mask_statfs_nfs_as_ext4.c

/*
  Patches statfs() syscall* to make programs think that NFS filesystems are actually ext4.

  Temporary fix for KDE Dolphin bug #452924.
  More info: https://bugs.kde.org/show_bug.cgi?id=452924#c28

  Compile with:
  cc -fPIC -shared -ldl -o mask_statfs_nfs_as_ext4.so mask_statfs_nfs_as_ext4.c

  Run Dolphin like so:
  LD_PRELOAD=./mask_statfs_nfs_as_ext4.so dolphin

  *technically just patches the libc wrapper for the syscall but most programs will use that instead
*/

#include <sys/vfs.h>

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <dlfcn.h>

int statfs(const char *path, struct statfs *buf) {
	// the original statfs
	int (*o_statfs)(const char *, struct statfs *) = dlsym(RTLD_NEXT, "statfs");

	int rc = o_statfs(path, buf);
	if (rc < 0) { return rc; }

	// if the filesystem is NFS, pretend that it's actually ext4
	if (buf->f_type == 0x6969) { // NFS magic
		buf->f_type = 0xef53; // ext4 magic
	}

	return rc;
}

# example .desktop file that opens Dolphin with the environment variable set

[Desktop Entry]
Categories=Qt;KDE;System;FileTools;FileManager;
Exec=env LD_PRELOAD=/home/USERNAME/mask_statfs_nfs_as_ext4.so dolphin %u
Icon=system-file-manager
MimeType=inode/directory;
Name=Dolphin
StartupWMClass=dolphin
Type=Application