diff options
| -rw-r--r-- | NEWS | 2 | ||||
| -rw-r--r-- | syslinux.c | 107 |
2 files changed, 69 insertions, 40 deletions
@@ -7,6 +7,8 @@ Changes in 1.70: header correctly. * SYSLINUX: Fix, again, "the bug that won't die": the use of the offset parameter with the SYSLINUX installer. + * SYSLINUX: Fix possible superblock corruption problem in the + SYSLINUX installer. Changes in 1.67: * Handle bug in the location of initrd. @@ -1,7 +1,7 @@ #ident "$Id$" /* ----------------------------------------------------------------------- * * - * Copyright 1998-2000 H. Peter Anvin - All Rights Reserved + * Copyright 1998-2002 H. Peter Anvin - All Rights Reserved * * 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 @@ -20,10 +20,11 @@ * access the filesystem directly like mtools does so we don't have to * mount the disk. Either that or if Linux gets an fmount() system call * we probably could do the mounting ourselves, and make this program - * setuid safe. + * setuid safe. Or perhaps try to link with mtools code... * */ +#define _XOPEN_SOURCE 500 /* Required on glibc 2.x */ #include <alloca.h> #include <errno.h> #include <fcntl.h> @@ -105,6 +106,63 @@ void usage(void) exit(1); } +/* + * read/write wrapper functions + */ +ssize_t xpread(int fd, void *buf, size_t count, off_t offset) +{ + ssize_t rv; + ssize_t done = 0; + + while ( count ) { + rv = pread(fd, buf, count, offset); + if ( rv == 0 ) { + fprintf(stderr, "%s: short read\n", program); + exit(1); + } else if ( rv == -1 ) { + if ( errno == EINTR ) { + continue; + } else { + perror(program); + exit(1); + } + } else { + offset += rv; + done += rv; + count -= rv; + } + } + + return done; +} + +ssize_t xpwrite(int fd, void *buf, size_t count, off_t offset) +{ + ssize_t rv; + ssize_t done = 0; + + while ( count ) { + rv = pwrite(fd, buf, count, offset); + if ( rv == 0 ) { + fprintf(stderr, "%s: short write\n", program); + exit(1); + } else if ( rv == -1 ) { + if ( errno == EINTR ) { + continue; + } else { + perror(program); + exit(1); + } + } else { + offset += rv; + done += rv; + count -= rv; + } + } + + return done; +} + int main(int argc, char *argv[]) { static unsigned char sectbuf[512]; @@ -182,22 +240,7 @@ int main(int argc, char *argv[]) } } - left = 512; - dp = sectbuf; - while ( left ) { - nb = read(dev_fd, dp, left); - if ( nb == -1 && errno == EINTR ) - continue; - if ( nb < 0 ) { - perror(device); - exit(1); - } else if ( nb == 0 ) { - fprintf(stderr, "%s: no boot sector\n", device); - exit(1); - } - dp += nb; - left -= nb; - } + xpread(dev_fd, sectbuf, 512, offset); close(dev_fd); sync(); @@ -421,32 +464,16 @@ umount: exit(1); } - if ( lseek(dev_fd, offset, SEEK_SET) != offset ) { - if ( !(force && errno == EBADF) ) { - fprintf(stderr, "%s: seek error", device); - exit(1); - } - } + /* Read the superblock again since it might have changed while mounted */ + xpread(dev_fd, sectbuf, 512, offset); /* Copy the old superblock into the new boot sector */ memcpy(bootsect+bsCopyStart, sectbuf+bsCopyStart, bsCopyLen); - - dp = bootsect; - left = bootsect_len; - while ( left ) { - nb = write(dev_fd, dp, left); - if ( nb == -1 && errno == EINTR ) - continue; - else if ( nb <= 0 ) { - perror(device); - exit(1); - } - - dp += nb; - left -= nb; - } - close(dev_fd); + /* Write new boot sector */ + xpwrite(dev_fd, bootsect, 512, offset); + + close(dev_fd); sync(); /* Done! */ |