Linker fails when compiling fuse files with "undefined reference to `fuse_main_real'

[William Woelke]

I had a working Fuse application when using Ubuntu 11.04, and I'm 99.9% sure I've
installed everything I need after re-installing Ubuntu 11.10.

I installed libfuse-dev and copied the
/usr/share/doc/libfuse-dev/examples/hello.c file to /tmp and ran the the command
listed at the top of the file:

gcc -Wall `pkg-config fuse --cflags --libs` hello.c -o hello

and it returns:

/tmp/ccYYt1z4.o: In function `main':
hello.c:(.text+0x33f): undefined reference to `fuse_main_real'
collect2: ld returned 1 exit status

libfuse-dev:
  Installed: 2.8.4-1.4ubuntu1
  Candidate: 2.8.4-1.4ubuntu1
  Version table:
 *** 2.8.4-1.4ubuntu1 0
        500 http://us.archive.ubuntu.com/ubuntu/ oneiric/main amd64 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: libfuse-dev 2.8.4-1.4ubuntu1 [modified: usr/share/doc/libfuse-dev/changelog.Debian.gz]
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 1.23-0ubuntu3
Architecture: amd64
Date: Wed Oct 19 19:00:51 2011
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Beta amd64 (20111004)
SourcePackage: fuse
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Jérôme DUMESNIL (jerome-dumesnil)]

This bug only appears when using "fuse_main" macro.
When underlying functions (fuse_new, fuse_mount, ...) are directly called, the problem doesn't appear.

[Jeremy Nickurak (nickurak)]

Any workaround?

[Flávio Martins (flavioxmartins)]

This should work:

gcc -Wall -o hello hello.c `pkg-config fuse --cflags --libs`

The order of sources and libraries matters.
If you want to know more, you can read http://webpages.charter.net/ppluzhnikov/linker.html

[Jeremy Nickurak (nickurak)]

2011/12/1 Flávio Martins <email address hidden>:
> This should work:
>
> gcc -Wall  -o hello hello.c `pkg-config fuse --cflags --libs`

So what changed such that the libfuse-dev example Makefile has stopped
working correctly?

--
Jeremy Nickurak -= Email/XMPP: -= <email address hidden> =-

[Henrik Ledin (henrik-ledin)]

I think I have found what is causing this issue.
It seems to be something wrong with pkg-config, when used inside of the `` chars

When running `pkg-config fuse --cflags --libs` it returns
-D_FILE_OFFSET_BITS=64: command not found

Without the `` chars it returns
-D_FILE_OFFSET_BITS=64 -I/usr/include/fuse -pthread -lfuse -lrt -ldl

I'm not familiar with pkg-config, so I don't know how to fix this issue.

Best regards,
Henrik

[Michał Wróbel (maw)]

I corrected the Makefile by reordering LDFLAGS similarly to how Flávio Martins (xhaker) suggested, fixed installation of fioc.h header which was needed to build all the examples (including cusexmp, fioc, fioclient, fsel, fselclient) and uploaded the package to my PPA (at the time of writing, pending to be built): https://launchpad.net/~maw/+archive/fixes

[noon (fabrice-bauzac)]

LDFLAGS is the variable for the linker flags.
Linker libs such as -lfuse should be put in the LDLIBS variable, not in LDFLAGS.

To solve the problem and simplify the Makefile at the same time:

In the Makefile, the LDFLAGS definition should be replaced with LDLIBS:

LDLIBS := $(shell pkg-config fuse --libs)

Also the 2-line fusexmp_fh section should be simplified with:

fusexml_fh: LDLIBS += -lulockmgr

(To make it even cleaner, there should be separate CFLAGS and CPPFLAGS pkg-config settings: --cflags-only-other and --cflags-only-I respectively)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Dimitri John Ledkov (xnox)]

pkg-config operates correct here. And fuse pkg-config (.pc) files are also correct. The makefile is broken and bad =) either use it as a bad example, and write better ones in your own projects (or e.g. use modern cmake / automake from scratch instead of hand writting bad makefiles).

If you wish to fix the example makefile, it's best to report this upstream.