miscbltin.c

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Miscellaneous builtins.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/resource.h>

#include <errno.h>
#include <poll.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "shell.h"
#include "options.h"
#include "var.h"
#include "output.h"
#include "memalloc.h"
#include "error.h"
#include "mystring.h"
#include "syntax.h"
#include "trap.h"

#undef eflag

#define	READ_BUFLEN	1024
struct fdctx {
	int	fd;
	size_t	off;	/* offset in buf */
	size_t	buflen;
	char	*ep;	/* tail pointer */
	char	buf[READ_BUFLEN];
};

static void fdctx_init(int, struct fdctx *);
static void fdctx_destroy(struct fdctx *);
static ssize_t fdgetc(struct fdctx *, char *);
int readcmd(int, char **);
int umaskcmd(int, char **);
int ulimitcmd(int, char **);

static void
fdctx_init(int fd, struct fdctx *fdc)
{
	off_t cur;

	/* Check if fd is seekable. */
	cur = lseek(fd, 0, SEEK_CUR);
	*fdc = (struct fdctx){
		.fd = fd,
		.buflen = (cur != -1) ? READ_BUFLEN : 1,
		.ep = &fdc->buf[0],	/* No data */
	};
}

static ssize_t
fdgetc(struct fdctx *fdc, char *c)
{
	ssize_t nread;

	if (&fdc->buf[fdc->off] == fdc->ep) {
		nread = read(fdc->fd, fdc->buf, fdc->buflen);
		if (nread > 0) {
			fdc->off = 0;
			fdc->ep = fdc->buf + nread;
		} else
			return (nread);
	}
	*c = fdc->buf[fdc->off++];

	return (1);
}

static void
fdctx_destroy(struct fdctx *fdc)
{
	off_t residue;

	if (fdc->buflen > 1) {
	/*
	 * Reposition the file offset.  Here is the layout of buf:
	 *
	 *     | off
	 *     v
	 * |*****************|-------|
	 * buf               ep   buf+buflen
	 *     |<- residue ->|
	 *
	 * off: current character
	 * ep:  offset just after read(2)
	 * residue: length for reposition
	 */
		residue = (fdc->ep - fdc->buf) - fdc->off;
		if (residue > 0)
			(void) lseek(fdc->fd, -residue, SEEK_CUR);
	}
}

/*
 * The read builtin.  The -r option causes backslashes to be treated like
 * ordinary characters.
 *
 * Note that if IFS=' :' then read x y should work so that:
 * 'a b'	x='a', y='b'
 * ' a b '	x='a', y='b'
 * ':b'		x='',  y='b'
 * ':'		x='',  y=''
 * '::'		x='',  y=''
 * ': :'	x='',  y=''
 * ':::'	x='',  y='::'
 * ':b c:'	x='',  y='b c:'
 */

int
readcmd(int argc __unused, char **argv __unused)
{
	char **ap;
	int backslash;
	char c;
	int rflag;
	char *prompt;
	const char *ifs;
	char *p;
	int startword;
	int status;
	int i;
	int is_ifs;
	int saveall = 0;
	ptrdiff_t lastnonifs, lastnonifsws;
	sigset_t set, oset;
	intmax_t number, timeout;
	struct timespec tnow, tend, tresid;
	struct pollfd pfd;
	char *endptr;
	ssize_t nread;
	int sig;
	struct fdctx fdctx;

	rflag = 0;
	prompt = NULL;
	timeout = -1;
	while ((i = nextopt("erp:t:")) != '\0') {
		switch(i) {
		case 'p':
			prompt = shoptarg;
			break;
		case 'e':
			break;
		case 'r':
			rflag = 1;
			break;
		case 't':
			timeout = 0;
			do {
				number = strtol(shoptarg, &endptr, 0);
				if (number < 0 || endptr == shoptarg)
					error("timeout value");
				switch (*endptr) {
				case 's':
					endptr++;
					break;
				case 'h':
					number *= 60;
					/* FALLTHROUGH */
				case 'm':
					number *= 60;
					endptr++;
					break;
				}
				if (*endptr != '\0' &&
				    !(*endptr >= '0' && *endptr <= '9'))
					error("timeout unit");
				timeout += number;
				shoptarg = endptr;
			} while (*shoptarg != '\0');
			break;
		}
	}
	if (prompt && isatty(0)) {
		out2str(prompt);
		flushall();
	}
	if (*(ap = argptr) == NULL)
		error("arg count");
	if ((ifs = bltinlookup("IFS", 1)) == NULL)
		ifs = " \t\n";

	if (timeout >= 0) {
		/*
		 * Wait for something to become available.
		 */
		pfd.fd = STDIN_FILENO;
		pfd.events = POLLIN;
		status = sig = 0;
		sigfillset(&set);
		sigprocmask(SIG_SETMASK, &set, &oset);
		if (pendingsig) {
			/* caught a signal already */
			status = -1;
		} else if (timeout == 0) {
			status = poll(&pfd, 1, 0);
		} else {
			clock_gettime(CLOCK_UPTIME, &tnow);
			tend = tnow;
			tend.tv_sec += timeout;
			do {
				timespecsub(&tend, &tnow, &tresid);
				status = ppoll(&pfd, 1, &tresid, &oset);
				if (status >= 0 || pendingsig != 0)
					break;
				clock_gettime(CLOCK_UPTIME, &tnow);
			} while (timespeccmp(&tnow, &tend, <));
		}
		sigprocmask(SIG_SETMASK, &oset, NULL);
		/*
		 * If there's nothing ready, return an error.
		 */
		if (status <= 0) {
			while (*ap != NULL)
				setvar(*ap++, "", 0);
			sig = pendingsig;
			return (128 + (sig != 0 ? sig : SIGALRM));
		}
	}

	status = 0;
	startword = 2;
	backslash = 0;
	STARTSTACKSTR(p);
	lastnonifs = lastnonifsws = -1;
	fdctx_init(STDIN_FILENO, &fdctx);
	for (;;) {
		c = 0;
		nread = fdgetc(&fdctx, &c);
		if (nread == -1) {
			if (errno == EINTR) {
				sig = pendingsig;
				if (sig == 0)
					continue;
				status = 128 + sig;
				break;
			}
			warning("read error: %s", strerror(errno));
			status = 2;
			break;
		} else if (nread != 1) {
			status = 1;
			break;
		}
		if (c == '\0')
			continue;
		CHECKSTRSPACE(1, p);
		if (backslash) {
			backslash = 0;
			if (c != '\n') {
				startword = 0;
				lastnonifs = lastnonifsws = p - stackblock();
				USTPUTC(c, p);
			}
			continue;
		}
		if (!rflag && c == '\\') {
			backslash++;
			continue;
		}
		if (c == '\n')
			break;
		if (strchr(ifs, c))
			is_ifs = strchr(" \t\n", c) ? 1 : 2;
		else
			is_ifs = 0;

		if (startword != 0) {
			if (is_ifs == 1) {
				/* Ignore leading IFS whitespace */
				if (saveall)
					USTPUTC(c, p);
				continue;
			}
			if (is_ifs == 2 && startword == 1) {
				/* Only one non-whitespace IFS per word */
				startword = 2;
				if (saveall) {
					lastnonifsws = p - stackblock();
					USTPUTC(c, p);
				}
				continue;
			}
		}

		if (is_ifs == 0) {
			/* append this character to the current variable */
			startword = 0;
			if (saveall)
				/* Not just a spare terminator */
				saveall++;
			lastnonifs = lastnonifsws = p - stackblock();
			USTPUTC(c, p);
			continue;
		}

		/* end of variable... */
		startword = is_ifs;

		if (ap[1] == NULL) {
			/* Last variable needs all IFS chars */
			saveall++;
			if (is_ifs == 2)
				lastnonifsws = p - stackblock();
			USTPUTC(c, p);
			continue;
		}

		STACKSTRNUL(p);
		setvar(*ap, stackblock(), 0);
		ap++;
		STARTSTACKSTR(p);
		lastnonifs = lastnonifsws = -1;
	}
	fdctx_destroy(&fdctx);
	STACKSTRNUL(p);

	/*
	 * Remove trailing IFS chars: always remove whitespace, don't remove
	 * non-whitespace unless it was naked
	 */
	if (saveall <= 1)
		lastnonifsws = lastnonifs;
	stackblock()[lastnonifsws + 1] = '\0';
	setvar(*ap, stackblock(), 0);

	/* Set any remaining args to "" */
	while (*++ap != NULL)
		setvar(*ap, "", 0);
	return status;
}



int
umaskcmd(int argc __unused, char **argv __unused)
{
	char *ap;
	int mask;
	int i;
	int symbolic_mode = 0;

	while ((i = nextopt("S")) != '\0') {
		symbolic_mode = 1;
	}

	INTOFF;
	mask = umask(0);
	umask(mask);
	INTON;

	if ((ap = *argptr) == NULL) {
		if (symbolic_mode) {
			char u[4], g[4], o[4];

			i = 0;
			if ((mask & S_IRUSR) == 0)
				u[i++] = 'r';
			if ((mask & S_IWUSR) == 0)
				u[i++] = 'w';
			if ((mask & S_IXUSR) == 0)
				u[i++] = 'x';
			u[i] = '\0';

			i = 0;
			if ((mask & S_IRGRP) == 0)
				g[i++] = 'r';
			if ((mask & S_IWGRP) == 0)
				g[i++] = 'w';
			if ((mask & S_IXGRP) == 0)
				g[i++] = 'x';
			g[i] = '\0';

			i = 0;
			if ((mask & S_IROTH) == 0)
				o[i++] = 'r';
			if ((mask & S_IWOTH) == 0)
				o[i++] = 'w';
			if ((mask & S_IXOTH) == 0)
				o[i++] = 'x';
			o[i] = '\0';

			out1fmt("u=%s,g=%s,o=%s\n", u, g, o);
		} else {
			out1fmt("%.4o\n", mask);
		}
	} else {
		if (is_digit(*ap)) {
			mask = 0;
			do {
				if (*ap >= '8' || *ap < '0')
					error("Illegal number: %s", *argptr);
				mask = (mask << 3) + (*ap - '0');
			} while (*++ap != '\0');
			umask(mask);
		} else {
			void *set;
			INTOFF;
			if ((set = setmode (ap)) == NULL)
				error("Illegal number: %s", ap);

			mask = getmode (set, ~mask & 0777);
			umask(~mask & 0777);
			free(set);
			INTON;
		}
	}
	return 0;
}

/*
 * ulimit builtin
 *
 * This code, originally by Doug Gwyn, Doug Kingston, Eric Gisin, and
 * Michael Rendell was ripped from pdksh 5.0.8 and hacked for use with
 * ash by J.T. Conklin.
 *
 * Public domain.
 */

struct limits {
	const char *name;
	const char *units;
	int	cmd;
	short	factor;	/* multiply by to get rlim_{cur,max} values */
	char	option;
};

static const struct limits limits[] = {
#ifdef RLIMIT_CPU
	{ "cpu time",		"seconds",	RLIMIT_CPU,	   1, 't' },
#endif
#ifdef RLIMIT_FSIZE
	{ "file size",		"512-blocks",	RLIMIT_FSIZE,	 512, 'f' },
#endif
#ifdef RLIMIT_DATA
	{ "data seg size",	"kbytes",	RLIMIT_DATA,	1024, 'd' },
#endif
#ifdef RLIMIT_STACK
	{ "stack size",		"kbytes",	RLIMIT_STACK,	1024, 's' },
#endif
#ifdef  RLIMIT_CORE
	{ "core file size",	"512-blocks",	RLIMIT_CORE,	 512, 'c' },
#endif
#ifdef RLIMIT_RSS
	{ "max memory size",	"kbytes",	RLIMIT_RSS,	1024, 'm' },
#endif
#ifdef RLIMIT_MEMLOCK
	{ "locked memory",	"kbytes",	RLIMIT_MEMLOCK, 1024, 'l' },
#endif
#ifdef RLIMIT_NPROC
	{ "max user processes",	(char *)0,	RLIMIT_NPROC,      1, 'u' },
#endif
#ifdef RLIMIT_NOFILE
	{ "open files",		(char *)0,	RLIMIT_NOFILE,     1, 'n' },
#endif
#ifdef RLIMIT_VMEM
	{ "virtual mem size",	"kbytes",	RLIMIT_VMEM,	1024, 'v' },
#endif
#ifdef RLIMIT_SWAP
	{ "swap limit",		"kbytes",	RLIMIT_SWAP,	1024, 'w' },
#endif
#ifdef RLIMIT_SBSIZE
	{ "socket buffer size",	"bytes",	RLIMIT_SBSIZE,	   1, 'b' },
#endif
#ifdef RLIMIT_NPTS
	{ "pseudo-terminals",	(char *)0,	RLIMIT_NPTS,	   1, 'p' },
#endif
#ifdef RLIMIT_KQUEUES
	{ "kqueues",		(char *)0,	RLIMIT_KQUEUES,	   1, 'k' },
#endif
#ifdef RLIMIT_UMTXP
	{ "umtx shared locks",	(char *)0,	RLIMIT_UMTXP,	   1, 'o' },
#endif
#ifdef RLIMIT_PIPEBUF
	{ "pipebuf",		(char *)0,	RLIMIT_PIPEBUF, 1024, 'y' },
#endif
	{ (char *) 0,		(char *)0,	0,		   0, '\0' }
};

enum limithow { SOFT = 0x1, HARD = 0x2 };

static void
printlimit(enum limithow how, const struct rlimit *limit,
    const struct limits *l)
{
	rlim_t val = 0;

	if (how & SOFT)
		val = limit->rlim_cur;
	else if (how & HARD)
		val = limit->rlim_max;
	if (val == RLIM_INFINITY)
		out1str("unlimited\n");
	else
	{
		val /= l->factor;
		out1fmt("%jd\n", (intmax_t)val);
	}
}

int
ulimitcmd(int argc __unused, char **argv __unused)
{
	rlim_t val = 0;
	enum limithow how = SOFT | HARD;
	const struct limits	*l;
	int		set, all = 0;
	int		optc, what;
	struct rlimit	limit;

	what = 'f';
	while ((optc = nextopt("HSatfdsmcnuvlbpwkoy")) != '\0')
		switch (optc) {
		case 'H':
			how = HARD;
			break;
		case 'S':
			how = SOFT;
			break;
		case 'a':
			all = 1;
			break;
		default:
			what = optc;
		}

	for (l = limits; l->name && l->option != what; l++)
		;
	if (!l->name)
		error("internal error (%c)", what);

	set = *argptr ? 1 : 0;
	if (set) {
		char *p = *argptr;

		if (all || argptr[1])
			error("too many arguments");
		if (strcmp(p, "unlimited") == 0)
			val = RLIM_INFINITY;
		else {
			char *end;
			uintmax_t uval;

			if (*p < '0' || *p > '9')
				error("bad number");
			errno = 0;
			uval = strtoumax(p, &end, 10);
			if (errno != 0 || *end != '\0')
				error("bad number");
			if (uval > UINTMAX_MAX / l->factor)
				error("bad number");
			uval *= l->factor;
			val = (rlim_t)uval;
			if (val < 0 || (uintmax_t)val != uval ||
			    val == RLIM_INFINITY)
				error("bad number");
		}
	}
	if (all) {
		for (l = limits; l->name; l++) {
			char optbuf[40];
			if (getrlimit(l->cmd, &limit) < 0)
				error("can't get limit: %s", strerror(errno));

			if (l->units)
				snprintf(optbuf, sizeof(optbuf),
					"(%s, -%c) ", l->units, l->option);
			else
				snprintf(optbuf, sizeof(optbuf),
					"(-%c) ", l->option);
			out1fmt("%-18s %18s ", l->name, optbuf);
			printlimit(how, &limit, l);
		}
		return 0;
	}

	if (getrlimit(l->cmd, &limit) < 0)
		error("can't get limit: %s", strerror(errno));
	if (set) {
		if (how & SOFT)
			limit.rlim_cur = val;
		if (how & HARD)
			limit.rlim_max = val;
		if (setrlimit(l->cmd, &limit) < 0)
			error("bad limit: %s", strerror(errno));
	} else
		printlimit(how, &limit, l);
	return 0;
}