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	niro	532	/*-
2			* Copyright (c) 1991, 1993
3			* The Regents of the University of California. All rights reserved.
4			* Copyright (c) 1997-2005
5			* Herbert Xu <herbert@gondor.apana.org.au>. All rights reserved.
6			*
7			* This code is derived from software contributed to Berkeley by
8			* Kenneth Almquist.
9			*
10			* Redistribution and use in source and binary forms, with or without
11			* modification, are permitted provided that the following conditions
12			* are met:
13			* 1. Redistributions of source code must retain the above copyright
14			* notice, this list of conditions and the following disclaimer.
15			* 2. Redistributions in binary form must reproduce the above copyright
16			* notice, this list of conditions and the following disclaimer in the
17			* documentation and/or other materials provided with the distribution.
18			* 3. Neither the name of the University nor the names of its contributors
19			* may be used to endorse or promote products derived from this software
20			* without specific prior written permission.
21			*
22			* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23			* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24			* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25			* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26			* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27			* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28			* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29			* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30			* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31			* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32			* SUCH DAMAGE.
33			*/
34
35			#include <sys/types.h>
36			#include <sys/stat.h>
37			#include <unistd.h>
38			#include <fcntl.h>
39			#include <stdlib.h>
40			#include <paths.h>
41
42			/*
43			* When commands are first encountered, they are entered in a hash table.
44			* This ensures that a full path search will not have to be done for them
45			* on each invocation.
46			*
47			* We should investigate converting to a linear search, even though that
48			* would make the command name "hash" a misnomer.
49			*/
50
51			#include "shell.h"
52			#include "main.h"
53			#include "nodes.h"
54			#include "parser.h"
55			#include "redir.h"
56			#include "eval.h"
57			#include "exec.h"
58			#include "builtins.h"
59			#include "var.h"
60			#include "options.h"
61			#include "output.h"
62			#include "syntax.h"
63			#include "memalloc.h"
64			#include "error.h"
65			#include "init.h"
66			#include "mystring.h"
67			#include "show.h"
68			#include "jobs.h"
69			#include "alias.h"
70			#include "system.h"
71
72
73			#define CMDTABLESIZE 31 /* should be prime */
74			#define ARB 1 /* actual size determined at run time */
75
76
77
78			struct tblentry {
79			struct tblentry next; / next entry in hash chain */
80			union param param; /* definition of builtin function */
81			short cmdtype; /* index identifying command */
82			char rehash; /* if set, cd done since entry created */
83			char cmdname[ARB]; /* name of command */
84			};
85
86
87			STATIC struct tblentry *cmdtable[CMDTABLESIZE];
88			STATIC int builtinloc = -1; /* index in path of %builtin, or -1 */
89
90
91			STATIC void tryexec(char , char , char *);
92			STATIC void printentry(struct tblentry *);
93			STATIC void clearcmdentry(int);
94			STATIC struct tblentry cmdlookup(const char , int);
95			STATIC void delete_cmd_entry(void);
96			STATIC void addcmdentry(char , struct cmdentry );
97			STATIC int describe_command(struct output , char , int);
98
99
100			/*
101			* Exec a program. Never returns. If you change this routine, you may
102			* have to change the find_command routine as well.
103			*/
104
105			void
106			shellexec(char *argv, const char path, int idx)
107			{
108			char *cmdname;
109			int e;
110			char **envp;
111			int exerrno;
112
113			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	niro	1122	char *const path_bshell = _PATH_BSHELL;
153	niro	532
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	niro	1122	if (cmd != path_bshell && errno == ENOEXEC) {
163			*argv-- = cmd;
164			*argv = cmd = path_bshell;
165	niro	532	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	niro	815	char *cmd;
836	niro	532	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	niro	815	cmd = *argptr;
853			if (verify && cmd)
854			return describe_command(out1, cmd, verify - VERIFY_BRIEF);
855	niro	532
856			return 0;
857			}