extlinux: Fix installation subdirectory patching

Commit a126f17f663c ("EXTLINUX: Initial XFS filesystem support") broke
the code that inserts the installation subdirectory into the Extended
Patch Area (EPA). The EPA entry is used to set the initial working
directory on boot.

This caused boot failures for users that chose an install directory
other than /boot/syslinux (technically, it failed for any path not in
'search_directories' in load_env32()) due to ldlinux.c32 failing to
load because the initial working directory was not set correctly.

Cc: Paulo Alcantara <pcacjr@zytor.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

1 files changed, 3 insertions, 7 deletions

diff --git a/extlinux/main.c b/extlinux/main.c
index fa54152e..01bfc9c4 100644
--- a/extlinux/main.c
+++ b/extlinux/main.c
@@ -440,13 +440,11 @@ int install_bootblock(int fd, const char *device)
     return 0;
 }
 
-static int rewrite_boot_image(int devfd, const char *filename)
+static int rewrite_boot_image(int devfd, const char *path, const char *filename)
 {
     int fd;
     int ret;
     int modbytes;
-    char path[PATH_MAX];
-    char slash;
 
     /* Let's create LDLINUX.SYS file again (if it already exists, of course) */
     fd = open(filename,  O_WRONLY | O_TRUNC | O_CREAT | O_SYNC,
@@ -470,8 +468,6 @@ static int rewrite_boot_image(int devfd, const char *filename)
 	goto error;
     }
 
-    sscanf(filename, "%s%cldlinux.sys", path, &slash);
-
     /* Map the file, and patch the initial sector accordingly */
     modbytes = patch_file_and_bootblock(fd, path, devfd);
 
@@ -525,7 +521,7 @@ int ext2_fat_install_file(const char *path, int devfd, struct stat *rst)
     }
     close(fd);
 
-    fd = rewrite_boot_image(devfd, file);
+    fd = rewrite_boot_image(devfd, path, file);
     if (fd < 0)
 	goto bail;
 
@@ -673,7 +669,7 @@ static int xfs_install_file(const char *path, int devfd, struct stat *rst)
 
     close(fd);
 
-    fd = rewrite_boot_image(devfd, file);
+    fd = rewrite_boot_image(devfd, path, file);
     if (fd < 0)
 	goto bail;