1 /* $OpenBSD: trim_sgr0.c,v 1.2 2023/10/17 09:52:09 nicm Exp $ */
2
3 /****************************************************************************
4 * Copyright 2020,2021 Thomas E. Dickey *
5 * Copyright 2005-2012,2017 Free Software Foundation, Inc. *
6 * *
7 * Permission is hereby granted, free of charge, to any person obtaining a *
8 * copy of this software and associated documentation files (the *
9 * "Software"), to deal in the Software without restriction, including *
10 * without limitation the rights to use, copy, modify, merge, publish, *
11 * distribute, distribute with modifications, sublicense, and/or sell *
12 * copies of the Software, and to permit persons to whom the Software is *
13 * furnished to do so, subject to the following conditions: *
14 * *
15 * The above copyright notice and this permission notice shall be included *
16 * in all copies or substantial portions of the Software. *
17 * *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
21 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, *
22 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR *
23 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR *
24 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
25 * *
26 * Except as contained in this notice, the name(s) of the above copyright *
27 * holders shall not be used in advertising or otherwise to promote the *
28 * sale, use or other dealings in this Software without prior written *
29 * authorization. *
30 ****************************************************************************/
31
32 /****************************************************************************
33 * Author: Thomas Dickey *
34 ****************************************************************************/
35
36 #include <curses.priv.h>
37
38 #include <ctype.h>
39
40 #include <tic.h>
41
42 MODULE_ID("$Id: trim_sgr0.c,v 1.2 2023/10/17 09:52:09 nicm Exp $")
43
44 #undef CUR
45 #define CUR tp->
46
47 #define CSI 233
48 #define ESC 033 /* ^[ */
49 #define L_BRACK '['
50
51 static char *
set_attribute_9(TERMTYPE2 * tp,int flag)52 set_attribute_9(TERMTYPE2 *tp, int flag)
53 {
54 const char *value;
55 char *result;
56
57 value = TIPARM_9(set_attributes, 0, 0, 0, 0, 0, 0, 0, 0, flag);
58 if (PRESENT(value))
59 result = strdup(value);
60 else
61 result = 0;
62 return result;
63 }
64
65 static int
is_csi(const char * s)66 is_csi(const char *s)
67 {
68 int result = 0;
69 if (s != 0) {
70 if (UChar(s[0]) == CSI)
71 result = 1;
72 else if (s[0] == ESC && s[1] == L_BRACK)
73 result = 2;
74 }
75 return result;
76 }
77
78 static char *
skip_zero(char * s)79 skip_zero(char *s)
80 {
81 if (s[0] == '0') {
82 if (s[1] == ';')
83 s += 2;
84 else if (isalpha(UChar(s[1])))
85 s += 1;
86 }
87 return s;
88 }
89
90 static const char *
skip_delay(const char * s)91 skip_delay(const char *s)
92 {
93 if (s[0] == '$' && s[1] == '<') {
94 s += 2;
95 while (isdigit(UChar(*s)) || *s == '/')
96 ++s;
97 if (*s == '>')
98 ++s;
99 }
100 return s;
101 }
102
103 /*
104 * Improve similar_sgr a little by moving the attr-string from the beginning
105 * to the end of the s-string.
106 */
107 static bool
rewrite_sgr(char * s,char * attr)108 rewrite_sgr(char *s, char *attr)
109 {
110 if (s != 0) {
111 if (PRESENT(attr)) {
112 size_t len_s = strlen(s);
113 size_t len_a = strlen(attr);
114
115 if (len_s > len_a && !strncmp(attr, s, len_a)) {
116 unsigned n;
117 TR(TRACE_DATABASE, ("rewrite:\n\t%s", s));
118 for (n = 0; n < len_s - len_a; ++n) {
119 s[n] = s[n + len_a];
120 }
121 _nc_STRCPY(s + n, attr, strlen(s) + 1);
122 TR(TRACE_DATABASE, ("to:\n\t%s", s));
123 }
124 }
125 return TRUE;
126 }
127 return FALSE; /* oops */
128 }
129
130 static bool
similar_sgr(char * a,char * b)131 similar_sgr(char *a, char *b)
132 {
133 bool result = FALSE;
134 if (a != 0 && b != 0) {
135 int csi_a = is_csi(a);
136 int csi_b = is_csi(b);
137 size_t len_a;
138 size_t len_b;
139
140 TR(TRACE_DATABASE, ("similar_sgr:\n\t%s\n\t%s",
141 _nc_visbuf2(1, a),
142 _nc_visbuf2(2, b)));
143 if (csi_a != 0 && csi_b != 0 && csi_a == csi_b) {
144 a += csi_a;
145 b += csi_b;
146 if (*a != *b) {
147 a = skip_zero(a);
148 b = skip_zero(b);
149 }
150 }
151 len_a = strlen(a);
152 len_b = strlen(b);
153 if (len_a && len_b) {
154 if (len_a > len_b)
155 result = (strncmp(a, b, len_b) == 0);
156 else
157 result = (strncmp(a, b, len_a) == 0);
158 }
159 TR(TRACE_DATABASE, ("...similar_sgr: %d\n\t%s\n\t%s", result,
160 _nc_visbuf2(1, a),
161 _nc_visbuf2(2, b)));
162 }
163 return result;
164 }
165
166 static unsigned
chop_out(char * string,unsigned i,unsigned j)167 chop_out(char *string, unsigned i, unsigned j)
168 {
169 TR(TRACE_DATABASE, ("chop_out %d..%d from %s", i, j, _nc_visbuf(string)));
170 while (string[j] != '\0') {
171 string[i++] = string[j++];
172 }
173 string[i] = '\0';
174 return i;
175 }
176
177 /*
178 * Compare, ignoring delays. Some of the delay values are inconsistent, and
179 * we do not want to be stopped by that.
180 *
181 * Returns the number of chars from 'full' that we matched. If any mismatch
182 * occurs, return zero.
183 */
184 static unsigned
compare_part(const char * part,const char * full)185 compare_part(const char *part, const char *full)
186 {
187 const char *next_part;
188 const char *next_full;
189 unsigned used_full = 0;
190 unsigned used_delay = 0;
191
192 while (*part != 0) {
193 if (*part != *full) {
194 used_full = 0;
195 break;
196 }
197
198 /*
199 * Adjust the return-value to allow the rare case of
200 * string<delay>string
201 * to remove the whole piece. The most common case is a delay at the
202 * end of the string. The adjusted string will retain the delay, which
203 * is conservative.
204 */
205 if (used_delay != 0) {
206 used_full += used_delay;
207 used_delay = 0;
208 }
209 if (*part == '$' && *full == '$') {
210 next_part = skip_delay(part);
211 next_full = skip_delay(full);
212 if (next_part != part && next_full != full) {
213 used_delay += (unsigned) (next_full - full);
214 full = next_full;
215 part = next_part;
216 continue;
217 }
218 }
219 ++used_full;
220 ++part;
221 ++full;
222 }
223 return used_full;
224 }
225
226 /*
227 * While 'sgr0' is the "same" as termcap 'me', there is a compatibility issue.
228 * The sgr/sgr0 capabilities include setting/clearing alternate character set
229 * mode. A termcap application cannot use sgr, so sgr0 strings that reset
230 * alternate character set mode will be misinterpreted. Here, we remove those
231 * from the more common ISO/ANSI/VT100 entries, which have sgr0 agreeing with
232 * sgr.
233 *
234 * This function returns the modified sgr0 if it can be modified, a null if
235 * an error occurs, or the original sgr0 if no change is needed.
236 */
237 NCURSES_EXPORT(char *)
_nc_trim_sgr0(TERMTYPE2 * tp)238 _nc_trim_sgr0(TERMTYPE2 *tp)
239 {
240 char *result = exit_attribute_mode;
241
242 T((T_CALLED("_nc_trim_sgr0()")));
243
244 if (PRESENT(exit_attribute_mode)
245 && PRESENT(set_attributes)) {
246 bool found = FALSE;
247 char *on = set_attribute_9(tp, 1);
248 char *off = set_attribute_9(tp, 0);
249 char *end = strdup(exit_attribute_mode);
250 char *tmp;
251 size_t i, j, k;
252
253 TR(TRACE_DATABASE, ("checking if we can trim sgr0 based on sgr"));
254 TR(TRACE_DATABASE, ("sgr0 %s", _nc_visbuf(end)));
255 TR(TRACE_DATABASE, ("sgr(9:off) %s", _nc_visbuf(off)));
256 TR(TRACE_DATABASE, ("sgr(9:on) %s", _nc_visbuf(on)));
257
258 if (!rewrite_sgr(on, enter_alt_charset_mode)
259 || !rewrite_sgr(off, exit_alt_charset_mode)
260 || !rewrite_sgr(end, exit_alt_charset_mode)) {
261 FreeIfNeeded(off);
262 } else if (similar_sgr(off, end)
263 && !similar_sgr(off, on)) {
264 TR(TRACE_DATABASE, ("adjusting sgr(9:off) : %s", _nc_visbuf(off)));
265 result = off;
266 /*
267 * If rmacs is a substring of sgr(0), remove that chunk.
268 */
269 if (PRESENT(exit_alt_charset_mode)) {
270 TR(TRACE_DATABASE, ("scan for rmacs %s", _nc_visbuf(exit_alt_charset_mode)));
271 j = strlen(off);
272 k = strlen(exit_alt_charset_mode);
273 if (j > k) {
274 for (i = 0; i <= (j - k); ++i) {
275 unsigned k2 = compare_part(exit_alt_charset_mode,
276 off + i);
277 if (k2 != 0) {
278 found = TRUE;
279 chop_out(off, (unsigned) i, (unsigned) (i + k2));
280 break;
281 }
282 }
283 }
284 }
285 /*
286 * SGR 10 would reset to normal font.
287 */
288 if (!found) {
289 if ((i = (size_t) is_csi(off)) != 0
290 && off[strlen(off) - 1] == 'm') {
291 TR(TRACE_DATABASE, ("looking for SGR 10 in %s",
292 _nc_visbuf(off)));
293 tmp = skip_zero(off + i);
294 if (tmp[0] == '1'
295 && skip_zero(tmp + 1) != tmp + 1) {
296 i = (size_t) (tmp - off);
297 if (off[i - 1] == ';')
298 i--;
299 j = (size_t) (skip_zero(tmp + 1) - off);
300 (void) chop_out(off, (unsigned) i, (unsigned) j);
301 found = TRUE;
302 }
303 }
304 }
305 if (!found
306 && (tmp = strstr(end, off)) != 0
307 && strcmp(end, off) != 0) {
308 i = (size_t) (tmp - end);
309 j = strlen(off);
310 tmp = strdup(end);
311 chop_out(tmp, (unsigned) i, (unsigned) j);
312 free(off);
313 result = tmp;
314 }
315 TR(TRACE_DATABASE, ("...adjusted sgr0 : %s", _nc_visbuf(result)));
316 if (!strcmp(result, exit_attribute_mode)) {
317 TR(TRACE_DATABASE, ("...same result, discard"));
318 free(result);
319 result = exit_attribute_mode;
320 }
321 } else {
322 /*
323 * Either the sgr does not reference alternate character set,
324 * or it is incorrect. That's too hard to decide right now.
325 */
326 free(off);
327 }
328 FreeIfNeeded(end);
329 FreeIfNeeded(on);
330 } else {
331 /*
332 * Possibly some applications are confused if sgr0 contains rmacs,
333 * but that would be a different bug report -TD
334 */
335 }
336
337 returnPtr(result);
338 }
339