checkout: allow detaching to HEAD even when switching to the tip of a branch
[git/repo.git] / tree-diff.c
blob852498eb49fe0cba5e1cd21661288e8321a4b20e
1 /*
2 * Helper functions for tree diff generation
3 */
4 #include "cache.h"
5 #include "diff.h"
6 #include "tree.h"
8 static char *malloc_base(const char *base, int baselen, const char *path, int pathlen)
10 char *newbase = xmalloc(baselen + pathlen + 2);
11 memcpy(newbase, base, baselen);
12 memcpy(newbase + baselen, path, pathlen);
13 memcpy(newbase + baselen + pathlen, "/", 2);
14 return newbase;
17 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
18 const char *base, int baselen);
20 static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt)
22 unsigned mode1, mode2;
23 const char *path1, *path2;
24 const unsigned char *sha1, *sha2;
25 int cmp, pathlen1, pathlen2;
27 sha1 = tree_entry_extract(t1, &path1, &mode1);
28 sha2 = tree_entry_extract(t2, &path2, &mode2);
30 pathlen1 = tree_entry_len(path1, sha1);
31 pathlen2 = tree_entry_len(path2, sha2);
32 cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
33 if (cmp < 0) {
34 show_entry(opt, "-", t1, base, baselen);
35 return -1;
37 if (cmp > 0) {
38 show_entry(opt, "+", t2, base, baselen);
39 return 1;
41 if (!opt->find_copies_harder && !hashcmp(sha1, sha2) && mode1 == mode2)
42 return 0;
45 * If the filemode has changed to/from a directory from/to a regular
46 * file, we need to consider it a remove and an add.
48 if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
49 show_entry(opt, "-", t1, base, baselen);
50 show_entry(opt, "+", t2, base, baselen);
51 return 0;
54 if (opt->recursive && S_ISDIR(mode1)) {
55 int retval;
56 char *newbase = malloc_base(base, baselen, path1, pathlen1);
57 if (opt->tree_in_recursive)
58 opt->change(opt, mode1, mode2,
59 sha1, sha2, base, path1);
60 retval = diff_tree_sha1(sha1, sha2, newbase, opt);
61 free(newbase);
62 return retval;
65 opt->change(opt, mode1, mode2, sha1, sha2, base, path1);
66 return 0;
70 * Is a tree entry interesting given the pathspec we have?
72 * Return:
73 * - 2 for "yes, and all subsequent entries will be"
74 * - 1 for yes
75 * - zero for no
76 * - negative for "no, and no subsequent entries will be either"
78 static int tree_entry_interesting(struct tree_desc *desc, const char *base, int baselen, struct diff_options *opt)
80 const char *path;
81 const unsigned char *sha1;
82 unsigned mode;
83 int i;
84 int pathlen;
85 int never_interesting = -1;
87 if (!opt->nr_paths)
88 return 1;
90 sha1 = tree_entry_extract(desc, &path, &mode);
92 pathlen = tree_entry_len(path, sha1);
94 for (i = 0; i < opt->nr_paths; i++) {
95 const char *match = opt->paths[i];
96 int matchlen = opt->pathlens[i];
97 int m = -1; /* signals that we haven't called strncmp() */
99 if (baselen >= matchlen) {
100 /* If it doesn't match, move along... */
101 if (strncmp(base, match, matchlen))
102 continue;
105 * The base is a subdirectory of a path which
106 * was specified, so all of them are interesting.
108 return 2;
111 /* Does the base match? */
112 if (strncmp(base, match, baselen))
113 continue;
115 match += baselen;
116 matchlen -= baselen;
118 if (never_interesting) {
120 * We have not seen any match that sorts later
121 * than the current path.
125 * Does match sort strictly earlier than path
126 * with their common parts?
128 m = strncmp(match, path,
129 (matchlen < pathlen) ? matchlen : pathlen);
130 if (m < 0)
131 continue;
134 * If we come here even once, that means there is at
135 * least one pathspec that would sort equal to or
136 * later than the path we are currently looking at.
137 * In other words, if we have never reached this point
138 * after iterating all pathspecs, it means all
139 * pathspecs are either outside of base, or inside the
140 * base but sorts strictly earlier than the current
141 * one. In either case, they will never match the
142 * subsequent entries. In such a case, we initialized
143 * the variable to -1 and that is what will be
144 * returned, allowing the caller to terminate early.
146 never_interesting = 0;
149 if (pathlen > matchlen)
150 continue;
152 if (matchlen > pathlen) {
153 if (match[pathlen] != '/')
154 continue;
155 if (!S_ISDIR(mode))
156 continue;
159 if (m == -1)
161 * we cheated and did not do strncmp(), so we do
162 * that here.
164 m = strncmp(match, path, pathlen);
167 * If common part matched earlier then it is a hit,
168 * because we rejected the case where path is not a
169 * leading directory and is shorter than match.
171 if (!m)
172 return 1;
174 return never_interesting; /* No matches */
177 /* A whole sub-tree went away or appeared */
178 static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
180 int all_interesting = 0;
181 while (desc->size) {
182 int show;
184 if (all_interesting)
185 show = 1;
186 else {
187 show = tree_entry_interesting(desc, base, baselen,
188 opt);
189 if (show == 2)
190 all_interesting = 1;
192 if (show < 0)
193 break;
194 if (show)
195 show_entry(opt, prefix, desc, base, baselen);
196 update_tree_entry(desc);
200 /* A file entry went away or appeared */
201 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
202 const char *base, int baselen)
204 unsigned mode;
205 const char *path;
206 const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
208 if (opt->recursive && S_ISDIR(mode)) {
209 enum object_type type;
210 int pathlen = tree_entry_len(path, sha1);
211 char *newbase = malloc_base(base, baselen, path, pathlen);
212 struct tree_desc inner;
213 void *tree;
214 unsigned long size;
216 tree = read_sha1_file(sha1, &type, &size);
217 if (!tree || type != OBJ_TREE)
218 die("corrupt tree sha %s", sha1_to_hex(sha1));
220 init_tree_desc(&inner, tree, size);
221 show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
223 free(tree);
224 free(newbase);
225 } else {
226 opt->add_remove(opt, prefix[0], mode, sha1, base, path);
230 static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt)
232 int all_interesting = 0;
233 while (t->size) {
234 int show;
236 if (all_interesting)
237 show = 1;
238 else {
239 show = tree_entry_interesting(t, base, baselen, opt);
240 if (show == 2)
241 all_interesting = 1;
243 if (!show) {
244 update_tree_entry(t);
245 continue;
247 /* Skip it all? */
248 if (show < 0)
249 t->size = 0;
250 return;
254 int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
256 int baselen = strlen(base);
258 for (;;) {
259 if (opt->quiet && opt->has_changes)
260 break;
261 if (opt->nr_paths) {
262 skip_uninteresting(t1, base, baselen, opt);
263 skip_uninteresting(t2, base, baselen, opt);
265 if (!t1->size) {
266 if (!t2->size)
267 break;
268 show_entry(opt, "+", t2, base, baselen);
269 update_tree_entry(t2);
270 continue;
272 if (!t2->size) {
273 show_entry(opt, "-", t1, base, baselen);
274 update_tree_entry(t1);
275 continue;
277 switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
278 case -1:
279 update_tree_entry(t1);
280 continue;
281 case 0:
282 update_tree_entry(t1);
283 /* Fallthrough */
284 case 1:
285 update_tree_entry(t2);
286 continue;
288 die("git-diff-tree: internal error");
290 return 0;
293 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
295 void *tree1, *tree2;
296 struct tree_desc t1, t2;
297 unsigned long size1, size2;
298 int retval;
300 tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
301 if (!tree1)
302 die("unable to read source tree (%s)", sha1_to_hex(old));
303 tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
304 if (!tree2)
305 die("unable to read destination tree (%s)", sha1_to_hex(new));
306 init_tree_desc(&t1, tree1, size1);
307 init_tree_desc(&t2, tree2, size2);
308 retval = diff_tree(&t1, &t2, base, opt);
309 free(tree1);
310 free(tree2);
311 return retval;
314 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
316 int retval;
317 void *tree;
318 unsigned long size;
319 struct tree_desc empty, real;
321 tree = read_object_with_reference(new, tree_type, &size, NULL);
322 if (!tree)
323 die("unable to read root tree (%s)", sha1_to_hex(new));
324 init_tree_desc(&real, tree, size);
326 init_tree_desc(&empty, "", 0);
327 retval = diff_tree(&empty, &real, base, opt);
328 free(tree);
329 return retval;
332 static int count_paths(const char **paths)
334 int i = 0;
335 while (*paths++)
336 i++;
337 return i;
340 void diff_tree_release_paths(struct diff_options *opt)
342 free(opt->pathlens);
345 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
347 opt->nr_paths = 0;
348 opt->pathlens = NULL;
349 opt->paths = NULL;
351 if (p) {
352 int i;
354 opt->paths = p;
355 opt->nr_paths = count_paths(p);
356 if (opt->nr_paths == 0) {
357 opt->pathlens = NULL;
358 return;
360 opt->pathlens = xmalloc(opt->nr_paths * sizeof(int));
361 for (i=0; i < opt->nr_paths; i++)
362 opt->pathlens[i] = strlen(p[i]);