filter.c

   1 /*@ S-nail - a mail user agent derived from Berkeley Mail.
   2  *@ Filter objects.
   3  *
   4  * Copyright (c) 2013 - 2014 Steffen (Daode) Nurpmeso <sdaoden@users.sf.net>.
   5  *
   6  * Permission to use, copy, modify, and/or distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #ifndef HAVE_AMALGAMATION
  20 # include "nail.h"
  21 #endif
  22
  23 /*
  24  * Quotation filter
  25  */
  26
  27 /*
  28  * TODO quotation filter: anticipate in future data: don't break if only WS
  29  * TODO or a LF escaping \ follows on the line (simply reuse the latter).
  30  */
  31
  32 #ifdef HAVE_QUOTE_FOLD
  33 CTA(QUOTE_MAX > 3);
  34
  35 enum qf_state {
  36    _QF_CLEAN,
  37    _QF_PREFIX,
  38    _QF_DATA
  39 };
  40
  41 struct qf_vc {
  42    struct quoteflt   *self;
  43    char const        *buf;
  44    size_t            len;
  45 };
  46
  47 /* Print out prefix and current quote */
  48 static ssize_t _qf_dump_prefix(struct quoteflt *self);
  49
  50 /* Add one data character */
  51 static ssize_t _qf_add_data(struct quoteflt *self, wchar_t wc);
  52
  53 /* State machine handlers */
  54 static ssize_t _qf_state_prefix(struct qf_vc *vc);
  55 static ssize_t _qf_state_data(struct qf_vc *vc);
  56
  57 static ssize_t
  58 _qf_dump_prefix(struct quoteflt *self)
  59 {
  60    ssize_t rv;
  61    size_t i;
  62    NYD_ENTER;
  63
  64    if ((i = self->qf_pfix_len) > 0 && i != fwrite(self->qf_pfix, 1, i,
  65          self->qf_os))
  66       goto jerr;
  67    rv = i;
  68
  69    if ((i = self->qf_currq.l) > 0 && i != fwrite(self->qf_currq.s, 1, i,
  70          self->qf_os))
  71       goto jerr;
  72    rv += i;
  73 jleave:
  74    NYD_LEAVE;
  75    return rv;
  76 jerr:
  77    rv = -1;
  78    goto jleave;
  79 }
  80
  81 static ssize_t
  82 _qf_add_data(struct quoteflt *self, wchar_t wc)
  83 {
  84    char *save_b;
  85    ui32_t save_l, save_w;
  86    ssize_t rv = 0;
  87    int w, l;
  88    NYD_ENTER;
  89
  90    save_l = save_w = 0; /* silence cc */
  91    save_b = NULL;
  92    /* <newline> ends state */
  93    if (wc == L'\n')
  94       goto jflush;
  95    if (wc == L'\r') /* TODO CR should be stripped in lower level!! */
  96       goto jleave;
  97
  98    /* Unroll <tab> to spaces */
  99    if (wc == L'\t') {
 100       save_l = self->qf_datw;
 101       save_w = (save_l + QUOTE_TAB_SPACES) & ~(QUOTE_TAB_SPACES - 1);
 102       save_w -= save_l;
 103       while (save_w-- > 0) {
 104          ssize_t j = _qf_add_data(self, L' ');
 105          if (j < 0) {
 106             rv = j;
 107             break;
 108          }
 109          rv += j;
 110       }
 111       goto jleave;
 112    }
 113
 114    w = wcwidth(wc);
 115    if (w == -1) {
 116 jbad:
 117       ++self->qf_datw;
 118       self->qf_dat.s[self->qf_dat.l++] = '?';
 119    } else {
 120       l = wctomb(self->qf_dat.s + self->qf_dat.l, wc);
 121       if (l < 0)
 122          goto jbad;
 123       self->qf_datw += (ui32_t)w;
 124       self->qf_dat.l += (size_t)l;
 125    }
 126
 127    /* TODO The last visual may excess (adjusted!) *qfold-max* if it's a wide;
 128     * TODO place it on the next line, break before */
 129    if (self->qf_datw >= self->qf_qfold_max) {
 130       /* If we have seen a nice breakpoint during traversal, shuffle data
 131        * around a bit so as to restore the trailing part after flushing */
 132       if (self->qf_brkl > 0) {
 133          save_w = self->qf_datw - self->qf_brkw;
 134          save_l = self->qf_dat.l - self->qf_brkl;
 135          save_b = self->qf_dat.s + self->qf_brkl + 2;
 136          memmove(save_b, save_b - 2, save_l);
 137          self->qf_dat.l = self->qf_brkl;
 138       }
 139
 140       self->qf_dat.s[self->qf_dat.l++] = '\\';
 141 jflush:
 142       self->qf_dat.s[self->qf_dat.l++] = '\n';
 143       rv = quoteflt_flush(self);
 144
 145       /* Restore takeovers, if any */
 146       if (save_b != NULL) {
 147          self->qf_brk_isws = FAL0;
 148          self->qf_datw += save_w;
 149          self->qf_dat.l = save_l;
 150          memmove(self->qf_dat.s, save_b, save_l);
 151       }
 152    } else if (self->qf_datw >= self->qf_qfold_min && !self->qf_brk_isws) {
 153       bool_t isws = iswspace(wc);
 154
 155       if ((isws && !self->qf_brk_isws) || self->qf_brkl == 0) {
 156          self->qf_brkl = self->qf_dat.l;
 157          self->qf_brkw = self->qf_datw;
 158          self->qf_brk_isws = isws;
 159       }
 160    }
 161
 162    /* If state changed to prefix, perform full reset (note this implies that
 163     * quoteflt_flush() performs too much work..) */
 164    if (wc == '\n') {
 165       self->qf_state = _QF_PREFIX;
 166       self->qf_wscnt = self->qf_datw = 0;
 167       self->qf_currq.l = 0;
 168    }
 169 jleave:
 170    NYD_LEAVE;
 171    return rv;
 172 }
 173
 174 static ssize_t
 175 _qf_state_prefix(struct qf_vc *vc)
 176 {
 177    struct quoteflt *self;
 178    ssize_t rv;
 179    char const *buf;
 180    size_t len, i;
 181    wchar_t wc;
 182    NYD_ENTER;
 183
 184    self = vc->self;
 185    rv = 0;
 186
 187    for (buf = vc->buf, len = vc->len; len > 0;) {
 188       /* xxx NULL BYTE! */
 189       i = mbrtowc(&wc, buf, len, self->qf_mbps);
 190       if (i == (size_t)-1) {
 191          /* On hard error, don't modify mbstate_t and step one byte */
 192          self->qf_mbps[0] = self->qf_mbps[1];
 193          ++buf;
 194          --len;
 195          self->qf_wscnt = 0;
 196          continue;
 197       }
 198       self->qf_mbps[1] = self->qf_mbps[0];
 199       if (i == (size_t)-2) {
 200          /* Redundant shift sequence, out of buffer */
 201          len = 0;
 202          break;
 203       }
 204       buf += i;
 205       len -= i;
 206
 207       if (wc == L'\n')
 208          goto jfin;
 209       if (iswspace(wc)) {
 210          ++self->qf_wscnt;
 211          continue;
 212       }
 213       if (i == 1 && ISQUOTE(wc)) {
 214          self->qf_wscnt = 0;
 215          if (self->qf_currq.l >= QUOTE_MAX - 3) {
 216             self->qf_currq.s[QUOTE_MAX - 3] = '.';
 217             self->qf_currq.s[QUOTE_MAX - 2] = '.';
 218             self->qf_currq.s[QUOTE_MAX - 1] = '.';
 219             self->qf_currq.l = QUOTE_MAX;
 220          } else
 221             self->qf_currq.s[self->qf_currq.l++] = buf[-1];
 222          continue;
 223       }
 224
 225       /* The quote is parsed and compressed; dump it */
 226 jfin:
 227       self->qf_datw = self->qf_pfix_len + self->qf_currq.l;
 228       self->qf_state = _QF_DATA;
 229       /* Overtake WS (xxx but we de-facto "normalize" to ASCII SP here) */
 230       while (self->qf_wscnt-- > 0 && self->qf_currq.l < QUOTE_MAX)
 231          self->qf_currq.s[self->qf_currq.l++] = ' ';
 232       self->qf_wscnt = 0;
 233       rv = _qf_add_data(self, wc);
 234       break;
 235    }
 236
 237    vc->buf = buf;
 238    vc->len = len;
 239    NYD_LEAVE;
 240    return rv;
 241 }
 242
 243 static ssize_t
 244 _qf_state_data(struct qf_vc *vc)
 245 {
 246    struct quoteflt *self;
 247    ssize_t rv;
 248    char const *buf;
 249    size_t len, i;
 250    wchar_t wc;
 251    NYD_ENTER;
 252
 253    self = vc->self;
 254    rv = 0;
 255
 256    for (buf = vc->buf, len = vc->len; len > 0;) {
 257       /* xxx NULL BYTE! */
 258       i = mbrtowc(&wc, buf, len, self->qf_mbps);
 259       if (i == (size_t)-1) {
 260          /* On hard error, don't modify mbstate_t and step one byte */
 261          self->qf_mbps[0] = self->qf_mbps[1];
 262          ++buf;
 263          --len;
 264          continue;
 265       }
 266       self->qf_mbps[1] = self->qf_mbps[0];
 267       if (i == (size_t)-2) {
 268          /* Redundant shift sequence, out of buffer */
 269          len = 0;
 270          break;
 271       }
 272       buf += i;
 273       len -= i;
 274
 275       {  ssize_t j = _qf_add_data(self, wc);
 276          if (j < 0) {
 277             rv = j;
 278             break;
 279          }
 280          rv += j;
 281       }
 282
 283       if (self->qf_state != _QF_DATA)
 284          break;
 285    }
 286
 287    vc->buf = buf;
 288    vc->len = len;
 289    NYD_LEAVE;
 290    return rv;
 291 }
 292 #endif /* HAVE_QUOTE_FOLD */
 293
 294 FL struct quoteflt *
 295 quoteflt_dummy(void) /* TODO LEGACY (until filters are plugged when needed) */
 296 {
 297    static struct quoteflt qf_i;
 298
 299    return &qf_i;
 300 }
 301
 302 FL void
 303 quoteflt_init(struct quoteflt *self, char const *prefix)
 304 {
 305 #ifdef HAVE_QUOTE_FOLD
 306    char *xcp, *cp;
 307 #endif
 308    NYD_ENTER;
 309
 310    memset(self, 0, sizeof *self);
 311
 312    if ((self->qf_pfix = prefix) != NULL)
 313       self->qf_pfix_len = (ui32_t)strlen(prefix);
 314
 315    /* Check wether the user wants the more fancy quoting algorithm */
 316    /* TODO *quote-fold*: QUOTE_MAX may excess it! */
 317 #ifdef HAVE_QUOTE_FOLD
 318    if (self->qf_pfix_len > 0 && (cp = ok_vlook(quote_fold)) != NULL) {
 319       ui32_t qmin, qmax = (ui32_t)strtol(cp, &xcp, 10);
 320       /* These magic values ensure we don't bail :) */
 321       if (qmax < self->qf_pfix_len + 6)
 322          qmax = self->qf_pfix_len + 6;
 323       --qmax; /* The newline escape */
 324       if (cp == xcp || *xcp == '\0')
 325          qmin = (qmax >> 1) + (qmax >> 2) + (qmax >> 5);
 326       else {
 327          qmin = (ui32_t)strtol(xcp + 1, NULL, 10);
 328          if (qmin < qmax >> 1)
 329             qmin = qmax >> 1;
 330          else if (qmin > qmax - 2)
 331             qmin = qmax - 2;
 332       }
 333       self->qf_qfold_min = qmin;
 334       self->qf_qfold_max = qmax;
 335
 336       /* Add pad for takeover copies, backslash and newline */
 337       self->qf_dat.s = salloc((qmax + 3) * mb_cur_max);
 338       self->qf_currq.s = salloc((QUOTE_MAX + 1) * mb_cur_max);
 339    }
 340 #endif
 341    NYD_LEAVE;
 342 }
 343
 344 FL void
 345 quoteflt_destroy(struct quoteflt *self) /* xxx inline */
 346 {
 347    NYD_ENTER;
 348    UNUSED(self);
 349    NYD_LEAVE;
 350 }
 351
 352 FL void
 353 quoteflt_reset(struct quoteflt *self, FILE *f) /* xxx inline */
 354 {
 355    NYD_ENTER;
 356    self->qf_os = f;
 357 #ifdef HAVE_QUOTE_FOLD
 358    self->qf_state = _QF_CLEAN;
 359    self->qf_dat.l =
 360    self->qf_currq.l = 0;
 361    memset(self->qf_mbps, 0, sizeof self->qf_mbps);
 362 #endif
 363    NYD_LEAVE;
 364 }
 365
 366 FL ssize_t
 367 quoteflt_push(struct quoteflt *self, char const *dat, size_t len)
 368 {
 369    /* (xxx Ideally the actual push() [and flush()] would be functions on their
 370     * xxx own, via indirect vtbl call ..) */
 371    ssize_t rv = 0;
 372    NYD_ENTER;
 373
 374    if (len == 0)
 375       goto jleave;
 376
 377    /* Bypass? XXX Finally, this filter simply should not be used, then */
 378    if (self->qf_pfix_len == 0) {
 379       if (len != fwrite(dat, 1, len, self->qf_os))
 380          goto jerr;
 381       rv = len;
 382    }
 383    /* Normal: place *indentprefix* at every BOL */
 384    else
 385 #ifdef HAVE_QUOTE_FOLD
 386       if (self->qf_qfold_max == 0)
 387 #endif
 388    {
 389       void *vp;
 390       size_t ll;
 391       bool_t pxok = (self->qf_qfold_min != 0);
 392
 393       for (;;) {
 394          if (!pxok) {
 395             ll = self->qf_pfix_len;
 396             if (ll != fwrite(self->qf_pfix, 1, ll, self->qf_os))
 397                goto jerr;
 398             rv += ll;
 399             pxok = TRU1;
 400          }
 401
 402          /* xxx Strictly speaking this is invalid, because only `/' and `.' are
 403           * xxx mandated by POSIX.1-2008 as "invariant across all locales
 404           * xxx supported"; though there is no charset known which uses this
 405           * xxx control char as part of a multibyte character; note that S-nail
 406           * XXX (and the Mail codebase as such) do not support EBCDIC */
 407          if ((vp = memchr(dat, '\n', len)) == NULL)
 408             ll = len;
 409          else {
 410             pxok = FAL0;
 411             ll = PTR2SIZE((char*)vp - dat) + 1;
 412          }
 413
 414          if (ll != fwrite(dat, sizeof *dat, ll, self->qf_os))
 415             goto jerr;
 416          rv += ll;
 417          if ((len -= ll) == 0)
 418             break;
 419          dat += ll;
 420       }
 421
 422       self->qf_qfold_min = pxok;
 423    }
 424    /* Overly complicated, though still only line-per-line: *quote-fold*.
 425     * - If .qf_currq.l is 0, then we are in a clean state.  Reset .qf_mbps;
 426     *   TODO note this means we assume that lines start with reset escape seq,
 427     *   TODO but i don't think this is any worse than what we currently do;
 428     *   TODO in 15.0, with the value carrier, we should carry conversion states
 429     *   TODO all along, only resetting on error (or at words for header =???=);
 430     *   TODO this still is weird for error handling, but we need to act more
 431     *   TODO stream-alike (though in practice i don't think cross-line states
 432     *   TODO can be found, because of compatibility reasons; however, being
 433     *   TODO a problem rather than a solution is not a good thing (tm))
 434     * - Lookout for a newline */
 435 #ifdef HAVE_QUOTE_FOLD
 436    else {
 437       struct qf_vc vc;
 438       ssize_t i;
 439
 440       vc.self = self;
 441       vc.buf = dat;
 442       vc.len = len;
 443       while (vc.len > 0) {
 444          switch (self->qf_state) {
 445          case _QF_CLEAN:
 446          case _QF_PREFIX:
 447             i = _qf_state_prefix(&vc);
 448             break;
 449          default: /* silence cc (`i' unused) */
 450          case _QF_DATA:
 451             i = _qf_state_data(&vc);
 452             break;
 453          }
 454          if (i < 0)
 455             goto jerr;
 456          rv += i;
 457       }
 458    }
 459 #endif /* HAVE_QUOTE_FOLD */
 460
 461 jleave:
 462    NYD_LEAVE;
 463    return rv;
 464 jerr:
 465    rv = -1;
 466    goto jleave;
 467 }
 468
 469 FL ssize_t
 470 quoteflt_flush(struct quoteflt *self)
 471 {
 472    ssize_t rv = 0;
 473    NYD_ENTER;
 474    UNUSED(self);
 475
 476 #ifdef HAVE_QUOTE_FOLD
 477    if (self->qf_dat.l > 0) {
 478       rv = _qf_dump_prefix(self);
 479       if (rv >= 0) {
 480          size_t i = self->qf_dat.l;
 481          if (i == fwrite(self->qf_dat.s, 1, i, self->qf_os))
 482             rv += i;
 483          else
 484             rv = -1;
 485          self->qf_dat.l = 0;
 486          self->qf_brk_isws = FAL0;
 487          self->qf_wscnt = self->qf_brkl = self->qf_brkw = 0;
 488          self->qf_datw = self->qf_pfix_len + self->qf_currq.l;
 489       }
 490    }
 491 #endif
 492    NYD_LEAVE;
 493    return rv;
 494 }
 495
 496 /* vim:set fenc=utf-8:s-it-mode */