lib/argp-fmtstream.c

   1 /* Word-wrapping and line-truncating streams
   2    Copyright (C) 1997-2019 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 program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program 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 General Public License for more details.
  15
  16    You should have received a copy of the GNU 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 \f
  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 \f
 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 \f
 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 \f
 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 */