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/* Copyright (C) 2006 by Paolo Giarrusso - modified from glibc' execvp.c.
Original copyright notice follows:
Copyright (C) 1991,92,1995-99,2002,2004 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <unistd.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#ifndef TEST
#include <um_malloc.h>
#include <stdio.h>
#define um_kmalloc malloc
#include <os.h>
/* Execute FILE, searching in the `PATH' environment variable if it contains
no slashes, with arguments ARGV and environment from `environ'. */
int execvp_noalloc(char *buf, const char *file, char *const argv[])
if (*file == '\0') {
return -ENOENT;
if (strchr (file, '/') != NULL) {
/* Don't search when it contains a slash. */
execv(file, argv);
} else {
int got_eacces;
size_t len, pathlen;
char *name, *p;
char *path = getenv("PATH");
if (path == NULL)
path = ":/bin:/usr/bin";
len = strlen(file) + 1;
pathlen = strlen(path);
/* Copy the file name at the top. */
name = memcpy(buf + pathlen + 1, file, len);
/* And add the slash. */
*--name = '/';
got_eacces = 0;
p = path;
do {
char *startp;
path = p;
//Let's avoid this GNU extension.
//p = strchrnul (path, ':');
p = strchr(path, ':');
if (!p)
p = strchr(path, '\0');
if (p == path)
/* Two adjacent colons, or a colon at the beginning or the end
of `PATH' means to search the current directory. */
startp = name + 1;
startp = memcpy(name - (p - path), path, p - path);
/* Try to execute this name. If it works, execv will not return. */
execv(startp, argv);
if (errno == ENOEXEC) {
switch (errno) {
case EACCES:
/* Record the we got a `Permission denied' error. If we end
up finding no executable we can use, we want to diagnose
that we did find one but were denied access. */
got_eacces = 1;
case ENOENT:
case ESTALE:
/* Those errors indicate the file is missing or not executable
by us, in which case we want to just try the next path
directory. */
case ENODEV:
/* Some strange filesystems like AFS return even
stranger error numbers. They cannot reasonably mean
anything else so ignore those, too. */
/* We won't go searching for the shell
* if it is not executable - the Linux
* kernel already handles this enough,
* for us. */
/* Some other error means we found an executable file, but
something went wrong executing it; return the error to our
caller. */
return -errno;
} while (*p++ != '\0');
/* We tried every element and none of them worked. */
if (got_eacces)
/* At least one failure was due to permissions, so report that
error. */
return -EACCES;
/* Return the error from the last attempt (probably ENOENT). */
return -errno;
#ifdef TEST
int main(int argc, char**argv)
char buf[PATH_MAX];
int ret;
if (!argc) {
os_warn("Not enough arguments\n");
return 1;
if (ret = execvp_noalloc(buf, argv[0], argv)) {
errno = -ret;
return 0;