1/*
2 * Copyright (C) 2005 Junio C Hamano
3 */
4#include <sys/types.h>
5#include <sys/wait.h>
6#include <signal.h>
7#include <limits.h>
8#include "cache.h"
9#include "diff.h"
10static const char *diff_opts = "-pu";
12static const char *external_diff(void)
14{
15 static const char *external_diff_cmd = NULL;
16 static int done_preparing = 0;
17 if (done_preparing)
19 return external_diff_cmd;
20 /*
22 * Default values above are meant to match the
23 * Linux kernel development style. Examples of
24 * alternative styles you can specify via environment
25 * variables are:
26 *
27 * GIT_DIFF_OPTS="-c";
28 */
29 if (gitenv("GIT_EXTERNAL_DIFF"))
30 external_diff_cmd = gitenv("GIT_EXTERNAL_DIFF");
31 /* In case external diff fails... */
33 diff_opts = gitenv("GIT_DIFF_OPTS") ? : diff_opts;
34 done_preparing = 1;
36 return external_diff_cmd;
37}
38/* Help to copy the thing properly quoted for the shell safety.
40 * any single quote is replaced with '\'', and the caller is
41 * expected to enclose the result within a single quote pair.
42 *
43 * E.g.
44 * original sq_expand result
45 * name ==> name ==> 'name'
46 * a b ==> a b ==> 'a b'
47 * a'b ==> a'\''b ==> 'a'\''b'
48 */
49static char *sq_expand(const char *src)
50{
51 static char *buf = NULL;
52 int cnt, c;
53 const char *cp;
54 char *bp;
55 /* count bytes needed to store the quoted string. */
57 for (cnt = 1, cp = src; *cp; cnt++, cp++)
58 if (*cp == '\'')
59 cnt += 3;
60 buf = xmalloc(cnt);
62 bp = buf;
63 while ((c = *src++)) {
64 if (c != '\'')
65 *bp++ = c;
66 else {
67 bp = strcpy(bp, "'\\''");
68 bp += 4;
69 }
70 }
71 *bp = 0;
72 return buf;
73}
74static struct diff_tempfile {
76 const char *name;
77 char hex[41];
78 char mode[10];
79 char tmp_path[50];
80} diff_temp[2];
81static void builtin_diff(const char *name,
83 struct diff_tempfile *temp)
84{
85 int i, next_at;
86 const char *git_prefix = "# mode: ";
87 const char *diff_cmd = "diff -L'%s%s' -L'%s%s'";
88 const char *diff_arg = "'%s' '%s'||:"; /* "||:" is to return 0 */
89 const char *input_name_sq[2];
90 const char *path0[2];
91 const char *path1[2];
92 const char *name_sq = sq_expand(name);
93 char *cmd;
94
95 /* diff_cmd and diff_arg have 6 %s in total which makes
96 * the sum of these strings 12 bytes larger than required.
97 * we use 2 spaces around diff-opts, and we need to count
98 * terminating NUL, so we subtract 9 here.
99 */
100 int cmd_size = (strlen(diff_cmd) + strlen(diff_opts) +
101 strlen(diff_arg) - 9);
102 for (i = 0; i < 2; i++) {
103 input_name_sq[i] = sq_expand(temp[i].name);
104 if (!strcmp(temp[i].name, "/dev/null")) {
105 path0[i] = "/dev/null";
106 path1[i] = "";
107 } else {
108 path0[i] = i ? "b/" : "a/";
109 path1[i] = name_sq;
110 }
111 cmd_size += (strlen(path0[i]) + strlen(path1[i]) +
112 strlen(input_name_sq[i]));
113 }
114 cmd = xmalloc(cmd_size);
116 next_at = 0;
118 next_at += snprintf(cmd+next_at, cmd_size-next_at,
119 diff_cmd,
120 path0[0], path1[0], path0[1], path1[1]);
121 next_at += snprintf(cmd+next_at, cmd_size-next_at,
122 " %s ", diff_opts);
123 next_at += snprintf(cmd+next_at, cmd_size-next_at,
124 diff_arg, input_name_sq[0], input_name_sq[1]);
125 if (!path1[0][0])
127 printf("%s. %s %s\n", git_prefix, temp[1].mode, name);
128 else if (!path1[1][0])
129 printf("%s%s . %s\n", git_prefix, temp[0].mode, name);
130 else {
131 if (strcmp(temp[0].mode, temp[1].mode))
132 printf("%s%s %s %s\n", git_prefix,
133 temp[0].mode, temp[1].mode, name);
134 if (strncmp(temp[0].mode, temp[1].mode, 3))
136 /* we do not run diff between different kind
137 * of objects.
138 */
139 exit(0);
140 }
141 fflush(NULL);
142 execlp("/bin/sh","sh", "-c", cmd, NULL);
143}
144/*
146 * Given a name and sha1 pair, if the dircache tells us the file in
147 * the work tree has that object contents, return true, so that
148 * prepare_temp_file() does not have to inflate and extract.
149 */
150static int work_tree_matches(const char *name, const unsigned char *sha1)
151{
152 struct cache_entry *ce;
153 struct stat st;
154 int pos, len;
155
156 /* We do not read the cache ourselves here, because the
157 * benchmark with my previous version that always reads cache
158 * shows that it makes things worse for diff-tree comparing
159 * two linux-2.6 kernel trees in an already checked out work
160 * tree. This is because most diff-tree comparison deals with
161 * only a small number of files, while reading the cache is
162 * expensive for a large project, and its cost outweighs the
163 * savings we get by not inflating the object to a temporary
164 * file. Practically, this code only helps when we are used
165 * by diff-cache --cached, which does read the cache before
166 * calling us.
167 */
168 if (!active_cache)
169 return 0;
170 len = strlen(name);
172 pos = cache_name_pos(name, len);
173 if (pos < 0)
174 return 0;
175 ce = active_cache[pos];
176 if ((lstat(name, &st) < 0) ||
177 !S_ISREG(st.st_mode) ||
178 cache_match_stat(ce, &st) ||
179 memcmp(sha1, ce->sha1, 20))
180 return 0;
181 return 1;
182}
183static void prep_temp_blob(struct diff_tempfile *temp,
185 void *blob,
186 unsigned long size,
187 unsigned char *sha1,
188 int mode)
189{
190 int fd;
191 strcpy(temp->tmp_path, ".diff_XXXXXX");
193 fd = mkstemp(temp->tmp_path);
194 if (fd < 0)
195 die("unable to create temp-file");
196 if (write(fd, blob, size) != size)
197 die("unable to write temp-file");
198 close(fd);
199 temp->name = temp->tmp_path;
200 strcpy(temp->hex, sha1_to_hex(sha1));
201 temp->hex[40] = 0;
202 sprintf(temp->mode, "%06o", mode);
203}
204static void prepare_temp_file(const char *name,
206 struct diff_tempfile *temp,
207 struct diff_spec *one)
208{
209 static unsigned char null_sha1[20] = { 0, };
210 int use_work_tree = 0;
211 if (!one->file_valid) {
213 not_a_valid_file:
214 /* A '-' entry produces this for file-2, and
215 * a '+' entry produces this for file-1.
216 */
217 temp->name = "/dev/null";
218 strcpy(temp->hex, ".");
219 strcpy(temp->mode, ".");
220 return;
221 }
222 if (one->sha1_valid &&
224 (!memcmp(one->blob_sha1, null_sha1, sizeof(null_sha1)) ||
225 work_tree_matches(name, one->blob_sha1)))
226 use_work_tree = 1;
227 if (!one->sha1_valid || use_work_tree) {
229 struct stat st;
230 temp->name = name;
231 if (lstat(temp->name, &st) < 0) {
232 if (errno == ENOENT)
233 goto not_a_valid_file;
234 die("stat(%s): %s", temp->name, strerror(errno));
235 }
236 if (S_ISLNK(st.st_mode)) {
237 int ret;
238 char *buf, buf_[1024];
239 buf = ((sizeof(buf_) < st.st_size) ?
240 xmalloc(st.st_size) : buf_);
241 ret = readlink(name, buf, st.st_size);
242 if (ret < 0)
243 die("readlink(%s)", name);
244 prep_temp_blob(temp, buf, st.st_size,
245 (one->sha1_valid ?
246 one->blob_sha1 : null_sha1),
247 (one->sha1_valid ?
248 one->mode : S_IFLNK));
249 }
250 else {
251 if (!one->sha1_valid)
252 strcpy(temp->hex, sha1_to_hex(null_sha1));
253 else
254 strcpy(temp->hex, sha1_to_hex(one->blob_sha1));
255 sprintf(temp->mode, "%06o",
256 S_IFREG |ce_permissions(st.st_mode));
257 }
258 return;
259 }
260 else {
261 void *blob;
262 char type[20];
263 unsigned long size;
264 blob = read_sha1_file(one->blob_sha1, type, &size);
266 if (!blob || strcmp(type, "blob"))
267 die("unable to read blob object for %s (%s)",
268 name, sha1_to_hex(one->blob_sha1));
269 prep_temp_blob(temp, blob, size, one->blob_sha1, one->mode);
270 free(blob);
271 }
272}
273static void remove_tempfile(void)
275{
276 int i;
277 for (i = 0; i < 2; i++)
279 if (diff_temp[i].name == diff_temp[i].tmp_path) {
280 unlink(diff_temp[i].name);
281 diff_temp[i].name = NULL;
282 }
283}
284static void remove_tempfile_on_signal(int signo)
286{
287 remove_tempfile();
288}
289/* An external diff command takes:
291 *
292 * diff-cmd name infile1 infile1-sha1 infile1-mode \
293 * infile2 infile2-sha1 infile2-mode.
294 *
295 */
296void run_external_diff(const char *name,
297 struct diff_spec *one,
298 struct diff_spec *two)
299{
300 struct diff_tempfile *temp = diff_temp;
301 pid_t pid;
302 int status;
303 static int atexit_asked = 0;
304 if (one && two) {
306 prepare_temp_file(name, &temp[0], one);
307 prepare_temp_file(name, &temp[1], two);
308 if (! atexit_asked &&
309 (temp[0].name == temp[0].tmp_path ||
310 temp[1].name == temp[1].tmp_path)) {
311 atexit_asked = 1;
312 atexit(remove_tempfile);
313 }
314 signal(SIGINT, remove_tempfile_on_signal);
315 }
316 fflush(NULL);
318 pid = fork();
319 if (pid < 0)
320 die("unable to fork");
321 if (!pid) {
322 const char *pgm = external_diff();
323 if (pgm) {
324 if (one && two)
325 execlp(pgm, pgm,
326 name,
327 temp[0].name, temp[0].hex, temp[0].mode,
328 temp[1].name, temp[1].hex, temp[1].mode,
329 NULL);
330 else
331 execlp(pgm, pgm, name, NULL);
332 }
333 /*
334 * otherwise we use the built-in one.
335 */
336 if (one && two)
337 builtin_diff(name, temp);
338 else
339 printf("* Unmerged path %s\n", name);
340 exit(0);
341 }
342 if (waitpid(pid, &status, 0) < 0 ||
343 !WIFEXITED(status) || WEXITSTATUS(status)) {
344 /* Earlier we did not check the exit status because
345 * diff exits non-zero if files are different, and
346 * we are not interested in knowing that. It was a
347 * mistake which made it harder to quit a diff-*
348 * session that uses the git-apply-patch-script as
349 * the GIT_EXTERNAL_DIFF. A custom GIT_EXTERNAL_DIFF
350 * should also exit non-zero only when it wants to
351 * abort the entire diff-* session.
352 */
353 remove_tempfile();
354 fprintf(stderr, "external diff died, stopping at %s.\n", name);
355 exit(1);
356 }
357 remove_tempfile();
358}
359void diff_addremove(int addremove, unsigned mode,
361 const unsigned char *sha1,
362 const char *base, const char *path)
363{
364 char concatpath[PATH_MAX];
365 struct diff_spec spec[2], *one, *two;
366 memcpy(spec[0].blob_sha1, sha1, 20);
368 spec[0].mode = mode;
369 spec[0].sha1_valid = spec[0].file_valid = 1;
370 spec[1].file_valid = 0;
371 if (addremove == '+') {
373 one = spec + 1; two = spec;
374 } else {
375 one = spec; two = one + 1;
376 }
377
378 if (path) {
379 strcpy(concatpath, base);
380 strcat(concatpath, path);
381 }
382 run_external_diff(path ? concatpath : base, one, two);
383}
384void diff_change(unsigned old_mode, unsigned new_mode,
386 const unsigned char *old_sha1,
387 const unsigned char *new_sha1,
388 const char *base, const char *path) {
389 char concatpath[PATH_MAX];
390 struct diff_spec spec[2];
391 memcpy(spec[0].blob_sha1, old_sha1, 20);
393 spec[0].mode = old_mode;
394 memcpy(spec[1].blob_sha1, new_sha1, 20);
395 spec[1].mode = new_mode;
396 spec[0].sha1_valid = spec[0].file_valid = 1;
397 spec[1].sha1_valid = spec[1].file_valid = 1;
398 if (path) {
400 strcpy(concatpath, base);
401 strcat(concatpath, path);
402 }
403 run_external_diff(path ? concatpath : base, &spec[0], &spec[1]);
404}
405void diff_unmerge(const char *path)
407{
408 run_external_diff(path, NULL, NULL);
409}