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