source: trunk/src/kash/exec.c@ 2649

/*      $NetBSD: exec.c,v 1.37 2003/08/07 09:05:31 agc Exp $    */

/*-
 * 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.
 */

#if 0
#ifndef lint
static char sccsid[] = "@(#)exec.c      8.4 (Berkeley) 6/8/95";
#else
__RCSID("$NetBSD: exec.c,v 1.37 2003/08/07 09:05:31 agc Exp $");
#endif /* not lint */
#endif

#include <sys/types.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>

/*
 * When commands are first encountered, they are entered in a hash table.
 * This ensures that a full path search will not have to be done for them
 * on each invocation.
 *
 * We should investigate converting to a linear search, even though that
 * would make the command name "hash" a misnomer.
 */

#include "shell.h"
#include "main.h"
#include "nodes.h"
#include "parser.h"
#include "redir.h"
#include "eval.h"
#include "exec.h"
#include "builtins.h"
#include "var.h"
#include "options.h"
#include "input.h"
#include "output.h"
#include "syntax.h"
#include "memalloc.h"
#include "error.h"
#include "init.h"
#include "mystring.h"
#include "show.h"
#include "jobs.h"
#include "alias.h"
#ifdef __INNOTEK_LIBC__
#include <InnoTekLIBC/backend.h>
#endif
#include "shinstance.h"

//#define CMDTABLESIZE 31               /* should be prime */
//#define ARB 1                 /* actual size determined at run time */
//
//
//
//struct tblentry {
//      struct tblentry *next;  /* next entry in hash chain */
//      union param param;      /* definition of builtin function */
//      short cmdtype;          /* index identifying command */
//      char rehash;            /* if set, cd done since entry created */
//      char cmdname[ARB];      /* name of command */
//};
//
//
//STATIC struct tblentry *cmdtable[CMDTABLESIZE];
//STATIC int builtinloc = -1;           /* index in path of %builtin, or -1 */
//int exerrno = 0;                      /* Last exec error */


STATIC void tryexec(shinstance *, char *, char **, char **, int, int);
STATIC void execinterp(shinstance *, char **, char **);
STATIC void printentry(shinstance *, struct tblentry *, int);
STATIC void clearcmdentry(shinstance *, int);
STATIC struct tblentry *cmdlookup(shinstance *, const char *, int);
STATIC void delete_cmd_entry(shinstance *);
#ifdef PC_EXE_EXTS
STATIC int stat_pc_exec_exts(shinstance *, char *fullname, struct stat *st, int has_ext);
#endif


extern char *const parsekwd[];

/*
 * Exec a program.  Never returns.  If you change this routine, you may
 * have to change the find_command routine as well.
 */

SH_NORETURN_1 void
shellexec(shinstance *psh, char **argv, char **envp, const char *path, int idx, int vforked)
{
        char *cmdname;
        int e;
#ifdef PC_EXE_EXTS
        int has_ext = (int)strlen(argv[0]) - 4;
        has_ext = has_ext > 0
            && argv[0][has_ext] == '.'
            /* use strstr and upper/lower permuated extensions to avoid multiple strcasecmp calls. */
            && strstr("exe;" "Exe;" "EXe;" "EXE;" "ExE;" "eXe;" "eXE;" "exE;"
                      "cmd;" "Cmd;" "CMd;" "CMD;" "CmD;" "cMd;" "cMD;" "cmD;"
                      "com;" "Com;" "COm;" "COM;" "CoM;" "cOm;" "cOM;" "coM;"
                      "bat;" "Bat;" "BAt;" "BAT;" "BaT;" "bAt;" "bAT;" "baT;"
                      "btm;" "Btm;" "BTm;" "BTM;" "BtM;" "bTm;" "bTM;" "btM;",
                      argv[0] + has_ext + 1)
               != NULL;
#else
        const int has_ext = 1;
#endif
        TRACE((psh, "shellexec: argv[0]=%s idx=%d\n", argv[0], idx));
        if (strchr(argv[0], '/') != NULL) {
                cmdname = stalloc(psh, strlen(argv[0]) + 5);
                strcpy(cmdname, argv[0]);
                tryexec(psh, cmdname, argv, envp, vforked, has_ext);
                TRACE((psh, "shellexec: cmdname=%s\n", cmdname));
                stunalloc(psh, cmdname);
                e = errno;
        } else {
                e = ENOENT;
                while ((cmdname = padvance(psh, &path, argv[0])) != NULL) {
                        if (--idx < 0 && psh->pathopt == NULL) {
                                tryexec(psh, cmdname, argv, envp, vforked, has_ext);
                                if (errno != ENOENT && errno != ENOTDIR)
                                        e = errno;
                        }
                        stunalloc(psh, cmdname);
                }
        }

        /* Map to POSIX errors */
        switch (e) {
        case EACCES:
                psh->exerrno = 126;
                break;
        case ENOENT:
                psh->exerrno = 127;
                break;
        default:
                psh->exerrno = 2;
                break;
        }
        TRACE((psh, "shellexec failed for '%s', errno %d, vforked %d, suppressint %d\n",
                argv[0], e, vforked, psh->suppressint ));
        exerror(psh, EXEXEC, "%s: %s", argv[0], errmsg(psh, e, E_EXEC));
        /* NOTREACHED */
}


STATIC void
tryexec(shinstance *psh, char *cmd, char **argv, char **envp, int vforked, int has_ext)
{
        int e;
#ifdef EXEC_HASH_BANG_SCRIPT
        char *p;
#endif
#ifdef PC_EXE_EXTS
        /* exploit the effect of stat_pc_exec_exts which adds the
         * correct extentions to the file.
         */
        struct stat st;
        if (!has_ext)
            stat_pc_exec_exts(psh, cmd, &st, 0);
#endif
#if defined(__INNOTEK_LIBC__) && defined(EXEC_HASH_BANG_SCRIPT)
        __libc_Back_gfProcessHandleHashBangScripts = 0;
#endif

#ifdef SYSV
        do {
                sh_execve(psh, cmd, argv, envp);
        } while (errno == EINTR);
#else
        sh_execve(psh, cmd, (const char * const*)argv, (const char * const*)envp);
#endif
        e = errno;
        if (e == ENOEXEC) {
                if (vforked) {
                        /* We are currently vfork(2)ed, so raise an
                         * exception, and evalcommand will try again
                         * with a normal fork(2).
                         */
                        exraise(psh, EXSHELLPROC);
                }
                initshellproc(psh);
                setinputfile(psh, cmd, 0);
                psh->commandname = psh->arg0 = savestr(psh, argv[0]);
#ifdef EXEC_HASH_BANG_SCRIPT
                pgetc(psh); pungetc(psh);               /* fill up input buffer */
                p = psh->parsenextc;
                if (psh->parsenleft > 2 && p[0] == '#' && p[1] == '!') {
                        argv[0] = cmd;
                        execinterp(psh, argv, envp);
                }
#endif
                setparam(psh, argv + 1);
                exraise(psh, EXSHELLPROC);
        }
        errno = e;
}

#ifdef EXEC_HASH_BANG_SCRIPT

/*
 * Checks if NAME is the (base) name of the shell executable or something
 * very similar.
 */
STATIC int
is_shell_exe_name(const char *name)
{
    return equal(name, "kmk_ash")
        || equal(name, "kmk_sh")
        || equal(name, "kash")
        || equal(name, "sh");
}

/*
 * Execute an interpreter introduced by "#!", for systems where this
 * feature has not been built into the kernel.  If the interpreter is
 * the shell, return (effectively ignoring the "#!").  If the execution
 * of the interpreter fails, exit.
 *
 * This code peeks inside the input buffer in order to avoid actually
 * reading any input.  It would benefit from a rewrite.
 */

#define NEWARGS 16

STATIC void
execinterp(shinstance *psh, char **argv, char **envp)
{
        int n;
        char *inp;
        char *outp;
        char c;
        char *p;
        char **ap;
        char *newargs[NEWARGS];
        int i;
        char **ap2;
        char **new;

        n = psh->parsenleft - 2;
        inp = psh->parsenextc + 2;
        ap = newargs;
        for (;;) {
                while (--n >= 0 && (*inp == ' ' || *inp == '\t'))
                        inp++;
                if (n < 0)
                        goto bad;
                if ((c = *inp++) == '\n')
                        break;
                if (ap == &newargs[NEWARGS])
bad:              error(psh, "Bad #! line");
                STARTSTACKSTR(psh, outp);
                do {
                        STPUTC(psh, c, outp);
                } while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n');
                STPUTC(psh, '\0', outp);
                n++, inp--;
                *ap++ = grabstackstr(psh, outp);
        }

        /* Special optimizations / builtins. */
        i = ap - newargs;
        if (i > 1 && equal(newargs[0], "/usr/bin/env"))  {
                /* /usr/bin/env <self> -> easy. */
                if (i == 2 && is_shell_exe_name(newargs[1])) {
                    TRACE((psh, "hash bang /usr/bin/env self\n"));
                    return;
                }
                /** @todo implement simple /usr/bin/env that locates an exec in the PATH. */

        } else if (i == 1) { /* if no args, maybe shell and no exec is needed. */
                p = strrchr(newargs[0], '/');
                if (!p)
                        p = newargs[0];
                if (is_shell_exe_name(p)) {
                        TRACE((psh, "hash bang self\n"));
                        return;
                }
        }

        /* Combine the argument lists and exec. */
        i = (char *)ap - (char *)newargs;               /* size in bytes */
        if (i == 0)
                error(psh, "Bad #! line");
        for (ap2 = argv ; *ap2++ != NULL ; );
        new = ckmalloc(psh, i + ((char *)ap2 - (char *)argv));
        ap = newargs, ap2 = new;
        while ((i -= sizeof (char **)) >= 0)
                *ap2++ = *ap++;
        ap = argv;
        while ((*ap2++ = *ap++))
            /* nothing*/;
        TRACE((psh, "hash bang '%s'\n", new[0]));
        shellexec(psh, new, envp, pathval(psh), 0, 0);
        /* NOTREACHED */
}

#endif /* EXEC_HASH_BANG_SCRIPT */


/*
 * Do a path search.  The variable path (passed by reference) should be
 * set to the start of the path before the first call; padvance will update
 * this value as it proceeds.  Successive calls to padvance will return
 * the possible path expansions in sequence.  If an option (indicated by
 * a percent sign) appears in the path entry then the global variable
 * psh->pathopt will be set to point to it; otherwise psh->pathopt will be set to
 * NULL.
 */

//const char *pathopt;

char *
padvance(shinstance *psh, const char **path, const char *name)
{
        const char *p;
        char *q;
        const char *start;
        int len;

        if (*path == NULL)
                return NULL;
        start = *path;
#ifdef PC_PATH_SEP
        for (p = start ; *p && *p != ';' && *p != '%' ; p++);
#else
        for (p = start ; *p && *p != ':' && *p != '%' ; p++);
#endif
        len = (int)(p - start + strlen(name) + 2);      /* "2" is for '/' and '\0' */
#ifdef PC_EXE_EXTS
        len += 4; /* "4" is for .exe/.com/.cmd/.bat/.btm */
#endif
        while (stackblocksize(psh) < len)
                growstackblock(psh);
        q = stackblock(psh);
        if (p != start) {
                memcpy(q, start, p - start);
                q += p - start;
                *q++ = '/';
        }
        strcpy(q, name);
        psh->pathopt = NULL;
        if (*p == '%') {
                psh->pathopt = ++p;
#ifdef PC_PATH_SEP
                while (*p && *p != ';')  p++;
#else
                while (*p && *p != ':')  p++;
#endif
        }
#ifdef PC_PATH_SEP
        if (*p == ';')
#else
        if (*p == ':')
#endif
                *path = p + 1;
        else
                *path = NULL;
        return stalloc(psh, len);
}


#ifdef PC_EXE_EXTS
STATIC int stat_pc_exec_exts(shinstance *psh, char *fullname, struct stat *st, int has_ext)
{
    /* skip the SYSV crap */
    if (shfile_stat(&psh->fdtab, fullname, st) >= 0)
        return 0;
    if (!has_ext && errno == ENOENT)
    {
        char *psz = strchr(fullname, '\0');
        memcpy(psz, ".exe", 5);
        if (shfile_stat(&psh->fdtab, fullname, st) >= 0)
            return 0;
        if (errno != ENOENT && errno != ENOTDIR)
            return -1;

        memcpy(psz, ".cmd", 5);
        if (shfile_stat(&psh->fdtab, fullname, st) >= 0)
            return 0;
        if (errno != ENOENT && errno != ENOTDIR)
            return -1;

        memcpy(psz, ".bat", 5);
        if (shfile_stat(&psh->fdtab, fullname, st) >= 0)
            return 0;
        if (errno != ENOENT && errno != ENOTDIR)
            return -1;

        memcpy(psz, ".com", 5);
        if (shfile_stat(&psh->fdtab, fullname, st) >= 0)
            return 0;
        if (errno != ENOENT && errno != ENOTDIR)
            return -1;

        memcpy(psz, ".btm", 5);
        if (shfile_stat(&psh->fdtab, fullname, st) >= 0)
            return 0;
        *psz = '\0';
    }
    return -1;
}
#endif /* PC_EXE_EXTS */



/*** Command hashing code ***/


int
hashcmd(shinstance *psh, int argc, char **argv)
{
        struct tblentry **pp;
        struct tblentry *cmdp;
        int c;
        int verbose;
        struct cmdentry entry;
        char *name;

        verbose = 0;
        while ((c = nextopt(psh, "rv")) != '\0') {
                if (c == 'r') {
                        clearcmdentry(psh, 0);
                } else if (c == 'v') {
                        verbose++;
                }
        }
        if (*psh->argptr == NULL) {
                for (pp = psh->cmdtable ; pp < &psh->cmdtable[CMDTABLESIZE] ; pp++) {
                        for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
                                if (verbose || cmdp->cmdtype == CMDNORMAL)
                                        printentry(psh, cmdp, verbose);
                        }
                }
                return 0;
        }
        while ((name = *psh->argptr) != NULL) {
                if ((cmdp = cmdlookup(psh, name, 0)) != NULL
                 && (cmdp->cmdtype == CMDNORMAL
                     || (cmdp->cmdtype == CMDBUILTIN && psh->builtinloc >= 0)))
                        delete_cmd_entry(psh);
                find_command(psh, name, &entry, DO_ERR, pathval(psh));
                if (verbose) {
                        if (entry.cmdtype != CMDUNKNOWN) {      /* if no error msg */
                                cmdp = cmdlookup(psh, name, 0);
                                printentry(psh, cmdp, verbose);
                        }
                        output_flushall(psh);
                }
                psh->argptr++;
        }
        return 0;
}


STATIC void
printentry(shinstance *psh, struct tblentry *cmdp, int verbose)
{
        int idx;
        const char *path;
        char *name;

        switch (cmdp->cmdtype) {
        case CMDNORMAL:
                idx = cmdp->param.index;
                path = pathval(psh);
                do {
                        name = padvance(psh, &path, cmdp->cmdname);
                        stunalloc(psh, name);
                } while (--idx >= 0);
                out1str(psh, name);
                break;
        case CMDSPLBLTIN:
                out1fmt(psh, "special builtin %s", cmdp->cmdname);
                break;
        case CMDBUILTIN:
                out1fmt(psh, "builtin %s", cmdp->cmdname);
                break;
        case CMDFUNCTION:
                out1fmt(psh, "function %s", cmdp->cmdname);
                if (verbose) {
                        struct procstat ps;
                        INTOFF;
                        commandtext(psh, &ps, cmdp->param.func);
                        INTON;
                        out1str(psh, "() { ");
                        out1str(psh, ps.cmd);
                        out1str(psh, "; }");
                }
                break;
        default:
                error(psh, "internal error: %s cmdtype %d", cmdp->cmdname, cmdp->cmdtype);
        }
        if (cmdp->rehash)
                out1c(psh, '*');
        out1c(psh, '\n');
}



/*
 * Resolve a command name.  If you change this routine, you may have to
 * change the shellexec routine as well.
 */

void
find_command(shinstance *psh, char *name, struct cmdentry *entry, int act, const char *path)
{
        struct tblentry *cmdp, loc_cmd;
        int idx;
        int prev;
        char *fullname;
        struct stat statb;
        int e;
        int (*bltin)(shinstance*,int,char **);

#ifdef PC_EXE_EXTS
        int has_ext = (int)(strlen(name) - 4);
        has_ext = has_ext > 0
            && name[has_ext] == '.'
            /* use strstr and upper/lower permuated extensions to avoid multiple strcasecmp calls. */
            && strstr("exe;" "Exe;" "EXe;" "EXE;" "ExE;" "eXe;" "eXE;" "exE;"
                      "cmd;" "Cmd;" "CMd;" "CMD;" "CmD;" "cMd;" "cMD;" "cmD;"
                      "com;" "Com;" "COm;" "COM;" "CoM;" "cOm;" "cOM;" "coM;"
                      "bat;" "Bat;" "BAt;" "BAT;" "BaT;" "bAt;" "bAT;" "baT;"
                      "btm;" "Btm;" "BTm;" "BTM;" "BtM;" "bTm;" "bTM;" "btM;",
                      name + has_ext + 1)
               != NULL;
#endif

        /* If name contains a slash, don't use PATH or hash table */
        if (strchr(name, '/') != NULL) {
                if (act & DO_ABS) {
                        while (shfile_stat(&psh->fdtab, name, &statb) < 0) {
#ifdef SYSV
                                if (errno == EINTR)
                                        continue;
#endif
                                if (errno != ENOENT && errno != ENOTDIR)
                                        e = errno;
                                entry->cmdtype = CMDUNKNOWN;
                                entry->u.index = -1;
                                return;
                        }
                        entry->cmdtype = CMDNORMAL;
                        entry->u.index = -1;
                        return;
                }
                entry->cmdtype = CMDNORMAL;
                entry->u.index = 0;
                return;
        }

        if (path != pathval(psh))
                act |= DO_ALTPATH;

        if (act & DO_ALTPATH && strstr(path, "%builtin") != NULL)
                act |= DO_ALTBLTIN;

        /* If name is in the table, check answer will be ok */
        if ((cmdp = cmdlookup(psh, name, 0)) != NULL) {
                do {
                        switch (cmdp->cmdtype) {
                        case CMDNORMAL:
                                if (act & DO_ALTPATH) {
                                        cmdp = NULL;
                                        continue;
                                }
                                break;
                        case CMDFUNCTION:
                                if (act & DO_NOFUNC) {
                                        cmdp = NULL;
                                        continue;
                                }
                                break;
                        case CMDBUILTIN:
                                if ((act & DO_ALTBLTIN) || psh->builtinloc >= 0) {
                                        cmdp = NULL;
                                        continue;
                                }
                                break;
                        }
                        /* if not invalidated by cd, we're done */
                        if (cmdp->rehash == 0)
                                goto success;
                } while (0);
        }

        /* If %builtin not in path, check for builtin next */
        if ((act & DO_ALTPATH ? !(act & DO_ALTBLTIN) : psh->builtinloc < 0) &&
            (bltin = find_builtin(psh, name)) != 0)
                goto builtin_success;

        /* We have to search path. */
        prev = -1;              /* where to start */
        if (cmdp) {             /* doing a rehash */
                if (cmdp->cmdtype == CMDBUILTIN)
                        prev = psh->builtinloc;
                else
                        prev = cmdp->param.index;
        }

        e = ENOENT;
        idx = -1;
loop:
        while ((fullname = padvance(psh, &path, name)) != NULL) {
                stunalloc(psh, fullname);
                idx++;
                if (psh->pathopt) {
                        if (prefix("builtin", psh->pathopt)) {
                                if ((bltin = find_builtin(psh, name)) == 0)
                                        goto loop;
                                goto builtin_success;
                        } else if (prefix("func", psh->pathopt)) {
                                /* handled below */
                        } else {
                                /* ignore unimplemented options */
                                goto loop;
                        }
                }
                /* if rehash, don't redo absolute path names */
                if (fullname[0] == '/' && idx <= prev) {
                        if (idx < prev)
                                goto loop;
                        TRACE((psh, "searchexec \"%s\": no change\n", name));
                        goto success;
                }
#ifdef PC_EXE_EXTS
                while (stat_pc_exec_exts(psh, fullname, &statb, has_ext) < 0) {
#else
                while (shfile_stat(&psh->fdtab, fullname, &statb) < 0) {
#endif
#ifdef SYSV
                        if (errno == EINTR)
                                continue;
#endif
                        if (errno != ENOENT && errno != ENOTDIR)
                                e = errno;

                        goto loop;
                }
                e = EACCES;     /* if we fail, this will be the error */
                if (!S_ISREG(statb.st_mode))
                        goto loop;
                if (psh->pathopt) {             /* this is a %func directory */
                        if (act & DO_NOFUNC)
                                goto loop;
                        stalloc(psh, strlen(fullname) + 1);
                        readcmdfile(psh, fullname);
                        if ((cmdp = cmdlookup(psh, name, 0)) == NULL ||
                            cmdp->cmdtype != CMDFUNCTION)
                                error(psh, "%s not defined in %s", name, fullname);
                        stunalloc(psh, fullname);
                        goto success;
                }
#ifdef notdef
                /* XXX this code stops root executing stuff, and is buggy
                   if you need a group from the group list. */
                if (statb.st_uid == sh_geteuid(psh)) {
                        if ((statb.st_mode & 0100) == 0)
                                goto loop;
                } else if (statb.st_gid == sh_getegid(psh)) {
                        if ((statb.st_mode & 010) == 0)
                                goto loop;
                } else {
                        if ((statb.st_mode & 01) == 0)
                                goto loop;
                }
#endif
                TRACE((psh, "searchexec \"%s\" returns \"%s\"\n", name, fullname));
                INTOFF;
                if (act & DO_ALTPATH) {
                        stalloc(psh, strlen(fullname) + 1);
                        cmdp = &loc_cmd;
                } else
                        cmdp = cmdlookup(psh, name, 1);
                cmdp->cmdtype = CMDNORMAL;
                cmdp->param.index = idx;
                INTON;
                goto success;
        }

        /* We failed.  If there was an entry for this command, delete it */
        if (cmdp)
                delete_cmd_entry(psh);
        if (act & DO_ERR)
                outfmt(psh->out2, "%s: %s\n", name, errmsg(psh, e, E_EXEC));
        entry->cmdtype = CMDUNKNOWN;
        return;

builtin_success:
        INTOFF;
        if (act & DO_ALTPATH)
                cmdp = &loc_cmd;
        else
                cmdp = cmdlookup(psh, name, 1);
        if (cmdp->cmdtype == CMDFUNCTION)
                /* DO_NOFUNC must have been set */
                cmdp = &loc_cmd;
        cmdp->cmdtype = CMDBUILTIN;
        cmdp->param.bltin = bltin;
        INTON;
success:
        cmdp->rehash = 0;
        entry->cmdtype = cmdp->cmdtype;
        entry->u = cmdp->param;
}



/*
 * Search the table of builtin commands.
 */

int
(*find_builtin(shinstance *psh, char *name))(shinstance *psh, int, char **)
{
        const struct builtincmd *bp;

        for (bp = builtincmd ; bp->name ; bp++) {
                if (*bp->name == *name && equal(bp->name, name))
                        return bp->builtin;
        }
        return 0;
}

int
(*find_splbltin(shinstance *psh, char *name))(shinstance *psh, int, char **)
{
        const struct builtincmd *bp;

        for (bp = splbltincmd ; bp->name ; bp++) {
                if (*bp->name == *name && equal(bp->name, name))
                        return bp->builtin;
        }
        return 0;
}

/*
 * At shell startup put special builtins into hash table.
 * ensures they are executed first (see posix).
 * We stop functions being added with the same name
 * (as they are impossible to call)
 */

void
hash_special_builtins(shinstance *psh)
{
        const struct builtincmd *bp;
        struct tblentry *cmdp;

        for (bp = splbltincmd ; bp->name ; bp++) {
                cmdp = cmdlookup(psh, bp->name, 1);
                cmdp->cmdtype = CMDSPLBLTIN;
                cmdp->param.bltin = bp->builtin;
        }
}



/*
 * Called when a cd is done.  Marks all commands so the next time they
 * are executed they will be rehashed.
 */

void
hashcd(shinstance *psh)
{
        struct tblentry **pp;
        struct tblentry *cmdp;

        for (pp = psh->cmdtable ; pp < &psh->cmdtable[CMDTABLESIZE] ; pp++) {
                for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
                        if (cmdp->cmdtype == CMDNORMAL
                         || (cmdp->cmdtype == CMDBUILTIN && psh->builtinloc >= 0))
                                cmdp->rehash = 1;
                }
        }
}



/*
 * Fix command hash table when PATH changed.
 * Called before PATH is changed.  The argument is the new value of PATH;
 * pathval(psh) still returns the old value at this point.
 * Called with interrupts off.
 */

void
changepath(shinstance *psh, const char *newval)
{
        const char *old, *new;
        int idx;
        int firstchange;
        int bltin;

        old = pathval(psh);
        new = newval;
        firstchange = 9999;     /* assume no change */
        idx = 0;
        bltin = -1;
        for (;;) {
                if (*old != *new) {
                        firstchange = idx;
#ifdef PC_PATH_SEP
                        if ((*old == '\0' && *new == ';')
                         || (*old == ';' && *new == '\0'))
#else
                        if ((*old == '\0' && *new == ':')
                         || (*old == ':' && *new == '\0'))
#endif
                                firstchange++;
                        old = new;      /* ignore subsequent differences */
                }
                if (*new == '\0')
                        break;
                if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
                        bltin = idx;
#ifdef PC_PATH_SEP
                if (*new == ';') {
#else
                if (*new == ':') {
#endif
                        idx++;
                }
                new++, old++;
        }
        if (psh->builtinloc < 0 && bltin >= 0)
                psh->builtinloc = bltin;                /* zap builtins */
        if (psh->builtinloc >= 0 && bltin < 0)
                firstchange = 0;
        clearcmdentry(psh, firstchange);
        psh->builtinloc = bltin;
}


/*
 * Clear out command entries.  The argument specifies the first entry in
 * PATH which has changed.
 */

STATIC void
clearcmdentry(shinstance *psh, int firstchange)
{
        struct tblentry **tblp;
        struct tblentry **pp;
        struct tblentry *cmdp;

        INTOFF;
        for (tblp = psh->cmdtable ; tblp < &psh->cmdtable[CMDTABLESIZE] ; tblp++) {
                pp = tblp;
                while ((cmdp = *pp) != NULL) {
                        if ((cmdp->cmdtype == CMDNORMAL &&
                             cmdp->param.index >= firstchange)
                         || (cmdp->cmdtype == CMDBUILTIN &&
                             psh->builtinloc >= firstchange)) {
                                *pp = cmdp->next;
                                ckfree(psh, cmdp);
                        } else {
                                pp = &cmdp->next;
                        }
                }
        }
        INTON;
}


/*
 * Delete all functions.
 */

#ifdef mkinit
MKINIT void deletefuncs(struct shinstance *);
MKINIT void hash_special_builtins(struct shinstance *);

INIT {
        hash_special_builtins(psh);
}

SHELLPROC {
        deletefuncs(psh);
}
#endif

void
deletefuncs(shinstance *psh)
{
        struct tblentry **tblp;
        struct tblentry **pp;
        struct tblentry *cmdp;

        INTOFF;
        for (tblp = psh->cmdtable ; tblp < &psh->cmdtable[CMDTABLESIZE] ; tblp++) {
                pp = tblp;
                while ((cmdp = *pp) != NULL) {
                        if (cmdp->cmdtype == CMDFUNCTION) {
                                *pp = cmdp->next;
                                freefunc(psh, cmdp->param.func);
                                ckfree(psh, cmdp);
                        } else {
                                pp = &cmdp->next;
                        }
                }
        }
        INTON;
}



/*
 * Locate a command in the command hash table.  If "add" is nonzero,
 * add the command to the table if it is not already present.  The
 * variable "lastcmdentry" is set to point to the address of the link
 * pointing to the entry, so that delete_cmd_entry can delete the
 * entry.
 */

struct tblentry **lastcmdentry;


STATIC struct tblentry *
cmdlookup(shinstance *psh, const char *name, int add)
{
        int hashval;
        const char *p;
        struct tblentry *cmdp;
        struct tblentry **pp;

        p = name;
        hashval = *p << 4;
        while (*p)
                hashval += *p++;
        hashval &= 0x7FFF;
        pp = &psh->cmdtable[hashval % CMDTABLESIZE];
        for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
                if (equal(cmdp->cmdname, name))
                        break;
                pp = &cmdp->next;
        }
        if (add && cmdp == NULL) {
                INTOFF;
                cmdp = *pp = ckmalloc(psh, sizeof (struct tblentry) - ARB
                                        + strlen(name) + 1);
                cmdp->next = NULL;
                cmdp->cmdtype = CMDUNKNOWN;
                cmdp->rehash = 0;
                strcpy(cmdp->cmdname, name);
                INTON;
        }
        lastcmdentry = pp;
        return cmdp;
}

/*
 * Delete the command entry returned on the last lookup.
 */

STATIC void
delete_cmd_entry(shinstance *psh)
{
        struct tblentry *cmdp;

        INTOFF;
        cmdp = *lastcmdentry;
        *lastcmdentry = cmdp->next;
        ckfree(psh, cmdp);
        INTON;
}



#ifdef notdef
void
getcmdentry(shinstance *psh, char *name, struct cmdentry *entry)
{
        struct tblentry *cmdp = cmdlookup(psh, name, 0);

        if (cmdp) {
                entry->u = cmdp->param;
                entry->cmdtype = cmdp->cmdtype;
        } else {
                entry->cmdtype = CMDUNKNOWN;
                entry->u.index = 0;
        }
}
#endif


/*
 * Add a new command entry, replacing any existing command entry for
 * the same name - except special builtins.
 */

STATIC void
addcmdentry(shinstance *psh, char *name, struct cmdentry *entry)
{
        struct tblentry *cmdp;

        INTOFF;
        cmdp = cmdlookup(psh, name, 1);
        if (cmdp->cmdtype != CMDSPLBLTIN) {
                if (cmdp->cmdtype == CMDFUNCTION) {
                        freefunc(psh, cmdp->param.func);
                }
                cmdp->cmdtype = entry->cmdtype;
                cmdp->param = entry->u;
        }
        INTON;
}


/*
 * Define a shell function.
 */

void
defun(shinstance *psh, char *name, union node *func)
{
        struct cmdentry entry;

        INTOFF;
        entry.cmdtype = CMDFUNCTION;
        entry.u.func = copyfunc(psh, func);
        addcmdentry(psh, name, &entry);
        INTON;
}


/*
 * Delete a function if it exists.
 */

int
unsetfunc(shinstance *psh, char *name)
{
        struct tblentry *cmdp;

        if ((cmdp = cmdlookup(psh, name, 0)) != NULL &&
            cmdp->cmdtype == CMDFUNCTION) {
                freefunc(psh, cmdp->param.func);
                delete_cmd_entry(psh);
                return (0);
        }
        return (1);
}

/*
 * Locate and print what a word is...
 * also used for 'command -[v|V]'
 */

int
typecmd(shinstance *psh, int argc, char **argv)
{
        struct cmdentry entry;
        struct tblentry *cmdp;
        char * const *pp;
        struct alias *ap;
        int err = 0;
        char *arg;
        int c;
        int V_flag = 0;
        int v_flag = 0;
        int p_flag = 0;

        while ((c = nextopt(psh, "vVp")) != 0) {
                switch (c) {
                case 'v': v_flag = 1; break;
                case 'V': V_flag = 1; break;
                case 'p': p_flag = 1; break;
                }
        }

        if (p_flag && (v_flag || V_flag))
                error(psh, "cannot specify -p with -v or -V");

        while ((arg = *psh->argptr++)) {
                if (!v_flag)
                        out1str(psh, arg);
                /* First look at the keywords */
                for (pp = parsekwd; *pp; pp++)
                        if (**pp == *arg && equal(*pp, arg))
                                break;

                if (*pp) {
                        if (v_flag)
                                err = 1;
                        else
                                out1str(psh, " is a shell keyword\n");
                        continue;
                }

                /* Then look at the aliases */
                if ((ap = lookupalias(psh, arg, 1)) != NULL) {
                        if (!v_flag)
                                out1fmt(psh, " is an alias for \n");
                        out1fmt(psh, "%s\n", ap->val);
                        continue;
                }

                /* Then check if it is a tracked alias */
                if ((cmdp = cmdlookup(psh, arg, 0)) != NULL) {
                        entry.cmdtype = cmdp->cmdtype;
                        entry.u = cmdp->param;
                } else {
                        /* Finally use brute force */
                        find_command(psh, arg, &entry, DO_ABS, pathval(psh));
                }

                switch (entry.cmdtype) {
                case CMDNORMAL: {
                        if (strchr(arg, '/') == NULL) {
                                const char *path = pathval(psh);
                                char *name;
                                int j = entry.u.index;
                                do {
                                        name = padvance(psh, &path, arg);
                                        stunalloc(psh, name);
                                } while (--j >= 0);
                                if (!v_flag)
                                        out1fmt(psh, " is%s ",
                                            cmdp ? " a tracked alias for" : "");
                                out1fmt(psh, "%s\n", name);
                        } else {
                                if (shfile_access(&psh->fdtab, arg, X_OK) == 0) {
                                        if (!v_flag)
                                                out1fmt(psh, " is ");
                                        out1fmt(psh, "%s\n", arg);
                                } else {
                                        if (!v_flag)
                                                out1fmt(psh, ": %s\n",
                                                    sh_strerror(psh, errno));
                                        else
                                                err = 126;
                                }
                        }
                        break;
                }
                case CMDFUNCTION:
                        if (!v_flag)
                                out1str(psh, " is a shell function\n");
                        else
                                out1fmt(psh, "%s\n", arg);
                        break;

                case CMDBUILTIN:
                        if (!v_flag)
                                out1str(psh, " is a shell builtin\n");
                        else
                                out1fmt(psh, "%s\n", arg);
                        break;

                case CMDSPLBLTIN:
                        if (!v_flag)
                                out1str(psh, " is a special shell builtin\n");
                        else
                                out1fmt(psh, "%s\n", arg);
                        break;

                default:
                        if (!v_flag)
                                out1str(psh, ": not found\n");
                        err = 127;
                        break;
                }
        }
        return err;
}