symbol lookup error: ./libproxychains4.so: undefined symbol: pthread_once about proxychains-ng

[jryaonj]

Same problem here

When compiled in CentOS 7, everything is OK and proxychains4 runs fine

but in Ubuntu 14.10, compilation is OK, but when I ran any program, all results as:
symbol lookup error: ./libproxychains4.so: undefined symbol: pthread_once

If I change the lpthread to pthread, then results like this:
symbol lookup error: ./libproxychains4.so: undefined symbol: dlsym

have no idea how to change the compile option

[jackyzy823]

in Makefile line 85
change to:
$(CC) -shared $(LDFLAGS) $(LD_SET_SONAME)$(LDSO_PATHNAME) -lpthread $(LIBDL) -o $@ $(LOBJS)

[jryaonj]

@jackyzy823 THX so much!

Now everything works as the original proxychains3 does

[kierr]

Thank you @jackyzy823 !

This has solved the issue for me too.

[jackyzy823]

You may google gcc link order for more detail and further understanding. :-)

[rofl0r]

@jackyzy823 care to create a pull request with your fix ?

[proudzhu]

This just breaks the linking on archlinux using gcc5.
$(CC) -shared -lpthread $(LIBDL) $(LDFLAGS) $(LD_SET_SONAME)$(LDSO_PATHNAME) -o $@ $(LOBJS) works fine.

[rofl0r]

@proudzhu how weird. are you using the latest commit? and please paste output of the make invocation including the error.

[proudzhu]

I'm using release 4.9.
the output of running proxychains ls

[proxychains] config file found: /etc/proxychains.conf
[proxychains] preloading /usr/lib/libproxychains4.so
ls: symbol lookup error: /usr/lib/libproxychains4.so: undefined symbol: pthread_once

but running proxychains curl *** is fine.
revert this commit 377b474, everything works.
I think it is related with gcc versions, maybe they change some default behaviours during gcc updates.
@Kieters @jryaonj Can you provides your gcc versions?
And the PKGBUILD is here proxychains-ng

[rofl0r]

@proudzhu try to revert e79e05a as well. does that work ? this commit seems to be the original cause of the regression

[proudzhu]

@rofl0r
Finally I found that I have "--as-needed" in my local LDFLAGS, it is set in the default makepkg.conf which will be loaded when building a package in archlinux.
Then I found this wiki, in section "Fixing problems with --as-needed", it says "libraries don't create problems, because they are allowed to have undefined symbols".
So in my system, $(CC) -shared -lpthread $(LIBDL) $(LDFLAGS) $(LD_SET_SONAME)$(LDSO_PATHNAME) -o $@ $(LOBJS) works, but $(CC) -shared $(LDFLAGS) $(LD_SET_SONAME)$(LDSO_PATHNAME) -lpthread $(LIBDL) -o $@ $(LOBJS) fails.
Maybe we should move "-lpthread $(LIBDL)" before $(LDFLAGS).
But I cannot figure out why the other users in the post failed to link against libpthread.
If it is a gcc link order issue as @jackyzy823 says ( but I'm confused as there is not other library in the argument), maybe we could change to
$(CC) -shared $(LD_SET_SONAME)$(LDSO_PATHNAME) -lpthread $(LIBDL) $(LDFLAGS) -o $@ $(LOBJS)?

[caikechao]

The package proxychains-ng 4.9-1 I installed from the Arch Linux repository also throws out the error below when I run proxychains firefox

[proxychains] config file found: /etc/proxychains.conf
[proxychains] preloading /usr/lib/libproxychains4.so
sh: symbol lookup error: /usr/lib/libproxychains4.so undefined symbol: pthread_once

But the version proxychains-ng 4.8.1-1 works fine.

[rofl0r]

rather than putting more ducttape (#65) on the broken linker command line,
i reverted the original commit that introduced the breakage by shuffling the ld arguments around, and the following fixup by @jackyzy823, and introduced a clean way to deal with user-supplied LDFLAGS. please check if that fixes your issues.

[proudzhu]

@rofl0r it works now, thanks.