usr/dash/exec.c

/*-
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1997-2005
 *	Herbert Xu <herbert@gondor.apana.org.au>.  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.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <paths.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 "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"
#include "system.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 */


STATIC void tryexec(char *, char **, char **);
STATIC void printentry(struct tblentry *);
STATIC void clearcmdentry(int);
STATIC struct tblentry *cmdlookup(const char *, int);
STATIC void delete_cmd_entry(void);
STATIC void addcmdentry(char *, struct cmdentry *);
STATIC int describe_command(struct output *, char *, int);


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

void
shellexec(char **argv, const char *path, int idx)
{
	char *cmdname;
	int e;
	char **envp;
	int exerrno;

	clearredir(1);
	envp = environment();
	if (strchr(argv[0], '/') != NULL) {
		tryexec(argv[0], argv, envp);
		e = errno;
	} else {
		e = ENOENT;
		while ((cmdname = padvance(&path, argv[0])) != NULL) {
			if (--idx < 0 && pathopt == NULL) {
				tryexec(cmdname, argv, envp);
				if (errno != ENOENT && errno != ENOTDIR)
					e = errno;
			}
			stunalloc(cmdname);
		}
	}

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


STATIC void
tryexec(char *cmd, char **argv, char **envp)
{
	int repeated = 0;
#if !defined(BSD) && !defined(linux)
	char *p;
#endif

repeat:
#ifdef SYSV
	do {
		execve(cmd, argv, envp);
	} while (errno == EINTR);
#else
	execve(cmd, argv, envp);
#endif
	if (repeated++) {
		ckfree(argv);
	} else if (errno == ENOEXEC) {
		char **ap;
		char **new;

		for (ap = argv; *ap; ap++)
			;
		ap = new = ckmalloc((ap - argv + 2) * sizeof(char *));
		*ap++ = cmd = _PATH_BSHELL;
		while ((*ap++ = *argv++))
			;
		argv = new;
		goto repeat;
	}
}


/*
 * 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
 * pathopt will be set to point to it; otherwise pathopt will be set to
 * NULL.
 */

const char *pathopt;

char *
padvance(const char **path, const char *name)
{
	const char *p;
	char *q;
	const char *start;
	size_t len;

	if (*path == NULL)
		return NULL;
	start = *path;
	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
	while (stackblocksize() < len)
		growstackblock();
	q = stackblock();
	if (p != start) {
		memcpy(q, start, p - start);
		q += p - start;
		*q++ = '/';
	}
	strcpy(q, name);
	pathopt = NULL;
	if (*p == '%') {
		pathopt = ++p;
		while (*p && *p != ':')  p++;
	}
	if (*p == ':')
		*path = p + 1;
	else
		*path = NULL;
	return stalloc(len);
}


/*** Command hashing code ***/


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

	while ((c = nextopt("r")) != '\0') {
		clearcmdentry(0);
		return 0;
	}
	if (*argptr == NULL) {
		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
				if (cmdp->cmdtype == CMDNORMAL)
					printentry(cmdp);
			}
		}
		return 0;
	}
	c = 0;
	while ((name = *argptr) != NULL) {
		if ((cmdp = cmdlookup(name, 0)) != NULL
		 && (cmdp->cmdtype == CMDNORMAL
		     || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
			delete_cmd_entry();
		find_command(name, &entry, DO_ERR, pathval());
		if (entry.cmdtype == CMDUNKNOWN)
			c = 1;
		argptr++;
	}
	return c;
}


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

	idx = cmdp->param.index;
	path = pathval();
	do {
		name = padvance(&path, cmdp->cmdname);
		stunalloc(name);
	} while (--idx >= 0);
	out1str(name);
	out1fmt(snlfmt, cmdp->rehash ? "*" : nullstr);
}


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

void
find_command(char *name, struct cmdentry *entry, int act, const char *path)
{
	struct tblentry *cmdp;
	int idx;
	int prev;
	char *fullname;
	struct stat64 statb;
	int e;
	int updatetbl;
	struct builtincmd *bcmd;

	/* If name contains a slash, don't use PATH or hash table */
	if (strchr(name, '/') != NULL) {
		entry->u.index = -1;
		if (act & DO_ABS) {
			while (stat64(name, &statb) < 0) {
#ifdef SYSV
				if (errno == EINTR)
					continue;
#endif
				entry->cmdtype = CMDUNKNOWN;
				return;
			}
		}
		entry->cmdtype = CMDNORMAL;
		return;
	}

	updatetbl = (path == pathval());
	if (!updatetbl) {
		act |= DO_ALTPATH;
		if (strstr(path, "%builtin") != NULL)
			act |= DO_ALTBLTIN;
	}

	/* If name is in the table, check answer will be ok */
	if ((cmdp = cmdlookup(name, 0)) != NULL) {
		int bit;

		switch (cmdp->cmdtype) {
		default:
#if DEBUG
			abort();
#endif
		case CMDNORMAL:
			bit = DO_ALTPATH;
			break;
		case CMDFUNCTION:
			bit = DO_NOFUNC;
			break;
		case CMDBUILTIN:
			bit = DO_ALTBLTIN;
			break;
		}
		if (act & bit) {
			updatetbl = 0;
			cmdp = NULL;
		} else if (cmdp->rehash == 0)
			/* if not invalidated by cd, we're done */
			goto success;
	}

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

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

	e = ENOENT;
	idx = -1;
loop:
	while ((fullname = padvance(&path, name)) != NULL) {
		stunalloc(fullname);
		idx++;
		if (pathopt) {
			if (prefix(pathopt, "builtin")) {
				if (bcmd)
					goto builtin_success;
				continue;
			} else if (!(act & DO_NOFUNC) &&
				   prefix(pathopt, "func")) {
				/* handled below */
			} else {
				/* ignore unimplemented options */
				continue;
			}
		}
		/* if rehash, don't redo absolute path names */
		if (fullname[0] == '/' && idx <= prev) {
			if (idx < prev)
				continue;
			TRACE(("searchexec \"%s\": no change\n", name));
			goto success;
		}
		while (stat64(fullname, &statb) < 0) {
#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))
			continue;
		if (pathopt) {		/* this is a %func directory */
			stalloc(strlen(fullname) + 1);
			readcmdfile(fullname);
			if ((cmdp = cmdlookup(name, 0)) == NULL ||
			    cmdp->cmdtype != CMDFUNCTION)
				sh_error("%s not defined in %s", name,
					 fullname);
			stunalloc(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 == geteuid()) {
			if ((statb.st_mode & 0100) == 0)
				goto loop;
		} else if (statb.st_gid == getegid()) {
			if ((statb.st_mode & 010) == 0)
				goto loop;
		} else {
			if ((statb.st_mode & 01) == 0)
				goto loop;
		}
#endif
		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
		if (!updatetbl) {
			entry->cmdtype = CMDNORMAL;
			entry->u.index = idx;
			return;
		}
		INTOFF;
		cmdp = cmdlookup(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 && updatetbl)
		delete_cmd_entry();
	if (act & DO_ERR)
		sh_warnx("%s: %s", name, errmsg(e, E_EXEC));
	entry->cmdtype = CMDUNKNOWN;
	return;

builtin_success:
	if (!updatetbl) {
		entry->cmdtype = CMDBUILTIN;
		entry->u.cmd = bcmd;
		return;
	}
	INTOFF;
	cmdp = cmdlookup(name, 1);
	cmdp->cmdtype = CMDBUILTIN;
	cmdp->param.cmd = bcmd;
	INTON;
success:
	cmdp->rehash = 0;
	entry->cmdtype = cmdp->cmdtype;
	entry->u = cmdp->param;
}


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

struct builtincmd *
find_builtin(const char *name)
{
	struct builtincmd *bp;

	bp = bsearch(
		&name, builtincmd, NUMBUILTINS, sizeof(struct builtincmd),
		pstrcmp
	);
	return bp;
}


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

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

	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
			if (cmdp->cmdtype == CMDNORMAL || (
				cmdp->cmdtype == CMDBUILTIN &&
				!(cmdp->param.cmd->flags & BUILTIN_REGULAR) &&
				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() still returns the old value at this point.
 * Called with interrupts off.
 */

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

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


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

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

	INTOFF;
	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
		pp = tblp;
		while ((cmdp = *pp) != NULL) {
			if ((cmdp->cmdtype == CMDNORMAL &&
			     cmdp->param.index >= firstchange)
			 || (cmdp->cmdtype == CMDBUILTIN &&
			     builtinloc >= firstchange)) {
				*pp = cmdp->next;
				ckfree(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.
 *
 * Interrupts must be off if called with add != 0.
 */

struct tblentry **lastcmdentry;


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

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

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

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

	INTOFF;
	cmdp = *lastcmdentry;
	*lastcmdentry = cmdp->next;
	if (cmdp->cmdtype == CMDFUNCTION)
		freefunc(cmdp->param.func);
	ckfree(cmdp);
	INTON;
}


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

	cmdp = cmdlookup(name, 1);
	if (cmdp->cmdtype == CMDFUNCTION) {
		freefunc(cmdp->param.func);
	}
	cmdp->cmdtype = entry->cmdtype;
	cmdp->param = entry->u;
	cmdp->rehash = 0;
}


/*
 * Define a shell function.
 */

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

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


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

void
unsetfunc(const char *name)
{
	struct tblentry *cmdp;

	if ((cmdp = cmdlookup(name, 0)) != NULL &&
	    cmdp->cmdtype == CMDFUNCTION)
		delete_cmd_entry();
}

/*
 * Locate and print what a word is...
 */

int
typecmd(int argc, char **argv)
{
	int i;
	int err = 0;

	for (i = 1; i < argc; i++) {
		err |= describe_command(out1, argv[i], 1);
	}
	return err;
}

STATIC int
describe_command(out, command, verbose)
	struct output *out;
	char *command;
	int verbose;
{
	struct cmdentry entry;
	struct tblentry *cmdp;
	const struct alias *ap;
	const char *path = pathval();

	if (verbose) {
		outstr(command, out);
	}

	/* First look at the keywords */
	if (findkwd(command)) {
		outstr(verbose ? " is a shell keyword" : command, out);
		goto out;
	}

	/* Then look at the aliases */
	if ((ap = lookupalias(command, 0)) != NULL) {
		if (verbose) {
			outfmt(out, " is an alias for %s", ap->val);
		} else {
			outstr("alias ", out);
			printalias(ap);
			return 0;
		}
		goto out;
	}

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

	switch (entry.cmdtype) {
	case CMDNORMAL: {
		int j = entry.u.index;
		char *p;
		if (j == -1) {
			p = command;
		} else {
			do {
				p = padvance(&path, command);
				stunalloc(p);
			} while (--j >= 0);
		}
		if (verbose) {
			outfmt(
				out, " is%s %s",
				cmdp ? " a tracked alias for" : nullstr, p
			);
		} else {
			outstr(p, out);
		}
		break;
	}

	case CMDFUNCTION:
		if (verbose) {
			outstr(" is a shell function", out);
		} else {
			outstr(command, out);
		}
		break;

	case CMDBUILTIN:
		if (verbose) {
			outfmt(
				out, " is a %sshell builtin",
				entry.u.cmd->flags & BUILTIN_SPECIAL ?
					"special " : nullstr
			);
		} else {
			outstr(command, out);
		}
		break;

	default:
		if (verbose) {
			outstr(": not found\n", out);
		}
		return 127;
	}

out:
	outc('\n', out);
	return 0;
}

int
commandcmd(argc, argv)
	int argc;
	char **argv;
{
	int c;
	enum {
		VERIFY_BRIEF = 1,
		VERIFY_VERBOSE = 2,
	} verify = 0;

	while ((c = nextopt("pvV")) != '\0')
		if (c == 'V')
			verify |= VERIFY_VERBOSE;
		else if (c == 'v')
			verify |= VERIFY_BRIEF;
#ifdef DEBUG
		else if (c != 'p')
			abort();
#endif

	if (verify)
		return describe_command(out1, *argptr, verify - VERIFY_BRIEF);

	return 0;
}
1	niro	532	/*-
2			* Copyright (c) 1991, 1993
3			* The Regents of the University of California. All rights reserved.
4			* Copyright (c) 1997-2005
5			* Herbert Xu <herbert@gondor.apana.org.au>. 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/types.h>
36			#include <sys/stat.h>
37			#include <unistd.h>
38			#include <fcntl.h>
39			#include <stdlib.h>
40			#include <paths.h>
41
42			/*
43			* When commands are first encountered, they are entered in a hash table.
44			* This ensures that a full path search will not have to be done for them
45			* on each invocation.
46			*
47			* We should investigate converting to a linear search, even though that
48			* would make the command name "hash" a misnomer.
49			*/
50
51			#include "shell.h"
52			#include "main.h"
53			#include "nodes.h"
54			#include "parser.h"
55			#include "redir.h"
56			#include "eval.h"
57			#include "exec.h"
58			#include "builtins.h"
59			#include "var.h"
60			#include "options.h"
61			#include "output.h"
62			#include "syntax.h"
63			#include "memalloc.h"
64			#include "error.h"
65			#include "init.h"
66			#include "mystring.h"
67			#include "show.h"
68			#include "jobs.h"
69			#include "alias.h"
70			#include "system.h"
71
72
73			#define CMDTABLESIZE 31 /* should be prime */
74			#define ARB 1 /* actual size determined at run time */
75
76
77
78			struct tblentry {
79			struct tblentry next; / next entry in hash chain */
80			union param param; /* definition of builtin function */
81			short cmdtype; /* index identifying command */
82			char rehash; /* if set, cd done since entry created */
83			char cmdname[ARB]; /* name of command */
84			};
85
86
87			STATIC struct tblentry *cmdtable[CMDTABLESIZE];
88			STATIC int builtinloc = -1; /* index in path of %builtin, or -1 */
89
90
91			STATIC void tryexec(char , char , char *);
92			STATIC void printentry(struct tblentry *);
93			STATIC void clearcmdentry(int);
94			STATIC struct tblentry cmdlookup(const char , int);
95			STATIC void delete_cmd_entry(void);
96			STATIC void addcmdentry(char , struct cmdentry );
97			STATIC int describe_command(struct output , char , int);
98
99
100			/*
101			* Exec a program. Never returns. If you change this routine, you may
102			* have to change the find_command routine as well.
103			*/
104
105			void
106			shellexec(char *argv, const char path, int idx)
107			{
108			char *cmdname;
109			int e;
110			char **envp;
111			int exerrno;
112
113			clearredir(1);
114			envp = environment();
115			if (strchr(argv[0], '/') != NULL) {
116			tryexec(argv[0], argv, envp);
117			e = errno;
118			} else {
119			e = ENOENT;
120			while ((cmdname = padvance(&path, argv[0])) != NULL) {
121			if (--idx < 0 && pathopt == NULL) {
122			tryexec(cmdname, argv, envp);
123			if (errno != ENOENT && errno != ENOTDIR)
124			e = errno;
125			}
126			stunalloc(cmdname);
127			}
128			}
129
130			/* Map to POSIX errors */
131			switch (e) {
132			case EACCES:
133			exerrno = 126;
134			break;
135			case ENOENT:
136			exerrno = 127;
137			break;
138			default:
139			exerrno = 2;
140			break;
141			}
142			exitstatus = exerrno;
143			TRACE(("shellexec failed for %s, errno %d, suppressint %d\n",
144			argv[0], e, suppressint ));
145			exerror(EXEXEC, "%s: %s", argv[0], errmsg(e, E_EXEC));
146			/* NOTREACHED */
147			}
148
149
150			STATIC void
151			tryexec(char cmd, char argv, char *envp)
152			{
153			int repeated = 0;
154			#if !defined(BSD) && !defined(linux)
155			char *p;
156			#endif
157
158			repeat:
159			#ifdef SYSV
160			do {
161			execve(cmd, argv, envp);
162			} while (errno == EINTR);
163			#else
164			execve(cmd, argv, envp);
165			#endif
166			if (repeated++) {
167			ckfree(argv);
168			} else if (errno == ENOEXEC) {
169			char **ap;
170			char **new;
171
172			for (ap = argv; *ap; ap++)
173			;
174			ap = new = ckmalloc((ap - argv + 2) * sizeof(char *));
175			*ap++ = cmd = _PATH_BSHELL;
176			while ((ap++ = argv++))
177			;
178			argv = new;
179			goto repeat;
180			}
181			}
182
183
184
185			/*
186			* Do a path search. The variable path (passed by reference) should be
187			* set to the start of the path before the first call; padvance will update
188			* this value as it proceeds. Successive calls to padvance will return
189			* the possible path expansions in sequence. If an option (indicated by
190			* a percent sign) appears in the path entry then the global variable
191			* pathopt will be set to point to it; otherwise pathopt will be set to
192			* NULL.
193			*/
194
195			const char *pathopt;
196
197			char *
198			padvance(const char *path, const char name)
199			{
200			const char *p;
201			char *q;
202			const char *start;
203			size_t len;
204
205			if (*path == NULL)
206			return NULL;
207			start = *path;
208			for (p = start ; p && p != ':' && *p != '%' ; p++);
209			len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */
210			while (stackblocksize() < len)
211			growstackblock();
212			q = stackblock();
213			if (p != start) {
214			memcpy(q, start, p - start);
215			q += p - start;
216			*q++ = '/';
217			}
218			strcpy(q, name);
219			pathopt = NULL;
220			if (*p == '%') {
221			pathopt = ++p;
222			while (p && p != ':') p++;
223			}
224			if (*p == ':')
225			*path = p + 1;
226			else
227			*path = NULL;
228			return stalloc(len);
229			}
230
231
232
233			/* Command hashing code */
234
235
236			int
237			hashcmd(int argc, char **argv)
238			{
239			struct tblentry **pp;
240			struct tblentry *cmdp;
241			int c;
242			struct cmdentry entry;
243			char *name;
244
245			while ((c = nextopt("r")) != '\0') {
246			clearcmdentry(0);
247			return 0;
248			}
249			if (*argptr == NULL) {
250			for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
251			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
252			if (cmdp->cmdtype == CMDNORMAL)
253			printentry(cmdp);
254			}
255			}
256			return 0;
257			}
258			c = 0;
259			while ((name = *argptr) != NULL) {
260			if ((cmdp = cmdlookup(name, 0)) != NULL
261			&& (cmdp->cmdtype == CMDNORMAL
262			\|\| (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
263			delete_cmd_entry();
264			find_command(name, &entry, DO_ERR, pathval());
265			if (entry.cmdtype == CMDUNKNOWN)
266			c = 1;
267			argptr++;
268			}
269			return c;
270			}
271
272
273			STATIC void
274			printentry(struct tblentry *cmdp)
275			{
276			int idx;
277			const char *path;
278			char *name;
279
280			idx = cmdp->param.index;
281			path = pathval();
282			do {
283			name = padvance(&path, cmdp->cmdname);
284			stunalloc(name);
285			} while (--idx >= 0);
286			out1str(name);
287			out1fmt(snlfmt, cmdp->rehash ? "*" : nullstr);
288			}
289
290
291
292			/*
293			* Resolve a command name. If you change this routine, you may have to
294			* change the shellexec routine as well.
295			*/
296
297			void
298			find_command(char name, struct cmdentry entry, int act, const char *path)
299			{
300			struct tblentry *cmdp;
301			int idx;
302			int prev;
303			char *fullname;
304			struct stat64 statb;
305			int e;
306			int updatetbl;
307			struct builtincmd *bcmd;
308
309			/* If name contains a slash, don't use PATH or hash table */
310			if (strchr(name, '/') != NULL) {
311			entry->u.index = -1;
312			if (act & DO_ABS) {
313			while (stat64(name, &statb) < 0) {
314			#ifdef SYSV
315			if (errno == EINTR)
316			continue;
317			#endif
318			entry->cmdtype = CMDUNKNOWN;
319			return;
320			}
321			}
322			entry->cmdtype = CMDNORMAL;
323			return;
324			}
325
326			updatetbl = (path == pathval());
327			if (!updatetbl) {
328			act \|= DO_ALTPATH;
329			if (strstr(path, "%builtin") != NULL)
330			act \|= DO_ALTBLTIN;
331			}
332
333			/* If name is in the table, check answer will be ok */
334			if ((cmdp = cmdlookup(name, 0)) != NULL) {
335			int bit;
336
337			switch (cmdp->cmdtype) {
338			default:
339			#if DEBUG
340			abort();
341			#endif
342			case CMDNORMAL:
343			bit = DO_ALTPATH;
344			break;
345			case CMDFUNCTION:
346			bit = DO_NOFUNC;
347			break;
348			case CMDBUILTIN:
349			bit = DO_ALTBLTIN;
350			break;
351			}
352			if (act & bit) {
353			updatetbl = 0;
354			cmdp = NULL;
355			} else if (cmdp->rehash == 0)
356			/* if not invalidated by cd, we're done */
357			goto success;
358			}
359
360			/* If %builtin not in path, check for builtin next */
361			bcmd = find_builtin(name);
362			if (bcmd && (bcmd->flags & BUILTIN_REGULAR \|\| (
363			act & DO_ALTPATH ? !(act & DO_ALTBLTIN) : builtinloc <= 0
364			)))
365			goto builtin_success;
366
367			/* We have to search path. */
368			prev = -1; /* where to start */
369			if (cmdp && cmdp->rehash) { /* doing a rehash */
370			if (cmdp->cmdtype == CMDBUILTIN)
371			prev = builtinloc;
372			else
373			prev = cmdp->param.index;
374			}
375
376			e = ENOENT;
377			idx = -1;
378			loop:
379			while ((fullname = padvance(&path, name)) != NULL) {
380			stunalloc(fullname);
381			idx++;
382			if (pathopt) {
383			if (prefix(pathopt, "builtin")) {
384			if (bcmd)
385			goto builtin_success;
386			continue;
387			} else if (!(act & DO_NOFUNC) &&
388			prefix(pathopt, "func")) {
389			/* handled below */
390			} else {
391			/* ignore unimplemented options */
392			continue;
393			}
394			}
395			/* if rehash, don't redo absolute path names */
396			if (fullname[0] == '/' && idx <= prev) {
397			if (idx < prev)
398			continue;
399			TRACE(("searchexec \"%s\": no change\n", name));
400			goto success;
401			}
402			while (stat64(fullname, &statb) < 0) {
403			#ifdef SYSV
404			if (errno == EINTR)
405			continue;
406			#endif
407			if (errno != ENOENT && errno != ENOTDIR)
408			e = errno;
409			goto loop;
410			}
411			e = EACCES; /* if we fail, this will be the error */
412			if (!S_ISREG(statb.st_mode))
413			continue;
414			if (pathopt) { /* this is a %func directory */
415			stalloc(strlen(fullname) + 1);
416			readcmdfile(fullname);
417			if ((cmdp = cmdlookup(name, 0)) == NULL \|\|
418			cmdp->cmdtype != CMDFUNCTION)
419			sh_error("%s not defined in %s", name,
420			fullname);
421			stunalloc(fullname);
422			goto success;
423			}
424			#ifdef notdef
425			/* XXX this code stops root executing stuff, and is buggy
426			if you need a group from the group list. */
427			if (statb.st_uid == geteuid()) {
428			if ((statb.st_mode & 0100) == 0)
429			goto loop;
430			} else if (statb.st_gid == getegid()) {
431			if ((statb.st_mode & 010) == 0)
432			goto loop;
433			} else {
434			if ((statb.st_mode & 01) == 0)
435			goto loop;
436			}
437			#endif
438			TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
439			if (!updatetbl) {
440			entry->cmdtype = CMDNORMAL;
441			entry->u.index = idx;
442			return;
443			}
444			INTOFF;
445			cmdp = cmdlookup(name, 1);
446			cmdp->cmdtype = CMDNORMAL;
447			cmdp->param.index = idx;
448			INTON;
449			goto success;
450			}
451
452			/* We failed. If there was an entry for this command, delete it */
453			if (cmdp && updatetbl)
454			delete_cmd_entry();
455			if (act & DO_ERR)
456			sh_warnx("%s: %s", name, errmsg(e, E_EXEC));
457			entry->cmdtype = CMDUNKNOWN;
458			return;
459
460			builtin_success:
461			if (!updatetbl) {
462			entry->cmdtype = CMDBUILTIN;
463			entry->u.cmd = bcmd;
464			return;
465			}
466			INTOFF;
467			cmdp = cmdlookup(name, 1);
468			cmdp->cmdtype = CMDBUILTIN;
469			cmdp->param.cmd = bcmd;
470			INTON;
471			success:
472			cmdp->rehash = 0;
473			entry->cmdtype = cmdp->cmdtype;
474			entry->u = cmdp->param;
475			}
476
477
478
479			/*
480			* Search the table of builtin commands.
481			*/
482
483			struct builtincmd *
484			find_builtin(const char *name)
485			{
486			struct builtincmd *bp;
487
488			bp = bsearch(
489			&name, builtincmd, NUMBUILTINS, sizeof(struct builtincmd),
490			pstrcmp
491			);
492			return bp;
493			}
494
495
496
497			/*
498			* Called when a cd is done. Marks all commands so the next time they
499			* are executed they will be rehashed.
500			*/
501
502			void
503			hashcd(void)
504			{
505			struct tblentry **pp;
506			struct tblentry *cmdp;
507
508			for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
509			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
510			if (cmdp->cmdtype == CMDNORMAL \|\| (
511			cmdp->cmdtype == CMDBUILTIN &&
512			!(cmdp->param.cmd->flags & BUILTIN_REGULAR) &&
513			builtinloc > 0
514			))
515			cmdp->rehash = 1;
516			}
517			}
518			}
519
520
521
522			/*
523			* Fix command hash table when PATH changed.
524			* Called before PATH is changed. The argument is the new value of PATH;
525			* pathval() still returns the old value at this point.
526			* Called with interrupts off.
527			*/
528
529			void
530			changepath(const char *newval)
531			{
532			const char old, new;
533			int idx;
534			int firstchange;
535			int bltin;
536
537			old = pathval();
538			new = newval;
539			firstchange = 9999; /* assume no change */
540			idx = 0;
541			bltin = -1;
542			for (;;) {
543			if (old != new) {
544			firstchange = idx;
545			if ((old == '\0' && new == ':')
546			\|\| (old == ':' && new == '\0'))
547			firstchange++;
548			old = new; /* ignore subsequent differences */
549			}
550			if (*new == '\0')
551			break;
552			if (*new == '%' && bltin < 0 && prefix(new + 1, "builtin"))
553			bltin = idx;
554			if (*new == ':') {
555			idx++;
556			}
557			new++, old++;
558			}
559			if (builtinloc < 0 && bltin >= 0)
560			builtinloc = bltin; /* zap builtins */
561			if (builtinloc >= 0 && bltin < 0)
562			firstchange = 0;
563			clearcmdentry(firstchange);
564			builtinloc = bltin;
565			}
566
567
568			/*
569			* Clear out command entries. The argument specifies the first entry in
570			* PATH which has changed.
571			*/
572
573			STATIC void
574			clearcmdentry(int firstchange)
575			{
576			struct tblentry **tblp;
577			struct tblentry **pp;
578			struct tblentry *cmdp;
579
580			INTOFF;
581			for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
582			pp = tblp;
583			while ((cmdp = *pp) != NULL) {
584			if ((cmdp->cmdtype == CMDNORMAL &&
585			cmdp->param.index >= firstchange)
586			\|\| (cmdp->cmdtype == CMDBUILTIN &&
587			builtinloc >= firstchange)) {
588			*pp = cmdp->next;
589			ckfree(cmdp);
590			} else {
591			pp = &cmdp->next;
592			}
593			}
594			}
595			INTON;
596			}
597
598
599
600			/*
601			* Locate a command in the command hash table. If "add" is nonzero,
602			* add the command to the table if it is not already present. The
603			* variable "lastcmdentry" is set to point to the address of the link
604			* pointing to the entry, so that delete_cmd_entry can delete the
605			* entry.
606			*
607			* Interrupts must be off if called with add != 0.
608			*/
609
610			struct tblentry **lastcmdentry;
611
612
613			STATIC struct tblentry *
614			cmdlookup(const char *name, int add)
615			{
616			unsigned int hashval;
617			const char *p;
618			struct tblentry *cmdp;
619			struct tblentry **pp;
620
621			p = name;
622			hashval = (unsigned char)*p << 4;
623			while (*p)
624			hashval += (unsigned char)*p++;
625			hashval &= 0x7FFF;
626			pp = &cmdtable[hashval % CMDTABLESIZE];
627			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
628			if (equal(cmdp->cmdname, name))
629			break;
630			pp = &cmdp->next;
631			}
632			if (add && cmdp == NULL) {
633			cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
634			+ strlen(name) + 1);
635			cmdp->next = NULL;
636			cmdp->cmdtype = CMDUNKNOWN;
637			strcpy(cmdp->cmdname, name);
638			}
639			lastcmdentry = pp;
640			return cmdp;
641			}
642
643			/*
644			* Delete the command entry returned on the last lookup.
645			*/
646
647			STATIC void
648			delete_cmd_entry(void)
649			{
650			struct tblentry *cmdp;
651
652			INTOFF;
653			cmdp = *lastcmdentry;
654			*lastcmdentry = cmdp->next;
655			if (cmdp->cmdtype == CMDFUNCTION)
656			freefunc(cmdp->param.func);
657			ckfree(cmdp);
658			INTON;
659			}
660
661
662
663			#ifdef notdef
664			void
665			getcmdentry(char name, struct cmdentry entry)
666			{
667			struct tblentry *cmdp = cmdlookup(name, 0);
668
669			if (cmdp) {
670			entry->u = cmdp->param;
671			entry->cmdtype = cmdp->cmdtype;
672			} else {
673			entry->cmdtype = CMDUNKNOWN;
674			entry->u.index = 0;
675			}
676			}
677			#endif
678
679
680			/*
681			* Add a new command entry, replacing any existing command entry for
682			* the same name - except special builtins.
683			*/
684
685			STATIC void
686			addcmdentry(char name, struct cmdentry entry)
687			{
688			struct tblentry *cmdp;
689
690			cmdp = cmdlookup(name, 1);
691			if (cmdp->cmdtype == CMDFUNCTION) {
692			freefunc(cmdp->param.func);
693			}
694			cmdp->cmdtype = entry->cmdtype;
695			cmdp->param = entry->u;
696			cmdp->rehash = 0;
697			}
698
699
700			/*
701			* Define a shell function.
702			*/
703
704			void
705			defun(char name, union node func)
706			{
707			struct cmdentry entry;
708
709			INTOFF;
710			entry.cmdtype = CMDFUNCTION;
711			entry.u.func = copyfunc(func);
712			addcmdentry(name, &entry);
713			INTON;
714			}
715
716
717			/*
718			* Delete a function if it exists.
719			*/
720
721			void
722			unsetfunc(const char *name)
723			{
724			struct tblentry *cmdp;
725
726			if ((cmdp = cmdlookup(name, 0)) != NULL &&
727			cmdp->cmdtype == CMDFUNCTION)
728			delete_cmd_entry();
729			}
730
731			/*
732			* Locate and print what a word is...
733			*/
734
735			int
736			typecmd(int argc, char **argv)
737			{
738			int i;
739			int err = 0;
740
741			for (i = 1; i < argc; i++) {
742			err \|= describe_command(out1, argv[i], 1);
743			}
744			return err;
745			}
746
747			STATIC int
748			describe_command(out, command, verbose)
749			struct output *out;
750			char *command;
751			int verbose;
752			{
753			struct cmdentry entry;
754			struct tblentry *cmdp;
755			const struct alias *ap;
756			const char *path = pathval();
757
758			if (verbose) {
759			outstr(command, out);
760			}
761
762			/* First look at the keywords */
763			if (findkwd(command)) {
764			outstr(verbose ? " is a shell keyword" : command, out);
765			goto out;
766			}
767
768			/* Then look at the aliases */
769			if ((ap = lookupalias(command, 0)) != NULL) {
770			if (verbose) {
771			outfmt(out, " is an alias for %s", ap->val);
772			} else {
773			outstr("alias ", out);
774			printalias(ap);
775			return 0;
776			}
777			goto out;
778			}
779
780			/* Then check if it is a tracked alias */
781			if ((cmdp = cmdlookup(command, 0)) != NULL) {
782			entry.cmdtype = cmdp->cmdtype;
783			entry.u = cmdp->param;
784			} else {
785			/* Finally use brute force */
786			find_command(command, &entry, DO_ABS, path);
787			}
788
789			switch (entry.cmdtype) {
790			case CMDNORMAL: {
791			int j = entry.u.index;
792			char *p;
793			if (j == -1) {
794			p = command;
795			} else {
796			do {
797			p = padvance(&path, command);
798			stunalloc(p);
799			} while (--j >= 0);
800			}
801			if (verbose) {
802			outfmt(
803			out, " is%s %s",
804			cmdp ? " a tracked alias for" : nullstr, p
805			);
806			} else {
807			outstr(p, out);
808			}
809			break;
810			}
811
812			case CMDFUNCTION:
813			if (verbose) {
814			outstr(" is a shell function", out);
815			} else {
816			outstr(command, out);
817			}
818			break;
819
820			case CMDBUILTIN:
821			if (verbose) {
822			outfmt(
823			out, " is a %sshell builtin",
824			entry.u.cmd->flags & BUILTIN_SPECIAL ?
825			"special " : nullstr
826			);
827			} else {
828			outstr(command, out);
829			}
830			break;
831
832			default:
833			if (verbose) {
834			outstr(": not found\n", out);
835			}
836			return 127;
837			}
838
839			out:
840			outc('\n', out);
841			return 0;
842			}
843
844			int
845			commandcmd(argc, argv)
846			int argc;
847			char **argv;
848			{
849			int c;
850			enum {
851			VERIFY_BRIEF = 1,
852			VERIFY_VERBOSE = 2,
853			} verify = 0;
854
855			while ((c = nextopt("pvV")) != '\0')
856			if (c == 'V')
857			verify \|= VERIFY_VERBOSE;
858			else if (c == 'v')
859			verify \|= VERIFY_BRIEF;
860			#ifdef DEBUG
861			else if (c != 'p')
862			abort();
863			#endif
864
865			if (verify)
866			return describe_command(out1, *argptr, verify - VERIFY_BRIEF);
867
868			return 0;
869			}