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redir.c revision 1.50 
      1 /*	$NetBSD: redir.c,v 1.50 2017/02/02 20:00:40 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1991, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Kenneth Almquist.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 #include <sys/cdefs.h>
     36 #ifndef lint
     37 #if 0
     38 static char sccsid[] = "@(#)redir.c	8.2 (Berkeley) 5/4/95";
     39 #else
     40 __RCSID("$NetBSD: redir.c,v 1.50 2017/02/02 20:00:40 christos Exp $");
     41 #endif
     42 #endif /* not lint */
     43 
     44 #include <sys/types.h>
     45 #include <sys/param.h>	/* PIPE_BUF */
     46 #include <sys/stat.h>
     47 #include <signal.h>
     48 #include <string.h>
     49 #include <fcntl.h>
     50 #include <errno.h>
     51 #include <unistd.h>
     52 #include <stdlib.h>
     53 
     54 /*
     55  * Code for dealing with input/output redirection.
     56  */
     57 
     58 #include "main.h"
     59 #include "builtins.h"
     60 #include "shell.h"
     61 #include "nodes.h"
     62 #include "jobs.h"
     63 #include "options.h"
     64 #include "expand.h"
     65 #include "redir.h"
     66 #include "output.h"
     67 #include "memalloc.h"
     68 #include "error.h"
     69 
     70 
     71 #define EMPTY -2		/* marks an unused slot in redirtab */
     72 #define CLOSED -1		/* fd was not open before redir */
     73 #ifndef PIPE_BUF
     74 # define PIPESIZE 4096		/* amount of buffering in a pipe */
     75 #else
     76 # define PIPESIZE PIPE_BUF
     77 #endif
     78 
     79 
     80 MKINIT
     81 struct renamelist {
     82 	struct renamelist *next;
     83 	int orig;
     84 	int into;
     85 };
     86 
     87 MKINIT
     88 struct redirtab {
     89 	struct redirtab *next;
     90 	struct renamelist *renamed;
     91 };
     92 
     93 
     94 MKINIT struct redirtab *redirlist;
     95 
     96 /*
     97  * We keep track of whether or not fd0 has been redirected.  This is for
     98  * background commands, where we want to redirect fd0 to /dev/null only
     99  * if it hasn't already been redirected.
    100  */
    101 STATIC int fd0_redirected = 0;
    102 
    103 /*
    104  * And also where to put internal use fds that should be out of the
    105  * way of user defined fds (normally)
    106  */
    107 STATIC int big_sh_fd = 0;
    108 
    109 STATIC const struct renamelist *is_renamed(const struct renamelist *, int);
    110 STATIC void fd_rename(struct redirtab *, int, int);
    111 STATIC void free_rl(struct redirtab *, int);
    112 STATIC void openredirect(union node *, char[10], int);
    113 STATIC int openhere(const union node *);
    114 STATIC int copyfd(int, int, int);
    115 STATIC void find_big_fd(void);
    116 
    117 STATIC const struct renamelist *
    118 is_renamed(const struct renamelist *rl, int fd)
    119 {
    120 	while (rl != NULL) {
    121 		if (rl->orig == fd)
    122 			return rl;
    123 		rl = rl->next;
    124 	}
    125 	return NULL;
    126 }
    127 
    128 STATIC void
    129 free_rl(struct redirtab *rt, int reset)
    130 {
    131 	struct renamelist *rl, *rn = rt->renamed;
    132 
    133 	while ((rl = rn) != NULL) {
    134 		rn = rl->next;
    135 		if (rl->orig == 0)
    136 			fd0_redirected--;
    137 		if (reset) {
    138 			if (rl->into < 0)
    139 				close(rl->orig);
    140 			else
    141 				movefd(rl->into, rl->orig);
    142 		}
    143 		ckfree(rl);
    144 	}
    145 	rt->renamed = NULL;
    146 }
    147 
    148 STATIC void
    149 fd_rename(struct redirtab *rt, int from, int to)
    150 {
    151 	struct renamelist *rl = ckmalloc(sizeof(struct renamelist));
    152 
    153 	rl->next = rt->renamed;
    154 	rt->renamed = rl;
    155 
    156 	rl->orig = from;
    157 	rl->into = to;
    158 }
    159 
    160 /*
    161  * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
    162  * old file descriptors are stashed away so that the redirection can be
    163  * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
    164  * standard output, and the standard error if it becomes a duplicate of
    165  * stdout, is saved in memory.
    166  */
    167 
    168 void
    169 redirect(union node *redir, int flags)
    170 {
    171 	union node *n;
    172 	struct redirtab *sv = NULL;
    173 	int i;
    174 	int fd;
    175 	char memory[10];	/* file descriptors to write to memory */
    176 
    177 	for (i = 10 ; --i >= 0 ; )
    178 		memory[i] = 0;
    179 	memory[1] = flags & REDIR_BACKQ;
    180 	if (flags & REDIR_PUSH) {
    181 		/* We don't have to worry about REDIR_VFORK here, as
    182 		 * flags & REDIR_PUSH is never true if REDIR_VFORK is set.
    183 		 */
    184 		sv = ckmalloc(sizeof (struct redirtab));
    185 		sv->renamed = NULL;
    186 		sv->next = redirlist;
    187 		redirlist = sv;
    188 	}
    189 	for (n = redir ; n ; n = n->nfile.next) {
    190 		fd = n->nfile.fd;
    191 		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
    192 		    n->ndup.dupfd == fd) {
    193 			/* redirect from/to same file descriptor */
    194 			/* make sure it stays open */
    195 			if (fcntl(fd, F_SETFD, 0) < 0)
    196 				error("fd %d: %s", fd, strerror(errno));
    197 			continue;
    198 		}
    199 
    200 		if ((flags & REDIR_PUSH) && !is_renamed(sv->renamed, fd)) {
    201 			INTOFF;
    202 			if (big_sh_fd < 10)
    203 				find_big_fd();
    204 			if ((i = fcntl(fd, F_DUPFD, big_sh_fd)) == -1) {
    205 				switch (errno) {
    206 				case EBADF:
    207 					i = CLOSED;
    208 					break;
    209 				case EMFILE:
    210 				case EINVAL:
    211 					find_big_fd();
    212 					i = fcntl(fd, F_DUPFD, big_sh_fd);
    213 					if (i >= 0)
    214 						break;
    215 					/* FALLTHRU */
    216 				default:
    217 					i = errno;
    218 					INTON;    /* XXX not needed here ? */
    219 					error("%d: %s", fd, strerror(i));
    220 					/* NOTREACHED */
    221 				}
    222 			}
    223 			if (i >= 0)
    224 				(void)fcntl(i, F_SETFD, FD_CLOEXEC);
    225 			fd_rename(sv, fd, i);
    226 			INTON;
    227 		}
    228 		if (fd == 0)
    229 			fd0_redirected++;
    230 		openredirect(n, memory, flags);
    231 	}
    232 	if (memory[1])
    233 		out1 = &memout;
    234 	if (memory[2])
    235 		out2 = &memout;
    236 }
    237 
    238 
    239 STATIC void
    240 openredirect(union node *redir, char memory[10], int flags)
    241 {
    242 	struct stat sb;
    243 	int fd = redir->nfile.fd;
    244 	char *fname;
    245 	int f;
    246 	int eflags, cloexec;
    247 
    248 	/*
    249 	 * We suppress interrupts so that we won't leave open file
    250 	 * descriptors around.  This may not be such a good idea because
    251 	 * an open of a device or a fifo can block indefinitely.
    252 	 */
    253 	INTOFF;
    254 	if (fd < 10)
    255 		memory[fd] = 0;
    256 	switch (redir->nfile.type) {
    257 	case NFROM:
    258 		fname = redir->nfile.expfname;
    259 		if (flags & REDIR_VFORK)
    260 			eflags = O_NONBLOCK;
    261 		else
    262 			eflags = 0;
    263 		if ((f = open(fname, O_RDONLY|eflags)) < 0)
    264 			goto eopen;
    265 		if (eflags)
    266 			(void)fcntl(f, F_SETFL, fcntl(f, F_GETFL, 0) & ~eflags);
    267 		break;
    268 	case NFROMTO:
    269 		fname = redir->nfile.expfname;
    270 		if ((f = open(fname, O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0)
    271 			goto ecreate;
    272 		break;
    273 	case NTO:
    274 		if (Cflag) {
    275 			fname = redir->nfile.expfname;
    276 			if ((f = open(fname, O_WRONLY)) == -1) {
    277 				if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL,
    278 				    0666)) < 0)
    279 					goto ecreate;
    280 			} else if (fstat(f, &sb) == -1) {
    281 				int serrno = errno;
    282 				close(f);
    283 				errno = serrno;
    284 				goto ecreate;
    285 			} else if (S_ISREG(sb.st_mode)) {
    286 				close(f);
    287 				errno = EEXIST;
    288 				goto ecreate;
    289 			}
    290 			break;
    291 		}
    292 		/* FALLTHROUGH */
    293 	case NCLOBBER:
    294 		fname = redir->nfile.expfname;
    295 		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
    296 			goto ecreate;
    297 		break;
    298 	case NAPPEND:
    299 		fname = redir->nfile.expfname;
    300 		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
    301 			goto ecreate;
    302 		break;
    303 	case NTOFD:
    304 	case NFROMFD:
    305 		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
    306 			if (fd < 10 && redir->ndup.dupfd < 10 &&
    307 			    memory[redir->ndup.dupfd])
    308 				memory[fd] = 1;
    309 			else if (copyfd(redir->ndup.dupfd, fd,
    310 			    (flags & REDIR_KEEP) == 0) < 0)
    311 				error("Redirect (from %d to %d) failed: %s",
    312 				    redir->ndup.dupfd, fd, strerror(errno));
    313 		} else
    314 			(void) close(fd);
    315 		INTON;
    316 		return;
    317 	case NHERE:
    318 	case NXHERE:
    319 		f = openhere(redir);
    320 		break;
    321 	default:
    322 		abort();
    323 	}
    324 
    325 	cloexec = fd > 2 && (flags & REDIR_KEEP) == 0;
    326 	if (f != fd) {
    327 		if (copyfd(f, fd, cloexec) < 0) {
    328 			int e = errno;
    329 
    330 			close(f);
    331 			error("redirect reassignment (fd %d) failed: %s", fd,
    332 			    strerror(e));
    333 		}
    334 		close(f);
    335 	} else if (cloexec)
    336 		(void)fcntl(f, F_SETFD, FD_CLOEXEC);
    337 
    338 	INTON;
    339 	return;
    340 ecreate:
    341 	exerrno = 1;
    342 	error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    343 eopen:
    344 	exerrno = 1;
    345 	error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
    346 }
    347 
    348 
    349 /*
    350  * Handle here documents.  Normally we fork off a process to write the
    351  * data to a pipe.  If the document is short, we can stuff the data in
    352  * the pipe without forking.
    353  */
    354 
    355 STATIC int
    356 openhere(const union node *redir)
    357 {
    358 	int pip[2];
    359 	int len = 0;
    360 
    361 	if (pipe(pip) < 0)
    362 		error("Pipe call failed");
    363 	if (redir->type == NHERE) {
    364 		len = strlen(redir->nhere.doc->narg.text);
    365 		if (len <= PIPESIZE) {
    366 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    367 			goto out;
    368 		}
    369 	}
    370 	if (forkshell(NULL, NULL, FORK_NOJOB) == 0) {
    371 		close(pip[0]);
    372 		signal(SIGINT, SIG_IGN);
    373 		signal(SIGQUIT, SIG_IGN);
    374 		signal(SIGHUP, SIG_IGN);
    375 #ifdef SIGTSTP
    376 		signal(SIGTSTP, SIG_IGN);
    377 #endif
    378 		signal(SIGPIPE, SIG_DFL);
    379 		if (redir->type == NHERE)
    380 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    381 		else
    382 			expandhere(redir->nhere.doc, pip[1]);
    383 		_exit(0);
    384 	}
    385 out:
    386 	close(pip[1]);
    387 	return pip[0];
    388 }
    389 
    390 
    391 
    392 /*
    393  * Undo the effects of the last redirection.
    394  */
    395 
    396 void
    397 popredir(void)
    398 {
    399 	struct redirtab *rp = redirlist;
    400 
    401 	INTOFF;
    402 	free_rl(rp, 1);
    403 	redirlist = rp->next;
    404 	ckfree(rp);
    405 	INTON;
    406 }
    407 
    408 /*
    409  * Undo all redirections.  Called on error or interrupt.
    410  */
    411 
    412 #ifdef mkinit
    413 
    414 INCLUDE "redir.h"
    415 
    416 RESET {
    417 	while (redirlist)
    418 		popredir();
    419 }
    420 
    421 SHELLPROC {
    422 	clearredir(0);
    423 }
    424 
    425 #endif
    426 
    427 /* Return true if fd 0 has already been redirected at least once.  */
    428 int
    429 fd0_redirected_p(void)
    430 {
    431 	return fd0_redirected != 0;
    432 }
    433 
    434 /*
    435  * Discard all saved file descriptors.
    436  */
    437 
    438 void
    439 clearredir(int vforked)
    440 {
    441 	struct redirtab *rp;
    442 	struct renamelist *rl;
    443 
    444 	for (rp = redirlist ; rp ; rp = rp->next) {
    445 		if (!vforked)
    446 			free_rl(rp, 0);
    447 		else for (rl = rp->renamed; rl; rl = rl->next)
    448 			if (rl->into >= 0)
    449 				close(rl->into);
    450 	}
    451 }
    452 
    453 
    454 
    455 /*
    456  * Copy a file descriptor to be == to.
    457  * cloexec indicates if we want close-on-exec or not.
    458  * Returns -1 if any error occurs.
    459  */
    460 
    461 STATIC int
    462 copyfd(int from, int to, int cloexec)
    463 {
    464 	int newfd;
    465 
    466 	if (cloexec && to > 2)
    467 		newfd = dup3(from, to, O_CLOEXEC);
    468 	else
    469 		newfd = dup2(from, to);
    470 
    471 	return newfd;
    472 }
    473 
    474 /*
    475  * rename fd from to be fd to (closing from).
    476  * close-on-exec is never set on 'to' (unless
    477  * from==to and it was set on from) - ie: a no-op
    478  * returns to (or errors() if an error occurs).
    479  *
    480  * This is mostly used for rearranging the
    481  * results from pipe().
    482  */
    483 int
    484 movefd(int from, int to)
    485 {
    486 	if (from == to)
    487 		return to;
    488 
    489 	(void) close(to);
    490 	if (copyfd(from, to, 0) != to) {
    491 		int e = errno;
    492 
    493 		(void) close(from);
    494 		error("Unable to make fd %d: %s", to, strerror(e));
    495 	}
    496 	(void) close(from);
    497 
    498 	return to;
    499 }
    500 
    501 STATIC void
    502 find_big_fd(void)
    503 {
    504 	int i, fd;
    505 
    506 	for (i = (1 << 10); i >= 10; i >>= 1) {
    507 		if ((fd = fcntl(0, F_DUPFD, i - 1)) >= 0) {
    508 			close(fd);
    509 			break;
    510 		}
    511 	}
    512 
    513 	fd = (i / 5) * 4;
    514 	if ((i - fd) > 100)
    515 		fd = i - 100;
    516 	else if (fd < 10)
    517 		fd = 10;
    518 
    519 	big_sh_fd = fd;
    520 }
    521 
    522 /*
    523  * If possible, move file descriptor fd out of the way
    524  * of expected user fd values.   Returns the new fd
    525  * (which may be the input fd if things do not go well.)
    526  * Always set close-on-exec on the result, and close
    527  * the input fd unless it is to be our result.
    528  */
    529 int
    530 to_upper_fd(int fd)
    531 {
    532 	int i;
    533 
    534 	if (big_sh_fd < 10)
    535 		find_big_fd();
    536 	do {
    537 		i = fcntl(fd, F_DUPFD_CLOEXEC, big_sh_fd);
    538 		if (i >= 0) {
    539 			if (fd != i)
    540 				close(fd);
    541 			return i;
    542 		}
    543 		if (errno != EMFILE)
    544 			break;
    545 		find_big_fd();
    546 	} while (big_sh_fd > 10);
    547 
    548 	/*
    549 	 * If we wanted to move this fd to some random high number
    550 	 * we certainly do not intend to pass it through exec, even
    551 	 * if the reassignment failed.
    552 	 */
    553 	(void)fcntl(fd, F_SETFD, FD_CLOEXEC);
    554 	return fd;
    555 }
    556 
    557 static const struct {
    558 	const char *name;
    559 	uint32_t value;
    560 } nv[] = {
    561 #ifdef O_APPEND
    562 	{ "append",	O_APPEND 	},
    563 #endif
    564 #ifdef O_ASYNC
    565 	{ "async",	O_ASYNC		},
    566 #endif
    567 #ifdef O_SYNC
    568 	{ "sync",	O_SYNC		},
    569 #endif
    570 #ifdef O_NONBLOCK
    571 	{ "nonblock",	O_NONBLOCK	},
    572 #endif
    573 #ifdef O_FSYNC
    574 	{ "fsync",	O_FSYNC		},
    575 #endif
    576 #ifdef O_DSYNC
    577 	{ "dsync",	O_DSYNC		},
    578 #endif
    579 #ifdef O_RSYNC
    580 	{ "rsync",	O_RSYNC		},
    581 #endif
    582 #ifdef O_ALTIO
    583 	{ "altio",	O_ALT_IO	},
    584 #endif
    585 #ifdef O_DIRECT
    586 	{ "direct",	O_DIRECT	},
    587 #endif
    588 #ifdef O_NOSIGPIPE
    589 	{ "nosigpipe",	O_NOSIGPIPE	},
    590 #endif
    591 #ifdef O_CLOEXEC
    592 	{ "cloexec",	O_CLOEXEC	},
    593 #endif
    594 };
    595 #define ALLFLAGS (O_APPEND|O_ASYNC|O_SYNC|O_NONBLOCK|O_DSYNC|O_RSYNC|\
    596     O_ALT_IO|O_DIRECT|O_NOSIGPIPE|O_CLOEXEC)
    597 
    598 static int
    599 getflags(int fd, int p)
    600 {
    601 	int c, f;
    602 
    603 	if ((c = fcntl(fd, F_GETFD)) == -1) {
    604 		if (!p)
    605 			return -1;
    606 		error("Can't get status for fd=%d (%s)", fd, strerror(errno));
    607 	}
    608 	if ((f = fcntl(fd, F_GETFL)) == -1) {
    609 		if (!p)
    610 			return -1;
    611 		error("Can't get flags for fd=%d (%s)", fd, strerror(errno));
    612 	}
    613 	if (c)
    614 		f |= O_CLOEXEC;
    615 	return f & ALLFLAGS;
    616 }
    617 
    618 static void
    619 printone(int fd, int p, int verbose)
    620 {
    621 	int f = getflags(fd, p);
    622 
    623 	if (f == -1)
    624 		return;
    625 
    626 	outfmt(out1, "%d:", fd);
    627 	for (size_t i = 0; i < __arraycount(nv); i++) {
    628 		if (f & nv[i].value) {
    629 			outfmt(out1, "%s%s", verbose ? "+" : "", nv[i].name);
    630 			f &= ~nv[i].value;
    631 		} else if (verbose)
    632 			outfmt(out1, "-%s", nv[i].name);
    633 		else
    634 			continue;
    635 		if (f || (verbose && i != __arraycount(nv) - 1))
    636 			outfmt(out1, ",");
    637 	}
    638 	outfmt(out1, "\n");
    639 }
    640 
    641 static int
    642 parseflags(char *s, int *p, int *n)
    643 {
    644 	int f = 0, *v;
    645 
    646 	*p = 0;
    647 	*n = 0;
    648 	for (s = strtok(s, ","); s; s = strtok(NULL, ",")) {
    649 		size_t i;
    650 		switch (*s) {
    651 		case '+':
    652 			v = p;
    653 			s++;
    654 			break;
    655 		case '-':
    656 			v = n;
    657 			s++;
    658 			break;
    659 		default:
    660 			v = &f;
    661 			break;
    662 		}
    663 
    664 		for (i = 0; i < __arraycount(nv); i++)
    665 			if (strcmp(s, nv[i].name) == 0) {
    666 				*v |= nv[i].value;
    667 				break;
    668 			}
    669 		if (i == __arraycount(nv))
    670 			error("Bad flag `%s'", s);
    671 	}
    672 	return f;
    673 }
    674 
    675 static void
    676 setone(int fd, int pos, int neg, int verbose)
    677 {
    678 	int f = getflags(fd, 1);
    679 	if (f == -1)
    680 		return;
    681 
    682 	int cloexec = -1;
    683 	if ((pos & O_CLOEXEC) && !(f & O_CLOEXEC))
    684 		cloexec = FD_CLOEXEC;
    685 	if ((neg & O_CLOEXEC) && (f & O_CLOEXEC))
    686 		cloexec = 0;
    687 
    688 	if (cloexec != -1 && fcntl(fd, F_SETFD, cloexec) == -1)
    689 		error("Can't set status for fd=%d (%s)", fd, strerror(errno));
    690 
    691 	pos &= ~O_CLOEXEC;
    692 	neg &= ~O_CLOEXEC;
    693 	f &= ~O_CLOEXEC;
    694 	int n = f;
    695 	n |= pos;
    696 	n &= ~neg;
    697 	if (n != f && fcntl(fd, F_SETFL, n) == -1)
    698 		error("Can't set flags for fd=%d (%s)", fd, strerror(errno));
    699 	if (verbose)
    700 		printone(fd, 1, verbose);
    701 }
    702 
    703 int
    704 fdflagscmd(int argc, char *argv[])
    705 {
    706 	char *num;
    707 	int verbose = 0, ch, pos = 0, neg = 0;
    708 	char *setflags = NULL;
    709 
    710 	optreset = 1; optind = 1; /* initialize getopt */
    711 	while ((ch = getopt(argc, argv, ":vs:")) != -1)
    712 		switch ((char)ch) {
    713 		case 'v':
    714 			verbose = 1;
    715 			break;
    716 		case 's':
    717 			setflags = optarg;
    718 			break;
    719 		case '?':
    720 		default:
    721 		msg:
    722 			error("Usage: fdflags [-v] [-s <flags>] [fd...]");
    723 			/* NOTREACHED */
    724 		}
    725 
    726 	argc -= optind, argv += optind;
    727 
    728 	if (setflags && parseflags(setflags, &pos, &neg))
    729 		error("Need + or - before flags");
    730 
    731 	if (argc == 0) {
    732 		if (setflags)
    733 			goto msg;
    734 		int maxfd = fcntl(0, F_MAXFD);
    735 		if (maxfd == -1)
    736 			error("Can't get max fd (%s)", strerror(errno));
    737 		for (int i = 0; i <= maxfd; i++)
    738 			printone(i, 0, verbose);
    739 		return 0;
    740 	}
    741 
    742 	while ((num = *argv++) != NULL) {
    743 		int e;
    744 		int fd = (int)strtoi(num, NULL, 0, 0, INT_MAX, &e);
    745 		if (e)
    746 			error("Can't parse `%s' (%s)", num, strerror(e));
    747 		if (setflags)
    748 			setone(fd, pos, neg, verbose);
    749 		else
    750 			printone(fd, 1, verbose);
    751 	}
    752 	return 0;
    753 }
    754