I'm trying to compile a go program to be completely standalone including the c libraries. The command I'm using is
[mm17@mm17 grogger]$ go build --ldflags '-extldflags "-static"' ./grogger.go
# command-line-arguments
/usr/bin/ld: cannot find -lgrok
collect2: ld returned 1 exit status
/home/mm17/go/pkg/tool/linux_amd64/6l: running gcc failed: unsuccessful exit status 0x100
So I'll modify the file that calls the grok library to have the following header
1 package grok
2
3 /*
4 #cgo LDFLAGS: -L /usr/lib/libgrok.so -lgrok
5 #include <grok.h>
6 */
7 import "C"
And then running the same command gives
[mm17@mm17 grogger]$ go build --ldflags '-extldflags "-static"' ./grogger.go
# github.com/blakesmith/go-grok
/usr/bin/ld: warning: cannot find entry symbol _start; defaulting to 0000000000400180
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_strlen':
../../blakesmith/go-grok/grok.go:169: undefined reference to `strlen'
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_grok_patterns_import_from_file':
../../blakesmith/go-grok/grok.go:159: undefined reference to `grok_patterns_import_from_file'
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_grok_pattern_add':
../../blakesmith/go-grok/grok.go:147: undefined reference to `grok_pattern_add'
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_grok_new':
../../blakesmith/go-grok/grok.go:132: undefined reference to `grok_new'
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_grok_match_walk_next':
../../blakesmith/go-grok/grok.go:123: undefined reference to `grok_match_walk_next'
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_grok_exec':
../../blakesmith/go-grok/grok.go:81: undefined reference to `grok_exec'
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_grok_discover_new':
../../blakesmith/go-grok/grok.go:68: undefined reference to `grok_discover_new'
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_grok_compile':
../../blakesmith/go-grok/grok.go:46: undefined reference to `grok_compile'
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_grok_match_walk_init':
../../blakesmith/go-grok/grok.go:108: undefined reference to `grok_match_walk_init'
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_grok_match_walk_end':
../../blakesmith/go-grok/grok.go:99: undefined reference to `grok_match_walk_end'
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_grok_free':
../../blakesmith/go-grok/grok.go:90: undefined reference to `grok_free'
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_grok_discover':
../../blakesmith/go-grok/grok.go:58: undefined reference to `grok_discover'
/tmp/go-build731085030/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_free':
../../blakesmith/go-grok/grok.go:34: undefined reference to `free'
collect2: ld returned 1 exit status
If I then just try to build it normally I also get the same things:
[mm17@mm17 grogger]$ go build grogger.go
# github.com/blakesmith/go-grok
/usr/bin/ld: warning: cannot find entry symbol _start; defaulting to 0000000000400180
/tmp/go-build294631148/github.com/blakesmith/go-grok/_obj/grok.cgo2.o: In function `_cgo_4244208c3352_Cfunc_strlen':
../../blakesmith/go-grok/grok.go:169: undefined reference to `strlen'
....
I'm sure I'm just doing something stupid, but I can't seem to figure it out, I'm pretty novice when it comes to gcc and go, this is my first non toy program.
When you compile native library with GCC make sure to use -fPIC option.
If library is compiled without -fPIC GO will not be able to locate functions in it.