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- lib/terminal.c
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*/
1 /*
2 Terminal emulation.
3
4 Copyright (C) 2025
5 Free Software Foundation, Inc.
6
7 This file is part of the Midnight Commander.
8 Authors:
9 Miguel de Icaza, 1994, 1995, 1996
10 Johannes Altmanninger, 2025
11
12 The Midnight Commander is free software: you can redistribute it
13 and/or modify it under the terms of the GNU General Public License as
14 published by the Free Software Foundation, either version 3 of the License,
15 or (at your option) any later version.
16
17 The Midnight Commander is distributed in the hope that it will be useful,
18 but WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 GNU General Public License for more details.
21
22 You should have received a copy of the GNU General Public License
23 along with this program. If not, see <https://www.gnu.org/licenses/>.
24 */
25
26 /** \file terminal.c
27 * \brief Source: terminal emulation.
28 * \author Johannes Altmanninger
29 * \date 2025
30 *
31 * Subshells running inside Midnight Commander may assume they run inside
32 * a terminal. This module helps us act like a real terminal in relevant
33 * aspects.
34 */
35
36 #include <config.h>
37
38 #include "lib/util.h"
39 #include "lib/strutil.h"
40
41 #include "lib/terminal.h"
42
43 /*** global variables ****************************************************************************/
44
45 /*** file scope macro definitions ****************************************************************/
46
47 /*** file scope type declarations ****************************************************************/
48
49 /*** forward declarations (file scope functions) *************************************************/
50
51 /* --------------------------------------------------------------------------------------------- */
52 /*** file scope functions ************************************************************************/
53 /* --------------------------------------------------------------------------------------------- */
54
55 /* --------------------------------------------------------------------------------------------- */
56 /*** public functions ****************************************************************************/
57 /* --------------------------------------------------------------------------------------------- */
58
59 /**
60 * Parse a CSI command, starting from the third byte (i.e. the first
61 * parameter byte, if any).
62 *
63 * On success, *sptr will point to one-past the end of the sequence.
64 * On failure, *sptr will point to the first invalid byte.
65 *
66 * Here's the format in a sort of pidgin BNF:
67 *
68 * CSI-command = Esc '[' parameters (intermediate-byte)* final-byte
69 * parameters = [0-9;:]+
70 * | [<=>?] (parameter-byte)* # private mode
71 * parameter-byte = [\x30-\x3F] # one of "0-9;:<=>?"
72 * intermediate-byte = [\x20–\x2F] # one of " !\"#$%&'()*+,-./"
73 * final-byte = [\x40-\x7e] # one of "@A–Z[\]^_`a–z{|}~"
74 */
75 gboolean
76 parse_csi (struct csi_command_t *out, const char **sptr, const char *end)
/* ![[next]](../icons/right.png)
![[first]](../icons/n_first.png)
*/
77 {
78 gboolean ok = FALSE;
79
80 const char *s = *sptr;
81 if (s == end)
82 goto invalid_sequence;
83
84 char c = *s;
85
86 #define NEXT_CHAR \
87 do \
88 { \
89 if (++s == end) \
90 goto invalid_sequence; \
91 c = *s; \
92 } \
93 while (0)
94
95 char private_mode = '\0';
96
97 if (c >= '<' && c <= '?') // "<=>?"
98 {
99 private_mode = c;
100 NEXT_CHAR;
101 }
102
103 // parameter bytes
104 size_t param_count = 0;
105
106 if (private_mode != '\0')
107 {
108 while (c >= 0x30 && c <= 0x3F)
109 NEXT_CHAR;
110 }
111 else
112 {
113 if (out != NULL)
114 // N.B. empty parameter strings are allowed. For our current use,
115 // treating them as zeroes happens to work.
116 memset (out->params, 0, sizeof (out->params));
117
118 uint32_t tmp = 0;
119 size_t sub_index = 0;
120
121 while (c >= 0x30 && c <= 0x3F)
122 {
123 if (c >= '0' && c <= '9')
124 {
125 if (param_count == 0)
126 param_count = 1;
127 if (tmp * 10 < tmp)
128 goto invalid_sequence; // overflow
129 tmp *= 10;
130 if (tmp + c - '0' < tmp)
131 goto invalid_sequence; // overflow
132 tmp += c - '0';
133 if (out != NULL)
134 out->params[param_count - 1][sub_index] = tmp;
135 }
136 else if (c == ':' && ++sub_index < G_N_ELEMENTS (out->params[0]))
137 tmp = 0;
138 else if (c == ';' && ++param_count <= G_N_ELEMENTS (out->params))
139 tmp = 0, sub_index = 0;
140 else
141 goto invalid_sequence;
142 NEXT_CHAR;
143 }
144 }
145
146 while (c >= 0x20 && c <= 0x2F) // intermediate bytes
147 NEXT_CHAR;
148 #undef NEXT_CHAR
149
150 if (c < 0x40 || c > 0x7E) // final byte
151 goto invalid_sequence;
152
153 ++s;
154 ok = TRUE;
155
156 if (out != NULL)
157 {
158 out->private_mode = private_mode;
159 out->param_count = param_count;
160 }
161
162 invalid_sequence:
163 *sptr = s;
164 return ok;
165 }
166
167 /* --------------------------------------------------------------------------------------------- */
168 /**
169 * Remove all control sequences (CSI, OSC) from the argument string.
170 *
171 * The 256-color and true-color escape sequences should allow either ';' or ':' inside as
172 * separator, actually, ':' is the more correct according to ECMA-48. Some terminal emulators
173 * (e.g. xterm, gnome-terminal) support this.
174 *
175 * Non-printable characters are also removed.
176 */
177
178 char *
179 strip_ctrl_codes (char *s)
/* ![[previous]](../icons/left.png)
*/
180 {
181 char *w; // Current position where the stripped data is written
182 const char *r; // Current position where the original data is read
183
184 if (s == NULL)
185 return NULL;
186
187 const char *end = s + strlen (s);
188
189 for (w = s, r = s; *r != '\0';)
190 {
191 if (*r == ESC_CHAR)
192 {
193 // Skip the control sequence's arguments
194 // '(' need to avoid strange 'B' letter in *Suse (if mc runs under root user)
195 if (*(++r) == '[' || *r == '(')
196 {
197 ++r;
198 parse_csi (NULL, &r, end);
199 // We're already past the sequence, no need to increment.
200 continue;
201 }
202 if (*r == ']')
203 {
204 /*
205 * Skip xterm's OSC (Operating System Command)
206 * https://www.xfree86.org/current/ctlseqs.html
207 * OSC P s ; P t ST
208 * OSC P s ; P t BEL
209 */
210 const char *new_r;
211
212 for (new_r = r; *new_r != '\0'; new_r++)
213 {
214 switch (*new_r)
215 {
216 // BEL
217 case '\a':
218 r = new_r;
219 goto osc_out;
220 case ESC_CHAR:
221 // ST
222 if (new_r[1] == '\\')
223 {
224 r = new_r + 1;
225 goto osc_out;
226 }
227 break;
228 default:
229 break;
230 }
231 }
232 osc_out:;
233 }
234
235 /*
236 * Now we are at the last character of the sequence.
237 * Skip it unless it's binary 0.
238 */
239 if (*r != '\0')
240 r++;
241 }
242 else
243 {
244 const char *n;
245
246 n = str_cget_next_char (r);
247 if (str_isprint (r))
248 {
249 memmove (w, r, n - r);
250 w += n - r;
251 }
252 r = n;
253 }
254 }
255
256 *w = '\0';
257 return s;
258 }
259
260 /* --------------------------------------------------------------------------------------------- */
261 /**
262 * Convert "\E" -> esc character and ^x to control-x key and ^^ to ^ key
263 *
264 * @param p pointer to string
265 *
266 * @return newly allocated string
267 */
268
269 char *
270 convert_controls (const char *p)
/* ![[last]](../icons/n_last.png)
*/
271 {
272 char *valcopy;
273 char *q;
274
275 valcopy = g_strdup (p);
276
277 // Parse the escape special character
278 for (q = valcopy; *p != '\0';)
279 switch (*p)
280 {
281 case '\\':
282 p++;
283
284 if (*p == 'e' || *p == 'E')
285 {
286 p++;
287 *q++ = ESC_CHAR;
288 }
289 break;
290
291 case '^':
292 p++;
293 if (*p == '^')
294 *q++ = *p++;
295 else
296 {
297 char c;
298
299 c = *p | 0x20;
300 if (c >= 'a' && c <= 'z')
301 {
302 *q++ = c - 'a' + 1;
303 p++;
304 }
305 else if (*p != '\0')
306 p++;
307 }
308 break;
309
310 default:
311 *q++ = *p++;
312 }
313
314 *q = '\0';
315 return valcopy;
316 }
317
318 /* --------------------------------------------------------------------------------------------- */
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*/