diff options
Diffstat (limited to 'syslxmod.c')
| -rw-r--r-- | syslxmod.c | 91 |
1 files changed, 74 insertions, 17 deletions
@@ -17,18 +17,9 @@ #define _XOPEN_SOURCE 500 /* Required on glibc 2.x */ #define _BSD_SOURCE -#include <alloca.h> -#include <errno.h> -#include <fcntl.h> -#include <mntent.h> -#include <paths.h> #include <stdio.h> +#include <inttypes.h> #include <string.h> -#include <stdlib.h> -#include <unistd.h> -#include <sys/stat.h> -#include <sys/types.h> -#include <sys/wait.h> #include "syslinux.h" @@ -64,25 +55,25 @@ enum bs_offsets { /* * Access functions for littleendian numbers, possibly misaligned. */ -static inline u_int16_t get_16(unsigned char *p) +static inline uint16_t get_16(unsigned char *p) { - return (u_int16_t)p[0] + ((u_int16_t)p[1] << 8); + return (uint16_t)p[0] + ((uint16_t)p[1] << 8); } -static inline u_int32_t get_32(unsigned char *p) +static inline uint32_t get_32(unsigned char *p) { - return (u_int32_t)p[0] + ((u_int32_t)p[1] << 8) + - ((u_int32_t)p[2] << 16) + ((u_int32_t)p[3] << 24); + return (uint32_t)p[0] + ((uint32_t)p[1] << 8) + + ((uint32_t)p[2] << 16) + ((uint32_t)p[3] << 24); } -static inline void set_16(unsigned char *p, u_int16_t v) +static inline void set_16(unsigned char *p, uint16_t v) { p[0] = (v & 0xff); p[1] = ((v >> 8) & 0xff); } #if 0 /* Not needed */ -static inline void set_32(unsigned char *p, u_int32_t v) +static inline void set_32(unsigned char *p, uint32_t v) { p[0] = (v & 0xff); p[1] = ((v >> 8) & 0xff); @@ -105,3 +96,69 @@ void syslinux_make_bootsect(void *bs) memcpy(bootsect+bsHead, syslinux_bootsect+bsHead, bsHeadLen); memcpy(bootsect+bsCode, syslinux_bootsect+bsCode, bsCodeLen); } + +/* + * Check to see that what we got was indeed an MS-DOS boot sector/superblock + */ +int syslinux_check_bootsect(void *bs, char* device) +{ + int veryold; + unsigned int sectors, clusters; + unsigned char *sectbuf = bs; + + if ( sectbuf[bsBootSignature] == 0x29 ) { + /* It's DOS, and it has all the new nice fields */ + + veryold = 0; + + sectors = get_16(sectbuf+bsSectors); + sectors = sectors ? sectors : get_32(sectbuf+bsHugeSectors); + clusters = sectors / sectbuf[bsSecPerClust]; + + if ( !memcmp(sectbuf+bsFileSysType, "FAT12 ", 8) ) { + if ( clusters > 4086 ) { + fprintf(stderr, "%s: ERROR: FAT12 but claims more than 4086 clusters\n", + device); + return 0; + } + } else if ( !memcmp(sectbuf+bsFileSysType, "FAT16 ", 8) ) { + if ( clusters <= 4086 ) { + fprintf(stderr, "%s: ERROR: FAT16 but claims less than 4086 clusters\n", + device); + return 0; + } + } else if ( !memcmp(sectbuf+bsFileSysType, "FAT ", 8) ) { + /* OS/2 sets up the filesystem as just `FAT'. */ + } else { + fprintf(stderr, "%s: filesystem type \"%8.8s\" not supported\n", + device, sectbuf+bsFileSysType); + return 0; + } + } else { + veryold = 1; + + if ( sectbuf[bsSecPerClust] & (sectbuf[bsSecPerClust] - 1) || + sectbuf[bsSecPerClust] == 0 ) { + fprintf(stderr, "%s: This doesn't look like a FAT filesystem\n", + device); + } + + sectors = get_16(sectbuf+bsSectors); + sectors = sectors ? sectors : get_32(sectbuf+bsHugeSectors); + clusters = sectors / sectbuf[bsSecPerClust]; + } + + if ( get_16(sectbuf+bsBytesPerSec) != 512 ) { + fprintf(stderr, "%s: Sector sizes other than 512 not supported\n", + device); + return 0; + } + + if ( sectbuf[bsSecPerClust] > 32 ) { + fprintf(stderr, "%s: Cluster sizes larger than 16K not supported\n", + device); + return 0; + } + + return 1; +} |