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)
{
	char *const path_bshell = _PATH_BSHELL;

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