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