Blame util.c

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/*
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 * Common "util" functions
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 * This file is part of the dmidecode project.
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 *
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 *   Copyright (C) 2002-2018 Jean Delvare <jdelvare@suse.de>
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 *
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 *   This program is free software; you can redistribute it and/or modify
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 *   it under the terms of the GNU General Public License as published by
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 *   the Free Software Foundation; either version 2 of the License, or
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 *   (at your option) any later version.
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 *
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 *   This program 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
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 *   GNU General Public License for more details.
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 *
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 *   You should have received a copy of the GNU General Public License
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 *   along with this program; if not, write to the Free Software
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 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
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 *
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 *   For the avoidance of doubt the "preferred form" of this code is one which
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 *   is in an open unpatent encumbered format. Where cryptographic key signing
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 *   forms part of the process of creating an executable the information
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 *   including keys needed to generate an equivalently functional executable
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 *   are deemed to be part of the source code.
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 */
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#include <sys/types.h>
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#include <sys/stat.h>
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#include "config.h"
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#ifdef USE_MMAP
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#include <sys/mman.h>
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#ifndef MAP_FAILED
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#define MAP_FAILED ((void *) -1)
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#endif /* !MAP_FAILED */
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#endif /* USE MMAP */
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <fcntl.h>
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#include <errno.h>
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#include "types.h"
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#include "util.h"
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static int myread(int fd, u8 *buf, size_t count, const char *prefix)
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{
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	ssize_t r = 1;
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	size_t r2 = 0;
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	while (r2 != count && r != 0)
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	{
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		r = read(fd, buf + r2, count - r2);
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		if (r == -1)
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		{
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			if (errno != EINTR)
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			{
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				perror(prefix);
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				return -1;
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			}
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		}
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		else
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			r2 += r;
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	}
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	if (r2 != count)
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	{
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		fprintf(stderr, "%s: Unexpected end of file\n", prefix);
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		return -1;
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	}
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	return 0;
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}
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int checksum(const u8 *buf, size_t len)
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{
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	u8 sum = 0;
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	size_t a;
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	for (a = 0; a < len; a++)
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		sum += buf[a];
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	return (sum == 0);
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}
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/*
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 * Reads all of file from given offset, up to max_len bytes.
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 * A buffer of at most max_len bytes is allocated by this function, and
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 * needs to be freed by the caller.
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 * This provides a similar usage model to mem_chunk()
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 *
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 * Returns a pointer to the allocated buffer, or NULL on error, and
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 * sets max_len to the length actually read.
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 */
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void *read_file(off_t base, size_t *max_len, const char *filename)
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{
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	struct stat statbuf;
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	int fd;
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	u8 *p;
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	/*
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	 * Don't print error message on missing file, as we will try to read
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	 * files that may or may not be present.
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	 */
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	if ((fd = open(filename, O_RDONLY)) == -1)
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	{
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		if (errno != ENOENT)
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			perror(filename);
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		return NULL;
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	}
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	/*
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	 * Check file size, don't allocate more than can be read.
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	 */
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	if (fstat(fd, &statbuf) == 0)
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	{
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		if (base >= statbuf.st_size)
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		{
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			fprintf(stderr, "%s: Can't read data beyond EOF\n",
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				filename);
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			p = NULL;
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			goto out;
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		}
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		if (*max_len > (size_t)statbuf.st_size - base)
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			*max_len = statbuf.st_size - base;
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	}
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	if ((p = malloc(*max_len)) == NULL)
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	{
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		perror("malloc");
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		goto out;
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	}
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	if (lseek(fd, base, SEEK_SET) == -1)
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	{
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		fprintf(stderr, "%s: ", filename);
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		perror("lseek");
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		goto err_free;
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	}
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	if (myread(fd, p, *max_len, filename) == 0)
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		goto out;
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err_free:
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	free(p);
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	p = NULL;
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out:
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	if (close(fd) == -1)
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		perror(filename);
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	return p;
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}
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/*
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 * Copy a physical memory chunk into a memory buffer.
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 * This function allocates memory.
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 */
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void *mem_chunk(off_t base, size_t len, const char *devmem)
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{
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	void *p;
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	int fd;
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#ifdef USE_MMAP
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	struct stat statbuf;
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	off_t mmoffset;
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	void *mmp;
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#endif
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	if ((fd = open(devmem, O_RDONLY)) == -1)
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	{
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		perror(devmem);
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		return NULL;
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	}
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	if ((p = malloc(len)) == NULL)
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	{
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		perror("malloc");
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		goto out;
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	}
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#ifdef USE_MMAP
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	if (fstat(fd, &statbuf) == -1)
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	{
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		fprintf(stderr, "%s: ", devmem);
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		perror("stat");
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		goto err_free;
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	}
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	/*
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	 * mmap() will fail with SIGBUS if trying to map beyond the end of
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	 * the file.
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	 */
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	if (S_ISREG(statbuf.st_mode) && base + (off_t)len > statbuf.st_size)
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	{
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		fprintf(stderr, "mmap: Can't map beyond end of file %s\n",
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			devmem);
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		goto err_free;
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	}
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#ifdef _SC_PAGESIZE
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	mmoffset = base % sysconf(_SC_PAGESIZE);
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#else
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	mmoffset = base % getpagesize();
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#endif /* _SC_PAGESIZE */
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	/*
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	 * Please note that we don't use mmap() for performance reasons here,
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	 * but to workaround problems many people encountered when trying
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	 * to read from /dev/mem using regular read() calls.
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	 */
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	mmp = mmap(NULL, mmoffset + len, PROT_READ, MAP_SHARED, fd, base - mmoffset);
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	if (mmp == MAP_FAILED)
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		goto try_read;
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	memcpy(p, (u8 *)mmp + mmoffset, len);
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	if (munmap(mmp, mmoffset + len) == -1)
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	{
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		fprintf(stderr, "%s: ", devmem);
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		perror("munmap");
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	}
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	goto out;
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try_read:
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#endif /* USE_MMAP */
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	if (lseek(fd, base, SEEK_SET) == -1)
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	{
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		fprintf(stderr, "%s: ", devmem);
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		perror("lseek");
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		goto err_free;
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	}
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	if (myread(fd, p, len, devmem) == 0)
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		goto out;
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err_free:
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	free(p);
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	p = NULL;
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out:
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	if (close(fd) == -1)
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		perror(devmem);
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	return p;
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}
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int write_dump(size_t base, size_t len, const void *data, const char *dumpfile, int add)
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{
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	FILE *f;
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	f = fopen(dumpfile, add ? "r+b" : "wb");
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	if (!f)
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	{
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		fprintf(stderr, "%s: ", dumpfile);
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		perror("fopen");
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		return -1;
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	}
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	if (fseek(f, base, SEEK_SET) != 0)
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	{
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		fprintf(stderr, "%s: ", dumpfile);
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		perror("fseek");
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		goto err_close;
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	}
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	if (fwrite(data, len, 1, f) != 1)
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	{
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		fprintf(stderr, "%s: ", dumpfile);
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		perror("fwrite");
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		goto err_close;
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	}
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	if (fclose(f))
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	{
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		fprintf(stderr, "%s: ", dumpfile);
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		perror("fclose");
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		return -1;
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	}
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	return 0;
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err_close:
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	fclose(f);
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	return -1;
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}
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/* Returns end - start + 1, assuming start < end */
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u64 u64_range(u64 start, u64 end)
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{
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	u64 res;
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	res.h = end.h - start.h;
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	res.l = end.l - start.l;
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	if (end.l < start.l)
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		res.h--;
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	if (++res.l == 0)
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		res.h++;
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	return res;
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}