Dual booting with shared DB drive possible?

@Здравко - thank you.  btw - who wrote this script? have you tested it? 

The script part is entirely mine and C-code is derived from number other publications.

Ooo.. I didn't see the question for test! Yes, I currently use it. :slight_smile:

TripleS, Sorry, my last publication was one of my drafts. For sure it will not work. It was debug version (some syntax error was still there, missing punctuation). After install I didn't use it for long time (multiple versions was on same place). The next is the last actual version:

#!/bin/bash
##############################################################################
#                    Workaround for Dropbox daemon
#                    -----------------------------
# Verified on Dropbox v73.4.118
# Just make it executable (if need, using
#   $ chmod a+x fix_dropbox
# ) and run it.
# Author: Здравко
#   www.dropboxforum.com/t5/user/viewprofilepage/user-id/422790
##############################################################################

# Figure out the target places.
USR_HOME=`realpath ~`
USR_LOCAL="$USR_HOME/.local"
USR_LOCAL_BIN="$USR_LOCAL/bin"
USR_LOCAL_LIB="$USR_LOCAL/lib"
DRB_REPLACEMENT="$USR_LOCAL_BIN/dropbox"
DRB_FIX_LIB="$USR_LOCAL_LIB/libdropbox_ext4.so"
USR_PROFILE="$USR_HOME/.profile"

##############################################################################
# Precheck and fix up some prerequisites.

# Ensure target directories are on their place.
if [[ ! -d $USR_LOCAL_BIN ]]
then
  echo "The Directory \"$USR_LOCAL_BIN\" doesn't exist, going to create it."
  mkdir -p $USR_LOCAL_BIN
  if [[ $? -ne 0 || ! -d $USR_LOCAL_BIN ]]
  then
    echo "Directory \"$USR_LOCAL_BIN\" creation fail! Exit."
    exit 1
  fi
fi
if [[ ! -d $USR_LOCAL_LIB ]]
then
  echo "The Directory \"$USR_LOCAL_LIB\" doesn't exist, going to create it."
  mkdir -p $USR_LOCAL_LIB
  if [[ $? -ne 0 || ! -d $USR_LOCAL_LIB ]]
  then
    echo "Directory \"$USR_LOCAL_LIB\" creation fail! Exit."
    exit 1
  fi
fi

# Ensure backup for any existing files.
if [[ -e $DRB_REPLACEMENT ]]
then
  if [[ -f $DRB_REPLACEMENT ]]
  then
    echo "\"$DRB_REPLACEMENT\" already exist, going to back it up."
    mv --backup=t -T $DRB_REPLACEMENT "${DRB_REPLACEMENT}.backup"
    if [[ $? -ne 0 || -e $DRB_REPLACEMENT ]]
    then
      echo "Error backing up \"$DRB_REPLACEMENT\" file! Exit."
      exit 1
    fi
  else
    echo "$DRB_REPLACEMENT is not regular file! Exit."
    exit 1
  fi
fi
if [[ -e $DRB_FIX_LIB ]]
then
  if [[ -f $DRB_FIX_LIB ]]
  then
    echo "\"$DRB_FIX_LIB\" already exist, going to back it up."
    mv --backup=t -T $DRB_FIX_LIB "${DRB_FIX_LIB}.backup"
    if [[ $? -ne 0 || -e $DRB_FIX_LIB ]]
    then
      echo "Error backing up \"$DRB_FIX_LIB\" file! Exit."
      exit 1
    fi
  else
    echo "$DRB_FIX_LIB is not regular file! Exit."
    exit 1
  fi
fi

# Ensure writing permissions.
if [[ ! -w $USR_LOCAL_BIN || ! -x $USR_LOCAL_BIN ]]
then
  chmod u+rwx $USR_LOCAL_BIN
  if [[ $? -ne 0 ]]
  then
    echo "The Directory \"$USR_LOCAL_BIN\" is inaccessible! Exit."
    exit 1
  fi
fi
if [[ ! -w $USR_LOCAL_LIB || ! -x $USR_LOCAL_LIB ]]
then
  chmod u+rwx $USR_LOCAL_LIB
  if [[ $? -ne 0 ]]
  then
    echo "The Directory \"$USR_LOCAL_LIB\" is inaccessible! Exit."
    exit 1
  fi
fi

##############################################################################
# Generate actual workaround components.

# Fixer - source and building.
gcc -shared -fPIC -ldl -xc -o $DRB_FIX_LIB - << EndOfSrc
// Functions replacements
#define _GNU_SOURCE

#include <stdlib.h>
#include <sys/vfs.h>
#include <linux/magic.h>
#include <dlfcn.h>
#include <sys/statvfs.h>
#include <stdarg.h>

static int (*orig_statfs)(const char *path, struct statfs *buf) = NULL;
static int (*orig_statfs64)(const char *path, struct statfs64 *buf) = NULL;
static int (*orig_open64)(const char *pathname, int flags, ...) = NULL;

int statfs(const char *path, struct statfs *buf) {
  if (orig_statfs == NULL) {
    orig_statfs = dlsym(RTLD_NEXT, "statfs");
  }
  register int retval = orig_statfs(path, buf);
  if (retval == 0) {
    buf->f_type = EXT4_SUPER_MAGIC;
  }
  return retval;
}
 
int statfs64(const char *path, struct statfs64 *buf) {
  if (orig_statfs64 == NULL) {
    orig_statfs64 = dlsym(RTLD_NEXT, "statfs64");
  }
  register int retval = orig_statfs64(path, buf);
  if (retval == 0) {
    buf->f_type = EXT4_SUPER_MAGIC;
  }
  return retval;
}

int open64(const char *pathname, int flags, ...) {
  if (orig_open64 == NULL) {
    orig_open64 = dlsym(RTLD_NEXT, "open64");
  }
  register const char *p0 = "/proc/filesystems", *p1 = pathname;
  while(*p0 && *p1 && *p0 == *p1) ++p0, ++p1;
  if (*p0 == '\0' && *p1 == '\0') {
    return -1;
  }
  va_list arg;
  va_start(arg, flags);
  mode_t mode = va_arg (arg, int);
  va_end(arg);
  return orig_open64(pathname, flags, mode);
}
EndOfSrc
if [[ $? -ne 0 ]]
then
  echo "Error building \"$DRB_FIX_LIB\"! Exit."
  exit 2
fi
echo "\"$DRB_FIX_LIB\" - build and ready."

# Wrapper generating.
cat > $DRB_REPLACEMENT << WrapperHead
#!/bin/bash
if [ \$1 == "start" ]
then
  sleep 1
  patchpath=\`which \$0\`
  if echo \$(for i in \`ps -C dropbox -o pid\`
            do ls -l /proc/\$i/exe 2>/dev/null | grep -v \$patchpath
            done) | grep dropbox > /dev/null
  then
    timeout=300
    # Make sure there isn't any concurrent start operation in progress.
    /usr/bin/dropbox running
    while [[ \$? -eq 0 && \$timeout -ne 0 ]]
    do
      sleep 1
      ((--timeout))
      if echo \$(for i in \`ps -C dropbox -o pid\`
                do ls -l /proc/\$i/exe 2>/dev/null | grep -v \$patchpath
                done) | grep dropbox > /dev/null
      then
        /usr/bin/dropbox running
      fi
    done
    # If there is running application instance, force its stop.
    /usr/bin/dropbox running
    while [[ \$? -ne 0 && \$timeout -ne 0 ]]
    do
      /usr/bin/dropbox stop
      sleep 1
      ((--timeout))
      /usr/bin/dropbox running
    done
    # If something goes wrong...
    if [[ \$timeout -eq 0 ]]
    then
      # ...notify somehow about.
      title="Problem launching Dropbox"
      mainmsg="Possible existing application instance dead"
      submsg="Check that, clear and try start again"
      if which notify-send > /dev/null
      then notify-send --icon=dropbox "\$title" "<b>\$mainmsg\!</b>\n\$submsg."
      elif which zenity > /dev/null
      then zenity --error --title="\$title" --timeout=10 --width=380 \\
        --text="<span size=\"xx-large\"><b>\$mainmsg\!</b>\n\$submsg.</span>" \\
        2> /dev/null
      else echo "  \$title!"
        echo "\$mainmsg."
        echo "\$submsg."
      fi
      exit 1
    fi
  fi
fi
WrapperHead
declare -p | grep "declare -x LD_PRELOAD" > /dev/null
if [[ $? -ne 0 ]]
then
  echo "export LD_PRELOAD=$DRB_FIX_LIB" >> $DRB_REPLACEMENT
else
  echo "LD_PRELOAD=$DRB_FIX_LIB:\$LD_PRELOAD" >> $DRB_REPLACEMENT
fi
echo "/usr/bin/dropbox \$@" >> $DRB_REPLACEMENT
chmod a+x $DRB_REPLACEMENT
echo "\"$DRB_REPLACEMENT\" - generated."

# Environment check and fixup (if need).
echo ""
echo ""
(
IFS=:
for a in $PATH
do
  if [[ "$a" == "$USR_LOCAL_BIN" ]]
  then
    exit 0
  elif [[ "$a" == "/usr/bin" ]]
  then
    break
  fi
done
exit 1
)
if [[ $? -ne 0 ]]
then
  echo "" >> $USR_PROFILE
  echo "" >> $USR_PROFILE
  echo "# Add $USR_LOCAL_BIN to \$PATH environment variable." >> $USR_PROFILE
  echo "# This addition is dedicated for Dropbox Workaround." >> $USR_PROFILE
  echo "# Remove theses lines when they are no more needed." >> $USR_PROFILE
  echo "PATH=\"$USR_LOCAL_BIN:\$PATH\"" >> $USR_PROFILE
  echo "" >> $USR_PROFILE
  echo "Your Dropbox is almost patched. You have to logout and login"
  echo " (or on Your opinion - restart), so all changes to take effect."
  echo "After Your next account login:"
fi
echo "Your Dropbox is already patched. Just start it from desktop GUI or type:"
echo "\$ dropbox start"
echo "in console."

Здравко Thanks for your posting, it looks like a new hope after so many months.

Could you please confirm what the script does?

Not only the workarround to have the Dropbox only once over the NTFS locations, but also a single DB which avoids reindexing every time one boots with the other OS, plus support for selective sync?

Hi paloi, Yes, I reinstall it just to be sure (after detecting that the last publication wasn't the recent). Exact function is: mask the underlying filesystem, so for Dropbox it looks like Ext4 (doesn't matter what is realy). The change is only how it looks like, there are no any actual changes in real filesystem.

I don't use selective sync, so this is not tested.

'..There is no common format that is supported on each operating system....'

That post doesn't make sense. You don't need compat formats on the drive system. Dropbox should just be copying down folders and files to the file system irrespective of what format. Any of those will support the same files - for instance, you can dload .docx or linux text files just fine to any format - disk format is irrelevent.

There is no technology reason why Dropbox decided to end support for this option - they supported it in the past I believe but functionality was removed.

Hi chasDSO,

Yes, You are absolutely right! I don't know (and not just me) why Dropbox set this limitation. My work is just workaround the limitation. :slight_smile:

---

chasDSO wrote:

'..There is no common format that is supported on each operating system....'

That post doesn't make sense.

---

In terms of Dropbox, yes, it does. Dropbox does not support NTFS for Linux, anything other than NTFS for Windows, etc. Are there workarounds? Yes, apparently, but that doesn't make my comment invalid. In reference to Dropbox and how it works, there is no common format that will allow the official Dropbox client to work across mutliple operating systems. I'm not talking hacks or workarounds. I'm not talking about Linux being able to access NTFS. I'm talking naitive Dropbox support of the file system.

Regardless, I removed that last post of mine since Здравко has a workaround.

---

There is no technology reason why Dropbox decided to end support for this option - they supported it in the past I believe but functionality was removed.

---

No one ever said there was a technology reason for it. No one is debating that. Dropbox simply doesn't support it anymore. Technically they never officially supported it, but it worked.

---

Rich wrote:

...

---

No one ever said there was a technology reason for it. No one is debating that. Dropbox simply doesn't support it anymore. Technically they never officially supported it, but it worked.

---

Almost, but not exactly! In fact You are right, there wasn't (and is not) any technology. Dropbox (or any other such service) don't need to support this. This is OS responsibility! And, in this context, it's not clear why was this limitation added (not support missing)! Support is not need.

---

Здравко wrote:

Support is not need.

---

You're confusing support from a technology standpoint (Product A working with Product B) and support from a business standpoint (Company A saying "No, we don't allow that.").

Dropbox never officially supported Dropbox being used in such a configuration. They didn't design it to work like that, and if a person wasn't careful they could cause damage to their files or possibly lose data (like by using Selective Sync in such a configuration). I'm guessing that's the reason Dropbox no longer supports their product being used in such a way. They could simply be trying to make it more idiot-proof, like they've been trying to do for years.