1 /* 2 * This file contains some code to guess where we have to load the 3 * RAM image device from, if started from CD. (In this case it's hard 4 * to tell where this is without diving into BIOS heuristics.) 5 * 6 * There is some nasty hard-codery in here ( MINIX cd label) that can be 7 * improved on. 8 * 9 * Changes: 10 * Jul 14, 2005 Created (Ben Gras) 11 * Feb 10, 2006 Changed into a standalone program (Philip Homburg) 12 * May 25, 2015 Installation CD overhaul (Jean-Baptiste Boric) 13 */ 14 15 #define CD_SECTOR 2048 16 #define SUPER_OFF 1024 17 #define AT_MINORS 8 18 #define MAGIC_OFF 24 19 20 #include <errno.h> 21 #include <fcntl.h> 22 #include <stdio.h> 23 #include <stdlib.h> 24 #include <string.h> 25 #include <unistd.h> 26 27 int main(void) 28 { 29 const int probelist[AT_MINORS] = { 2, 3, 1, 0, 6, 7, 5, 4 }; 30 int controller, disk, r, fd; 31 off_t pos; 32 char name[] = "/dev/c0dX"; 33 char pvd[CD_SECTOR]; 34 35 for(controller = 0; controller <= 1; controller++) { 36 name[6] = '0' + controller; 37 for(disk = 0; disk < AT_MINORS; disk++) { 38 name[8]= '0' + probelist[disk]; 39 40 fprintf(stderr, "Trying %s \r", name); 41 fflush(stderr); 42 43 fd = open(name, O_RDONLY); 44 if ((fd < 0) && (errno != ENXIO)) { 45 fprintf(stderr, "open '%s' failed: %s\n", 46 name, strerror(errno)); 47 continue; 48 } 49 50 /* Try to read PVD. */ 51 pos = lseek(fd, 16*CD_SECTOR, SEEK_SET); 52 if (pos != 16*CD_SECTOR) { 53 close(fd); 54 continue; 55 } 56 r = read(fd, pvd, sizeof(pvd)); 57 close(fd); 58 if (r != sizeof(pvd)) { 59 continue; 60 } 61 62 /* Check PVD ID. */ 63 if (pvd[0] != 1 || pvd[1] != 'C' || pvd[2] != 'D' || 64 pvd[3] != '0' || pvd[4] != '0' || pvd[5] != '1' || 65 pvd[6] != 1 || 66 strncmp(pvd + 40, "MINIX", 5) != 0) { 67 continue; 68 } 69 70 fprintf(stderr, "\nFound.\n"); 71 printf("%s\n", name); 72 return 0; 73 } 74 } 75 76 fprintf(stderr, "\nNot found.\n"); 77 return 1; 78 } 79