88 lines
2.1 KiB
C
88 lines
2.1 KiB
C
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/* This file contains some code to guess where we have to load the
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* RAM image device from, if started from CD. (In this case it's hard
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* to tell where this is without diving into BIOS heuristics.)
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*
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* There is some nasty hard-codery in here (e.g. AT minor device numbers,
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* MINIX cd label) that can be improved on.
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*
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* Changes:
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* Jul 14, 2005 Created (Ben Gras)
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*/
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#include "fs.h"
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#include "super.h"
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#include <minix/com.h>
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#include <string.h>
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/*===========================================================================*
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* cdprobe *
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*===========================================================================*/
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PUBLIC int cdprobe(void)
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{
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#define CD_SECTOR 2048
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#define AT_MAJOR 3
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#define AT_MINORS 4
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int i, minors[AT_MINORS] = { 0, 5, 10, 15 }, dev = 0, found = 0;
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char pvd[CD_SECTOR];
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for(i = 0; i < AT_MINORS && !found; i++) {
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struct super_block probe_super;
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int r, minor;
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dev = (AT_MAJOR << MAJOR) | minors[i];
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/* 1. The drive should be a CD - which is not write-openable.
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* Check for this.
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*/
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if((r = dev_open(dev, FS_PROC_NR, R_BIT|W_BIT)) == OK) {
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dev_close(dev);
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continue;
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}
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/* 2. The drive should be a CD. Open whole drive and
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* check for the PVD.
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*/
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if((r = dev_open(dev, FS_PROC_NR, R_BIT)) != OK) {
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continue;
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}
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if((r = dev_io(DEV_READ, dev, FS_PROC_NR, pvd,
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16*CD_SECTOR, sizeof(pvd), 0)) != sizeof(pvd)) {
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dev_close(dev);
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continue;
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}
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dev_close(dev);
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/* Check PVD ID. */
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if(pvd[0] != 1 || pvd[1] != 'C' || pvd[2] != 'D' ||
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pvd[3] != '0' || pvd[4] != '0' || pvd[5] != '1' || pvd[6] != 1 ||
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strncmp(pvd + 40, "MINIX", 5)) {
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continue;
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}
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/* 3. Both c0dXp1 and p2 should have a superblock. */
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for(minor = minors[i]+2; minor <= minors[i]+3; minor++) {
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dev = (AT_MAJOR << MAJOR) | minor;
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if((r = dev_open(dev, FS_PROC_NR, R_BIT)) != OK)
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continue;
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probe_super.s_dev = dev;
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r = read_super(&probe_super);
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dev_close(dev);
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if(r != OK) {
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break;
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}
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}
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if(minor > minors[i]+3) {
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/* Success? Then set dev to p1. */
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dev = (AT_MAJOR << MAJOR) | (minors[i]+2);
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found = 1;
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break;
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}
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}
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if(!found) return NO_DEV;
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return dev;
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}
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