linux/syslinux: handle the null pathname case

Fix mishandling of the null pathname case in the syslinux installer,
and generally clean up the handling of the subpath name.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/linux/syslinux.c b/linux/syslinux.c
index 888df3d..20de62a 100644 (file)
--- a/linux/syslinux.c
+++ b/linux/syslinux.c
@@ -1,6 +1,7 @@
 /* ----------------------------------------------------------------------- *
  *
  *   Copyright 1998-2008 H. Peter Anvin - All Rights Reserved
+ *   Copyright 2009-2010 Intel Corporation; author: H. Peter Anvin
  *
  *   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
@@ -281,11 +282,19 @@ int main(int argc, char *argv[])
     umask(077);
     parse_options(argc, argv, MODE_SYSLINUX);
 
-    asprintf(&subdir, "%s%s",
-            opt.directory[0] == '/' ? "" : "/", opt.directory);
-    if (!subdir) {
-       perror(program);
-       exit(1);
+    /* Note: subdir is guaranteed to start and end in / */
+    if (opt.directory && opt.directory[0]) {
+       int len = strlen(opt.directory);
+       asprintf(&subdir, "%s%s%s",
+                opt.directory[0] == '/' ? "" : "/",
+                opt.directory,
+                opt.directory[len-1] == '/' ? "" : "/");
+       if (!subdir) {
+           perror(program);
+           exit(1);
+       }
+    } else {
+       subdir = "/";
     }
 
     if (!opt.device)
@@ -377,9 +386,8 @@ int main(int argc, char *argv[])
        die("mount failed");
     }
 
-    ldlinux_path = alloca(strlen(mntpath) +  (subdir ? strlen(subdir) + 2 : 0));
-    sprintf(ldlinux_path, "%s%s%s",
-           mntpath, subdir ? "//" : "", subdir ? subdir : "");
+    ldlinux_path = alloca(strlen(mntpath) + strlen(subdir) + 1);
+    sprintf(ldlinux_path, "%s%s", mntpath, subdir);
 
     ldlinux_name = alloca(strlen(ldlinux_path) + 14);
     if (!ldlinux_name) {
@@ -387,7 +395,7 @@ int main(int argc, char *argv[])
        err = 1;
        goto umount;
     }
-    sprintf(ldlinux_name, "%s//ldlinux.sys", ldlinux_path);
+    sprintf(ldlinux_name, "%sldlinux.sys", ldlinux_path);
 
     /* update ADV only ? */
     if (opt.update_only == -1) {