1/* Word-wrapping and line-truncating streams
2 Copyright (C) 1997-2017 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 <http://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# define __vsnprintf(s, l, f, a) _IO_vsnprintf (s, l, f, a)
46#endif
47
48#define INIT_BUF_SIZE 200
49#define PRINTF_SIZE_GUESS 150
50
51/* Return an argp_fmtstream that outputs to STREAM, and which prefixes lines
52 written on it with LMARGIN spaces and limits them to RMARGIN columns
53 total. If WMARGIN >= 0, words that extend past RMARGIN are wrapped by
54 replacing the whitespace before them with a newline and WMARGIN spaces.
55 Otherwise, chars beyond RMARGIN are simply dropped until a newline.
56 Returns NULL if there was an error. */
57argp_fmtstream_t
58__argp_make_fmtstream (FILE *stream,
59 size_t lmargin, size_t rmargin, ssize_t wmargin)
60{
61 argp_fmtstream_t fs;
62
63 fs = (struct argp_fmtstream *) malloc (sizeof (struct argp_fmtstream));
64 if (fs != NULL)
65 {
66 fs->stream = stream;
67
68 fs->lmargin = lmargin;
69 fs->rmargin = rmargin;
70 fs->wmargin = wmargin;
71 fs->point_col = 0;
72 fs->point_offs = 0;
73
74 fs->buf = (char *) malloc (INIT_BUF_SIZE);
75 if (! fs->buf)
76 {
77 free (fs);
78 fs = 0;
79 }
80 else
81 {
82 fs->p = fs->buf;
83 fs->end = fs->buf + INIT_BUF_SIZE;
84 }
85 }
86
87 return fs;
88}
89#if 0
90/* Not exported. */
91#ifdef weak_alias
92weak_alias (__argp_make_fmtstream, argp_make_fmtstream)
93#endif
94#endif
95
96/* Flush FS to its stream, and free it (but don't close the stream). */
97void
98__argp_fmtstream_free (argp_fmtstream_t fs)
99{
100 __argp_fmtstream_update (fs);
101 if (fs->p > fs->buf)
102 {
103#ifdef _LIBC
104 __fxprintf (fs->stream, "%.*s", (int) (fs->p - fs->buf), fs->buf);
105#else
106 fwrite_unlocked (fs->buf, 1, fs->p - fs->buf, fs->stream);
107#endif
108 }
109 free (fs->buf);
110 free (fs);
111}
112#if 0
113/* Not exported. */
114#ifdef weak_alias
115weak_alias (__argp_fmtstream_free, argp_fmtstream_free)
116#endif
117#endif
118
119/* Process FS's buffer so that line wrapping is done from POINT_OFFS to the
120 end of its buffer. This code is mostly from glibc stdio/linewrap.c. */
121void
122__argp_fmtstream_update (argp_fmtstream_t fs)
123{
124 char *buf, *nl;
125 size_t len;
126
127 /* Scan the buffer for newlines. */
128 buf = fs->buf + fs->point_offs;
129 while (buf < fs->p)
130 {
131 size_t r;
132
133 if (fs->point_col == 0 && fs->lmargin != 0)
134 {
135 /* We are starting a new line. Print spaces to the left margin. */
136 const size_t pad = fs->lmargin;
137 if (fs->p + pad < fs->end)
138 {
139 /* We can fit in them in the buffer by moving the
140 buffer text up and filling in the beginning. */
141 memmove (buf + pad, buf, fs->p - buf);
142 fs->p += pad; /* Compensate for bigger buffer. */
143 memset (buf, ' ', pad); /* Fill in the spaces. */
144 buf += pad; /* Don't bother searching them. */
145 }
146 else
147 {
148 /* No buffer space for spaces. Must flush. */
149 size_t i;
150 for (i = 0; i < pad; i++)
151 {
152 if (_IO_fwide (fs->stream, 0) > 0)
153 putwc_unlocked (L' ', fs->stream);
154 else
155 putc_unlocked (' ', fs->stream);
156 }
157 }
158 fs->point_col = pad;
159 }
160
161 len = fs->p - buf;
162 nl = memchr (buf, '\n', len);
163
164 if (fs->point_col < 0)
165 fs->point_col = 0;
166
167 if (!nl)
168 {
169 /* The buffer ends in a partial line. */
170
171 if (fs->point_col + len < fs->rmargin)
172 {
173 /* The remaining buffer text is a partial line and fits
174 within the maximum line width. Advance point for the
175 characters to be written and stop scanning. */
176 fs->point_col += len;
177 break;
178 }
179 else
180 /* Set the end-of-line pointer for the code below to
181 the end of the buffer. */
182 nl = fs->p;
183 }
184 else if (fs->point_col + (nl - buf) < (ssize_t) fs->rmargin)
185 {
186 /* The buffer contains a full line that fits within the maximum
187 line width. Reset point and scan the next line. */
188 fs->point_col = 0;
189 buf = nl + 1;
190 continue;
191 }
192
193 /* This line is too long. */
194 r = fs->rmargin - 1;
195
196 if (fs->wmargin < 0)
197 {
198 /* Truncate the line by overwriting the excess with the
199 newline and anything after it in the buffer. */
200 if (nl < fs->p)
201 {
202 memmove (buf + (r - fs->point_col), nl, fs->p - nl);
203 fs->p -= buf + (r - fs->point_col) - nl;
204 /* Reset point for the next line and start scanning it. */
205 fs->point_col = 0;
206 buf += r + 1; /* Skip full line plus \n. */
207 }
208 else
209 {
210 /* The buffer ends with a partial line that is beyond the
211 maximum line width. Advance point for the characters
212 written, and discard those past the max from the buffer. */
213 fs->point_col += len;
214 fs->p -= fs->point_col - r;
215 break;
216 }
217 }
218 else
219 {
220 /* Do word wrap. Go to the column just past the maximum line
221 width and scan back for the beginning of the word there.
222 Then insert a line break. */
223
224 char *p, *nextline;
225 int i;
226
227 p = buf + (r + 1 - fs->point_col);
228 while (p >= buf && !isblank (*p))
229 --p;
230 nextline = p + 1; /* This will begin the next line. */
231
232 if (nextline > buf)
233 {
234 /* Swallow separating blanks. */
235 if (p >= buf)
236 do
237 --p;
238 while (p >= buf && isblank (*p));
239 nl = p + 1; /* The newline will replace the first blank. */
240 }
241 else
242 {
243 /* A single word that is greater than the maximum line width.
244 Oh well. Put it on an overlong line by itself. */
245 p = buf + (r + 1 - fs->point_col);
246 /* Find the end of the long word. */
247 do
248 ++p;
249 while (p < nl && !isblank (*p));
250 if (p == nl)
251 {
252 /* It already ends a line. No fussing required. */
253 fs->point_col = 0;
254 buf = nl + 1;
255 continue;
256 }
257 /* We will move the newline to replace the first blank. */
258 nl = p;
259 /* Swallow separating blanks. */
260 do
261 ++p;
262 while (isblank (*p));
263 /* The next line will start here. */
264 nextline = p;
265 }
266
267 /* Note: There are a bunch of tests below for
268 NEXTLINE == BUF + LEN + 1; this case is where NL happens to fall
269 at the end of the buffer, and NEXTLINE is in fact empty (and so
270 we need not be careful to maintain its contents). */
271
272 if ((nextline == buf + len + 1
273 ? fs->end - nl < fs->wmargin + 1
274 : nextline - (nl + 1) < fs->wmargin)
275 && fs->p > nextline)
276 {
277 /* The margin needs more blanks than we removed. */
278 if (fs->end - fs->p > fs->wmargin + 1)
279 /* Make some space for them. */
280 {
281 size_t mv = fs->p - nextline;
282 memmove (nl + 1 + fs->wmargin, nextline, mv);
283 nextline = nl + 1 + fs->wmargin;
284 len = nextline + mv - buf;
285 *nl++ = '\n';
286 }
287 else
288 /* Output the first line so we can use the space. */
289 {
290#ifdef _LIBC
291 __fxprintf (fs->stream, "%.*s\n",
292 (int) (nl - fs->buf), fs->buf);
293#else
294 if (nl > fs->buf)
295 fwrite_unlocked (fs->buf, 1, nl - fs->buf, fs->stream);
296 putc_unlocked ('\n', fs->stream);
297#endif
298
299 len += buf - fs->buf;
300 nl = buf = fs->buf;
301 }
302 }
303 else
304 /* We can fit the newline and blanks in before
305 the next word. */
306 *nl++ = '\n';
307
308 if (nextline - nl >= fs->wmargin
309 || (nextline == buf + len + 1 && fs->end - nextline >= fs->wmargin))
310 /* Add blanks up to the wrap margin column. */
311 for (i = 0; i < fs->wmargin; ++i)
312 *nl++ = ' ';
313 else
314 for (i = 0; i < fs->wmargin; ++i)
315 if (_IO_fwide (fs->stream, 0) > 0)
316 putwc_unlocked (L' ', fs->stream);
317 else
318 putc_unlocked (' ', fs->stream);
319
320 /* Copy the tail of the original buffer into the current buffer
321 position. */
322 if (nl < nextline)
323 memmove (nl, nextline, buf + len - nextline);
324 len -= nextline - buf;
325
326 /* Continue the scan on the remaining lines in the buffer. */
327 buf = nl;
328
329 /* Restore bufp to include all the remaining text. */
330 fs->p = nl + len;
331
332 /* Reset the counter of what has been output this line. If wmargin
333 is 0, we want to avoid the lmargin getting added, so we set
334 point_col to a magic value of -1 in that case. */
335 fs->point_col = fs->wmargin ? fs->wmargin : -1;
336 }
337 }
338
339 /* Remember that we've scanned as far as the end of the buffer. */
340 fs->point_offs = fs->p - fs->buf;
341}
342
343/* Ensure that FS has space for AMOUNT more bytes in its buffer, either by
344 growing the buffer, or by flushing it. True is returned iff we succeed. */
345int
346__argp_fmtstream_ensure (struct argp_fmtstream *fs, size_t amount)
347{
348 if ((size_t) (fs->end - fs->p) < amount)
349 {
350 ssize_t wrote;
351
352 /* Flush FS's buffer. */
353 __argp_fmtstream_update (fs);
354
355#ifdef _LIBC
356 __fxprintf (fs->stream, "%.*s", (int) (fs->p - fs->buf), fs->buf);
357 wrote = fs->p - fs->buf;
358#else
359 wrote = fwrite_unlocked (fs->buf, 1, fs->p - fs->buf, fs->stream);
360#endif
361 if (wrote == fs->p - fs->buf)
362 {
363 fs->p = fs->buf;
364 fs->point_offs = 0;
365 }
366 else
367 {
368 fs->p -= wrote;
369 fs->point_offs -= wrote;
370 memmove (fs->buf, fs->buf + wrote, fs->p - fs->buf);
371 return 0;
372 }
373
374 if ((size_t) (fs->end - fs->buf) < amount)
375 /* Gotta grow the buffer. */
376 {
377 size_t old_size = fs->end - fs->buf;
378 size_t new_size = old_size + amount;
379 char *new_buf;
380
381 if (new_size < old_size || ! (new_buf = realloc (fs->buf, new_size)))
382 {
383 __set_errno (ENOMEM);
384 return 0;
385 }
386
387 fs->buf = new_buf;
388 fs->end = new_buf + new_size;
389 fs->p = fs->buf;
390 }
391 }
392
393 return 1;
394}
395
396ssize_t
397__argp_fmtstream_printf (struct argp_fmtstream *fs, const char *fmt, ...)
398{
399 int out;
400 size_t avail;
401 size_t size_guess = PRINTF_SIZE_GUESS; /* How much space to reserve. */
402
403 do
404 {
405 va_list args;
406
407 if (! __argp_fmtstream_ensure (fs, size_guess))
408 return -1;
409
410 va_start (args, fmt);
411 avail = fs->end - fs->p;
412 out = __vsnprintf (fs->p, avail, fmt, args);
413 va_end (args);
414 if ((size_t) out >= avail)
415 size_guess = out + 1;
416 }
417 while ((size_t) out >= avail);
418
419 fs->p += out;
420
421 return out;
422}
423#if 0
424/* Not exported. */
425#ifdef weak_alias
426weak_alias (__argp_fmtstream_printf, argp_fmtstream_printf)
427#endif
428#endif
429
430#endif /* !ARGP_FMTSTREAM_USE_LINEWRAP */
431