+/*-
+ * 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.
+ */
+
+#ifndef lint
+static char sccsid[] = "@(#)exec.c 5.17 (Berkeley) 6/17/91";
+#endif /* not lint */
+
+#include <sys/types.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#if __STDC__
+# include <stdarg.h>
+#else
+# include <varargs.h>
+#endif
+
+#include "csh.h"
+#include "extern.h"
+
+/*
+ * 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.
+ */
+extern char **environ;
+
+/*
+ * 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 */
+static int hits, misses;
+
+/* 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 hashval = 0, hashval1, 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]);
+ Vexpath = expath;
+
+ 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 */
+ /*
+ * 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;
+ /*
+ * We must do this AFTER any possible forking (like `foo` in glob) so that
+ * this shell can still do subprocesses.
+ */
+ (void) sigsetmask((sigset_t) 0);
+ /*
+ * 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 */
+ Vsav = sav;
+ if (havhash)
+ hashval = hashname(*av);
+ i = 0;
+ hits++;
+ 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) {
+ hashval1 = hash(hashval, i);
+ if (!bit(xhash, hashval1))
+ goto cont;
+ }
+ if (pv[0][0] == 0 || eq(pv[0], STRdot)) /* don't make ./xxx */
+ texec(*av, av);
+ else {
+ dp = Strspl(*pv, sav);
+ Vdp = dp;
+ texec(dp, av);
+ Vdp = 0;
+ xfree((ptr_t) dp);
+ }
+ misses++;
+cont:
+ pv++;
+ i++;
+ } while (*pv);
+ hits--;
+ Vsav = 0;
+ xfree((ptr_t) sav);
+ pexerr();
+}
+
+static void
+pexerr()
+{
+ /* Couldn't find the damn thing */
+ if (expath) {
+ setname(short2str(expath));
+ Vexpath = 0;
+ 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);
+ Vt = t;
+ errno = 0; /* don't use a previous error */
+ (void) execve(f, t, environ);
+ Vt = 0;
+ 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] = NULL;
+#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);
+ Vt = t;
+ (void) execve(f, t, environ);
+ Vt = 0;
+ blkfree((Char **) t);
+ /* The sky is falling, the sky is falling! */
+
+ case ENOMEM:
+ stderror(ERR_SYSTEM, f, strerror(errno));
+
+ case ENOENT:
+ break;
+
+ default:
+ if (exerr == 0) {
+ exerr = strerror(errno);
+ if (expath)
+ xfree((ptr_t) expath);
+ expath = Strsave(sf);
+ Vexpath = expath;
+ }
+ }
+}
+
+/*ARGSUSED*/
+void
+execash(t, kp)
+ char **t;
+ register struct command *kp;
+{
+ if (chkstop == 0 && setintr)
+ panystop(0);
+ 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()
+{
+ DIR *dirp;
+ register struct dirent *dp;
+ register int cnt;
+ int i = 0;
+ struct varent *v = adrof(STRpath);
+ Char **pv;
+ int hashval;
+
+ 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;
+ 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;
+ hashval = hash(hashname(str2short(dp->d_name)), i);
+ bis(xhash, hashval);
+ /* tw_add_comm_name (dp->d_name); */
+ }
+ (void) closedir(dirp);
+ }
+}
+
+void
+dounhash()
+{
+ havhash = 0;
+}
+
+void
+hashstat()
+{
+ if (hits + misses)
+ xprintf("%d hits, %d misses, %d%%\n",
+ hits, misses, 100 * hits / (hits + misses));
+}
+
+/*
+ * Hash a command name.
+ */
+static int
+hashname(cp)
+ register Char *cp;
+{
+ register long h = 0;
+
+ while (*cp)
+ h = hash(h, *cp++);
+ return ((int) h);
+}
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