1 /* Word-wrapping and line-truncating streams
2 Copyright (C) 1997-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Written by Miles Bader <miles@gnu.ai.mit.edu>.
5
6 This file is free software: you can redistribute it and/or modify
7 it under the terms of the GNU Lesser General Public License as
8 published by the Free Software Foundation, either version 3 of the
9 License, or (at your option) any later version.
10
11 This file is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public License
17 along with this program. If not, see <https://www.gnu.org/licenses/>. */
18
19 /* This package emulates glibc 'line_wrap_stream' semantics for systems that
20 don't have that. */
21
22 #ifdef HAVE_CONFIG_H
23 # include <config.h>
24 #endif
25
26 #include <stdlib.h>
27 #include <string.h>
28 #include <errno.h>
29 #include <stdarg.h>
30 #include <ctype.h>
31
32 #include "argp-fmtstream.h"
33 #include "argp-namefrob.h"
34
35 #ifndef ARGP_FMTSTREAM_USE_LINEWRAP
36
37 #ifndef isblank
38 #define isblank(ch) ((ch)==' ' || (ch)=='\t')
39 #endif
40
41 #ifdef _LIBC
42 # include <wchar.h>
43 # include <libio/libioP.h>
44 # define __vsnprintf(s, l, f, a) _IO_vsnprintf (s, l, f, a)
45 #endif
46
47 #define INIT_BUF_SIZE 200
48 #define PRINTF_SIZE_GUESS 150
49
50 /* Return an argp_fmtstream that outputs to STREAM, and which prefixes lines
51 written on it with LMARGIN spaces and limits them to RMARGIN columns
52 total. If WMARGIN >= 0, words that extend past RMARGIN are wrapped by
53 replacing the whitespace before them with a newline and WMARGIN spaces.
54 Otherwise, chars beyond RMARGIN are simply dropped until a newline.
55 Returns NULL if there was an error. */
56 argp_fmtstream_t
57 __argp_make_fmtstream (FILE *stream,
58 size_t lmargin, size_t rmargin, ssize_t wmargin)
59 {
60 argp_fmtstream_t fs;
61
62 fs = (struct argp_fmtstream *) malloc (sizeof (struct argp_fmtstream));
63 if (fs != NULL)
64 {
65 fs->stream = stream;
66
67 fs->lmargin = lmargin;
68 fs->rmargin = rmargin;
69 fs->wmargin = wmargin;
70 fs->point_col = 0;
71 fs->point_offs = 0;
72
73 fs->buf = (char *) malloc (INIT_BUF_SIZE);
74 if (! fs->buf)
75 {
76 free (fs);
77 fs = 0;
78 }
79 else
80 {
81 fs->p = fs->buf;
82 fs->end = fs->buf + INIT_BUF_SIZE;
83 }
84 }
85
86 return fs;
87 }
88 #if 0
89 /* Not exported. */
90 #ifdef weak_alias
91 weak_alias (__argp_make_fmtstream, argp_make_fmtstream)
92 #endif
93 #endif
94
95 /* Flush FS to its stream, and free it (but don't close the stream). */
96 void
97 __argp_fmtstream_free (argp_fmtstream_t fs)
98 {
99 __argp_fmtstream_update (fs);
100 if (fs->p > fs->buf)
101 {
102 #ifdef _LIBC
103 __fxprintf (fs->stream, "%.*s", (int) (fs->p - fs->buf), fs->buf);
104 #else
105 fwrite_unlocked (fs->buf, 1, fs->p - fs->buf, fs->stream);
106 #endif
107 }
108 free (fs->buf);
109 free (fs);
110 }
111 #if 0
112 /* Not exported. */
113 #ifdef weak_alias
114 weak_alias (__argp_fmtstream_free, argp_fmtstream_free)
115 #endif
116 #endif
117
118 /* Process FS's buffer so that line wrapping is done from POINT_OFFS to the
119 end of its buffer. This code is mostly from glibc stdio/linewrap.c. */
120 void
121 __argp_fmtstream_update (argp_fmtstream_t fs)
122 {
123 char *buf, *nl;
124 size_t len;
125
126 /* Scan the buffer for newlines. */
127 buf = fs->buf + fs->point_offs;
128 while (buf < fs->p)
129 {
130 size_t r;
131
132 if (fs->point_col == 0 && fs->lmargin != 0)
133 {
134 /* We are starting a new line. Print spaces to the left margin. */
135 const size_t pad = fs->lmargin;
136 if (fs->p + pad < fs->end)
137 {
138 /* We can fit in them in the buffer by moving the
139 buffer text up and filling in the beginning. */
140 memmove (buf + pad, buf, fs->p - buf);
141 fs->p += pad; /* Compensate for bigger buffer. */
142 memset (buf, ' ', pad); /* Fill in the spaces. */
143 buf += pad; /* Don't bother searching them. */
144 }
145 else
146 {
147 /* No buffer space for spaces. Must flush. */
148 size_t i;
149 for (i = 0; i < pad; i++)
150 {
151 #ifdef _LIBC
152 if (_IO_fwide (fs->stream, 0) > 0)
153 putwc_unlocked (L' ', fs->stream);
154 else
155 #endif
156 putc_unlocked (' ', fs->stream);
157 }
158 }
159 fs->point_col = pad;
160 }
161
162 len = fs->p - buf;
163 nl = memchr (buf, '\n', len);
164
165 if (fs->point_col < 0)
166 fs->point_col = 0;
167
168 if (!nl)
169 {
170 /* The buffer ends in a partial line. */
171
172 if (fs->point_col + len < fs->rmargin)
173 {
174 /* The remaining buffer text is a partial line and fits
175 within the maximum line width. Advance point for the
176 characters to be written and stop scanning. */
177 fs->point_col += len;
178 break;
179 }
180 else
181 /* Set the end-of-line pointer for the code below to
182 the end of the buffer. */
183 nl = fs->p;
184 }
185 else if (fs->point_col + (nl - buf) < (ssize_t) fs->rmargin)
186 {
187 /* The buffer contains a full line that fits within the maximum
188 line width. Reset point and scan the next line. */
189 fs->point_col = 0;
190 buf = nl + 1;
191 continue;
192 }
193
194 /* This line is too long. */
195 r = fs->rmargin - 1;
196
197 if (fs->wmargin < 0)
198 {
199 /* Truncate the line by overwriting the excess with the
200 newline and anything after it in the buffer. */
201 if (nl < fs->p)
202 {
203 memmove (buf + (r - fs->point_col), nl, fs->p - nl);
204 fs->p -= buf + (r - fs->point_col) - nl;
205 /* Reset point for the next line and start scanning it. */
206 fs->point_col = 0;
207 buf += r + 1; /* Skip full line plus \n. */
208 }
209 else
210 {
211 /* The buffer ends with a partial line that is beyond the
212 maximum line width. Advance point for the characters
213 written, and discard those past the max from the buffer. */
214 fs->point_col += len;
215 fs->p -= fs->point_col - r;
216 break;
217 }
218 }
219 else
220 {
221 /* Do word wrap. Go to the column just past the maximum line
222 width and scan back for the beginning of the word there.
223 Then insert a line break. */
224
225 char *p, *nextline;
226 int i;
227
228 p = buf + (r + 1 - fs->point_col);
229 while (p >= buf && !isblank ((unsigned char) *p))
230 --p;
231 nextline = p + 1; /* This will begin the next line. */
232
233 if (nextline > buf)
234 {
235 /* Swallow separating blanks. */
236 if (p >= buf)
237 do
238 --p;
239 while (p >= buf && isblank ((unsigned char) *p));
240 nl = p + 1; /* The newline will replace the first blank. */
241 }
242 else
243 {
244 /* A single word that is greater than the maximum line width.
245 Oh well. Put it on an overlong line by itself. */
246 p = buf + (r + 1 - fs->point_col);
247 /* Find the end of the long word. */
248 if (p < nl)
249 do
250 ++p;
251 while (p < nl && !isblank ((unsigned char) *p));
252 if (p == nl)
253 {
254 /* It already ends a line. No fussing required. */
255 fs->point_col = 0;
256 buf = nl + 1;
257 continue;
258 }
259 /* We will move the newline to replace the first blank. */
260 nl = p;
261 /* Swallow separating blanks. */
262 do
263 ++p;
264 while (isblank ((unsigned char) *p));
265 /* The next line will start here. */
266 nextline = p;
267 }
268
269 /* Note: There are a bunch of tests below for
270 NEXTLINE == BUF + LEN + 1; this case is where NL happens to fall
271 at the end of the buffer, and NEXTLINE is in fact empty (and so
272 we need not be careful to maintain its contents). */
273
274 if ((nextline == buf + len + 1
275 ? fs->end - nl < fs->wmargin + 1
276 : nextline - (nl + 1) < fs->wmargin)
277 && fs->p > nextline)
278 {
279 /* The margin needs more blanks than we removed. */
280 if (fs->end - fs->p > fs->wmargin + 1)
281 /* Make some space for them. */
282 {
283 size_t mv = fs->p - nextline;
284 memmove (nl + 1 + fs->wmargin, nextline, mv);
285 nextline = nl + 1 + fs->wmargin;
286 len = nextline + mv - buf;
287 *nl++ = '\n';
288 }
289 else
290 /* Output the first line so we can use the space. */
291 {
292 #ifdef _LIBC
293 __fxprintf (fs->stream, "%.*s\n",
294 (int) (nl - fs->buf), fs->buf);
295 #else
296 if (nl > fs->buf)
297 fwrite_unlocked (fs->buf, 1, nl - fs->buf, fs->stream);
298 putc_unlocked ('\n', fs->stream);
299 #endif
300
301 len += buf - fs->buf;
302 nl = buf = fs->buf;
303 }
304 }
305 else
306 /* We can fit the newline and blanks in before
307 the next word. */
308 *nl++ = '\n';
309
310 if (nextline - nl >= fs->wmargin
311 || (nextline == buf + len + 1 && fs->end - nextline >= fs->wmargin))
312 /* Add blanks up to the wrap margin column. */
313 for (i = 0; i < fs->wmargin; ++i)
314 *nl++ = ' ';
315 else
316 for (i = 0; i < fs->wmargin; ++i)
317 #ifdef _LIBC
318 if (_IO_fwide (fs->stream, 0) > 0)
319 putwc_unlocked (L' ', fs->stream);
320 else
321 #endif
322 putc_unlocked (' ', fs->stream);
323
324 /* Copy the tail of the original buffer into the current buffer
325 position. */
326 if (nl < nextline)
327 memmove (nl, nextline, buf + len - nextline);
328 len -= nextline - buf;
329
330 /* Continue the scan on the remaining lines in the buffer. */
331 buf = nl;
332
333 /* Restore bufp to include all the remaining text. */
334 fs->p = nl + len;
335
336 /* Reset the counter of what has been output this line. If wmargin
337 is 0, we want to avoid the lmargin getting added, so we set
338 point_col to a magic value of -1 in that case. */
339 fs->point_col = fs->wmargin ? fs->wmargin : -1;
340 }
341 }
342
343 /* Remember that we've scanned as far as the end of the buffer. */
344 fs->point_offs = fs->p - fs->buf;
345 }
346
347 /* Ensure that FS has space for AMOUNT more bytes in its buffer, either by
348 growing the buffer, or by flushing it. True is returned iff we succeed. */
349 int
350 __argp_fmtstream_ensure (struct argp_fmtstream *fs, size_t amount)
351 {
352 if ((size_t) (fs->end - fs->p) < amount)
353 {
354 ssize_t wrote;
355
356 /* Flush FS's buffer. */
357 __argp_fmtstream_update (fs);
358
359 #ifdef _LIBC
360 __fxprintf (fs->stream, "%.*s", (int) (fs->p - fs->buf), fs->buf);
361 wrote = fs->p - fs->buf;
362 #else
363 wrote = fwrite_unlocked (fs->buf, 1, fs->p - fs->buf, fs->stream);
364 #endif
365 if (wrote == fs->p - fs->buf)
366 {
367 fs->p = fs->buf;
368 fs->point_offs = 0;
369 }
370 else
371 {
372 fs->p -= wrote;
373 fs->point_offs -= wrote;
374 memmove (fs->buf, fs->buf + wrote, fs->p - fs->buf);
375 return 0;
376 }
377
378 if ((size_t) (fs->end - fs->buf) < amount)
379 /* Gotta grow the buffer. */
380 {
381 size_t old_size = fs->end - fs->buf;
382 size_t new_size = old_size + amount;
383 char *new_buf;
384
385 if (new_size < old_size || ! (new_buf = realloc (fs->buf, new_size)))
386 {
387 __set_errno (ENOMEM);
388 return 0;
389 }
390
391 fs->buf = new_buf;
392 fs->end = new_buf + new_size;
393 fs->p = fs->buf;
394 }
395 }
396
397 return 1;
398 }
399
400 ssize_t
401 __argp_fmtstream_printf (struct argp_fmtstream *fs, const char *fmt, ...)
402 {
403 int out;
404 size_t avail;
405 size_t size_guess = PRINTF_SIZE_GUESS; /* How much space to reserve. */
406
407 do
408 {
409 va_list args;
410
411 if (! __argp_fmtstream_ensure (fs, size_guess))
412 return -1;
413
414 va_start (args, fmt);
415 avail = fs->end - fs->p;
416 out = __vsnprintf (fs->p, avail, fmt, args);
417 va_end (args);
418 if ((size_t) out >= avail)
419 size_guess = out + 1;
420 }
421 while ((size_t) out >= avail);
422
423 fs->p += out;
424
425 return out;
426 }
427 #if 0
428 /* Not exported. */
429 #ifdef weak_alias
430 weak_alias (__argp_fmtstream_printf, argp_fmtstream_printf)
431 #endif
432 #endif
433
434 #endif /* !ARGP_FMTSTREAM_USE_LINEWRAP */