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 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library 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 GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20 /* This package emulates glibc `line_wrap_stream' semantics for systems that
21 don't have that. */
22
23 #ifdef HAVE_CONFIG_H
24 # include <config.h>
25 #endif
26
27 #include <stdlib.h>
28 #include <string.h>
29 #include <errno.h>
30 #include <stdarg.h>
31 #include <ctype.h>
32
33 #include <argp-fmtstream.h>
34 #include "argp-namefrob.h"
35
36 #ifndef ARGP_FMTSTREAM_USE_LINEWRAP
37
38 #ifndef isblank
39 #define isblank(ch) ((ch)==' ' || (ch)=='\t')
40 #endif
41
42 #ifdef _LIBC
43 # include <wchar.h>
44 # include <libio/libioP.h>
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 (*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 (*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 do
249 ++p;
250 while (p < nl && !isblank (*p));
251 if (p == nl)
252 {
253 /* It already ends a line. No fussing required. */
254 fs->point_col = 0;
255 buf = nl + 1;
256 continue;
257 }
258 /* We will move the newline to replace the first blank. */
259 nl = p;
260 /* Swallow separating blanks. */
261 do
262 ++p;
263 while (isblank (*p));
264 /* The next line will start here. */
265 nextline = p;
266 }
267
268 /* Note: There are a bunch of tests below for
269 NEXTLINE == BUF + LEN + 1; this case is where NL happens to fall
270 at the end of the buffer, and NEXTLINE is in fact empty (and so
271 we need not be careful to maintain its contents). */
272
273 if ((nextline == buf + len + 1
274 ? fs->end - nl < fs->wmargin + 1
275 : nextline - (nl + 1) < fs->wmargin)
276 && fs->p > nextline)
277 {
278 /* The margin needs more blanks than we removed. */
279 if (fs->end - fs->p > fs->wmargin + 1)
280 /* Make some space for them. */
281 {
282 size_t mv = fs->p - nextline;
283 memmove (nl + 1 + fs->wmargin, nextline, mv);
284 nextline = nl + 1 + fs->wmargin;
285 len = nextline + mv - buf;
286 *nl++ = '\n';
287 }
288 else
289 /* Output the first line so we can use the space. */
290 {
291 #ifdef _LIBC
292 __fxprintf (fs->stream, "%.*s\n",
293 (int) (nl - fs->buf), fs->buf);
294 #else
295 if (nl > fs->buf)
296 fwrite_unlocked (fs->buf, 1, nl - fs->buf, fs->stream);
297 putc_unlocked ('\n', fs->stream);
298 #endif
299
300 len += buf - fs->buf;
301 nl = buf = fs->buf;
302 }
303 }
304 else
305 /* We can fit the newline and blanks in before
306 the next word. */
307 *nl++ = '\n';
308
309 if (nextline - nl >= fs->wmargin
310 || (nextline == buf + len + 1 && fs->end - nextline >= fs->wmargin))
311 /* Add blanks up to the wrap margin column. */
312 for (i = 0; i < fs->wmargin; ++i)
313 *nl++ = ' ';
314 else
315 for (i = 0; i < fs->wmargin; ++i)
316 #ifdef _LIBC
317 if (_IO_fwide (fs->stream, 0) > 0)
318 putwc_unlocked (L' ', fs->stream);
319 else
320 #endif
321 putc_unlocked (' ', fs->stream);
322
323 /* Copy the tail of the original buffer into the current buffer
324 position. */
325 if (nl < nextline)
326 memmove (nl, nextline, buf + len - nextline);
327 len -= nextline - buf;
328
329 /* Continue the scan on the remaining lines in the buffer. */
330 buf = nl;
331
332 /* Restore bufp to include all the remaining text. */
333 fs->p = nl + len;
334
335 /* Reset the counter of what has been output this line. If wmargin
336 is 0, we want to avoid the lmargin getting added, so we set
337 point_col to a magic value of -1 in that case. */
338 fs->point_col = fs->wmargin ? fs->wmargin : -1;
339 }
340 }
341
342 /* Remember that we've scanned as far as the end of the buffer. */
343 fs->point_offs = fs->p - fs->buf;
344 }
345
346 /* Ensure that FS has space for AMOUNT more bytes in its buffer, either by
347 growing the buffer, or by flushing it. True is returned iff we succeed. */
348 int
349 __argp_fmtstream_ensure (struct argp_fmtstream *fs, size_t amount)
350 {
351 if ((size_t) (fs->end - fs->p) < amount)
352 {
353 ssize_t wrote;
354
355 /* Flush FS's buffer. */
356 __argp_fmtstream_update (fs);
357
358 #ifdef _LIBC
359 __fxprintf (fs->stream, "%.*s", (int) (fs->p - fs->buf), fs->buf);
360 wrote = fs->p - fs->buf;
361 #else
362 wrote = fwrite_unlocked (fs->buf, 1, fs->p - fs->buf, fs->stream);
363 #endif
364 if (wrote == fs->p - fs->buf)
365 {
366 fs->p = fs->buf;
367 fs->point_offs = 0;
368 }
369 else
370 {
371 fs->p -= wrote;
372 fs->point_offs -= wrote;
373 memmove (fs->buf, fs->buf + wrote, fs->p - fs->buf);
374 return 0;
375 }
376
377 if ((size_t) (fs->end - fs->buf) < amount)
378 /* Gotta grow the buffer. */
379 {
380 size_t old_size = fs->end - fs->buf;
381 size_t new_size = old_size + amount;
382 char *new_buf;
383
384 if (new_size < old_size || ! (new_buf = realloc (fs->buf, new_size)))
385 {
386 __set_errno (ENOMEM);
387 return 0;
388 }
389
390 fs->buf = new_buf;
391 fs->end = new_buf + new_size;
392 fs->p = fs->buf;
393 }
394 }
395
396 return 1;
397 }
398
399 ssize_t
400 __argp_fmtstream_printf (struct argp_fmtstream *fs, const char *fmt, ...)
401 {
402 int out;
403 size_t avail;
404 size_t size_guess = PRINTF_SIZE_GUESS; /* How much space to reserve. */
405
406 do
407 {
408 va_list args;
409
410 if (! __argp_fmtstream_ensure (fs, size_guess))
411 return -1;
412
413 va_start (args, fmt);
414 avail = fs->end - fs->p;
415 out = __vsnprintf_internal (fs->p, avail, fmt, args, 0);
416 va_end (args);
417 if ((size_t) out >= avail)
418 size_guess = out + 1;
419 }
420 while ((size_t) out >= avail);
421
422 fs->p += out;
423
424 return out;
425 }
426 #if 0
427 /* Not exported. */
428 #ifdef weak_alias
429 weak_alias (__argp_fmtstream_printf, argp_fmtstream_printf)
430 #endif
431 #endif
432
433 #endif /* !ARGP_FMTSTREAM_USE_LINEWRAP */