sh/input.c

   1 /*-
   2  * Copyright (c) 1991, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Kenneth Almquist.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #ifndef lint
  34 #if 0
  35 static char sccsid[] = "@(#)input.c     8.3 (Berkeley) 6/9/95";
  36 #endif
  37 #endif /* not lint */
  38 #include <sys/cdefs.h>
  39 __FBSDID("$FreeBSD: head/bin/sh/input.c 314436 2017-02-28 23:42:47Z imp $");
  40
  41 #include <stdio.h>      /* defines BUFSIZ */
  42 #include <fcntl.h>
  43 #include <errno.h>
  44 #include <unistd.h>
  45 #include <stdlib.h>
  46 #include <string.h>
  47
  48 /*
  49  * This file implements the input routines used by the parser.
  50  */
  51
  52 #include "shell.h"
  53 #include "redir.h"
  54 #include "syntax.h"
  55 #include "input.h"
  56 #include "output.h"
  57 #include "options.h"
  58 #include "memalloc.h"
  59 #include "error.h"
  60 #include "alias.h"
  61 #include "parser.h"
  62 #include "myhistedit.h"
  63 #include "trap.h"
  64
  65 #define EOF_NLEFT -99           /* value of parsenleft when EOF pushed back */
  66
  67 struct strpush {
  68         struct strpush *prev;   /* preceding string on stack */
  69         const char *prevstring;
  70         int prevnleft;
  71         int prevlleft;
  72         struct alias *ap;       /* if push was associated with an alias */
  73 };
  74
  75 /*
  76  * The parsefile structure pointed to by the global variable parsefile
  77  * contains information about the current file being read.
  78  */
  79
  80 struct parsefile {
  81         struct parsefile *prev; /* preceding file on stack */
  82         int linno;              /* current line */
  83         int fd;                 /* file descriptor (or -1 if string) */
  84         int nleft;              /* number of chars left in this line */
  85         int lleft;              /* number of lines left in this buffer */
  86         const char *nextc;      /* next char in buffer */
  87         char *buf;              /* input buffer */
  88         struct strpush *strpush; /* for pushing strings at this level */
  89         struct strpush basestrpush; /* so pushing one is fast */
  90 };
  91
  92
  93 int plinno = 1;                 /* input line number */
  94 int parsenleft;                 /* copy of parsefile->nleft */
  95 static int parselleft;          /* copy of parsefile->lleft */
  96 const char *parsenextc;         /* copy of parsefile->nextc */
  97 static char basebuf[BUFSIZ + 1];/* buffer for top level input file */
  98 static struct parsefile basepf = {      /* top level input file */
  99         .nextc = basebuf,
 100         .buf = basebuf
 101 };
 102 static struct parsefile *parsefile = &basepf;   /* current input file */
 103 int whichprompt;                /* 1 == PS1, 2 == PS2 */
 104
 105 #ifndef __APPLE__
 106 EditLine *el;                   /* cookie for editline package */
 107 #endif /* !__APPLE__ */
 108
 109 static void pushfile(void);
 110 static int preadfd(void);
 111 static void popstring(void);
 112
 113 #ifdef __APPLE__
 114 // Remove when 28988691 is fixed. Added _ to avoid conflict with future libc definition.
 115 static char *
 116 strchrnul_(const char *p, int ch)
 117 {
 118         char c;
 119
 120         c = ch;
 121         for (;; ++p) {
 122                 if (*p == c || *p == '\0')
 123                         return ((char *)p);
 124         }
 125         /* NOTREACHED */
 126 }
 127 #endif /* __APPLE__ */
 128
 129 void
 130 resetinput(void)
 131 {
 132         popallfiles();
 133         parselleft = parsenleft = 0;    /* clear input buffer */
 134 }
 135
 136
 137
 138 /*
 139  * Read a character from the script, returning PEOF on end of file.
 140  * Nul characters in the input are silently discarded.
 141  */
 142
 143 int
 144 pgetc(void)
 145 {
 146         return pgetc_macro();
 147 }
 148
 149
 150 static int
 151 preadfd(void)
 152 {
 153         int nr;
 154         parsenextc = parsefile->buf;
 155
 156 retry:
 157 #ifndef NO_HISTORY
 158         if (parsefile->fd == 0 && el) {
 159                 static const char *rl_cp;
 160                 static int el_len;
 161
 162                 if (rl_cp == NULL) {
 163                         el_resize(el);
 164                         rl_cp = el_gets(el, &el_len);
 165                 }
 166                 if (rl_cp == NULL)
 167                         nr = el_len == 0 ? 0 : -1;
 168                 else {
 169                         nr = el_len;
 170                         if (nr > BUFSIZ)
 171                                 nr = BUFSIZ;
 172                         memcpy(parsefile->buf, rl_cp, nr);
 173                         if (nr != el_len) {
 174                                 el_len -= nr;
 175                                 rl_cp += nr;
 176                         } else
 177                                 rl_cp = NULL;
 178                 }
 179         } else
 180 #endif
 181                 nr = read(parsefile->fd, parsefile->buf, BUFSIZ);
 182
 183         if (nr <= 0) {
 184                 if (nr < 0) {
 185                         if (errno == EINTR)
 186                                 goto retry;
 187                         if (parsefile->fd == 0 && errno == EWOULDBLOCK) {
 188                                 int flags = fcntl(0, F_GETFL, 0);
 189                                 if (flags >= 0 && flags & O_NONBLOCK) {
 190                                         flags &=~ O_NONBLOCK;
 191                                         if (fcntl(0, F_SETFL, flags) >= 0) {
 192                                                 out2fmt_flush("sh: turning off NDELAY mode\n");
 193                                                 goto retry;
 194                                         }
 195                                 }
 196                         }
 197                 }
 198                 nr = -1;
 199         }
 200         return nr;
 201 }
 202
 203 /*
 204  * Refill the input buffer and return the next input character:
 205  *
 206  * 1) If a string was pushed back on the input, pop it;
 207  * 2) If an EOF was pushed back (parsenleft == EOF_NLEFT) or we are reading
 208  *    from a string so we can't refill the buffer, return EOF.
 209  * 3) If there is more in this buffer, use it else call read to fill it.
 210  * 4) Process input up to the next newline, deleting nul characters.
 211  */
 212
 213 int
 214 preadbuffer(void)
 215 {
 216         char *p, *q, *r, *end;
 217         char savec;
 218
 219         while (parsefile->strpush) {
 220                 /*
 221                  * Add a space to the end of an alias to ensure that the
 222                  * alias remains in use while parsing its last word.
 223                  * This avoids alias recursions.
 224                  */
 225                 if (parsenleft == -1 && parsefile->strpush->ap != NULL)
 226                         return ' ';
 227                 popstring();
 228                 if (--parsenleft >= 0)
 229                         return (*parsenextc++);
 230         }
 231         if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
 232                 return PEOF;
 233
 234 again:
 235         if (parselleft <= 0) {
 236                 if ((parselleft = preadfd()) == -1) {
 237                         parselleft = parsenleft = EOF_NLEFT;
 238                         return PEOF;
 239                 }
 240         }
 241
 242         p = parsefile->buf + (parsenextc - parsefile->buf);
 243         end = p + parselleft;
 244         *end = '\0';
 245         q = strchrnul_(p, '\n');
 246         if (q != end && *q == '\0') {
 247                 /* delete nul characters */
 248                 for (r = q; q != end; q++) {
 249                         if (*q != '\0')
 250                                 *r++ = *q;
 251                 }
 252                 parselleft -= end - r;
 253                 if (parselleft == 0)
 254                         goto again;
 255                 end = p + parselleft;
 256                 *end = '\0';
 257                 q = strchrnul_(p, '\n');
 258         }
 259         if (q == end) {
 260                 parsenleft = parselleft;
 261                 parselleft = 0;
 262         } else /* *q == '\n' */ {
 263                 q++;
 264                 parsenleft = q - parsenextc;
 265                 parselleft -= parsenleft;
 266         }
 267         parsenleft--;
 268
 269         savec = *q;
 270         *q = '\0';
 271
 272 #ifndef NO_HISTORY
 273         if (parsefile->fd == 0 && hist &&
 274             parsenextc[strspn(parsenextc, " \t\n")] != '\0') {
 275                 HistEvent he;
 276                 INTOFF;
 277                 history(hist, &he, whichprompt == 1 ? H_ENTER : H_ADD,
 278                     parsenextc);
 279                 INTON;
 280         }
 281 #endif
 282
 283         if (vflag) {
 284                 out2str(parsenextc);
 285                 flushout(out2);
 286         }
 287
 288         *q = savec;
 289
 290         return *parsenextc++;
 291 }
 292
 293 /*
 294  * Returns if we are certain we are at EOF. Does not cause any more input
 295  * to be read from the outside world.
 296  */
 297
 298 int
 299 preadateof(void)
 300 {
 301         if (parsenleft > 0)
 302                 return 0;
 303         if (parsefile->strpush)
 304                 return 0;
 305         if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
 306                 return 1;
 307         return 0;
 308 }
 309
 310 /*
 311  * Undo the last call to pgetc.  Only one character may be pushed back.
 312  * PEOF may be pushed back.
 313  */
 314
 315 void
 316 pungetc(void)
 317 {
 318         parsenleft++;
 319         parsenextc--;
 320 }
 321
 322 /*
 323  * Push a string back onto the input at this current parsefile level.
 324  * We handle aliases this way.
 325  */
 326 void
 327 pushstring(const char *s, int len, struct alias *ap)
 328 {
 329         struct strpush *sp;
 330
 331         INTOFF;
 332 /*out2fmt_flush("*** calling pushstring: %s, %d\n", s, len);*/
 333         if (parsefile->strpush) {
 334                 sp = ckmalloc(sizeof (struct strpush));
 335                 sp->prev = parsefile->strpush;
 336                 parsefile->strpush = sp;
 337         } else
 338                 sp = parsefile->strpush = &(parsefile->basestrpush);
 339         sp->prevstring = parsenextc;
 340         sp->prevnleft = parsenleft;
 341         sp->prevlleft = parselleft;
 342         sp->ap = ap;
 343         if (ap)
 344                 ap->flag |= ALIASINUSE;
 345         parsenextc = s;
 346         parsenleft = len;
 347         INTON;
 348 }
 349
 350 static void
 351 popstring(void)
 352 {
 353         struct strpush *sp = parsefile->strpush;
 354
 355         INTOFF;
 356         if (sp->ap) {
 357                 if (parsenextc != sp->ap->val &&
 358                     (parsenextc[-1] == ' ' || parsenextc[-1] == '\t'))
 359                         forcealias();
 360                 sp->ap->flag &= ~ALIASINUSE;
 361         }
 362         parsenextc = sp->prevstring;
 363         parsenleft = sp->prevnleft;
 364         parselleft = sp->prevlleft;
 365 /*out2fmt_flush("*** calling popstring: restoring to '%s'\n", parsenextc);*/
 366         parsefile->strpush = sp->prev;
 367         if (sp != &(parsefile->basestrpush))
 368                 ckfree(sp);
 369         INTON;
 370 }
 371
 372 /*
 373  * Set the input to take input from a file.  If push is set, push the
 374  * old input onto the stack first.
 375  */
 376
 377 void
 378 setinputfile(const char *fname, int push)
 379 {
 380         int fd;
 381         int fd2;
 382
 383         INTOFF;
 384         if ((fd = open(fname, O_RDONLY | O_CLOEXEC)) < 0)
 385                 error("cannot open %s: %s", fname, strerror(errno));
 386         if (fd < 10) {
 387                 fd2 = fcntl(fd, F_DUPFD_CLOEXEC, 10);
 388                 close(fd);
 389                 if (fd2 < 0)
 390                         error("Out of file descriptors");
 391                 fd = fd2;
 392         }
 393         setinputfd(fd, push);
 394         INTON;
 395 }
 396
 397
 398 /*
 399  * Like setinputfile, but takes an open file descriptor (which should have
 400  * its FD_CLOEXEC flag already set).  Call this with interrupts off.
 401  */
 402
 403 void
 404 setinputfd(int fd, int push)
 405 {
 406         if (push) {
 407                 pushfile();
 408                 parsefile->buf = ckmalloc(BUFSIZ + 1);
 409         }
 410         if (parsefile->fd > 0)
 411                 close(parsefile->fd);
 412         parsefile->fd = fd;
 413         if (parsefile->buf == NULL)
 414                 parsefile->buf = ckmalloc(BUFSIZ + 1);
 415         parselleft = parsenleft = 0;
 416         plinno = 1;
 417 }
 418
 419
 420 /*
 421  * Like setinputfile, but takes input from a string.
 422  */
 423
 424 void
 425 setinputstring(const char *string, int push)
 426 {
 427         INTOFF;
 428         if (push)
 429                 pushfile();
 430         parsenextc = string;
 431         parselleft = parsenleft = strlen(string);
 432         parsefile->buf = NULL;
 433         plinno = 1;
 434         INTON;
 435 }
 436
 437
 438
 439 /*
 440  * To handle the "." command, a stack of input files is used.  Pushfile
 441  * adds a new entry to the stack and popfile restores the previous level.
 442  */
 443
 444 static void
 445 pushfile(void)
 446 {
 447         struct parsefile *pf;
 448
 449         parsefile->nleft = parsenleft;
 450         parsefile->lleft = parselleft;
 451         parsefile->nextc = parsenextc;
 452         parsefile->linno = plinno;
 453         pf = (struct parsefile *)ckmalloc(sizeof (struct parsefile));
 454         pf->prev = parsefile;
 455         pf->fd = -1;
 456         pf->strpush = NULL;
 457         pf->basestrpush.prev = NULL;
 458         parsefile = pf;
 459 }
 460
 461
 462 void
 463 popfile(void)
 464 {
 465         struct parsefile *pf = parsefile;
 466
 467         INTOFF;
 468         if (pf->fd >= 0)
 469                 close(pf->fd);
 470         if (pf->buf)
 471                 ckfree(pf->buf);
 472         while (pf->strpush)
 473                 popstring();
 474         parsefile = pf->prev;
 475         ckfree(pf);
 476         parsenleft = parsefile->nleft;
 477         parselleft = parsefile->lleft;
 478         parsenextc = parsefile->nextc;
 479         plinno = parsefile->linno;
 480         INTON;
 481 }
 482
 483
 484 /*
 485  * Return current file (to go back to it later using popfilesupto()).
 486  */
 487
 488 struct parsefile *
 489 getcurrentfile(void)
 490 {
 491         return parsefile;
 492 }
 493
 494
 495 /*
 496  * Pop files until the given file is on top again. Useful for regular
 497  * builtins that read shell commands from files or strings.
 498  * If the given file is not an active file, an error is raised.
 499  */
 500
 501 void
 502 popfilesupto(struct parsefile *file)
 503 {
 504         while (parsefile != file && parsefile != &basepf)
 505                 popfile();
 506         if (parsefile != file)
 507                 error("popfilesupto() misused");
 508 }
 509
 510 /*
 511  * Return to top level.
 512  */
 513
 514 void
 515 popallfiles(void)
 516 {
 517         while (parsefile != &basepf)
 518                 popfile();
 519 }
 520
 521
 522
 523 /*
 524  * Close the file(s) that the shell is reading commands from.  Called
 525  * after a fork is done.
 526  */
 527
 528 void
 529 closescript(void)
 530 {
 531         popallfiles();
 532         if (parsefile->fd > 0) {
 533                 close(parsefile->fd);
 534                 parsefile->fd = 0;
 535         }
 536 }