c064e10580d5e1f7185f3f32ee19319292f6b43d
[git/git.git] / diff.c
1 /*
2 * Copyright (C) 2005 Junio C Hamano
3 */
4 #include <sys/types.h>
5 #include <sys/wait.h>
6 #include "cache.h"
7 #include "diff.h"
8
9 static char *diff_opts = "-pu";
10
11 static const char *external_diff(void)
12 {
13 static char *external_diff_cmd = NULL;
14 static int done_preparing = 0;
15
16 if (done_preparing)
17 return external_diff_cmd;
18
19 /*
20 * Default values above are meant to match the
21 * Linux kernel development style. Examples of
22 * alternative styles you can specify via environment
23 * variables are:
24 *
25 * GIT_DIFF_OPTS="-c";
26 */
27 if (getenv("GIT_EXTERNAL_DIFF"))
28 external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
29
30 /* In case external diff fails... */
31 diff_opts = getenv("GIT_DIFF_OPTS") ? : diff_opts;
32
33 done_preparing = 1;
34 return external_diff_cmd;
35 }
36
37 /* Help to copy the thing properly quoted for the shell safety.
38 * any single quote is replaced with '\'', and the caller is
39 * expected to enclose the result within a single quote pair.
40 *
41 * E.g.
42 * original sq_expand result
43 * name ==> name ==> 'name'
44 * a b ==> a b ==> 'a b'
45 * a'b ==> a'\''b ==> 'a'\''b'
46 */
47 static char *sq_expand(const char *src)
48 {
49 static char *buf = NULL;
50 int cnt, c;
51 const char *cp;
52 char *bp;
53
54 /* count bytes needed to store the quoted string. */
55 for (cnt = 1, cp = src; *cp; cnt++, cp++)
56 if (*cp == '\'')
57 cnt += 3;
58
59 buf = xmalloc(cnt);
60 bp = buf;
61 while ((c = *src++)) {
62 if (c != '\'')
63 *bp++ = c;
64 else {
65 bp = strcpy(bp, "'\\''");
66 bp += 4;
67 }
68 }
69 *bp = 0;
70 return buf;
71 }
72
73 static struct diff_tempfile {
74 const char *name;
75 char hex[41];
76 char mode[10];
77 char tmp_path[50];
78 } diff_temp[2];
79
80 static void builtin_diff(const char *name,
81 struct diff_tempfile *temp)
82 {
83 int i, next_at;
84 const char *diff_cmd = "diff -L'%s%s%s' -L'%s%s%s'";
85 const char *diff_arg = "'%s' '%s'";
86 const char *input_name_sq[2];
87 const char *path0[2];
88 const char *path1[2];
89 char mode[2][20];
90 const char *name_sq = sq_expand(name);
91 char *cmd;
92
93 /* diff_cmd and diff_arg have 8 %s in total which makes
94 * the sum of these strings 16 bytes larger than required.
95 * we use 2 spaces around diff-opts, and we need to count
96 * terminating NUL, so we subtract 13 here.
97 */
98 int cmd_size = (strlen(diff_cmd) + strlen(diff_opts) +
99 strlen(diff_arg) - 13);
100 for (i = 0; i < 2; i++) {
101 input_name_sq[i] = sq_expand(temp[i].name);
102 if (!strcmp(temp[i].name, "/dev/null")) {
103 path0[i] = "/dev/null";
104 path1[i] = "";
105 mode[i][0] = 0;
106 } else {
107 path0[i] = i ? "l/" : "k/";
108 path1[i] = name_sq;
109 sprintf(mode[i], " (mode:%s)", temp[i].mode);
110 }
111 cmd_size += (strlen(path0[i]) + strlen(path1[i]) +
112 strlen(mode[i]) + strlen(input_name_sq[i]));
113 }
114
115 cmd = xmalloc(cmd_size);
116
117 next_at = 0;
118 next_at += snprintf(cmd+next_at, cmd_size-next_at,
119 diff_cmd,
120 path0[0], path1[0], mode[0],
121 path0[1], path1[1], mode[1]);
122 next_at += snprintf(cmd+next_at, cmd_size-next_at,
123 " %s ", diff_opts);
124 next_at += snprintf(cmd+next_at, cmd_size-next_at,
125 diff_arg, input_name_sq[0], input_name_sq[1]);
126
127 execlp("/bin/sh","sh", "-c", cmd, NULL);
128 }
129
130 static void prepare_temp_file(const char *name,
131 struct diff_tempfile *temp,
132 struct diff_spec *one)
133 {
134 static unsigned char null_sha1[20] = { 0, };
135
136 if (!one->file_valid) {
137 not_a_valid_file:
138 temp->name = "/dev/null";
139 strcpy(temp->hex, ".");
140 strcpy(temp->mode, ".");
141 return;
142 }
143
144 if (one->sha1_valid &&
145 !memcmp(one->u.sha1, null_sha1, sizeof(null_sha1))) {
146 one->sha1_valid = 0;
147 one->u.name = name;
148 }
149
150 if (!one->sha1_valid) {
151 struct stat st;
152 temp->name = one->u.name;
153 if (stat(temp->name, &st) < 0) {
154 if (errno == ENOENT)
155 goto not_a_valid_file;
156 die("stat(%s): %s", temp->name, strerror(errno));
157 }
158 strcpy(temp->hex, ".");
159 sprintf(temp->mode, "%06o",
160 S_IFREG |ce_permissions(st.st_mode));
161 }
162 else {
163 int fd;
164 void *blob;
165 char type[20];
166 unsigned long size;
167
168 blob = read_sha1_file(one->u.sha1, type, &size);
169 if (!blob || strcmp(type, "blob"))
170 die("unable to read blob object for %s (%s)",
171 name, sha1_to_hex(one->u.sha1));
172
173 strcpy(temp->tmp_path, ".diff_XXXXXX");
174 fd = mkstemp(temp->tmp_path);
175 if (fd < 0)
176 die("unable to create temp-file");
177 if (write(fd, blob, size) != size)
178 die("unable to write temp-file");
179 close(fd);
180 free(blob);
181 temp->name = temp->tmp_path;
182 strcpy(temp->hex, sha1_to_hex(one->u.sha1));
183 temp->hex[40] = 0;
184 sprintf(temp->mode, "%06o", one->mode);
185 }
186 }
187
188 static void remove_tempfile(void)
189 {
190 int i;
191
192 for (i = 0; i < 2; i++)
193 if (diff_temp[i].name == diff_temp[i].tmp_path) {
194 unlink(diff_temp[i].name);
195 diff_temp[i].name = NULL;
196 }
197 }
198
199 /* An external diff command takes:
200 *
201 * diff-cmd name infile1 infile1-sha1 infile1-mode \
202 * infile2 infile2-sha1 infile2-mode.
203 *
204 */
205 void run_external_diff(const char *name,
206 struct diff_spec *one,
207 struct diff_spec *two)
208 {
209 struct diff_tempfile *temp = diff_temp;
210 int pid, status;
211 static int atexit_asked = 0;
212
213 if (one && two) {
214 prepare_temp_file(name, &temp[0], one);
215 prepare_temp_file(name, &temp[1], two);
216 if (! atexit_asked &&
217 (temp[0].name == temp[0].tmp_path ||
218 temp[1].name == temp[1].tmp_path)) {
219 atexit_asked = 1;
220 atexit(remove_tempfile);
221 }
222 }
223
224 fflush(NULL);
225 pid = fork();
226 if (pid < 0)
227 die("unable to fork");
228 if (!pid) {
229 const char *pgm = external_diff();
230 if (pgm) {
231 if (one && two)
232 execlp(pgm, pgm,
233 name,
234 temp[0].name, temp[0].hex, temp[0].mode,
235 temp[1].name, temp[1].hex, temp[1].mode,
236 NULL);
237 else
238 execlp(pgm, pgm, name, NULL);
239 }
240 /*
241 * otherwise we use the built-in one.
242 */
243 if (one && two)
244 builtin_diff(name, temp);
245 else
246 printf("* Unmerged path %s\n", name);
247 exit(0);
248 }
249 if (waitpid(pid, &status, 0) < 0 || !WIFEXITED(status))
250 die("diff program failed");
251
252 remove_tempfile();
253 }
254
255 void diff_addremove(int addremove, unsigned mode,
256 const unsigned char *sha1,
257 const char *base, const char *path)
258 {
259 char concatpath[PATH_MAX];
260 struct diff_spec spec[2], *one, *two;
261
262 memcpy(spec[0].u.sha1, sha1, 20);
263 spec[0].mode = mode;
264 spec[0].sha1_valid = spec[0].file_valid = 1;
265 spec[1].file_valid = 0;
266
267 if (addremove == '+') {
268 one = spec + 1; two = spec;
269 } else {
270 one = spec; two = one + 1;
271 }
272
273 if (path) {
274 strcpy(concatpath, base);
275 strcat(concatpath, path);
276 }
277 run_external_diff(path ? concatpath : base, one, two);
278 }
279
280 void diff_change(unsigned old_mode, unsigned new_mode,
281 const unsigned char *old_sha1,
282 const unsigned char *new_sha1,
283 const char *base, const char *path) {
284 char concatpath[PATH_MAX];
285 struct diff_spec spec[2];
286
287 memcpy(spec[0].u.sha1, old_sha1, 20);
288 spec[0].mode = old_mode;
289 memcpy(spec[1].u.sha1, new_sha1, 20);
290 spec[1].mode = new_mode;
291 spec[0].sha1_valid = spec[0].file_valid = 1;
292 spec[1].sha1_valid = spec[1].file_valid = 1;
293
294 if (path) {
295 strcpy(concatpath, base);
296 strcat(concatpath, path);
297 }
298 run_external_diff(path ? concatpath : base, &spec[0], &spec[1]);
299 }
300
301 void diff_unmerge(const char *path)
302 {
303 run_external_diff(path, NULL, NULL);
304 }