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