bin/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("$FreeBSD$");
  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 #ifndef NO_HISTORY
  63 #include "myhistedit.h"
  64 #endif
  65 #include "trap.h"
  66
  67 #define EOF_NLEFT -99           /* value of parsenleft when EOF pushed back */
  68
  69 struct strpush {
  70         struct strpush *prev;   /* preceding string on stack */
  71         const char *prevstring;
  72         int prevnleft;
  73         int prevlleft;
  74         struct alias *ap;       /* if push was associated with an alias */
  75 };
  76
  77 /*
  78  * The parsefile structure pointed to by the global variable parsefile
  79  * contains information about the current file being read.
  80  */
  81
  82 struct parsefile {
  83         struct parsefile *prev; /* preceding file on stack */
  84         int linno;              /* current line */
  85         int fd;                 /* file descriptor (or -1 if string) */
  86         int nleft;              /* number of chars left in this line */
  87         int lleft;              /* number of lines left in this buffer */
  88         const char *nextc;      /* next char in buffer */
  89         char *buf;              /* input buffer */
  90         struct strpush *strpush; /* for pushing strings at this level */
  91         struct strpush basestrpush; /* so pushing one is fast */
  92 };
  93
  94
  95 int plinno = 1;                 /* input line number */
  96 int parsenleft;                 /* copy of parsefile->nleft */
  97 static int parselleft;          /* copy of parsefile->lleft */
  98 const char *parsenextc;         /* copy of parsefile->nextc */
  99 static char basebuf[BUFSIZ + 1];/* buffer for top level input file */
 100 static struct parsefile basepf = {      /* top level input file */
 101         .nextc = basebuf,
 102         .buf = basebuf
 103 };
 104 static struct parsefile *parsefile = &basepf;   /* current input file */
 105 int whichprompt;                /* 1 == PS1, 2 == PS2 */
 106
 107 #ifndef NO_HISTORY
 108 EditLine *el;                   /* cookie for editline package */
 109 #endif
 110
 111 static void pushfile(void);
 112 static int preadfd(void);
 113 static void popstring(void);
 114
 115 void
 116 resetinput(void)
 117 {
 118         popallfiles();
 119         parselleft = parsenleft = 0;    /* clear input buffer */
 120 }
 121
 122
 123
 124 /*
 125  * Read a character from the script, returning PEOF on end of file.
 126  * Nul characters in the input are silently discarded.
 127  */
 128
 129 int
 130 pgetc(void)
 131 {
 132         return pgetc_macro();
 133 }
 134
 135
 136 static int
 137 preadfd(void)
 138 {
 139         int nr;
 140         parsenextc = parsefile->buf;
 141
 142 retry:
 143 #ifndef NO_HISTORY
 144         if (parsefile->fd == 0 && el) {
 145                 static const char *rl_cp;
 146                 static int el_len;
 147
 148                 if (rl_cp == NULL) {
 149                         el_resize(el);
 150                         rl_cp = el_gets(el, &el_len);
 151                 }
 152                 if (rl_cp == NULL)
 153                         nr = el_len == 0 ? 0 : -1;
 154                 else {
 155                         nr = el_len;
 156                         if (nr > BUFSIZ)
 157                                 nr = BUFSIZ;
 158                         memcpy(parsefile->buf, rl_cp, nr);
 159                         if (nr != el_len) {
 160                                 el_len -= nr;
 161                                 rl_cp += nr;
 162                         } else
 163                                 rl_cp = NULL;
 164                 }
 165         } else
 166 #endif
 167                 nr = read(parsefile->fd, parsefile->buf, BUFSIZ);
 168
 169         if (nr <= 0) {
 170                 if (nr < 0) {
 171                         if (errno == EINTR)
 172                                 goto retry;
 173                         if (parsefile->fd == 0 && errno == EWOULDBLOCK) {
 174                                 int flags = fcntl(0, F_GETFL, 0);
 175                                 if (flags >= 0 && flags & O_NONBLOCK) {
 176                                         flags &=~ O_NONBLOCK;
 177                                         if (fcntl(0, F_SETFL, flags) >= 0) {
 178                                                 out2fmt_flush("sh: turning off NDELAY mode\n");
 179                                                 goto retry;
 180                                         }
 181                                 }
 182                         }
 183                 }
 184                 nr = -1;
 185         }
 186         return nr;
 187 }
 188
 189 /*
 190  * Refill the input buffer and return the next input character:
 191  *
 192  * 1) If a string was pushed back on the input, pop it;
 193  * 2) If an EOF was pushed back (parsenleft == EOF_NLEFT) or we are reading
 194  *    from a string so we can't refill the buffer, return EOF.
 195  * 3) If there is more in this buffer, use it else call read to fill it.
 196  * 4) Process input up to the next newline, deleting nul characters.
 197  */
 198
 199 int
 200 preadbuffer(void)
 201 {
 202         char *p, *q;
 203         int more;
 204         char savec;
 205
 206         while (parsefile->strpush) {
 207                 /*
 208                  * Add a space to the end of an alias to ensure that the
 209                  * alias remains in use while parsing its last word.
 210                  * This avoids alias recursions.
 211                  */
 212                 if (parsenleft == -1 && parsefile->strpush->ap != NULL)
 213                         return ' ';
 214                 popstring();
 215                 if (--parsenleft >= 0)
 216                         return (*parsenextc++);
 217         }
 218         if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
 219                 return PEOF;
 220         flushout(&output);
 221         flushout(&errout);
 222
 223 again:
 224         if (parselleft <= 0) {
 225                 if ((parselleft = preadfd()) == -1) {
 226                         parselleft = parsenleft = EOF_NLEFT;
 227                         return PEOF;
 228                 }
 229         }
 230
 231         q = p = parsefile->buf + (parsenextc - parsefile->buf);
 232
 233         /* delete nul characters */
 234         for (more = 1; more;) {
 235                 switch (*p) {
 236                 case '\0':
 237                         p++;    /* Skip nul */
 238                         goto check;
 239
 240                 case '\n':
 241                         parsenleft = q - parsenextc;
 242                         more = 0; /* Stop processing here */
 243                         break;
 244
 245                 default:
 246                         break;
 247                 }
 248
 249                 *q++ = *p++;
 250 check:
 251                 if (--parselleft <= 0) {
 252                         parsenleft = q - parsenextc - 1;
 253                         if (parsenleft < 0)
 254                                 goto again;
 255                         *q = '\0';
 256                         more = 0;
 257                 }
 258         }
 259
 260         savec = *q;
 261         *q = '\0';
 262
 263 #ifndef NO_HISTORY
 264         if (parsefile->fd == 0 && hist &&
 265             parsenextc[strspn(parsenextc, " \t\n")] != '\0') {
 266                 HistEvent he;
 267                 INTOFF;
 268                 history(hist, &he, whichprompt == 1 ? H_ENTER : H_ADD,
 269                     parsenextc);
 270                 INTON;
 271         }
 272 #endif
 273
 274         if (vflag) {
 275                 out2str(parsenextc);
 276                 flushout(out2);
 277         }
 278
 279         *q = savec;
 280
 281         return *parsenextc++;
 282 }
 283
 284 /*
 285  * Returns if we are certain we are at EOF. Does not cause any more input
 286  * to be read from the outside world.
 287  */
 288
 289 int
 290 preadateof(void)
 291 {
 292         if (parsenleft > 0)
 293                 return 0;
 294         if (parsefile->strpush)
 295                 return 0;
 296         if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
 297                 return 1;
 298         return 0;
 299 }
 300
 301 /*
 302  * Undo the last call to pgetc.  Only one character may be pushed back.
 303  * PEOF may be pushed back.
 304  */
 305
 306 void
 307 pungetc(void)
 308 {
 309         parsenleft++;
 310         parsenextc--;
 311 }
 312
 313 /*
 314  * Push a string back onto the input at this current parsefile level.
 315  * We handle aliases this way.
 316  */
 317 void
 318 pushstring(const char *s, int len, struct alias *ap)
 319 {
 320         struct strpush *sp;
 321
 322         INTOFF;
 323 /*out2fmt_flush("*** calling pushstring: %s, %d\n", s, len);*/
 324         if (parsefile->strpush) {
 325                 sp = ckmalloc(sizeof (struct strpush));
 326                 sp->prev = parsefile->strpush;
 327                 parsefile->strpush = sp;
 328         } else
 329                 sp = parsefile->strpush = &(parsefile->basestrpush);
 330         sp->prevstring = parsenextc;
 331         sp->prevnleft = parsenleft;
 332         sp->prevlleft = parselleft;
 333         sp->ap = ap;
 334         if (ap)
 335                 ap->flag |= ALIASINUSE;
 336         parsenextc = s;
 337         parsenleft = len;
 338         INTON;
 339 }
 340
 341 static void
 342 popstring(void)
 343 {
 344         struct strpush *sp = parsefile->strpush;
 345
 346         INTOFF;
 347         if (sp->ap) {
 348                 if (parsenextc != sp->ap->val &&
 349                     (parsenextc[-1] == ' ' || parsenextc[-1] == '\t'))
 350                         forcealias();
 351                 sp->ap->flag &= ~ALIASINUSE;
 352         }
 353         parsenextc = sp->prevstring;
 354         parsenleft = sp->prevnleft;
 355         parselleft = sp->prevlleft;
 356 /*out2fmt_flush("*** calling popstring: restoring to '%s'\n", parsenextc);*/
 357         parsefile->strpush = sp->prev;
 358         if (sp != &(parsefile->basestrpush))
 359                 ckfree(sp);
 360         INTON;
 361 }
 362
 363 /*
 364  * Set the input to take input from a file.  If push is set, push the
 365  * old input onto the stack first.
 366  */
 367
 368 void
 369 setinputfile(const char *fname, int push)
 370 {
 371         int fd;
 372         int fd2;
 373
 374         INTOFF;
 375         if ((fd = open(fname, O_RDONLY | O_CLOEXEC_MAYBE)) < 0)
 376                 error("cannot open %s: %s", fname, strerror(errno));
 377         if (fd < 10) {
 378                 fd2 = fcntl(fd, F_DUPFD_CLOEXEC_MAYBE, 10);
 379                 close(fd);
 380                 if (fd2 < 0)
 381                         error("Out of file descriptors");
 382                 fd = fd2;
 383         }
 384         setinputfd(fd, push);
 385         INTON;
 386 }
 387
 388
 389 /*
 390  * Like setinputfile, but takes an open file descriptor (which should have
 391  * its FD_CLOEXEC flag already set).  Call this with interrupts off.
 392  */
 393
 394 void
 395 setinputfd(int fd, int push)
 396 {
 397 #if !defined(O_CLOEXEC) || !defined(F_DUPFD_CLOEXEC)
 398         fcntl(fd, F_SETFD, FD_CLOEXEC);
 399 #endif
 400         if (push) {
 401                 pushfile();
 402                 parsefile->buf = ckmalloc(BUFSIZ + 1);
 403         }
 404         if (parsefile->fd > 0)
 405                 close(parsefile->fd);
 406         parsefile->fd = fd;
 407         if (parsefile->buf == NULL)
 408                 parsefile->buf = ckmalloc(BUFSIZ + 1);
 409         parselleft = parsenleft = 0;
 410         plinno = 1;
 411 }
 412
 413
 414 /*
 415  * Like setinputfile, but takes input from a string.
 416  */
 417
 418 void
 419 setinputstring(const char *string, int push)
 420 {
 421         INTOFF;
 422         if (push)
 423                 pushfile();
 424         parsenextc = string;
 425         parselleft = parsenleft = strlen(string);
 426         parsefile->buf = NULL;
 427         plinno = 1;
 428         INTON;
 429 }
 430
 431
 432
 433 /*
 434  * To handle the "." command, a stack of input files is used.  Pushfile
 435  * adds a new entry to the stack and popfile restores the previous level.
 436  */
 437
 438 static void
 439 pushfile(void)
 440 {
 441         struct parsefile *pf;
 442
 443         parsefile->nleft = parsenleft;
 444         parsefile->lleft = parselleft;
 445         parsefile->nextc = parsenextc;
 446         parsefile->linno = plinno;
 447         pf = (struct parsefile *)ckmalloc(sizeof (struct parsefile));
 448         pf->prev = parsefile;
 449         pf->fd = -1;
 450         pf->strpush = NULL;
 451         pf->basestrpush.prev = NULL;
 452         parsefile = pf;
 453 }
 454
 455
 456 void
 457 popfile(void)
 458 {
 459         struct parsefile *pf = parsefile;
 460
 461         INTOFF;
 462         if (pf->fd >= 0)
 463                 close(pf->fd);
 464         if (pf->buf)
 465                 ckfree(pf->buf);
 466         while (pf->strpush)
 467                 popstring();
 468         parsefile = pf->prev;
 469         ckfree(pf);
 470         parsenleft = parsefile->nleft;
 471         parselleft = parsefile->lleft;
 472         parsenextc = parsefile->nextc;
 473         plinno = parsefile->linno;
 474         INTON;
 475 }
 476
 477
 478 /*
 479  * Return current file (to go back to it later using popfilesupto()).
 480  */
 481
 482 struct parsefile *
 483 getcurrentfile(void)
 484 {
 485         return parsefile;
 486 }
 487
 488
 489 /*
 490  * Pop files until the given file is on top again. Useful for regular
 491  * builtins that read shell commands from files or strings.
 492  * If the given file is not an active file, an error is raised.
 493  */
 494
 495 void
 496 popfilesupto(struct parsefile *file)
 497 {
 498         while (parsefile != file && parsefile != &basepf)
 499                 popfile();
 500         if (parsefile != file)
 501                 error("popfilesupto() misused");
 502 }
 503
 504 /*
 505  * Return to top level.
 506  */
 507
 508 void
 509 popallfiles(void)
 510 {
 511         while (parsefile != &basepf)
 512                 popfile();
 513 }
 514
 515
 516
 517 /*
 518  * Close the file(s) that the shell is reading commands from.  Called
 519  * after a fork is done.
 520  */
 521
 522 void
 523 closescript(void)
 524 {
 525         popallfiles();
 526         if (parsefile->fd > 0) {
 527                 close(parsefile->fd);
 528                 parsefile->fd = 0;
 529         }
 530 }