Actually make the -o option work properly.syslinux-1.6x-merge-2

1 files changed, 9 insertions, 2 deletions

diff --git a/syslinux.c b/syslinux.c
index fb82fc54..8728a31c 100644
--- a/syslinux.c
+++ b/syslinux.c
@@ -101,7 +101,7 @@ static u_int32_t get_32(unsigned char *p)
 
 void usage(void)
 {
-  fprintf(stderr, "Usage: %s [-sf] device\n", program);
+  fprintf(stderr, "Usage: %s [-sf] [-o offset] device\n", program);
   exit(1);
 }
 
@@ -139,7 +139,7 @@ int main(int argc, char *argv[])
 	} else if ( *opt == 'f' ) {
 	  force = 1;		/* Force install */
 	} else if ( *opt == 'o' && argp[1] ) {
-	  offset = atol(*++argp); /* Byte offset */
+	  offset = strtoul(*++argp, NULL, 0); /* Byte offset */
 	} else {
 	  usage();
 	}
@@ -421,6 +421,13 @@ umount:
     exit(1);
   }
 
+  if ( lseek(dev_fd, offset, SEEK_SET) != offset ) {
+    if ( !(force && errno == EBADF) ) {
+      fprintf(stderr, "%s: seek error", device);
+      exit(1);
+    }
+  }
+
   /* Copy the old superblock into the new boot sector */
   memcpy(bootsect+bsCopyStart, sectbuf+bsCopyStart, bsCopyLen);