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1/*
2 * LibXDiff by Davide Libenzi ( File Differential Library )
3 * Copyright (C) 2003 Davide Libenzi
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, see
17 * <http://www.gnu.org/licenses/>.
18 *
19 * Davide Libenzi <davidel@xmailserver.org>
20 *
21 */
22
23#include "xinclude.h"
24
25
26static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb)
27{
28 xrecord_t *rec = &xdf->recs[ri];
29
30 if (xdl_emit_diffrec(rec->ptr, rec->size, pre, strlen(pre), ecb) < 0)
31 return -1;
32
33 return 0;
34}
35
36static long saturating_add(long a, long b)
37{
38 return signed_add_overflows(a, b) ? LONG_MAX : a + b;
39}
40
41/*
42 * Starting at the passed change atom, find the latest change atom to be included
43 * inside the differential hunk according to the specified configuration.
44 * Also advance xscr if the first changes must be discarded.
45 */
46xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg)
47{
48 xdchange_t *xch, *xchp, *lxch;
49 long max_common = saturating_add(saturating_add(xecfg->ctxlen,
50 xecfg->ctxlen),
51 xecfg->interhunkctxlen);
52 long max_ignorable = xecfg->ctxlen;
53 long ignored = 0; /* number of ignored blank lines */
54
55 /* remove ignorable changes that are too far before other changes */
56 for (xchp = *xscr; xchp && xchp->ignore; xchp = xchp->next) {
57 xch = xchp->next;
58
59 if (xch == NULL ||
60 xch->i1 - (xchp->i1 + xchp->chg1) >= max_ignorable)
61 *xscr = xch;
62 }
63
64 if (!*xscr)
65 return NULL;
66
67 lxch = *xscr;
68
69 for (xchp = *xscr, xch = xchp->next; xch; xchp = xch, xch = xch->next) {
70 long distance = xch->i1 - (xchp->i1 + xchp->chg1);
71 if (distance > max_common)
72 break;
73
74 if (distance < max_ignorable && (!xch->ignore || lxch == xchp)) {
75 lxch = xch;
76 ignored = 0;
77 } else if (distance < max_ignorable && xch->ignore) {
78 ignored += xch->chg2;
79 } else if (lxch != xchp &&
80 xch->i1 + ignored - (lxch->i1 + lxch->chg1) > max_common) {
81 break;
82 } else if (!xch->ignore) {
83 lxch = xch;
84 ignored = 0;
85 } else {
86 ignored += xch->chg2;
87 }
88 }
89
90 return lxch;
91}
92
93
94static long def_ff(const char *rec, long len, char *buf, long sz)
95{
96 if (len > 0 &&
97 (isalpha((unsigned char)*rec) || /* identifier? */
98 *rec == '_' || /* also identifier? */
99 *rec == '$')) { /* identifiers from VMS and other esoterico */
100 if (len > sz)
101 len = sz;
102 while (0 < len && isspace((unsigned char)rec[len - 1]))
103 len--;
104 memcpy(buf, rec, len);
105 return len;
106 }
107 return -1;
108}
109
110static long match_func_rec(xdfile_t *xdf, xdemitconf_t const *xecfg, long ri,
111 char *buf, long sz)
112{
113 xrecord_t *rec = &xdf->recs[ri];
114
115 if (!xecfg->find_func)
116 return def_ff(rec->ptr, rec->size, buf, sz);
117 return xecfg->find_func(rec->ptr, rec->size, buf, sz, xecfg->find_func_priv);
118}
119
120static int is_func_rec(xdfile_t *xdf, xdemitconf_t const *xecfg, long ri)
121{
122 char dummy[1];
123 return match_func_rec(xdf, xecfg, ri, dummy, sizeof(dummy)) >= 0;
124}
125
126struct func_line {
127 long len;
128 char buf[80];
129};
130
131static long get_func_line(xdfenv_t *xe, xdemitconf_t const *xecfg,
132 struct func_line *func_line, long start, long limit)
133{
134 long l, size, step = (start > limit) ? -1 : 1;
135 char *buf, dummy[1];
136
137 buf = func_line ? func_line->buf : dummy;
138 size = func_line ? sizeof(func_line->buf) : sizeof(dummy);
139
140 for (l = start; l != limit && 0 <= l && l < xe->xdf1.nrec; l += step) {
141 long len = match_func_rec(&xe->xdf1, xecfg, l, buf, size);
142 if (len >= 0) {
143 if (func_line)
144 func_line->len = len;
145 return l;
146 }
147 }
148 return -1;
149}
150
151static int is_empty_rec(xdfile_t *xdf, long ri)
152{
153 xrecord_t *rec = &xdf->recs[ri];
154 long i = 0;
155
156 for (; i < rec->size && XDL_ISSPACE(rec->ptr[i]); i++);
157
158 return i == rec->size;
159}
160
161int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
162 xdemitconf_t const *xecfg) {
163 long s1, s2, e1, e2, lctx;
164 xdchange_t *xch, *xche;
165 long funclineprev = -1;
166 struct func_line func_line = { 0 };
167
168 for (xch = xscr; xch; xch = xche->next) {
169 xdchange_t *xchp = xch;
170 xche = xdl_get_hunk(&xch, xecfg);
171 if (!xch)
172 break;
173
174pre_context_calculation:
175 s1 = XDL_MAX(xch->i1 - xecfg->ctxlen, 0);
176 s2 = XDL_MAX(xch->i2 - xecfg->ctxlen, 0);
177
178 if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
179 long fs1, i1 = xch->i1;
180
181 /* Appended chunk? */
182 if (i1 >= xe->xdf1.nrec) {
183 long i2 = xch->i2;
184
185 /*
186 * We don't need additional context if
187 * a whole function was added.
188 */
189 while (i2 < xe->xdf2.nrec) {
190 if (is_func_rec(&xe->xdf2, xecfg, i2))
191 goto post_context_calculation;
192 i2++;
193 }
194
195 /*
196 * Otherwise get more context from the
197 * pre-image.
198 */
199 i1 = xe->xdf1.nrec - 1;
200 }
201
202 fs1 = get_func_line(xe, xecfg, NULL, i1, -1);
203 while (fs1 > 0 && !is_empty_rec(&xe->xdf1, fs1 - 1) &&
204 !is_func_rec(&xe->xdf1, xecfg, fs1 - 1))
205 fs1--;
206 if (fs1 < 0)
207 fs1 = 0;
208 if (fs1 < s1) {
209 s2 = XDL_MAX(s2 - (s1 - fs1), 0);
210 s1 = fs1;
211
212 /*
213 * Did we extend context upwards into an
214 * ignored change?
215 */
216 while (xchp != xch &&
217 xchp->i1 + xchp->chg1 <= s1 &&
218 xchp->i2 + xchp->chg2 <= s2)
219 xchp = xchp->next;
220
221 /* If so, show it after all. */
222 if (xchp != xch) {
223 xch = xchp;
224 goto pre_context_calculation;
225 }
226 }
227 }
228
229 post_context_calculation:
230 lctx = xecfg->ctxlen;
231 lctx = XDL_MIN(lctx, xe->xdf1.nrec - (xche->i1 + xche->chg1));
232 lctx = XDL_MIN(lctx, xe->xdf2.nrec - (xche->i2 + xche->chg2));
233
234 e1 = xche->i1 + xche->chg1 + lctx;
235 e2 = xche->i2 + xche->chg2 + lctx;
236
237 if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
238 long fe1 = get_func_line(xe, xecfg, NULL,
239 xche->i1 + xche->chg1,
240 xe->xdf1.nrec);
241 while (fe1 > 0 && is_empty_rec(&xe->xdf1, fe1 - 1))
242 fe1--;
243 if (fe1 < 0)
244 fe1 = xe->xdf1.nrec;
245 if (fe1 > e1) {
246 e2 = XDL_MIN(e2 + (fe1 - e1), xe->xdf2.nrec);
247 e1 = fe1;
248 }
249
250 /*
251 * Overlap with next change? Then include it
252 * in the current hunk and start over to find
253 * its new end.
254 */
255 if (xche->next) {
256 long l = XDL_MIN(xche->next->i1,
257 xe->xdf1.nrec - 1);
258 if (l - xecfg->ctxlen <= e1 ||
259 get_func_line(xe, xecfg, NULL, l, e1) < 0) {
260 xche = xche->next;
261 goto post_context_calculation;
262 }
263 }
264 }
265
266 /*
267 * Emit current hunk header.
268 */
269
270 if (xecfg->flags & XDL_EMIT_FUNCNAMES) {
271 get_func_line(xe, xecfg, &func_line,
272 s1 - 1, funclineprev);
273 funclineprev = s1 - 1;
274 }
275 if (!(xecfg->flags & XDL_EMIT_NO_HUNK_HDR) &&
276 xdl_emit_hunk_hdr(s1 + 1, e1 - s1, s2 + 1, e2 - s2,
277 func_line.buf, func_line.len, ecb) < 0)
278 return -1;
279
280 /*
281 * Emit pre-context.
282 */
283 for (; s2 < xch->i2; s2++)
284 if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
285 return -1;
286
287 for (s1 = xch->i1, s2 = xch->i2;; xch = xch->next) {
288 /*
289 * Merge previous with current change atom.
290 */
291 for (; s1 < xch->i1 && s2 < xch->i2; s1++, s2++)
292 if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
293 return -1;
294
295 /*
296 * Removes lines from the first file.
297 */
298 for (s1 = xch->i1; s1 < xch->i1 + xch->chg1; s1++)
299 if (xdl_emit_record(&xe->xdf1, s1, "-", ecb) < 0)
300 return -1;
301
302 /*
303 * Adds lines from the second file.
304 */
305 for (s2 = xch->i2; s2 < xch->i2 + xch->chg2; s2++)
306 if (xdl_emit_record(&xe->xdf2, s2, "+", ecb) < 0)
307 return -1;
308
309 if (xch == xche)
310 break;
311 s1 = xch->i1 + xch->chg1;
312 s2 = xch->i2 + xch->chg2;
313 }
314
315 /*
316 * Emit post-context.
317 */
318 for (s2 = xche->i2 + xche->chg2; s2 < e2; s2++)
319 if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
320 return -1;
321 }
322
323 return 0;
324}