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 "cache.h"
8#include "diff.h"
9static char *diff_opts = "-pu";
11static const char *external_diff(void)
13{
14 static char *external_diff_cmd = NULL;
15 static int done_preparing = 0;
16 if (done_preparing)
18 return external_diff_cmd;
19 /*
21 * Default values above are meant to match the
22 * Linux kernel development style. Examples of
23 * alternative styles you can specify via environment
24 * variables are:
25 *
26 * GIT_DIFF_OPTS="-c";
27 */
28 if (getenv("GIT_EXTERNAL_DIFF"))
29 external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
30 /* In case external diff fails... */
32 diff_opts = getenv("GIT_DIFF_OPTS") ? : diff_opts;
33 done_preparing = 1;
35 return external_diff_cmd;
36}
37/* Help to copy the thing properly quoted for the shell safety.
39 * any single quote is replaced with '\'', and the caller is
40 * expected to enclose the result within a single quote pair.
41 *
42 * E.g.
43 * original sq_expand result
44 * name ==> name ==> 'name'
45 * a b ==> a b ==> 'a b'
46 * a'b ==> a'\''b ==> 'a'\''b'
47 */
48static char *sq_expand(const char *src)
49{
50 static char *buf = NULL;
51 int cnt, c;
52 const char *cp;
53 char *bp;
54 /* count bytes needed to store the quoted string. */
56 for (cnt = 1, cp = src; *cp; cnt++, cp++)
57 if (*cp == '\'')
58 cnt += 3;
59 buf = xmalloc(cnt);
61 bp = buf;
62 while ((c = *src++)) {
63 if (c != '\'')
64 *bp++ = c;
65 else {
66 bp = strcpy(bp, "'\\''");
67 bp += 4;
68 }
69 }
70 *bp = 0;
71 return buf;
72}
73static struct diff_tempfile {
75 const char *name;
76 char hex[41];
77 char mode[10];
78 char tmp_path[50];
79} diff_temp[2];
80static void builtin_diff(const char *name,
82 struct diff_tempfile *temp)
83{
84 int i, next_at;
85 const char *diff_cmd = "diff -L'%s%s' -L'%s%s'";
86 const char *diff_arg = "'%s' '%s'||:"; /* "||:" is to return 0 */
87 const char *input_name_sq[2];
88 const char *path0[2];
89 const char *path1[2];
90 const char *name_sq = sq_expand(name);
91 char *cmd;
92
93 /* diff_cmd and diff_arg have 6 %s in total which makes
94 * the sum of these strings 12 bytes larger than required.
95 * we use 2 spaces around diff-opts, and we need to count
96 * terminating NUL, so we subtract 9 here.
97 */
98 int cmd_size = (strlen(diff_cmd) + strlen(diff_opts) +
99 strlen(diff_arg) - 9);
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 } else {
106 path0[i] = i ? "b/" : "a/";
107 path1[i] = name_sq;
108 }
109 cmd_size += (strlen(path0[i]) + strlen(path1[i]) +
110 strlen(input_name_sq[i]));
111 }
112 cmd = xmalloc(cmd_size);
114 next_at = 0;
116 next_at += snprintf(cmd+next_at, cmd_size-next_at,
117 diff_cmd,
118 path0[0], path1[0], path0[1], path1[1]);
119 next_at += snprintf(cmd+next_at, cmd_size-next_at,
120 " %s ", diff_opts);
121 next_at += snprintf(cmd+next_at, cmd_size-next_at,
122 diff_arg, input_name_sq[0], input_name_sq[1]);
123 if (!path1[0][0])
125 printf("Created: %s (mode:%s)\n", name, temp[1].mode);
126 else if (!path1[1][0])
127 printf("Deleted: %s\n", name);
128 else if (strcmp(temp[0].mode, temp[1].mode)) {
129 printf("Mode changed: %s (%s->%s)\n", name,
130 temp[0].mode, temp[1].mode);
131 /* Be careful. We do not want to diff between
132 * symlink and a file.
133 */
134 if (strncmp(temp[0].mode, "120", 3) !=
135 strncmp(temp[1].mode, "120", 3))
136 exit(0);
137 }
138 fflush(NULL);
139 execlp("/bin/sh","sh", "-c", cmd, NULL);
140}
141/*
143 * Given a name and sha1 pair, if the dircache tells us the file in
144 * the work tree has that object contents, return true, so that
145 * prepare_temp_file() does not have to inflate and extract.
146 */
147static int work_tree_matches(const char *name, const unsigned char *sha1)
148{
149 struct cache_entry *ce;
150 struct stat st;
151 int pos, len;
152
153 /* We do not read the cache ourselves here, because the
154 * benchmark with my previous version that always reads cache
155 * shows that it makes things worse for diff-tree comparing
156 * two linux-2.6 kernel trees in an already checked out work
157 * tree. This is because most diff-tree comparison deals with
158 * only a small number of files, while reading the cache is
159 * expensive for a large project, and its cost outweighs the
160 * savings we get by not inflating the object to a temporary
161 * file. Practically, this code only helps when we are used
162 * by diff-cache --cached, which does read the cache before
163 * calling us.
164 */
165 if (!active_cache)
166 return 0;
167 len = strlen(name);
169 pos = cache_name_pos(name, len);
170 if (pos < 0)
171 return 0;
172 ce = active_cache[pos];
173 if ((lstat(name, &st) < 0) ||
174 !S_ISREG(st.st_mode) ||
175 cache_match_stat(ce, &st) ||
176 memcmp(sha1, ce->sha1, 20))
177 return 0;
178 return 1;
179}
180static void prep_temp_blob(struct diff_tempfile *temp,
182 void *blob,
183 unsigned long size,
184 unsigned char *sha1,
185 int mode)
186{
187 int fd;
188 strcpy(temp->tmp_path, ".diff_XXXXXX");
190 fd = mkstemp(temp->tmp_path);
191 if (fd < 0)
192 die("unable to create temp-file");
193 if (write(fd, blob, size) != size)
194 die("unable to write temp-file");
195 close(fd);
196 temp->name = temp->tmp_path;
197 strcpy(temp->hex, sha1_to_hex(sha1));
198 temp->hex[40] = 0;
199 sprintf(temp->mode, "%06o", mode);
200}
201static void prepare_temp_file(const char *name,
203 struct diff_tempfile *temp,
204 struct diff_spec *one)
205{
206 static unsigned char null_sha1[20] = { 0, };
207 int use_work_tree = 0;
208 if (!one->file_valid) {
210 not_a_valid_file:
211 /* A '-' entry produces this for file-2, and
212 * a '+' entry produces this for file-1.
213 */
214 temp->name = "/dev/null";
215 strcpy(temp->hex, ".");
216 strcpy(temp->mode, ".");
217 return;
218 }
219 if (one->sha1_valid &&
221 (!memcmp(one->blob_sha1, null_sha1, sizeof(null_sha1)) ||
222 work_tree_matches(name, one->blob_sha1)))
223 use_work_tree = 1;
224 if (!one->sha1_valid || use_work_tree) {
226 struct stat st;
227 temp->name = name;
228 if (lstat(temp->name, &st) < 0) {
229 if (errno == ENOENT)
230 goto not_a_valid_file;
231 die("stat(%s): %s", temp->name, strerror(errno));
232 }
233 if (S_ISLNK(st.st_mode)) {
234 int ret;
235 char *buf, buf_[1024];
236 buf = ((sizeof(buf_) < st.st_size) ?
237 xmalloc(st.st_size) : buf_);
238 ret = readlink(name, buf, st.st_size);
239 if (ret < 0)
240 die("readlink(%s)", name);
241 prep_temp_blob(temp, buf, st.st_size,
242 (one->sha1_valid ?
243 one->blob_sha1 : null_sha1),
244 (one->sha1_valid ?
245 one->mode : S_IFLNK));
246 }
247 else {
248 if (!one->sha1_valid)
249 strcpy(temp->hex, sha1_to_hex(null_sha1));
250 else
251 strcpy(temp->hex, sha1_to_hex(one->blob_sha1));
252 sprintf(temp->mode, "%06o",
253 S_IFREG |ce_permissions(st.st_mode));
254 }
255 return;
256 }
257 else {
258 void *blob;
259 char type[20];
260 unsigned long size;
261 blob = read_sha1_file(one->blob_sha1, type, &size);
263 if (!blob || strcmp(type, "blob"))
264 die("unable to read blob object for %s (%s)",
265 name, sha1_to_hex(one->blob_sha1));
266 prep_temp_blob(temp, blob, size, one->blob_sha1, one->mode);
267 free(blob);
268 }
269}
270static void remove_tempfile(void)
272{
273 int i;
274 for (i = 0; i < 2; i++)
276 if (diff_temp[i].name == diff_temp[i].tmp_path) {
277 unlink(diff_temp[i].name);
278 diff_temp[i].name = NULL;
279 }
280}
281static void remove_tempfile_on_signal(int signo)
283{
284 remove_tempfile();
285}
286/* An external diff command takes:
288 *
289 * diff-cmd name infile1 infile1-sha1 infile1-mode \
290 * infile2 infile2-sha1 infile2-mode.
291 *
292 */
293void run_external_diff(const char *name,
294 struct diff_spec *one,
295 struct diff_spec *two)
296{
297 struct diff_tempfile *temp = diff_temp;
298 pid_t pid;
299 int status;
300 static int atexit_asked = 0;
301 if (one && two) {
303 prepare_temp_file(name, &temp[0], one);
304 prepare_temp_file(name, &temp[1], two);
305 if (! atexit_asked &&
306 (temp[0].name == temp[0].tmp_path ||
307 temp[1].name == temp[1].tmp_path)) {
308 atexit_asked = 1;
309 atexit(remove_tempfile);
310 }
311 signal(SIGINT, remove_tempfile_on_signal);
312 }
313 fflush(NULL);
315 pid = fork();
316 if (pid < 0)
317 die("unable to fork");
318 if (!pid) {
319 const char *pgm = external_diff();
320 if (pgm) {
321 if (one && two)
322 execlp(pgm, pgm,
323 name,
324 temp[0].name, temp[0].hex, temp[0].mode,
325 temp[1].name, temp[1].hex, temp[1].mode,
326 NULL);
327 else
328 execlp(pgm, pgm, name, NULL);
329 }
330 /*
331 * otherwise we use the built-in one.
332 */
333 if (one && two)
334 builtin_diff(name, temp);
335 else
336 printf("* Unmerged path %s\n", name);
337 exit(0);
338 }
339 if (waitpid(pid, &status, 0) < 0 ||
340 !WIFEXITED(status) || WEXITSTATUS(status)) {
341 /* Earlier we did not check the exit status because
342 * diff exits non-zero if files are different, and
343 * we are not interested in knowing that. It was a
344 * mistake which made it harder to quit a diff-*
345 * session that uses the git-apply-patch-script as
346 * the GIT_EXTERNAL_DIFF. A custom GIT_EXTERNAL_DIFF
347 * should also exit non-zero only when it wants to
348 * abort the entire diff-* session.
349 */
350 remove_tempfile();
351 fprintf(stderr, "external diff died, stopping at %s.\n", name);
352 exit(1);
353 }
354 remove_tempfile();
355}
356void diff_addremove(int addremove, unsigned mode,
358 const unsigned char *sha1,
359 const char *base, const char *path)
360{
361 char concatpath[PATH_MAX];
362 struct diff_spec spec[2], *one, *two;
363 memcpy(spec[0].blob_sha1, sha1, 20);
365 spec[0].mode = mode;
366 spec[0].sha1_valid = spec[0].file_valid = 1;
367 spec[1].file_valid = 0;
368 if (addremove == '+') {
370 one = spec + 1; two = spec;
371 } else {
372 one = spec; two = one + 1;
373 }
374
375 if (path) {
376 strcpy(concatpath, base);
377 strcat(concatpath, path);
378 }
379 run_external_diff(path ? concatpath : base, one, two);
380}
381void diff_change(unsigned old_mode, unsigned new_mode,
383 const unsigned char *old_sha1,
384 const unsigned char *new_sha1,
385 const char *base, const char *path) {
386 char concatpath[PATH_MAX];
387 struct diff_spec spec[2];
388 memcpy(spec[0].blob_sha1, old_sha1, 20);
390 spec[0].mode = old_mode;
391 memcpy(spec[1].blob_sha1, new_sha1, 20);
392 spec[1].mode = new_mode;
393 spec[0].sha1_valid = spec[0].file_valid = 1;
394 spec[1].sha1_valid = spec[1].file_valid = 1;
395 if (path) {
397 strcpy(concatpath, base);
398 strcat(concatpath, path);
399 }
400 run_external_diff(path ? concatpath : base, &spec[0], &spec[1]);
401}
402void diff_unmerge(const char *path)
404{
405 run_external_diff(path, NULL, NULL);
406}