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;

	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;
{
	char *cmd;
	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

	cmd = *argptr;
	if (verify && cmd)
		return describe_command(out1, cmd, 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	envp = environment();
114	if (strchr(argv[0], '/') != NULL) {
115	tryexec(argv[0], argv, envp);
116	e = errno;
117	} else {
118	e = ENOENT;
119	while ((cmdname = padvance(&path, argv[0])) != NULL) {
120	if (--idx < 0 && pathopt == NULL) {
121	tryexec(cmdname, argv, envp);
122	if (errno != ENOENT && errno != ENOTDIR)
123	e = errno;
124	}
125	stunalloc(cmdname);
126	}
127	}
128
129	/* Map to POSIX errors */
130	switch (e) {
131	case EACCES:
132	exerrno = 126;
133	break;
134	case ENOENT:
135	exerrno = 127;
136	break;
137	default:
138	exerrno = 2;
139	break;
140	}
141	exitstatus = exerrno;
142	TRACE(("shellexec failed for %s, errno %d, suppressint %d\n",
143	argv[0], e, suppressint ));
144	exerror(EXEXEC, "%s: %s", argv[0], errmsg(e, E_EXEC));
145	/* NOTREACHED */
146	}
147
148
149	STATIC void
150	tryexec(char cmd, char argv, char *envp)
151	{
152	int repeated = 0;
153	#if !defined(BSD) && !defined(linux)
154	char *p;
155	#endif
156
157	repeat:
158	#ifdef SYSV
159	do {
160	execve(cmd, argv, envp);
161	} while (errno == EINTR);
162	#else
163	execve(cmd, argv, envp);
164	#endif
165	if (repeated++) {
166	ckfree(argv);
167	} else if (errno == ENOEXEC) {
168	char **ap;
169	char **new;
170
171	for (ap = argv; *ap; ap++)
172	;
173	ap = new = ckmalloc((ap - argv + 2) * sizeof(char *));
174	*ap++ = cmd = _PATH_BSHELL;
175	while ((ap++ = argv++))
176	;
177	argv = new;
178	goto repeat;
179	}
180	}
181
182
183
184	/*
185	* Do a path search. The variable path (passed by reference) should be
186	* set to the start of the path before the first call; padvance will update
187	* this value as it proceeds. Successive calls to padvance will return
188	* the possible path expansions in sequence. If an option (indicated by
189	* a percent sign) appears in the path entry then the global variable
190	* pathopt will be set to point to it; otherwise pathopt will be set to
191	* NULL.
192	*/
193
194	const char *pathopt;
195
196	char *
197	padvance(const char *path, const char name)
198	{
199	const char *p;
200	char *q;
201	const char *start;
202	size_t len;
203
204	if (*path == NULL)
205	return NULL;
206	start = *path;
207	for (p = start ; p && p != ':' && *p != '%' ; p++);
208	len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */
209	while (stackblocksize() < len)
210	growstackblock();
211	q = stackblock();
212	if (p != start) {
213	memcpy(q, start, p - start);
214	q += p - start;
215	*q++ = '/';
216	}
217	strcpy(q, name);
218	pathopt = NULL;
219	if (*p == '%') {
220	pathopt = ++p;
221	while (p && p != ':') p++;
222	}
223	if (*p == ':')
224	*path = p + 1;
225	else
226	*path = NULL;
227	return stalloc(len);
228	}
229
230
231
232	/* Command hashing code */
233
234
235	int
236	hashcmd(int argc, char **argv)
237	{
238	struct tblentry **pp;
239	struct tblentry *cmdp;
240	int c;
241	struct cmdentry entry;
242	char *name;
243
244	while ((c = nextopt("r")) != '\0') {
245	clearcmdentry(0);
246	return 0;
247	}
248	if (*argptr == NULL) {
249	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
250	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
251	if (cmdp->cmdtype == CMDNORMAL)
252	printentry(cmdp);
253	}
254	}
255	return 0;
256	}
257	c = 0;
258	while ((name = *argptr) != NULL) {
259	if ((cmdp = cmdlookup(name, 0)) != NULL
260	&& (cmdp->cmdtype == CMDNORMAL
261	\|\| (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
262	delete_cmd_entry();
263	find_command(name, &entry, DO_ERR, pathval());
264	if (entry.cmdtype == CMDUNKNOWN)
265	c = 1;
266	argptr++;
267	}
268	return c;
269	}
270
271
272	STATIC void
273	printentry(struct tblentry *cmdp)
274	{
275	int idx;
276	const char *path;
277	char *name;
278
279	idx = cmdp->param.index;
280	path = pathval();
281	do {
282	name = padvance(&path, cmdp->cmdname);
283	stunalloc(name);
284	} while (--idx >= 0);
285	out1str(name);
286	out1fmt(snlfmt, cmdp->rehash ? "*" : nullstr);
287	}
288
289
290
291	/*
292	* Resolve a command name. If you change this routine, you may have to
293	* change the shellexec routine as well.
294	*/
295
296	void
297	find_command(char name, struct cmdentry entry, int act, const char *path)
298	{
299	struct tblentry *cmdp;
300	int idx;
301	int prev;
302	char *fullname;
303	struct stat64 statb;
304	int e;
305	int updatetbl;
306	struct builtincmd *bcmd;
307
308	/* If name contains a slash, don't use PATH or hash table */
309	if (strchr(name, '/') != NULL) {
310	entry->u.index = -1;
311	if (act & DO_ABS) {
312	while (stat64(name, &statb) < 0) {
313	#ifdef SYSV
314	if (errno == EINTR)
315	continue;
316	#endif
317	entry->cmdtype = CMDUNKNOWN;
318	return;
319	}
320	}
321	entry->cmdtype = CMDNORMAL;
322	return;
323	}
324
325	updatetbl = (path == pathval());
326	if (!updatetbl) {
327	act \|= DO_ALTPATH;
328	if (strstr(path, "%builtin") != NULL)
329	act \|= DO_ALTBLTIN;
330	}
331
332	/* If name is in the table, check answer will be ok */
333	if ((cmdp = cmdlookup(name, 0)) != NULL) {
334	int bit;
335
336	switch (cmdp->cmdtype) {
337	default:
338	#if DEBUG
339	abort();
340	#endif
341	case CMDNORMAL:
342	bit = DO_ALTPATH;
343	break;
344	case CMDFUNCTION:
345	bit = DO_NOFUNC;
346	break;
347	case CMDBUILTIN:
348	bit = DO_ALTBLTIN;
349	break;
350	}
351	if (act & bit) {
352	updatetbl = 0;
353	cmdp = NULL;
354	} else if (cmdp->rehash == 0)
355	/* if not invalidated by cd, we're done */
356	goto success;
357	}
358
359	/* If %builtin not in path, check for builtin next */
360	bcmd = find_builtin(name);
361	if (bcmd && (bcmd->flags & BUILTIN_REGULAR \|\| (
362	act & DO_ALTPATH ? !(act & DO_ALTBLTIN) : builtinloc <= 0
363	)))
364	goto builtin_success;
365
366	/* We have to search path. */
367	prev = -1; /* where to start */
368	if (cmdp && cmdp->rehash) { /* doing a rehash */
369	if (cmdp->cmdtype == CMDBUILTIN)
370	prev = builtinloc;
371	else
372	prev = cmdp->param.index;
373	}
374
375	e = ENOENT;
376	idx = -1;
377	loop:
378	while ((fullname = padvance(&path, name)) != NULL) {
379	stunalloc(fullname);
380	idx++;
381	if (pathopt) {
382	if (prefix(pathopt, "builtin")) {
383	if (bcmd)
384	goto builtin_success;
385	continue;
386	} else if (!(act & DO_NOFUNC) &&
387	prefix(pathopt, "func")) {
388	/* handled below */
389	} else {
390	/* ignore unimplemented options */
391	continue;
392	}
393	}
394	/* if rehash, don't redo absolute path names */
395	if (fullname[0] == '/' && idx <= prev) {
396	if (idx < prev)
397	continue;
398	TRACE(("searchexec \"%s\": no change\n", name));
399	goto success;
400	}
401	while (stat64(fullname, &statb) < 0) {
402	#ifdef SYSV
403	if (errno == EINTR)
404	continue;
405	#endif
406	if (errno != ENOENT && errno != ENOTDIR)
407	e = errno;
408	goto loop;
409	}
410	e = EACCES; /* if we fail, this will be the error */
411	if (!S_ISREG(statb.st_mode))
412	continue;
413	if (pathopt) { /* this is a %func directory */
414	stalloc(strlen(fullname) + 1);
415	readcmdfile(fullname);
416	if ((cmdp = cmdlookup(name, 0)) == NULL \|\|
417	cmdp->cmdtype != CMDFUNCTION)
418	sh_error("%s not defined in %s", name,
419	fullname);
420	stunalloc(fullname);
421	goto success;
422	}
423	#ifdef notdef
424	/* XXX this code stops root executing stuff, and is buggy
425	if you need a group from the group list. */
426	if (statb.st_uid == geteuid()) {
427	if ((statb.st_mode & 0100) == 0)
428	goto loop;
429	} else if (statb.st_gid == getegid()) {
430	if ((statb.st_mode & 010) == 0)
431	goto loop;
432	} else {
433	if ((statb.st_mode & 01) == 0)
434	goto loop;
435	}
436	#endif
437	TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
438	if (!updatetbl) {
439	entry->cmdtype = CMDNORMAL;
440	entry->u.index = idx;
441	return;
442	}
443	INTOFF;
444	cmdp = cmdlookup(name, 1);
445	cmdp->cmdtype = CMDNORMAL;
446	cmdp->param.index = idx;
447	INTON;
448	goto success;
449	}
450
451	/* We failed. If there was an entry for this command, delete it */
452	if (cmdp && updatetbl)
453	delete_cmd_entry();
454	if (act & DO_ERR)
455	sh_warnx("%s: %s", name, errmsg(e, E_EXEC));
456	entry->cmdtype = CMDUNKNOWN;
457	return;
458
459	builtin_success:
460	if (!updatetbl) {
461	entry->cmdtype = CMDBUILTIN;
462	entry->u.cmd = bcmd;
463	return;
464	}
465	INTOFF;
466	cmdp = cmdlookup(name, 1);
467	cmdp->cmdtype = CMDBUILTIN;
468	cmdp->param.cmd = bcmd;
469	INTON;
470	success:
471	cmdp->rehash = 0;
472	entry->cmdtype = cmdp->cmdtype;
473	entry->u = cmdp->param;
474	}
475
476
477
478	/*
479	* Search the table of builtin commands.
480	*/
481
482	struct builtincmd *
483	find_builtin(const char *name)
484	{
485	struct builtincmd *bp;
486
487	bp = bsearch(
488	&name, builtincmd, NUMBUILTINS, sizeof(struct builtincmd),
489	pstrcmp
490	);
491	return bp;
492	}
493
494
495
496	/*
497	* Called when a cd is done. Marks all commands so the next time they
498	* are executed they will be rehashed.
499	*/
500
501	void
502	hashcd(void)
503	{
504	struct tblentry **pp;
505	struct tblentry *cmdp;
506
507	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
508	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
509	if (cmdp->cmdtype == CMDNORMAL \|\| (
510	cmdp->cmdtype == CMDBUILTIN &&
511	!(cmdp->param.cmd->flags & BUILTIN_REGULAR) &&
512	builtinloc > 0
513	))
514	cmdp->rehash = 1;
515	}
516	}
517	}
518
519
520
521	/*
522	* Fix command hash table when PATH changed.
523	* Called before PATH is changed. The argument is the new value of PATH;
524	* pathval() still returns the old value at this point.
525	* Called with interrupts off.
526	*/
527
528	void
529	changepath(const char *newval)
530	{
531	const char old, new;
532	int idx;
533	int firstchange;
534	int bltin;
535
536	old = pathval();
537	new = newval;
538	firstchange = 9999; /* assume no change */
539	idx = 0;
540	bltin = -1;
541	for (;;) {
542	if (old != new) {
543	firstchange = idx;
544	if ((old == '\0' && new == ':')
545	\|\| (old == ':' && new == '\0'))
546	firstchange++;
547	old = new; /* ignore subsequent differences */
548	}
549	if (*new == '\0')
550	break;
551	if (*new == '%' && bltin < 0 && prefix(new + 1, "builtin"))
552	bltin = idx;
553	if (*new == ':') {
554	idx++;
555	}
556	new++, old++;
557	}
558	if (builtinloc < 0 && bltin >= 0)
559	builtinloc = bltin; /* zap builtins */
560	if (builtinloc >= 0 && bltin < 0)
561	firstchange = 0;
562	clearcmdentry(firstchange);
563	builtinloc = bltin;
564	}
565
566
567	/*
568	* Clear out command entries. The argument specifies the first entry in
569	* PATH which has changed.
570	*/
571
572	STATIC void
573	clearcmdentry(int firstchange)
574	{
575	struct tblentry **tblp;
576	struct tblentry **pp;
577	struct tblentry *cmdp;
578
579	INTOFF;
580	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
581	pp = tblp;
582	while ((cmdp = *pp) != NULL) {
583	if ((cmdp->cmdtype == CMDNORMAL &&
584	cmdp->param.index >= firstchange)
585	\|\| (cmdp->cmdtype == CMDBUILTIN &&
586	builtinloc >= firstchange)) {
587	*pp = cmdp->next;
588	ckfree(cmdp);
589	} else {
590	pp = &cmdp->next;
591	}
592	}
593	}
594	INTON;
595	}
596
597
598
599	/*
600	* Locate a command in the command hash table. If "add" is nonzero,
601	* add the command to the table if it is not already present. The
602	* variable "lastcmdentry" is set to point to the address of the link
603	* pointing to the entry, so that delete_cmd_entry can delete the
604	* entry.
605	*
606	* Interrupts must be off if called with add != 0.
607	*/
608
609	struct tblentry **lastcmdentry;
610
611
612	STATIC struct tblentry *
613	cmdlookup(const char *name, int add)
614	{
615	unsigned int hashval;
616	const char *p;
617	struct tblentry *cmdp;
618	struct tblentry **pp;
619
620	p = name;
621	hashval = (unsigned char)*p << 4;
622	while (*p)
623	hashval += (unsigned char)*p++;
624	hashval &= 0x7FFF;
625	pp = &cmdtable[hashval % CMDTABLESIZE];
626	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
627	if (equal(cmdp->cmdname, name))
628	break;
629	pp = &cmdp->next;
630	}
631	if (add && cmdp == NULL) {
632	cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
633	+ strlen(name) + 1);
634	cmdp->next = NULL;
635	cmdp->cmdtype = CMDUNKNOWN;
636	strcpy(cmdp->cmdname, name);
637	}
638	lastcmdentry = pp;
639	return cmdp;
640	}
641
642	/*
643	* Delete the command entry returned on the last lookup.
644	*/
645
646	STATIC void
647	delete_cmd_entry(void)
648	{
649	struct tblentry *cmdp;
650
651	INTOFF;
652	cmdp = *lastcmdentry;
653	*lastcmdentry = cmdp->next;
654	if (cmdp->cmdtype == CMDFUNCTION)
655	freefunc(cmdp->param.func);
656	ckfree(cmdp);
657	INTON;
658	}
659
660
661
662	#ifdef notdef
663	void
664	getcmdentry(char name, struct cmdentry entry)
665	{
666	struct tblentry *cmdp = cmdlookup(name, 0);
667
668	if (cmdp) {
669	entry->u = cmdp->param;
670	entry->cmdtype = cmdp->cmdtype;
671	} else {
672	entry->cmdtype = CMDUNKNOWN;
673	entry->u.index = 0;
674	}
675	}
676	#endif
677
678
679	/*
680	* Add a new command entry, replacing any existing command entry for
681	* the same name - except special builtins.
682	*/
683
684	STATIC void
685	addcmdentry(char name, struct cmdentry entry)
686	{
687	struct tblentry *cmdp;
688
689	cmdp = cmdlookup(name, 1);
690	if (cmdp->cmdtype == CMDFUNCTION) {
691	freefunc(cmdp->param.func);
692	}
693	cmdp->cmdtype = entry->cmdtype;
694	cmdp->param = entry->u;
695	cmdp->rehash = 0;
696	}
697
698
699	/*
700	* Define a shell function.
701	*/
702
703	void
704	defun(char name, union node func)
705	{
706	struct cmdentry entry;
707
708	INTOFF;
709	entry.cmdtype = CMDFUNCTION;
710	entry.u.func = copyfunc(func);
711	addcmdentry(name, &entry);
712	INTON;
713	}
714
715
716	/*
717	* Delete a function if it exists.
718	*/
719
720	void
721	unsetfunc(const char *name)
722	{
723	struct tblentry *cmdp;
724
725	if ((cmdp = cmdlookup(name, 0)) != NULL &&
726	cmdp->cmdtype == CMDFUNCTION)
727	delete_cmd_entry();
728	}
729
730	/*
731	* Locate and print what a word is...
732	*/
733
734	int
735	typecmd(int argc, char **argv)
736	{
737	int i;
738	int err = 0;
739
740	for (i = 1; i < argc; i++) {
741	err \|= describe_command(out1, argv[i], 1);
742	}
743	return err;
744	}
745
746	STATIC int
747	describe_command(out, command, verbose)
748	struct output *out;
749	char *command;
750	int verbose;
751	{
752	struct cmdentry entry;
753	struct tblentry *cmdp;
754	const struct alias *ap;
755	const char *path = pathval();
756
757	if (verbose) {
758	outstr(command, out);
759	}
760
761	/* First look at the keywords */
762	if (findkwd(command)) {
763	outstr(verbose ? " is a shell keyword" : command, out);
764	goto out;
765	}
766
767	/* Then look at the aliases */
768	if ((ap = lookupalias(command, 0)) != NULL) {
769	if (verbose) {
770	outfmt(out, " is an alias for %s", ap->val);
771	} else {
772	outstr("alias ", out);
773	printalias(ap);
774	return 0;
775	}
776	goto out;
777	}
778
779	/* Then check if it is a tracked alias */
780	if ((cmdp = cmdlookup(command, 0)) != NULL) {
781	entry.cmdtype = cmdp->cmdtype;
782	entry.u = cmdp->param;
783	} else {
784	/* Finally use brute force */
785	find_command(command, &entry, DO_ABS, path);
786	}
787
788	switch (entry.cmdtype) {
789	case CMDNORMAL: {
790	int j = entry.u.index;
791	char *p;
792	if (j == -1) {
793	p = command;
794	} else {
795	do {
796	p = padvance(&path, command);
797	stunalloc(p);
798	} while (--j >= 0);
799	}
800	if (verbose) {
801	outfmt(
802	out, " is%s %s",
803	cmdp ? " a tracked alias for" : nullstr, p
804	);
805	} else {
806	outstr(p, out);
807	}
808	break;
809	}
810
811	case CMDFUNCTION:
812	if (verbose) {
813	outstr(" is a shell function", out);
814	} else {
815	outstr(command, out);
816	}
817	break;
818
819	case CMDBUILTIN:
820	if (verbose) {
821	outfmt(
822	out, " is a %sshell builtin",
823	entry.u.cmd->flags & BUILTIN_SPECIAL ?
824	"special " : nullstr
825	);
826	} else {
827	outstr(command, out);
828	}
829	break;
830
831	default:
832	if (verbose) {
833	outstr(": not found\n", out);
834	}
835	return 127;
836	}
837
838	out:
839	outc('\n', out);
840	return 0;
841	}
842
843	int
844	commandcmd(argc, argv)
845	int argc;
846	char **argv;
847	{
848	char *cmd;
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	cmd = *argptr;
866	if (verify && cmd)
867	return describe_command(out1, cmd, verify - VERIFY_BRIEF);
868
869	return 0;
870	}