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| Current File : //usr/src/bin/sh/exec.c |
/*-
* Copyright (c) 1991, 1993
* The Regents of the University of California. 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.
* 4. 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.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)exec.c 8.4 (Berkeley) 6/8/95";
#endif
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/bin/sh/exec.c 231790 2012-02-15 22:45:57Z jilles $");
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <paths.h>
#include <stdlib.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 "input.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"
#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 */
int special; /* flag for special builtin commands */
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];
int exerrno = 0; /* Last exec error */
static void tryexec(char *, char **, char **);
static void printentry(struct tblentry *, int);
static struct tblentry *cmdlookup(const char *, int);
static void delete_cmd_entry(void);
static void addcmdentry(const char *, struct cmdentry *);
/*
* Exec a program. Never returns. If you change this routine, you may
* have to change the find_command routine as well.
*
* The argv array may be changed and element argv[-1] should be writable.
*/
void
shellexec(char **argv, char **envp, const char *path, int idx)
{
char *cmdname;
int e;
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;
if (e == ENOEXEC)
break;
}
stunalloc(cmdname);
}
}
/* Map to POSIX errors */
if (e == ENOENT || e == ENOTDIR) {
exerrno = 127;
exerror(EXEXEC, "%s: not found", argv[0]);
} else {
exerrno = 126;
exerror(EXEXEC, "%s: %s", argv[0], strerror(e));
}
}
static void
tryexec(char *cmd, char **argv, char **envp)
{
int e, in;
ssize_t n;
char buf[256];
execve(cmd, argv, envp);
e = errno;
if (e == ENOEXEC) {
INTOFF;
in = open(cmd, O_RDONLY | O_NONBLOCK);
if (in != -1) {
n = pread(in, buf, sizeof buf, 0);
close(in);
if (n > 0 && memchr(buf, '\0', n) != NULL) {
errno = ENOEXEC;
return;
}
}
*argv = cmd;
*--argv = _PATH_BSHELL;
execve(_PATH_BSHELL, argv, envp);
}
errno = e;
}
/*
* 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, *start;
char *q;
int len;
if (*path == NULL)
return NULL;
start = *path;
for (p = start; *p && *p != ':' && *p != '%'; p++)
; /* nothing */
len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */
STARTSTACKSTR(q);
CHECKSTRSPACE(len, q);
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 __unused, char **argv __unused)
{
struct tblentry **pp;
struct tblentry *cmdp;
int c;
int verbose;
struct cmdentry entry;
char *name;
verbose = 0;
while ((c = nextopt("rv")) != '\0') {
if (c == 'r') {
clearcmdentry();
} else if (c == 'v') {
verbose++;
}
}
if (*argptr == NULL) {
for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
if (cmdp->cmdtype == CMDNORMAL)
printentry(cmdp, verbose);
}
}
return 0;
}
while ((name = *argptr) != NULL) {
if ((cmdp = cmdlookup(name, 0)) != NULL
&& cmdp->cmdtype == CMDNORMAL)
delete_cmd_entry();
find_command(name, &entry, DO_ERR, pathval());
if (verbose) {
if (entry.cmdtype != CMDUNKNOWN) { /* if no error msg */
cmdp = cmdlookup(name, 0);
if (cmdp != NULL)
printentry(cmdp, verbose);
else
outfmt(out2, "%s: not found\n", name);
}
flushall();
}
argptr++;
}
return 0;
}
static void
printentry(struct tblentry *cmdp, int verbose)
{
int idx;
const char *path;
char *name;
if (cmdp->cmdtype == CMDNORMAL) {
idx = cmdp->param.index;
path = pathval();
do {
name = padvance(&path, cmdp->cmdname);
stunalloc(name);
} while (--idx >= 0);
out1str(name);
} else if (cmdp->cmdtype == CMDBUILTIN) {
out1fmt("builtin %s", cmdp->cmdname);
} else if (cmdp->cmdtype == CMDFUNCTION) {
out1fmt("function %s", cmdp->cmdname);
if (verbose) {
INTOFF;
name = commandtext(getfuncnode(cmdp->param.func));
out1c(' ');
out1str(name);
ckfree(name);
INTON;
}
#ifdef DEBUG
} else {
error("internal error: cmdtype %d", cmdp->cmdtype);
#endif
}
if (cmdp->rehash)
out1c('*');
out1c('\n');
}
/*
* Resolve a command name. If you change this routine, you may have to
* change the shellexec routine as well.
*/
void
find_command(const char *name, struct cmdentry *entry, int act,
const char *path)
{
struct tblentry *cmdp, loc_cmd;
int idx;
int prev;
char *fullname;
struct stat statb;
int e;
int i;
int spec;
/* If name contains a slash, don't use the hash table */
if (strchr(name, '/') != NULL) {
entry->cmdtype = CMDNORMAL;
entry->u.index = 0;
return;
}
/* If name is in the table, and not invalidated by cd, we're done */
if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0) {
if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC)
cmdp = NULL;
else
goto success;
}
/* Check for builtin next */
if ((i = find_builtin(name, &spec)) >= 0) {
INTOFF;
cmdp = cmdlookup(name, 1);
if (cmdp->cmdtype == CMDFUNCTION)
cmdp = &loc_cmd;
cmdp->cmdtype = CMDBUILTIN;
cmdp->param.index = i;
cmdp->special = spec;
INTON;
goto success;
}
/* We have to search path. */
prev = -1; /* where to start */
if (cmdp) { /* doing a rehash */
if (cmdp->cmdtype == CMDBUILTIN)
prev = -1;
else
prev = cmdp->param.index;
}
e = ENOENT;
idx = -1;
loop:
while ((fullname = padvance(&path, name)) != NULL) {
stunalloc(fullname);
idx++;
if (pathopt) {
if (prefix("func", pathopt)) {
/* handled below */
} else {
goto loop; /* ignore unimplemented options */
}
}
/* if rehash, don't redo absolute path names */
if (fullname[0] == '/' && idx <= prev) {
if (idx < prev)
goto loop;
TRACE(("searchexec \"%s\": no change\n", name));
goto success;
}
if (stat(fullname, &statb) < 0) {
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))
goto loop;
if (pathopt) { /* this is a %func directory */
stalloc(strlen(fullname) + 1);
readcmdfile(fullname);
if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
error("%s not defined in %s", name, fullname);
stunalloc(fullname);
goto success;
}
#ifdef notdef
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));
INTOFF;
cmdp = cmdlookup(name, 1);
if (cmdp->cmdtype == CMDFUNCTION)
cmdp = &loc_cmd;
cmdp->cmdtype = CMDNORMAL;
cmdp->param.index = idx;
INTON;
goto success;
}
/* We failed. If there was an entry for this command, delete it */
if (cmdp && cmdp->cmdtype != CMDFUNCTION)
delete_cmd_entry();
if (act & DO_ERR) {
if (e == ENOENT || e == ENOTDIR)
outfmt(out2, "%s: not found\n", name);
else
outfmt(out2, "%s: %s\n", name, strerror(e));
}
entry->cmdtype = CMDUNKNOWN;
entry->u.index = 0;
return;
success:
cmdp->rehash = 0;
entry->cmdtype = cmdp->cmdtype;
entry->u = cmdp->param;
entry->special = cmdp->special;
}
/*
* Search the table of builtin commands.
*/
int
find_builtin(const char *name, int *special)
{
const struct builtincmd *bp;
for (bp = builtincmd ; bp->name ; bp++) {
if (*bp->name == *name && equal(bp->name, name)) {
*special = bp->special;
return bp->code;
}
}
return -1;
}
/*
* 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->rehash = 1;
}
}
}
/*
* 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)
{
clearcmdentry();
}
/*
* Clear out command entries. The argument specifies the first entry in
* PATH which has changed.
*/
void
clearcmdentry(void)
{
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) {
*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.
*/
static struct tblentry **lastcmdentry;
static struct tblentry *
cmdlookup(const char *name, int add)
{
int hashval;
const char *p;
struct tblentry *cmdp;
struct tblentry **pp;
p = name;
hashval = *p << 4;
while (*p)
hashval += *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) {
INTOFF;
cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
+ strlen(name) + 1);
cmdp->next = NULL;
cmdp->cmdtype = CMDUNKNOWN;
cmdp->rehash = 0;
strcpy(cmdp->cmdname, name);
INTON;
}
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;
ckfree(cmdp);
INTON;
}
/*
* Add a new command entry, replacing any existing command entry for
* the same name.
*/
static void
addcmdentry(const char *name, struct cmdentry *entry)
{
struct tblentry *cmdp;
INTOFF;
cmdp = cmdlookup(name, 1);
if (cmdp->cmdtype == CMDFUNCTION) {
unreffunc(cmdp->param.func);
}
cmdp->cmdtype = entry->cmdtype;
cmdp->param = entry->u;
INTON;
}
/*
* Define a shell function.
*/
void
defun(const 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.
*/
int
unsetfunc(const char *name)
{
struct tblentry *cmdp;
if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
unreffunc(cmdp->param.func);
delete_cmd_entry();
return (0);
}
return (0);
}
/*
* Shared code for the following builtin commands:
* type, command -v, command -V
*/
int
typecmd_impl(int argc, char **argv, int cmd, const char *path)
{
struct cmdentry entry;
struct tblentry *cmdp;
const char *const *pp;
struct alias *ap;
int i;
int error1 = 0;
if (path != pathval())
clearcmdentry();
for (i = 1; i < argc; i++) {
/* First look at the keywords */
for (pp = parsekwd; *pp; pp++)
if (**pp == *argv[i] && equal(*pp, argv[i]))
break;
if (*pp) {
if (cmd == TYPECMD_SMALLV)
out1fmt("%s\n", argv[i]);
else
out1fmt("%s is a shell keyword\n", argv[i]);
continue;
}
/* Then look at the aliases */
if ((ap = lookupalias(argv[i], 1)) != NULL) {
if (cmd == TYPECMD_SMALLV)
out1fmt("alias %s='%s'\n", argv[i], ap->val);
else
out1fmt("%s is an alias for %s\n", argv[i],
ap->val);
continue;
}
/* Then check if it is a tracked alias */
if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
entry.cmdtype = cmdp->cmdtype;
entry.u = cmdp->param;
entry.special = cmdp->special;
}
else {
/* Finally use brute force */
find_command(argv[i], &entry, 0, path);
}
switch (entry.cmdtype) {
case CMDNORMAL: {
if (strchr(argv[i], '/') == NULL) {
const char *path2 = path;
char *name;
int j = entry.u.index;
do {
name = padvance(&path2, argv[i]);
stunalloc(name);
} while (--j >= 0);
if (cmd == TYPECMD_SMALLV)
out1fmt("%s\n", name);
else
out1fmt("%s is%s %s\n", argv[i],
(cmdp && cmd == TYPECMD_TYPE) ?
" a tracked alias for" : "",
name);
} else {
if (eaccess(argv[i], X_OK) == 0) {
if (cmd == TYPECMD_SMALLV)
out1fmt("%s\n", argv[i]);
else
out1fmt("%s is %s\n", argv[i],
argv[i]);
} else {
if (cmd != TYPECMD_SMALLV)
outfmt(out2, "%s: %s\n",
argv[i], strerror(errno));
error1 |= 127;
}
}
break;
}
case CMDFUNCTION:
if (cmd == TYPECMD_SMALLV)
out1fmt("%s\n", argv[i]);
else
out1fmt("%s is a shell function\n", argv[i]);
break;
case CMDBUILTIN:
if (cmd == TYPECMD_SMALLV)
out1fmt("%s\n", argv[i]);
else if (entry.special)
out1fmt("%s is a special shell builtin\n",
argv[i]);
else
out1fmt("%s is a shell builtin\n", argv[i]);
break;
default:
if (cmd != TYPECMD_SMALLV)
outfmt(out2, "%s: not found\n", argv[i]);
error1 |= 127;
break;
}
}
if (path != pathval())
clearcmdentry();
return error1;
}
/*
* Locate and print what a word is...
*/
int
typecmd(int argc, char **argv)
{
return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1));
}