/* ----------------------------------------------------------------------- *
*
* Copyright 2007-2008 H. Peter Anvin - All Rights Reserved
* Copyright 2010 Intel Corporation; author: H. Peter Anvin
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, Inc., 53 Temple Place Ste 330,
* Boston MA 02111-1307, USA; either version 2 of the License, or
* (at your option) any later version; incorporated herein by reference.
*
* ----------------------------------------------------------------------- */
/*
* advio.c
*
* Linux ADV I/O
*
* Return 0 on success, -1 on error, and set errno.
*
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "syslxint.h"
#include "syslxcom.h"
/*
* Read the ADV from an existing instance, or initialize if invalid.
* Returns -1 on fatal errors, 0 if ADV is okay, 1 if the ADV is
* invalid, and 2 if the file does not exist.
*/
int read_adv(const char *path, const char *cfg)
{
char *file;
int fd = -1;
struct stat st;
int err = 0;
int rv;
rv = asprintf(&file, "%s%s%s", path,
path[0] && path[strlen(path) - 1] == '/' ? "" : "/", cfg);
if (rv < 0 || !file) {
perror(program);
return -1;
}
fd = open(file, O_RDONLY);
if (fd < 0) {
if (errno != ENOENT) {
err = -1;
} else {
syslinux_reset_adv(syslinux_adv);
err = 2; /* Nonexistence is not a fatal error */
}
} else if (fstat(fd, &st)) {
err = -1;
} else if (st.st_size < 2 * ADV_SIZE) {
/* Too small to be useful */
syslinux_reset_adv(syslinux_adv);
err = 0; /* Nothing to read... */
} else if (xpread(fd, syslinux_adv, 2 * ADV_SIZE,
st.st_size - 2 * ADV_SIZE) != 2 * ADV_SIZE) {
err = -1;
} else {
/* We got it... maybe? */
err = syslinux_validate_adv(syslinux_adv) ? 1 : 0;
}
if (err < 0)
perror(file);
if (fd >= 0)
close(fd);
free(file);
return err;
}
/*
* Update the ADV in an existing installation.
*/
int write_adv(const char *path, const char *cfg)
{
unsigned char advtmp[2 * ADV_SIZE];
char *file;
int fd = -1;
struct stat st, xst;
int err = 0;
int rv;
rv = asprintf(&file, "%s%s%s", path,
path[0] && path[strlen(path) - 1] == '/' ? "" : "/", cfg);
if (rv < 0 || !file) {
perror(program);
return -1;
}
fd = open(file, O_RDONLY);
if (fd < 0) {
err = -1;
} else if (fstat(fd, &st)) {
err = -1;
} else if (st.st_size < 2 * ADV_SIZE) {
/* Too small to be useful */
err = -2;
} else if (xpread(fd, advtmp, 2 * ADV_SIZE,
st.st_size - 2 * ADV_SIZE) != 2 * ADV_SIZE) {
err = -1;
} else {
/* We got it... maybe? */
err = syslinux_validate_adv(advtmp) ? -2 : 0;
if (!err) {
/* Got a good one, write our own ADV here */
clear_attributes(fd);
/* Need to re-open read-write */
close(fd);
fd = open(file, O_RDWR | O_SYNC);
if (fd < 0) {
err = -1;
} else if (fstat(fd, &xst) || xst.st_ino != st.st_ino ||
xst.st_dev != st.st_dev || xst.st_size != st.st_size) {
fprintf(stderr, "%s: race condition on write\n", file);
err = -2;
}
/* Write our own version ... */
if (xpwrite(fd, syslinux_adv, 2 * ADV_SIZE,
st.st_size - 2 * ADV_SIZE) != 2 * ADV_SIZE) {
err = -1;
}
sync();
set_attributes(fd);
}
}
if (err == -2)
fprintf(stderr, "%s: cannot write auxilliary data (need --update)?\n",
file);
else if (err == -1)
perror(file);
if (fd >= 0)
close(fd);
if (file)
free(file);
return err;
}
