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