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	/*-
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	}