I'm trying to load a C shared library within Ruby using Fiddle.
Here is a minimal example:
require 'fiddle'
require 'fiddle/import'
module Era
extend Fiddle::Importer
dlload './ServerApi.so'
extern 'int era_init_lib()'
extern 'void era_deinit_lib()'
extern 'int era_process_request(const char* request, char** response)'
extern 'void era_free(char* response)'
end
Era.era_init_lib
begin
# ...
ensure
Era.era_deinit_lib
end
The shared library loads without issues. However when I call Era.era_init_lib it tries to load additional libraries (Network.so and Protobuf.so). I have these file located in the current working directory (in the same directory as ServerApi.so).
However when I try to execute the code above I receive the following error:
! Failed to load library: /home/username/.rvm/rubies/ruby-2.6.5/bin/Network.so, error: /home/username/.rvm/rubies/ruby-2.6.5/bin/Network.so: cannot open shared object file: No such file or directory
If I place the file at the location the error describes everything works fine.
My guess is that the C working directory of fiddle is different from the Ruby working directory. I would like to keep the project files within the project and not in the Ruby installation directory.
How can I use Network.so from my project folder?
All the *.so files are provided by a third-party. I do not have the source and as a result cannot change these files. The function signatures are provided by the documentation.
Searching for Network.so in the strace gives me these results:
readlink("/proc/self/exe", "/home/username/.rvm/rubies/ruby-2."..., 4096) = 44
openat(AT_FDCWD, "/home/username/.rvm/rubies/ruby-2.6.5/bin/Network.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
futex(0x7fcc16666d90, FUTEX_WAKE_PRIVATE, 2147483647) = 0
futex(0x7fcc16b44520, FUTEX_WAKE_PRIVATE, 2147483647) = 0
write(2, "! Failed to load library: ", 26! Failed to load library: ) = 26
write(2, "/home/username/.rvm/rubies/ruby-2."..., 50/home/username/.rvm/rubies/ruby-2.6.5/bin/Network.so) = 50
write(2, ", error: ", 9, error: ) = 9
write(2, "/home/username/.rvm/rubies/ruby-2."..., 109/home/username/.rvm/rubies/ruby-2.6.5/bin/Network.so: cannot open shared object file: No such file or directory) = 109
write(2, "\n", 1) = 1
I've also written a C script which does the same thing which works perfectly fine when the files are dropped into the same directory. So it might be the fault of the library, which I assume checks the location of the current running program, then tries to load the library from that folder. This would explain the behavior when ran as a Ruby script (since it runs as part of the Ruby program), whereas a C binary runs standalone.
For those that want to re-create the (Linux) issue. You can download the necessary files from here. Which gives you the server-linux-x86_64.sh file.
Supported distros are: Suse, Ubuntu, Debian, Red Hat and CentOS but others may also work fine.
You can either run the installer, which should place the files in /opt/eset/RemoteAdministrator/Server. Or, assuming most of you don't want to install the full application you can run the following command:
sed '1,/^# Start of TAR\.GZ file #$/d' server-linux-x86_64.sh | sed '1d' > server-linux-x86_64.tar.gz
Which removes all the installer instructions from the .sh file and only leaves the binary .tar.gz data, writing it to server-linux-x86_64.tar.gz.
Copy the files ServerApi.so, Protobuf.so and Network.so into a directory of your liking. Create a Ruby script (with the question code) in the same directory and run the script.
Because ServerApi.so checks /proc/self/exe for the location of all subsequent files to load, and it is very difficult to modify this target by normal means, it is easier to just modify ServerApi.so itself so that it uses something else besides proc for the source.
If we run strings ServerApi.so, we can verify that the location to check is stored inside a string in ServerApi.so:
strings ServerApi.so | grep 'proc/self/exe'
B/proc/self/exe
So now all we need to do is modify this string to something else that works for us.
The easiest way to modify the string is to replace it with something that is exactly the same length as the original. This way we do not have to worry about changing the end-of-string zero padding or accidentally changing the total size of ServerApi.so.
Here we can see a suitable candidate could be /tmp/scriptexe:
/proc/self/exe
/tmp/scriptexe <- same length
So let's do that:
sed -e 's/proc\/self\/exe/tmp\/scriptexe/' ServerApi.so > ServerApi_Mod.so
Now we can verify the change:
strings ServerApi_Mod.so | grep scriptexe
B/tmp/scriptexe
Next we need to create /tmp/scriptexe to actually point to our Ruby script:
ln -s /the/full/path/to/our/ruby/script.rb /tmp/scriptexe
Then we modify our script:
dlload './ServerApi_Mod.so
Now we can run it as normal:
ruby script.rb
And everything should work.
If we read the strace output we see that the library obtains the current executable location from /proc/self/exe, and then searches subsequent libraries from there.
/proc/self/exe is not easily modifiable, but by using a hard link to a Ruby executable in the current directory we can trick it to point to a new folder.
Problem is making a hard link requires root.
In any case, here is a self-contained solution (note that it will ask for root password the first time you run it, in order to create the hard link).
Put this at the top of your script:
# Obtain path to current executable
exe = File.readlink("/proc/self/exe")
# Check if we are running the hard-liked version
if !exe.match /localruby/
if !File.exist?('localruby')
# Create a hard link to the current Ruby exe using sudo
system("sudo ln #{exe} localruby")
end
puts "Restarting..."
# In order to prevent infinite busy loop in case of some mishap
sleep 1
# Rerun self using the hard-linked Ruby executable.
# This will make /proc/self/exe point to the hard-link, which then
# allows the ESET library to search for .so files in current folder.
exec('./localruby', File.expand_path(__FILE__))
end
require 'fiddle'
require 'fiddle/import'
# ...rest of your script goes here...
A simple solution without any extra Ruby code is to just create the hard link manually, and then always run the script with ./localruby myscript.rb, instead of using the normal ruby myscript.rb.
This might be a trivial question, but I've searched and found nothing about it. I'm trying to make a complex application on ruby and I have my classes on different .rb files which the "Main" class requires. As it's written in the code:
require 'Book.rb'
require 'Person.rb'
These files that contains the classes are in the same directory, so what I'm looking for is a Batch command which allows me to include these files, like the one for one file but extended:
ruby Main.rb
Which, of course fails saying that it can't find 'Book.rb' (returns error and doesn't look for the other)
Thank you for your help.
Thanks to the user Abhi y found this post. The command that worked for me was:
irb -I . -r Main.rb
From which you can get further information on the link.
I am using 2 set of scripts for soap communication, inside they are identical classes and variables therefore when using the main script I need to put condition.
if A
require A.rb
if B
require B.rb
The problem is that the ruby2exe does not include these script when compiling the main script.
If have put the 2 require on the top of the file it does not work but then the main script confuse between the classes in the two files.
Idea how to solve it ?
Thanks
Eran
Try to include both at the beginning so the compiler picks them up, later at line +520 you do the include again, i presume the last included file will be what is used.
Also try the ocra compiler which is more recent then ruby2exe.
I've been working on my first Ruby project, and in the process of trying to organize my files into different directories, I've run into trouble with having .rb files load non-ruby files (e.g. .txt files) local to themselves.
For example, suppose a project has the following structure:
myproject/
bin/
runner.rb
lib/
foo.rb
fooinfo.txt
test/
testfoo.rb
And the file contents are as follows:
runner.rb
require_relative '../lib/foo.rb'
foo.rb
File.open('./fooinfo.txt') do |file|
while line = file.gets
puts line
end
end
If I cd to lib and run foo.rb, it has no trouble finding fooinfo.txt in its own directory and printing its contents.
However, if I cd to bin and run runner.rb, I get
in `initialize': No such file or directory - ./fooinfo.txt (Errno::ENOENT)
I assume this is because File.open searches relative to whatever directory the top level program is run from.
Is there a way to ensure that foo.rb can find fooinfo.rb regardless of where it is run/required from (assuming that foo.rb and fooinfo.rb always maintain the same location relative to eachother)?
I'd like to be able to run foo.rb from bin/runner.rb, and a test file in test/, and have it be able to find fooinfo.txt in both cases.
Ideally, I'd like to have a solution that would work even if the entire myproject directory were moved.
Is there something like require_relative that can locate a non-ruby file?
Try using __FILE__ and File.dirname to build absolute paths. For example:
File.open(File.expand_path(File.dirname(__FILE__)) + './fooinfo.txt') do |file|
...
end
In this case, the simplest thing is to just change
File.open('./fooinfo.txt')
to
File.open('../lib/fooinfo.txt')
That will work from from any project subdirectory directly under your project root (including lib/).
The more robust solution, useful in larger projects, is to have a PROJECT_ROOT constant that you can use from anywhere. If you have lib/const.rb:
module Const
PROJECT_ROOT = File.expand_path("..", File.dirname(__FILE__))
end
Then (assuming you've requireed that file) you can use:
File.open(Const::PROJECT_ROOT + '/lib/fooinfo.txt')
Ahead of creating a tarball we are generating several files to be added to the package. For example:
# from Rakefile
# generate fileA (copy is just an example, the file is really generated dynamically)
FileUtils.cp("fileA", "myFileA")
Rake::PackageTask.new("package name") do |p|
p.need_tar_gz = true
p.package_files.include("myFileA") # generated a few lines before
end
After executing rake package it is just the right time for cleanup (to remove myFileA that was copied on purpose). The question is how to do it right?