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/*
* Copyright (c) 2019 Yubico AB. All rights reserved.
* Use of this source code is governed by a BSD-style
* license that can be found in the LICENSE file.
* SPDX-License-Identifier: BSD-2-Clause
*/
/*
* cc -fPIC -D_GNU_SOURCE -shared -o preload-fuzz.so preload-fuzz.c
* LD_PRELOAD=$(realpath preload-fuzz.so)
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <dlfcn.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define FUZZ_DEV_PREFIX "nodev"
static int fd_fuzz = -1;
static int (*open_f)(const char *, int, mode_t);
static int (*close_f)(int);
static ssize_t (*write_f)(int, const void *, size_t);
int
open(const char *path, int flags, ...)
{
va_list ap;
mode_t mode;
va_start(ap, flags);
mode = va_arg(ap, mode_t);
va_end(ap);
if (open_f == NULL) {
open_f = dlsym(RTLD_NEXT, "open");
if (open_f == NULL) {
warnx("%s: dlsym", __func__);
errno = EACCES;
return (-1);
}
}
if (strncmp(path, FUZZ_DEV_PREFIX, strlen(FUZZ_DEV_PREFIX)) != 0)
return (open_f(path, flags, mode));
if (fd_fuzz != -1) {
warnx("%s: fd_fuzz != -1", __func__);
errno = EACCES;
return (-1);
}
if ((fd_fuzz = dup(STDIN_FILENO)) < 0) {
warn("%s: dup", __func__);
errno = EACCES;
return (-1);
}
return (fd_fuzz);
}
int
close(int fd)
{
if (close_f == NULL) {
close_f = dlsym(RTLD_NEXT, "close");
if (close_f == NULL) {
warnx("%s: dlsym", __func__);
errno = EACCES;
return (-1);
}
}
if (fd == fd_fuzz)
fd_fuzz = -1;
return (close_f(fd));
}
ssize_t
write(int fd, const void *buf, size_t nbytes)
{
if (write_f == NULL) {
write_f = dlsym(RTLD_NEXT, "write");
if (write_f == NULL) {
warnx("%s: dlsym", __func__);
errno = EBADF;
return (-1);
}
}
if (fd != fd_fuzz)
return (write_f(fd, buf, nbytes));
return (nbytes);
}
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