/* $Header: /home/hyperion/mu/christos/src/sys/tcsh-6.00/RCS/sh.exec.c,v 3.0 1991/07/04 21:49:28 christos Exp $ */
/*
 * sh.exec.c: Search, find, and execute a command!
 */
/*-
 * Copyright (c) 1980, 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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.
 */
#include "config.h"
#if !defined(lint) && !defined(pdp11)
static char *rcsid() 
    { return "$Id: sh.exec.c,v 3.0 1991/07/04 21:49:28 christos Exp $"; }
#endif

#include "sh.h"
#include "tw.h"

/*
 * C shell
 */

/*
 * System level search and execute of a command.
 * We look in each directory for the specified command name.
 * If the name contains a '/' then we execute only the full path name.
 * If there is no search path then we execute only full path names.
 */

/*
 * As we search for the command we note the first non-trivial error
 * message for presentation to the user.  This allows us often
 * to show that a file has the wrong mode/no access when the file
 * is not in the last component of the search path, so we must
 * go on after first detecting the error.
 */
static char *exerr;		/* Execution error message */
static Char *expath;		/* Path for exerr */

/*
 * Xhash is an array of HSHSIZ bits (HSHSIZ / 8 chars), which are used
 * to hash execs.  If it is allocated (havhash true), then to tell
 * whether ``name'' is (possibly) present in the i'th component
 * of the variable path, you look at the bit in xhash indexed by
 * hash(hashname("name"), i).  This is setup automatically
 * after .login is executed, and recomputed whenever ``path'' is
 * changed.
 * The two part hash function is designed to let texec() call the
 * more expensive hashname() only once and the simple hash() several
 * times (once for each path component checked).
 * Byte size is assumed to be 8.
 */
#define	HSHSIZ		8192	/* 1k bytes */
#define HSHMASK		(HSHSIZ - 1)
#define HSHMUL		243
static char xhash[HSHSIZ / 8];

#define hash(a, b)	((a) * HSHMUL + (b) & HSHMASK)
#define bit(h, b)	((h)[(b) >> 3] & 1 << ((b) & 7))	/* bit test */
#define bis(h, b)	((h)[(b) >> 3] |= 1 << ((b) & 7))	/* bit set */
#ifdef VFORK
static int hits, misses;

#endif

/* Dummy search path for just absolute search when no path */
static Char *justabs[] = {STRNULL, 0};

static	void	pexerr		__P((void));
static	void	texec		__P((Char *, Char **));
static	int	hashname	__P((Char *));

void
doexec(t)
    register struct command *t;
{
    register Char *dp, **pv, **av, *sav;
    register struct varent *v;
    register bool slash;
    register int hshval = 0, hshval1, i;
    Char   *blk[2];

    /*
     * Glob the command name. We will search $path even if this does something,
     * as in sh but not in csh.  One special case: if there is no PATH, then we
     * execute only commands which start with '/'.
     */
    blk[0] = t->t_dcom[0];
    blk[1] = 0;
    gflag = 0, tglob(blk);
    if (gflag) {
	pv = globall(blk);
	if (pv == 0) {
	    setname(short2str(blk[0]));
	    stderror(ERR_NAME | ERR_NOMATCH);
	}
	gargv = 0;
    }
    else
	pv = saveblk(blk);

    trim(pv);

    exerr = 0;
    expath = Strsave(pv[0]);
#ifdef VFORK
    Vexpath = expath;
#endif

    v = adrof(STRpath);
    if (v == 0 && expath[0] != '/') {
	blkfree(pv);
	pexerr();
    }
    slash = any(short2str(expath), '/');

    /*
     * Glob the argument list, if necessary. Otherwise trim off the quote bits.
     */
    gflag = 0;
    av = &t->t_dcom[1];
    tglob(av);
    if (gflag) {
	av = globall(av);
	if (av == 0) {
	    blkfree(pv);
	    setname(short2str(expath));
	    stderror(ERR_NAME | ERR_NOMATCH);
	}
	gargv = 0;
    }
    else
	av = saveblk(av);

    blkfree(t->t_dcom);
    t->t_dcom = blkspl(pv, av);
    xfree((ptr_t) pv);
    xfree((ptr_t) av);
    av = t->t_dcom;
    trim(av);

    if (*av == NULL || **av == '\0')
	pexerr();

    xechoit(av);		/* Echo command if -x */
#ifdef FIOCLEX
    /*
     * Since all internal file descriptors are set to close on exec, we don't
     * need to close them explicitly here.  Just reorient ourselves for error
     * messages.
     */
    SHIN = 0;
    SHOUT = 1;
    SHDIAG = 2;
    OLDSTD = 0;
    isoutatty = isatty(SHOUT);
    isdiagatty = isatty(SHDIAG);
#else
    closech();			/* Close random fd's */
#endif
    /*
     * We must do this AFTER any possible forking (like `foo` in glob) so that
     * this shell can still do subprocesses.
     */
#ifdef BSDSIGS
    (void) sigsetmask((sigmask_t) 0);
#else				/* BSDSIGS */
    (void) sigrelse(SIGINT);
    (void) sigrelse(SIGCHLD);
#endif				/* BSDSIGS */

    /*
     * If no path, no words in path, or a / in the filename then restrict the
     * command search.
     */
    if (v == 0 || v->vec[0] == 0 || slash)
	pv = justabs;
    else
	pv = v->vec;
    sav = Strspl(STRslash, *av);/* / command name for postpending */
#ifdef VFORK
    Vsav = sav;
#endif
    if (havhash)
	hshval = hashname(*av);
    i = 0;
#ifdef VFORK
    hits++;
#endif
    do {
	/*
	 * Try to save time by looking at the hash table for where this command
	 * could be.  If we are doing delayed hashing, then we put the names in
	 * one at a time, as the user enters them.  This is kinda like Korn
	 * Shell's "tracked aliases".
	 */
	if (!slash && pv[0][0] == '/' && havhash) {
	    hshval1 = hash(hshval, i);
	    if (!bit(xhash, hshval1))
		goto cont;
	}
	if (pv[0][0] == 0 || eq(pv[0], STRdot))	/* don't make ./xxx */
	    texec(*av, av);
	else {
	    dp = Strspl(*pv, sav);
#ifdef VFORK
	    Vdp = dp;
#endif
	    texec(dp, av);
#ifdef VFORK
	    Vdp = 0;
#endif
	    xfree((ptr_t) dp);
	}
#ifdef VFORK
	misses++;
#endif
cont:
	pv++;
	i++;
    } while (*pv);
#ifdef VFORK
    hits--;
#endif
#ifdef VFORK
    Vsav = 0;
#endif
    xfree((ptr_t) sav);
    pexerr();
}

static void
pexerr()
{
    /* Couldn't find the damn thing */
    if (expath) {
	setname(short2str(expath));
#ifdef VFORK
	Vexpath = 0;
#endif
	xfree((ptr_t) expath);
	expath = 0;
    }
    else
	setname("");
    if (exerr)
	stderror(ERR_NAME | ERR_STRING, exerr);
    stderror(ERR_NAME | ERR_COMMAND);
}

/*
 * Execute command f, arg list t.
 * Record error message if not found.
 * Also do shell scripts here.
 */
static void
texec(sf, st)
    Char   *sf;
    register Char **st;
{
    register char **t;
    register char *f;
    register struct varent *v;
    register Char **vp;
    Char   *lastsh[2];
    int     fd;
    unsigned char c;
    Char   *st0, **ost;

    /* The order for the conversions is significant */
    t = short2blk(st);
    f = short2str(sf);
#ifdef VFORK
    Vt = t;
#endif
    errno = 0;			/* don't use a previous error */
#ifdef apollo
    /*
     * If we try to execute an nfs mounted directory on the apollo, we
     * hang forever. So until apollo fixes that..
     */
    {
	struct stat stb;
	if (stat(f, &stb) == 0 && S_ISDIR(stb.st_mode))
	    errno = EISDIR;
    }
    if (errno == 0)
#endif
    (void) execv(f, t);
#ifdef VFORK
    Vt = 0;
#endif
    blkfree((Char **) t);
    switch (errno) {

    case ENOEXEC:
	/*
	 * From: casper@fwi.uva.nl (Casper H.S. Dik) If we could not execute
	 * it, don't feed it to the shell if it looks like a binary!
	 */
	if ((fd = open(f, O_RDONLY)) != -1) {
	    if (read(fd, (char *) &c, 1) == 1) {
		if (!Isprint(c) && (c != '\n' && c != '\t')) {
		    (void) close(fd);
		    /*
		     * We *know* what ENOEXEC means.
		     */
		    stderror(ERR_ARCH, f, strerror(errno));
		}
	    }
#ifdef _PATH_BSHELL
	    else
		c = '#';
#endif
	    (void) close(fd);
	}
	/*
	 * If there is an alias for shell, then put the words of the alias in
	 * front of the argument list replacing the command name. Note no
	 * interpretation of the words at this point.
	 */
	v = adrof1(STRshell, &aliases);
	if (v == 0) {
	    vp = lastsh;
	    vp[0] = adrof(STRshell) ? value(STRshell) : STR_SHELLPATH;
	    vp[1] = NOSTR;
#ifdef _PATH_BSHELL
	    if (fd != -1 && c != '#')
		vp[0] = STR_BSHELL;
#endif
	}
	else
	    vp = v->vec;
	st0 = st[0];
	st[0] = sf;
	ost = st;
	st = blkspl(vp, st);	/* Splice up the new arglst */
	ost[0] = st0;
	sf = *st;
	/* The order for the conversions is significant */
	t = short2blk(st);
	f = short2str(sf);
	xfree((ptr_t) st);
#ifdef VFORK
	Vt = t;
#endif
	(void) execv(f, t);
#ifdef VFORK
	Vt = 0;
#endif
	blkfree((Char **) t);
	/* The sky is falling, the sky is falling! */

    case ENOMEM:
	stderror(ERR_SYSTEM, f, strerror(errno));

#ifdef _IBMR2
    case 0:			/* execv fails and returns 0! */
#endif				/* _IBMR2 */
    case ENOENT:
	break;

    default:
	if (exerr == 0) {
	    exerr = strerror(errno);
	    if (expath)
		xfree((ptr_t) expath);
	    expath = Strsave(sf);
#ifdef VFORK
	    Vexpath = expath;
#endif
	}
    }
}

/*ARGSUSED*/
void
execash(t, kp)
    char  **t;
    register struct command *kp;
{
    if (chkstop == 0 && setintr)
	panystop(0);
#ifdef notdef
    /*
     * Why we don't want to close SH* on exec? I think we do... Christos
     */
#ifndef FIOCLEX
    didcch = 1;
#endif
#endif				/* notdef */
    rechist();
    (void) signal(SIGINT, parintr);
    (void) signal(SIGQUIT, parintr);
    (void) signal(SIGTERM, parterm);	/* if doexec loses, screw */
    lshift(kp->t_dcom, 1);
    exiterr = 1;
    doexec(kp);
    /* NOTREACHED */
}

void
xechoit(t)
    Char  **t;
{
    if (adrof(STRecho)) {
	flush();
	haderr = 1;
	blkpr(t), xputchar('\n');
	haderr = 0;
    }
}

/*VARARGS0*/
void
dohash()
{
#ifdef COMMENT
    struct stat stb;
#endif
    DIR    *dirp;
    register struct dirent *dp;
    register int cnt;
    int     i = 0;
    struct varent *v = adrof(STRpath);
    Char  **pv;
    int     hshval;

    tw_clear_comm_list();
    havhash = 1;
    for (cnt = 0; cnt < sizeof xhash; cnt++)
	xhash[cnt] = 0;
    if (v == 0)
	return;
    for (pv = v->vec; *pv; pv++, i++) {
	if (pv[0][0] != '/')
	    continue;
	dirp = opendir(short2str(*pv));
	if (dirp == NULL)
	    continue;
#ifdef COMMENT			/* this isn't needed.  opendir won't open
				 * non-dirs */
	if (fstat(dirp->dd_fd, &stb) < 0 || !S_ISDIR(stb.st_mode)) {
	    (void) closedir(dirp);
	    continue;
	}
#endif
	while ((dp = readdir(dirp)) != NULL) {
	    if (dp->d_ino == 0)
		continue;
	    if (dp->d_name[0] == '.' &&
		(dp->d_name[1] == '\0' ||
		 dp->d_name[1] == '.' && dp->d_name[2] == '\0'))
		continue;
	    hshval = hash(hashname(str2short(dp->d_name)), i);
	    bis(xhash, hshval);
	    /* tw_comm_name_add (dp->d_name); */
	}
	(void) closedir(dirp);
    }
}

void
dounhash()
{
    havhash = 0;
}

#ifdef VFORK
void
hashstat()
{
    if (hits + misses)
	xprintf("%d hits, %d misses, %d%%\n",
		hits, misses, 100 * hits / (hits + misses));
}

#endif

/*
 * Hash a command name.
 */
static int
hashname(cp)
    register Char *cp;
{
    register long h = 0;

    while (*cp)
	h = hash(h, *cp++);
    return ((int) h);
}

int
iscommand(name)
    Char   *name;
{
    register Char **pv;
    register Char *sav;
    register struct varent *v;
    register bool slash = any(short2str(name), '/');
    register int hshval = 0, hshval1, i;

    v = adrof(STRpath);
    if (v == 0 || v->vec[0] == 0 || slash)
	pv = justabs;
    else
	pv = v->vec;
    sav = Strspl(STRslash, name);	/* / command name for postpending */
    if (havhash)
	hshval = hashname(name);
    i = 0;
    do {
	if (!slash && pv[0][0] == '/' && havhash) {
	    hshval1 = hash(hshval, i);
	    if (!bit(xhash, hshval1))
		goto cont;
	}
	if (pv[0][0] == 0 || eq(pv[0], STRdot)) {	/* don't make ./xxx */
	    if (executable(NULL, name, 0)) {
		xfree((ptr_t) sav);
		return i + 1;
	    }
	}
	else {
	    if (executable(*pv, sav, 0)) {
		xfree((ptr_t) sav);
		return i + 1;
	    }
	}
cont:
	pv++;
	i++;
    } while (*pv);
    xfree((ptr_t) sav);
    return 0;
}

/* Also by:
 *  Andreas Luik <luik@isaak.isa.de>
 *  I S A  GmbH - Informationssysteme fuer computerintegrierte Automatisierung
 *  Azenberstr. 35
 *  D-7000 Stuttgart 1
 *  West-Germany
 * is the executable() routine below and changes to iscommand().
 * Thanks again!!
 */

/*
 * executable() examines the pathname obtained by concatenating dir and name
 * (dir may be NULL), and returns 1 either if it is executable by us, or
 * if dir_ok is set and the pathname refers to a directory.
 * This is a bit kludgy, but in the name of optimization...
 */
int
executable(dir, name, dir_ok)
    Char   *dir, *name;
    bool    dir_ok;
{
    struct stat stbuf;
    Char    path[MAXPATHLEN + 1];
    char   *strname;

    if (dir && *dir) {
	copyn(path, dir, MAXPATHLEN);
	catn(path, name, MAXPATHLEN);
	strname = short2str(path);
    }
    else
	strname = short2str(name);
    return (stat(strname, &stbuf) != -1 &&
	    ((S_ISREG(stbuf.st_mode) &&
    /* save time by not calling access() in the hopeless case */
	      (stbuf.st_mode & (S_IXOTH | S_IXGRP | S_IXUSR)) &&
	      access(strname, X_OK) == 0) ||
	     (dir_ok && S_ISDIR(stbuf.st_mode))));
}

void
tellmewhat(lex)
    struct wordent *lex;
{
    register int i;
    register struct biltins *bptr;
    register struct wordent *sp = lex->next;
    bool    aliased = 0;
    Char   *s0, *s1, *s2;
    Char    qc;

    if (adrof1(sp->word, &aliases)) {
	alias(lex);
	sp = lex->next;
	aliased = 1;
    }

    s0 = sp->word;		/* to get the memory freeing right... */

    /* handle quoted alias hack */
    if ((*(sp->word) & (QUOTE | TRIM)) == QUOTE)
	(sp->word)++;

    /* do quoting, if it hasn't been done */
    s1 = s2 = sp->word;
    while (*s2)
	switch (*s2) {
	case '\'':
	case '"':
	    qc = *s2++;
	    while (*s2 && *s2 != qc)
		*s1++ = *s2++ | QUOTE;
	    if (*s2)
		s2++;
	    break;
	case '\\':
	    if (*++s2)
		*s1++ = *s2++ | QUOTE;
	    break;
	default:
	    *s1++ = *s2++;
	}
    *s1 = '\0';

    for (bptr = bfunc; bptr < &bfunc[nbfunc]; bptr++) {
	if (eq(sp->word, str2short(bptr->bname))) {
	    if (aliased)
		prlex(lex);
	    xprintf("%s: shell built-in command.\n", short2str(sp->word));
	    flush();
	    sp->word = s0;	/* we save and then restore this */
	    return;
	}
    }

    if (i = iscommand(strip(sp->word))) {
	register Char **pv;
	register struct varent *v;
	bool    slash = any(short2str(sp->word), '/');

	v = adrof(STRpath);
	if (v == 0 || v->vec[0] == 0 || slash)
	    pv = justabs;
	else
	    pv = v->vec;

	while (--i)
	    pv++;
	if (pv[0][0] == 0 || eq(pv[0], STRdot)) {
	    sp->word = Strspl(STRdt_l, sp->word);
	    prlex(lex);
	    xfree((ptr_t) sp->word);
	    sp->word = s0;	/* we save and then restore this */
	    return;
	}
	s1 = Strspl(*pv, STRslash);
	sp->word = Strspl(s1, sp->word);
	xfree((ptr_t) s1);
	prlex(lex);
	xfree((ptr_t) sp->word);
    }
    else {
	if (aliased)
	    prlex(lex);
	xprintf("%s: Command not found.\n", short2str(sp->word));
	flush();
    }
    sp->word = s0;		/* we save and then restore this */
}
