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xdl_merge(): fix an off-by-one bug
[thirdparty/git.git] / xdiff / xmerge.c
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857b933e
JS		 1/*
2 * LibXDiff by Davide Libenzi ( File Differential Library )
3 * Copyright (C) 2003-2006 Davide Libenzi, Johannes E. Schindelin
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 *
19 * Davide Libenzi <davidel@xmailserver.org>
20 *
21 */
22
23#include "xinclude.h"
24
25typedef struct s_xdmerge {
26 struct s_xdmerge *next;
27 /*
28 * 0 = conflict,
29 * 1 = no conflict, take first,
30 * 2 = no conflict, take second.
31 */
32 int mode;
33 long i1, i2;
34 long chg1, chg2;
35} xdmerge_t;
36
37static int xdl_append_merge(xdmerge_t **merge, int mode,
38 long i1, long chg1, long i2, long chg2)
39{
40 xdmerge_t *m = *merge;
41 if (m && mode == m->mode &&
42 (i1 == m->i1 + m->chg1 || i2 == m->i2 + m->chg2)) {
43 m->chg1 = i1 + chg1 - m->i1;
44 m->chg2 = i2 + chg2 - m->i2;
45 } else {
46 m = xdl_malloc(sizeof(xdmerge_t));
47 if (!m)
48 return -1;
49 m->next = NULL;
50 m->mode = mode;
51 m->i1 = i1;
52 m->chg1 = chg1;
53 m->i2 = i2;
54 m->chg2 = chg2;
55 if (*merge)
56 (*merge)->next = m;
57 *merge = m;
58 }
59 return 0;
60}
61
62static int xdl_cleanup_merge(xdmerge_t *c)
63{
64 int count = 0;
65 xdmerge_t *next_c;
66
67 /* were there conflicts? */
68 for (; c; c = next_c) {
69 if (c->mode == 0)
70 count++;
71 next_c = c->next;
72 free(c);
73 }
74 return count;
75}
76
77static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,
78 int line_count, long flags)
79{
80 int i;
81 xrecord_t **rec1 = xe1->xdf2.recs + i1;
82 xrecord_t **rec2 = xe2->xdf2.recs + i2;
83
84 for (i = 0; i < line_count; i++) {
85 int result = xdl_recmatch(rec1[i]->ptr, rec1[i]->size,
86 rec2[i]->ptr, rec2[i]->size, flags);
87 if (!result)
88 return -1;
89 }
90 return 0;
91}
92
93static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
94{
95 xrecord_t **recs = xe->xdf2.recs + i;
96 int size = 0;
97
98 if (count < 1)
99 return 0;
100
101 for (i = 0; i < count; size += recs[i++]->size)
102 if (dest)
103 memcpy(dest + size, recs[i]->ptr, recs[i]->size);
104 if (add_nl) {
105 i = recs[count - 1]->size;
106 if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') {
107 if (dest)
108 dest[size] = '\n';
109 size++;
110 }
111 }
112 return size;
113}
114
115static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
116 xdfenv_t *xe2, const char *name2, xdmerge_t *m, char *dest)
117{
118 const int marker_size = 7;
119 int marker1_size = (name1 ? strlen(name1) + 1 : 0);
120 int marker2_size = (name2 ? strlen(name2) + 1 : 0);
121 int conflict_marker_size = 3 * (marker_size + 1)
122 + marker1_size + marker2_size;
123 int size, i1, j;
124
125 for (size = i1 = 0; m; m = m->next) {
126 if (m->mode == 0) {
127 size += xdl_recs_copy(xe1, i1, m->i1 - i1, 0,
128 dest ? dest + size : NULL);
129 if (dest) {
130 for (j = 0; j < marker_size; j++)
131 dest[size++] = '<';
132 if (marker1_size) {
133 dest[size] = ' ';
134 memcpy(dest + size + 1, name1,
135 marker1_size - 1);
136 size += marker1_size;
137 }
138 dest[size++] = '\n';
139 } else
140 size += conflict_marker_size;
141 size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
142 dest ? dest + size : NULL);
143 if (dest) {
144 for (j = 0; j < marker_size; j++)
145 dest[size++] = '=';
146 dest[size++] = '\n';
147 }
148 size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
149 dest ? dest + size : NULL);
150 if (dest) {
151 for (j = 0; j < marker_size; j++)
152 dest[size++] = '>';
153 if (marker2_size) {
154 dest[size] = ' ';
155 memcpy(dest + size + 1, name2,
156 marker2_size - 1);
157 size += marker2_size;
158 }
159 dest[size++] = '\n';
160 }
161 } else if (m->mode == 1)
162 size += xdl_recs_copy(xe1, i1, m->i1 + m->chg1 - i1, 0,
163 dest ? dest + size : NULL);
164 else if (m->mode == 2)
165 size += xdl_recs_copy(xe2, m->i2 - m->i1 + i1,
166 m->i1 + m->chg2 - i1, 0,
167 dest ? dest + size : NULL);
168 i1 = m->i1 + m->chg1;
169 }
170 size += xdl_recs_copy(xe1, i1, xe1->xdf2.nrec - i1, 0,
171 dest ? dest + size : NULL);
172 return size;
173}
174
175/*
176 * Sometimes, changes are not quite identical, but differ in only a few
177 * lines. Try hard to show only these few lines as conflicting.
178 */
179static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
180 xpparam_t const *xpp)
181{
182 for (; m; m = m->next) {
183 mmfile_t t1, t2;
184 xdfenv_t xe;
185 xdchange_t *xscr, *x;
186 int i1 = m->i1, i2 = m->i2;
187
188 /* let's handle just the conflicts */
189 if (m->mode)
190 continue;
191
192 /*
193 * This probably does not work outside git, since
194 * we have a very simple mmfile structure.
195 */
196 t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
875b8ce4
JS		 197 t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
198 + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
199 t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
200 t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
201 + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
857b933e
JS		 202 if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
203 return -1;
204 if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
205 xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
206 xdl_build_script(&xe, &xscr) < 0) {
207 xdl_free_env(&xe);
208 return -1;
209 }
210 if (!xscr) {
211 /* If this happens, it's a bug. */
212 xdl_free_env(&xe);
213 return -2;
214 }
215 x = xscr;
216 m->i1 = xscr->i1 + i1;
217 m->chg1 = xscr->chg1;
218 m->i2 = xscr->i2 + i2;
219 m->chg2 = xscr->chg2;
220 while (xscr->next) {
221 xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
222 if (!m2) {
223 xdl_free_env(&xe);
224 xdl_free_script(x);
225 return -1;
226 }
227 xscr = xscr->next;
228 m2->next = m->next;
229 m->next = m2;
230 m = m2;
231 m->mode = 0;
232 m->i1 = xscr->i1 + i1;
233 m->chg1 = xscr->chg1;
234 m->i2 = xscr->i2 + i2;
235 m->chg2 = xscr->chg2;
236 }
237 xdl_free_env(&xe);
238 xdl_free_script(x);
239 }
240 return 0;
241}
242
243/*
244 * level == 0: mark all overlapping changes as conflict
245 * level == 1: mark overlapping changes as conflict only if not identical
246 * level == 2: analyze non-identical changes for minimal conflict set
247 *
248 * returns < 0 on error, == 0 for no conflicts, else number of conflicts
249 */
250static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
251 xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
252 int level, xpparam_t const *xpp, mmbuffer_t *result) {
253 xdmerge_t *changes, *c;
254 int i1, i2, chg1, chg2;
255
256 c = changes = NULL;
257
258 while (xscr1 && xscr2) {
259 if (!changes)
260 changes = c;
261 if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
262 i1 = xscr1->i2;
263 i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
264 chg1 = xscr1->chg2;
265 chg2 = xscr1->chg1;
266 if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
267 xdl_cleanup_merge(changes);
268 return -1;
269 }
270 xscr1 = xscr1->next;
271 continue;
272 }
273 if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
274 i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
275 i2 = xscr2->i2;
276 chg1 = xscr2->chg1;
277 chg2 = xscr2->chg2;
278 if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
279 xdl_cleanup_merge(changes);
280 return -1;
281 }
282 xscr2 = xscr2->next;
283 continue;
284 }
285 if (level < 1 || xscr1->i1 != xscr2->i1 ||
286 xscr1->chg1 != xscr2->chg1 ||
287 xscr1->chg2 != xscr2->chg2 ||
288 xdl_merge_cmp_lines(xe1, xscr1->i2,
289 xe2, xscr2->i2,
290 xscr1->chg2, xpp->flags)) {
291 /* conflict */
292 int off = xscr1->i1 - xscr2->i1;
293 int ffo = off + xscr1->chg1 - xscr2->chg1;
294
295 i1 = xscr1->i2;
296 i2 = xscr2->i2;
297 if (off > 0)
298 i1 -= off;
299 else
300 i2 += off;
301 chg1 = xscr1->i2 + xscr1->chg2 - i1;
302 chg2 = xscr2->i2 + xscr2->chg2 - i2;
303 if (ffo > 0)
304 chg2 += ffo;
305 else
306 chg1 -= ffo;
307 if (xdl_append_merge(&c, 0, i1, chg1, i2, chg2)) {
308 xdl_cleanup_merge(changes);
309 return -1;
310 }
311 }
312
313 i1 = xscr1->i1 + xscr1->chg1;
314 i2 = xscr2->i1 + xscr2->chg1;
315
316 if (i1 > i2) {
317 xscr1->chg1 -= i1 - i2;
318 xscr1->i1 = i2;
319 xscr1->i2 += xscr1->chg2;
320 xscr1->chg2 = 0;
321 xscr1 = xscr1->next;
322 } else if (i2 > i1) {
323 xscr2->chg1 -= i2 - i1;
324 xscr2->i1 = i1;
325 xscr2->i2 += xscr2->chg2;
326 xscr2->chg2 = 0;
327 xscr2 = xscr2->next;
328 } else {
329 xscr1 = xscr1->next;
330 xscr2 = xscr2->next;
331 }
332 }
333 while (xscr1) {
334 if (!changes)
335 changes = c;
336 i1 = xscr1->i2;
337 i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
338 chg1 = xscr1->chg2;
339 chg2 = xscr1->chg1;
340 if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
341 xdl_cleanup_merge(changes);
342 return -1;
343 }
344 xscr1 = xscr1->next;
345 }
346 while (xscr2) {
347 if (!changes)
348 changes = c;
349 i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
350 i2 = xscr2->i2;
351 chg1 = xscr2->chg1;
352 chg2 = xscr2->chg2;
353 if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
354 xdl_cleanup_merge(changes);
355 return -1;
356 }
357 xscr2 = xscr2->next;
358 }
359 if (!changes)
360 changes = c;
361 /* refine conflicts */
362 if (level > 1 && xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0) {
363 xdl_cleanup_merge(changes);
364 return -1;
365 }
366 /* output */
367 if (result) {
368 int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
369 changes, NULL);
370 result->ptr = xdl_malloc(size);
371 if (!result->ptr) {
372 xdl_cleanup_merge(changes);
373 return -1;
374 }
375 result->size = size;
376 xdl_fill_merge_buffer(xe1, name1, xe2, name2, changes,
377 result->ptr);
378 }
379 return xdl_cleanup_merge(changes);
380}
381
382int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
383 mmfile_t *mf2, const char *name2,
384 xpparam_t const *xpp, int level, mmbuffer_t *result) {
385 xdchange_t *xscr1, *xscr2;
386 xdfenv_t xe1, xe2;
53a7085a 387 int status;
857b933e
JS		 388
389 result->ptr = NULL;
390 result->size = 0;
391
392 if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
393 xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
394 return -1;
395 }
396 if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
397 xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
398 xdl_build_script(&xe1, &xscr1) < 0) {
399 xdl_free_env(&xe1);
400 return -1;
401 }
402 if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
403 xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
404 xdl_build_script(&xe2, &xscr2) < 0) {
405 xdl_free_env(&xe2);
406 return -1;
407 }
53a7085a 408 status = 0;
857b933e
JS		 409 if (xscr1 || xscr2) {
410 if (!xscr1) {
411 result->ptr = xdl_malloc(mf2->size);
412 memcpy(result->ptr, mf2->ptr, mf2->size);
413 result->size = mf2->size;
414 } else if (!xscr2) {
415 result->ptr = xdl_malloc(mf1->size);
416 memcpy(result->ptr, mf1->ptr, mf1->size);
417 result->size = mf1->size;
53a7085a
JH		 418 } else {
419 status = xdl_do_merge(&xe1, xscr1, name1,
420 &xe2, xscr2, name2,
421 level, xpp, result);
857b933e
JS		 422 }
423 xdl_free_script(xscr1);
424 xdl_free_script(xscr2);
425 }
426 xdl_free_env(&xe1);
427 xdl_free_env(&xe2);
428
53a7085a 429 return status;
857b933e 430}
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