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plugin: Open : invalid ELF header with non-main package #19882

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wiless opened this issue Apr 7, 2017 · 7 comments
Closed

plugin: Open : invalid ELF header with non-main package #19882

wiless opened this issue Apr 7, 2017 · 7 comments
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FrozenDueToAge WaitingForInfo Issue is not actionable because of missing required information, which needs to be provided.
Milestone
Go1.9Maybe

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@wiless
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wiless commented Apr 7, 2017 •
edited

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go version go1.8 linux/amd64

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/root/go"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build619068367=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"

What did you do?

package plugme

import "fmt"

func Run() {
	fmt.Print("Hello, I am running..")
}

If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on play.golang.org is best.
https://play.golang.org/p/nLF1o0CejJ

Seems that when we call the plugin.Open() it expects that the functions are defined with the same main package. Usually, when the built abcd.so plugin is built and shipped we may not know the package name.

What did you expect to see?

Hello, I am running..

What did you see instead?

panic: plugin.Open: /root/go/src/github.com/wiless/plugin.so: invalid ELF header

goroutine 1 [running]:
main.main()
	/root/go/src/github.com/wiless/main.go:10 +0x1e6
@ianlancetaylor
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How precisely did you build the plugin?

@ianlancetaylor ianlancetaylor changed the title plugin Open : invalid ELF header with non-main package plugin: Open : invalid ELF header with non-main package Apr 7, 2017
@wiless
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wiless commented Apr 7, 2017

go build -buildmode=plugin -o plugin.so

@ianlancetaylor
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What is the output of readelf -h /root/go/src/github.com/wiless/plugin.so?

@bradfitz bradfitz added the WaitingForInfo Issue is not actionable because of missing required information, which needs to be provided. label Apr 8, 2017
@wiless
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wiless commented Apr 8, 2017 


File: plugin.so(__.PKGDEF       )
readelf: Error: Not an ELF file - it has the wrong magic bytes at the start

File: plugin.so(_go_.o          )
readelf: Error: Not an ELF file - it has the wrong magic bytes at the start

@ianlancetaylor
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That is what I would expect for a file built without -buildmode=plugin.

Oh, I see what you mean. If you use -buildmode=plugin but you don't build a main package, you get an object that can go into a plugin, but you don't get an actual plugin. That is a meaningful thing to do, but can be confusing. Hmmm.

@ianlancetaylor ianlancetaylor added this to the Go1.9Maybe milestone Apr 8, 2017
@ianlancetaylor
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CC @crawshaw

@fsenart fsenart mentioned this issue Apr 9, 2017
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@tzneal
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tzneal commented Apr 21, 2017

Duplicate of #19023, which is the older issue.

@tzneal tzneal closed this as completed Apr 21, 2017
@golang golang locked and limited conversation to collaborators Apr 21, 2018
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@bradfitz @tzneal @ianlancetaylor @wiless @gopherbot