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 *diff_cmd = "diff -L'%s%s' -L'%s%s'";
87 const char *diff_arg = "'%s' '%s'||:"; /* "||:" is to return 0 */
88 const char *input_name_sq[2];
89 const char *path0[2];
90 const char *path1[2];
91 const char *name_sq = sq_expand(name);
92 char *cmd;
93
94 /* diff_cmd and diff_arg have 6 %s in total which makes
95 * the sum of these strings 12 bytes larger than required.
96 * we use 2 spaces around diff-opts, and we need to count
97 * terminating NUL, so we subtract 9 here.
98 */
99 int cmd_size = (strlen(diff_cmd) + strlen(diff_opts) +
100 strlen(diff_arg) - 9);
101 for (i = 0; i < 2; i++) {
102 input_name_sq[i] = sq_expand(temp[i].name);
103 if (!strcmp(temp[i].name, "/dev/null")) {
104 path0[i] = "/dev/null";
105 path1[i] = "";
106 } else {
107 path0[i] = i ? "b/" : "a/";
108 path1[i] = name_sq;
109 }
110 cmd_size += (strlen(path0[i]) + strlen(path1[i]) +
111 strlen(input_name_sq[i]));
112 }
113 cmd = xmalloc(cmd_size);
115 next_at = 0;
117 next_at += snprintf(cmd+next_at, cmd_size-next_at,
118 diff_cmd,
119 path0[0], path1[0], path0[1], path1[1]);
120 next_at += snprintf(cmd+next_at, cmd_size-next_at,
121 " %s ", diff_opts);
122 next_at += snprintf(cmd+next_at, cmd_size-next_at,
123 diff_arg, input_name_sq[0], input_name_sq[1]);
124 if (!path1[0][0])
126 printf("Created: %s (mode:%s)\n", name, temp[1].mode);
127 else if (!path1[1][0])
128 printf("Deleted: %s\n", name);
129 else if (strcmp(temp[0].mode, temp[1].mode)) {
130 printf("Mode changed: %s (%s->%s)\n", name,
131 temp[0].mode, temp[1].mode);
132 /* Be careful. We do not want to diff between
133 * symlink and a file.
134 */
135 if (strncmp(temp[0].mode, "120", 3) !=
136 strncmp(temp[1].mode, "120", 3))
137 exit(0);
138 }
139 fflush(NULL);
140 execlp("/bin/sh","sh", "-c", cmd, NULL);
141}
142/*
144 * Given a name and sha1 pair, if the dircache tells us the file in
145 * the work tree has that object contents, return true, so that
146 * prepare_temp_file() does not have to inflate and extract.
147 */
148static int work_tree_matches(const char *name, const unsigned char *sha1)
149{
150 struct cache_entry *ce;
151 struct stat st;
152 int pos, len;
153
154 /* We do not read the cache ourselves here, because the
155 * benchmark with my previous version that always reads cache
156 * shows that it makes things worse for diff-tree comparing
157 * two linux-2.6 kernel trees in an already checked out work
158 * tree. This is because most diff-tree comparison deals with
159 * only a small number of files, while reading the cache is
160 * expensive for a large project, and its cost outweighs the
161 * savings we get by not inflating the object to a temporary
162 * file. Practically, this code only helps when we are used
163 * by diff-cache --cached, which does read the cache before
164 * calling us.
165 */
166 if (!active_cache)
167 return 0;
168 len = strlen(name);
170 pos = cache_name_pos(name, len);
171 if (pos < 0)
172 return 0;
173 ce = active_cache[pos];
174 if ((lstat(name, &st) < 0) ||
175 !S_ISREG(st.st_mode) ||
176 cache_match_stat(ce, &st) ||
177 memcmp(sha1, ce->sha1, 20))
178 return 0;
179 return 1;
180}
181static void prep_temp_blob(struct diff_tempfile *temp,
183 void *blob,
184 unsigned long size,
185 unsigned char *sha1,
186 int mode)
187{
188 int fd;
189 strcpy(temp->tmp_path, ".diff_XXXXXX");
191 fd = mkstemp(temp->tmp_path);
192 if (fd < 0)
193 die("unable to create temp-file");
194 if (write(fd, blob, size) != size)
195 die("unable to write temp-file");
196 close(fd);
197 temp->name = temp->tmp_path;
198 strcpy(temp->hex, sha1_to_hex(sha1));
199 temp->hex[40] = 0;
200 sprintf(temp->mode, "%06o", mode);
201}
202static void prepare_temp_file(const char *name,
204 struct diff_tempfile *temp,
205 struct diff_spec *one)
206{
207 static unsigned char null_sha1[20] = { 0, };
208 int use_work_tree = 0;
209 if (!one->file_valid) {
211 not_a_valid_file:
212 /* A '-' entry produces this for file-2, and
213 * a '+' entry produces this for file-1.
214 */
215 temp->name = "/dev/null";
216 strcpy(temp->hex, ".");
217 strcpy(temp->mode, ".");
218 return;
219 }
220 if (one->sha1_valid &&
222 (!memcmp(one->blob_sha1, null_sha1, sizeof(null_sha1)) ||
223 work_tree_matches(name, one->blob_sha1)))
224 use_work_tree = 1;
225 if (!one->sha1_valid || use_work_tree) {
227 struct stat st;
228 temp->name = name;
229 if (lstat(temp->name, &st) < 0) {
230 if (errno == ENOENT)
231 goto not_a_valid_file;
232 die("stat(%s): %s", temp->name, strerror(errno));
233 }
234 if (S_ISLNK(st.st_mode)) {
235 int ret;
236 char *buf, buf_[1024];
237 buf = ((sizeof(buf_) < st.st_size) ?
238 xmalloc(st.st_size) : buf_);
239 ret = readlink(name, buf, st.st_size);
240 if (ret < 0)
241 die("readlink(%s)", name);
242 prep_temp_blob(temp, buf, st.st_size,
243 (one->sha1_valid ?
244 one->blob_sha1 : null_sha1),
245 (one->sha1_valid ?
246 one->mode : S_IFLNK));
247 }
248 else {
249 if (!one->sha1_valid)
250 strcpy(temp->hex, sha1_to_hex(null_sha1));
251 else
252 strcpy(temp->hex, sha1_to_hex(one->blob_sha1));
253 sprintf(temp->mode, "%06o",
254 S_IFREG |ce_permissions(st.st_mode));
255 }
256 return;
257 }
258 else {
259 void *blob;
260 char type[20];
261 unsigned long size;
262 blob = read_sha1_file(one->blob_sha1, type, &size);
264 if (!blob || strcmp(type, "blob"))
265 die("unable to read blob object for %s (%s)",
266 name, sha1_to_hex(one->blob_sha1));
267 prep_temp_blob(temp, blob, size, one->blob_sha1, one->mode);
268 free(blob);
269 }
270}
271static void remove_tempfile(void)
273{
274 int i;
275 for (i = 0; i < 2; i++)
277 if (diff_temp[i].name == diff_temp[i].tmp_path) {
278 unlink(diff_temp[i].name);
279 diff_temp[i].name = NULL;
280 }
281}
282static void remove_tempfile_on_signal(int signo)
284{
285 remove_tempfile();
286}
287/* An external diff command takes:
289 *
290 * diff-cmd name infile1 infile1-sha1 infile1-mode \
291 * infile2 infile2-sha1 infile2-mode.
292 *
293 */
294void run_external_diff(const char *name,
295 struct diff_spec *one,
296 struct diff_spec *two)
297{
298 struct diff_tempfile *temp = diff_temp;
299 pid_t pid;
300 int status;
301 static int atexit_asked = 0;
302 if (one && two) {
304 prepare_temp_file(name, &temp[0], one);
305 prepare_temp_file(name, &temp[1], two);
306 if (! atexit_asked &&
307 (temp[0].name == temp[0].tmp_path ||
308 temp[1].name == temp[1].tmp_path)) {
309 atexit_asked = 1;
310 atexit(remove_tempfile);
311 }
312 signal(SIGINT, remove_tempfile_on_signal);
313 }
314 fflush(NULL);
316 pid = fork();
317 if (pid < 0)
318 die("unable to fork");
319 if (!pid) {
320 const char *pgm = external_diff();
321 if (pgm) {
322 if (one && two)
323 execlp(pgm, pgm,
324 name,
325 temp[0].name, temp[0].hex, temp[0].mode,
326 temp[1].name, temp[1].hex, temp[1].mode,
327 NULL);
328 else
329 execlp(pgm, pgm, name, NULL);
330 }
331 /*
332 * otherwise we use the built-in one.
333 */
334 if (one && two)
335 builtin_diff(name, temp);
336 else
337 printf("* Unmerged path %s\n", name);
338 exit(0);
339 }
340 if (waitpid(pid, &status, 0) < 0 ||
341 !WIFEXITED(status) || WEXITSTATUS(status)) {
342 /* Earlier we did not check the exit status because
343 * diff exits non-zero if files are different, and
344 * we are not interested in knowing that. It was a
345 * mistake which made it harder to quit a diff-*
346 * session that uses the git-apply-patch-script as
347 * the GIT_EXTERNAL_DIFF. A custom GIT_EXTERNAL_DIFF
348 * should also exit non-zero only when it wants to
349 * abort the entire diff-* session.
350 */
351 remove_tempfile();
352 fprintf(stderr, "external diff died, stopping at %s.\n", name);
353 exit(1);
354 }
355 remove_tempfile();
356}
357void diff_addremove(int addremove, unsigned mode,
359 const unsigned char *sha1,
360 const char *base, const char *path)
361{
362 char concatpath[PATH_MAX];
363 struct diff_spec spec[2], *one, *two;
364 memcpy(spec[0].blob_sha1, sha1, 20);
366 spec[0].mode = mode;
367 spec[0].sha1_valid = spec[0].file_valid = 1;
368 spec[1].file_valid = 0;
369 if (addremove == '+') {
371 one = spec + 1; two = spec;
372 } else {
373 one = spec; two = one + 1;
374 }
375
376 if (path) {
377 strcpy(concatpath, base);
378 strcat(concatpath, path);
379 }
380 run_external_diff(path ? concatpath : base, one, two);
381}
382void diff_change(unsigned old_mode, unsigned new_mode,
384 const unsigned char *old_sha1,
385 const unsigned char *new_sha1,
386 const char *base, const char *path) {
387 char concatpath[PATH_MAX];
388 struct diff_spec spec[2];
389 memcpy(spec[0].blob_sha1, old_sha1, 20);
391 spec[0].mode = old_mode;
392 memcpy(spec[1].blob_sha1, new_sha1, 20);
393 spec[1].mode = new_mode;
394 spec[0].sha1_valid = spec[0].file_valid = 1;
395 spec[1].sha1_valid = spec[1].file_valid = 1;
396 if (path) {
398 strcpy(concatpath, base);
399 strcat(concatpath, path);
400 }
401 run_external_diff(path ? concatpath : base, &spec[0], &spec[1]);
402}
403void diff_unmerge(const char *path)
405{
406 run_external_diff(path, NULL, NULL);
407}