = 0;
50         xmp.favor = 0;
51
52         if (startup_info->have_repository) {
53                 /* Read the configuration file */
54                 git_config(git_xmerge_config, NULL);
55                 if (0 <= git_xmerge_style)
56                         xmp.style = git_xmerge_style;
57         }
58
59         argc = parse_options(argc, argv, prefix, options, merge_file_usage, 0);
60         if (argc != 3)
61                 usage_with_options(merge_file_usage, options);
62         if (quiet) {
63                 if (!freopen("/dev/null", "w", stderr))
64                         return error("failed to redirect stderr to /dev/null: "
65                                      "%s\n", strerror(errno));
66         }
67
68         for (i = 0; i < 3; i++) {
69                 if (!names[i])
70                         names[i] = argv[i];
71                 if (read_mmfile(mmfs + i, argv[i]))
72                         return -1;
73                 if (buffer_is_binary(mmfs[i].ptr, mmfs[i].size))
74                         return error("Cannot merge binary files: %s\n",
75                                         argv[i]);
76         }
77
78         xmp.ancestor = names[1];
79         xmp.file1 = names[0];
80         xmp.file2 = names[2];
81         ret = xdl_merge(mmfs + 1, mmfs + 0, mmfs + 2, &xmp, &result);
82
83         for (i = 0; i < 3; i++)
84                 free(mmfs[i].ptr);
85
86         if (ret >= 0) {
87                 const char *filename = argv[0];
88                 FILE *f = to_stdout ? stdout : fopen(filename, "wb");
89
90                 if (!f)
91                         ret = error("Could not open %s for writing", filename);
92                 else if (result.size &&
93                          fwrite(result.ptr, result.size, 1, f) != 1)
94                         ret = error("Could not write to %s", filename);
95                 else if (fclose(f))
96                         ret = error("Could not close %s", filename);
97                 free(result.ptr);
98         }
99
100         return ret;
101 }