Initial commit

.gitignore

@@ -0,0 +1,2 @@
+*.o
+*.so

Makefile

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+INSTALL_DIR=/usr/local
+
+libdropbox_ext4.so: dropbox_ext4.o
+	$(LD) -shared -ldl -o $@ $^ && strip $@
+
+%.o: %.c
+	$(CC) -fPIC -D_GNU_SOURCE -Wall -Os -o $@ -c $<
+
+clean:
+	rm -f *.o *.so
+
+install: libdropbox_ext4.so
+	install $^ $(INSTALL_DIR)/lib/ && \
+	echo -e "#!/bin/bash\n\nLD_PRELOAD=$(INSTALL_DIR)/lib/$^ exec /usr/bin/dropbox \"\$$@\"" > $(INSTALL_DIR)/bin/dropbox
+
+uninstall:
+	rm -f $(INSTALL_DIR)/bin/dropbox && \
+	rm -f $(INSTALL_DIR)/lib/libdropbox_ext4.so

README.md

@@ -1,2 +1,20 @@
-# dropbox_ext4
-Hack to make Dropbox work on non-ext4 filesystems
+# Dropbox ext4 Hack
+
+Gets around Dropbox dropping support for non-ext4 filesystems by wrapping the `statfs64` function and overwriting the filesystem type.
+
+## Install the pre-built hack
+
+Just run:
+
+    sudo ./fix_dropbox.py
+    dropbox stop
+    dropbox start
+
+It will install the hack into `/usr/local/`. You can modify `fix_dropbox.py` to customize that.
+
+## Install from source
+
+Make sure you have GCC installed and run the following:
+
+    make
+    sudo make install

dropbox_ext4.c

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+/*
+ * Wraps statfs64 and changes the filesystem type to EXT4.
+ */
+
+#include <stdlib.h>
+#include <dlfcn.h>
+#include <sys/vfs.h>
+#include <linux/magic.h>
+
+int statfs64(const char *path, struct statfs64 *buf) {
+  static int (*_orig_statfs64)(const char *path, struct statfs64 *buf) = NULL;
+
+  if (_orig_statfs64 == NULL) {
+    _orig_statfs64 = dlsym(RTLD_NEXT, "statfs64");
+  }
+
+  int retval = _orig_statfs64(path, buf);
+  if (retval == 0) {
+    buf->f_type = EXT4_SUPER_MAGIC;
+  }
+  return retval;
+}

encode_lib.py

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+#!/usr/bin/env python3
+
+"""
+Encodes the shared library so it can be stored inline in `fix_installer.py`.
+"""
+
+import base64
+import gzip
+import textwrap
+
+
+INPUT_FILE = 'libdropbox_ext4.so'
+
+
+def main():
+    with open(INPUT_FILE, 'rb') as fd:
+        contents = fd.read()
+
+    encoded_contents = base64.b85encode(gzip.compress(contents)).decode()
+
+    print("ENCODED_LIB_CONTENTS = (")
+    for line in textwrap.wrap(encoded_contents, 128):
+        print("    '%s'" % line)
+    print(")")
+
+
+if __name__ == '__main__':
+    main()

fix_dropbox.py

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+#!/usr/bin/env python3
+
+import base64
+import gzip
+import os
+import subprocess
+
+# Install a wrapper script as /usr/local/bin/dropbox.
+# It *should* be in $PATH before /usr/bin/dropbox, and therefore take precedence.
+INSTALL_PATH = '/usr/local/'
+
+# Replace with ~/.local/ if you like - but make sure it's in the $PATH before /usr/bin/!
+# INSTALL_PATH = os.path.expanduser('~/.local/')
+
+# Base85-encoded gzipped libdropbox_ext4.so, generated by `encode_lib.py`,
+ENCODED_LIB_CONTENTS = (
+    'ABzY8O?7))0{`t;-D}fO6u(K<wR2q-#j&~xMwzh98QRXyq0D`6QRc@s21AjMu9+$HV>apBe3>v5`ylL3@UQTB;Db-1e}VWS=#zra8gJ5bYIC<*Me!*=$UXOb-Fxo2hrq'
+    'czvkP-P#}R};t`L{o=d1h#$lppe6Dk`eAv#K=)3Xhc#@G`4ln~h)UB6a$T@lt7Wgoo-A+2(LKfZ}y9PE)sz<cq7ooOY%4?OM?^=tWq{kU2lt8unKet2g6db?jCO21?D6'
+    'nG!AAV1^9*g<4T_StuN_6O1H*+&o9E3i&KBPY3RI+IhZqLL(*t=sF?$OV$gS=)J{85!NyiKeA3OQX7yO+|$anP0d%HLWF;q>`$hkfW#O;G`VPFt6pFY@3^vVc=u1f0)U'
+    'MlS+5U#5tRxW9O*}I&*o`RegHzIL?Y%`L?W9zAmb}V>hXWl)KeusdH4V?!Iw8zNRK>B{V`cYUQ0;`RsHJ()r{4a#(#OEPp2C_MN*gYX>CcINs00CBkh<TyHcS*`tB?QQ'
+    '1lQZO{e1NJVK*j9u$&e-L>@#(ORg4)?iN;@Qp6&!l$VT}_J86MjaF?FuuZye-BkKPg5?fB*pk1PBlyK!5-N{vI4dTZq4p#9lQ9{S@|uPeFeK_;H}^XwUX*($9XhUXT4l'
+    '7-%=H4~E|zr|41>cn5fl_Y3f={Qt=p_OUEp!2a{o)0gD_`5P+(@~Dzf5^^%07>!>{B<21kBO|N2U6r3t4bW!NGA+Ag>uI8xx@8h2vt4jIMvvMhqTDN#l})2$Ws3zLqfu'
+    'SS$mz;P&L)a&Y|*h)^x90tFtzoPo;SQz^n7-WdKT@fCG9|ovR2IJje`Ae^3l%p>#NK=#1P0)A7Se3D6GLVb%k`Vu8z1mf2^MqpyQc3MLOP~-VvvvrfTu?ei~)sXQ=`;i'
+    'agdSQn^9=h%v~;6jS#|V|DvQ4>|u--P@3h=e(cF4c=*x&NKe_Zo<BwG|Jy~kR^c+34Yqv<bSgQbIhM4_^HYGv-#5?c7d?(P5yT#f$_)lo3KCopF#t<!Tw0^!yNtby-1c'
+    '0kC){)VgEQINB^NF`QsYAi7kNtPLuol0dn-cOwben00'
+)
+
+LIBRARY_PATH = os.path.join(INSTALL_PATH, 'lib', 'libdropbox_ext4.so')
+SCRIPT_PATH = os.path.join(INSTALL_PATH, 'bin', 'dropbox')
+
+DROPBOX_WRAPPER_CONTENTS = '''
+#!/bin/bash
+
+LD_PRELOAD=%s exec /usr/bin/dropbox "$@"
+'''.lstrip() % LIBRARY_PATH
+
+
+def main():
+    # Install the library.
+    os.makedirs(os.path.join(INSTALL_PATH, 'bin'), exist_ok=True)
+
+    with open(LIBRARY_PATH, 'wb') as fd:
+        fd.write(gzip.decompress(base64.b85decode(ENCODED_LIB_CONTENTS)))
+        os.fchmod(fd.fileno(), 0o755)
+
+    # Install the wrapper script.
+    os.makedirs(os.path.join(INSTALL_PATH, 'lib'), exist_ok=True)
+
+    with open(SCRIPT_PATH, 'w') as fd:
+        fd.write(DROPBOX_WRAPPER_CONTENTS)
+        os.fchmod(fd.fileno(), 0o755)
+
+    print("Installed the library and the wrapper script at:\n  %s\n  %s" % (LIBRARY_PATH, SCRIPT_PATH))
+    print("(To uninstall, simply delete them.)")
+
+    # Check that the correct 'dropbox' is in the $PATH.
+    result = subprocess.check_output(['which', 'dropbox']).decode().rstrip()
+    if result != SCRIPT_PATH:
+        print()
+        print("You will need to fix your $PATH! Currently, %r takes precedence." % result)
+
+
+if __name__ == '__main__':
+    main()