Thanks.
There's a more fundamental problem, though. Try running
go build -linkshared hello.go
as a non-privileged user. You'll get a bunch of permission denied messages.
(I had mentioned this
back in January). This is why I'm fooling around running the compiler and
linker manually.
I suggest you add this to your test suite.
Cordially,
Jon Forrest
On Friday, August 11, 2023 at 10:00:12 PM UTC-7 Ian Lance Taylor wrote:
> On Fri, Aug 11, 2023 at 6:15 PM jlfo...@berkeley.edu
> <jlfo...@berkeley.edu> wrote:
> >
> > Now that Go 1.21 has been released, I've returned to trying to figure
> out how to
> > dynamically link a Go program. Back in January I posted the results of
> my first attempt
> > with an earlier version of Go, which was:
> >
> > 1) Building a Go shared library by running
> >
> > go install -buildmode=shared std
> >
> > as root works fine.
> >
> > 2) Building a dynamically linked Go executable as a non-privileged user
> by adding
> >
> > -linkshared
> >
> > to "go build" fails with lots of file access permission errors because
> > the go build tool tries to write to the Go shared library, which a
> non-privileged
> > user can't do.
> >
> > 3) Building a dynamically link Go executable as root works but a new
> version
> > of the Go shared library gets made in the process. This makes this
> command
> > take much longer than it should. Plus, having to be root is a
> non-starter.
> >
> > I started looking at what "go build" is doing by adding the "-x" option.
> > I was able to figure out how to build and link the following program
> >
> > package main
> > func main() {
> > }
> >
> > using a shared library. This was quite an accomplishment. But, then I
> tried making it into
> > a "Hello, world!" program.
> >
> > package main
> > import "fmt"
> > func main() {
> > fmt.Println("Hello, world!\n")
> > }
> >
> > This also compiles and links, but running it results in
> >
> > panic: runtime error: invalid memory address or nil pointer dereference
> > [signal SIGSEGV: segmentation violation code=0x1 addr=0x0
> pc=0x7fe02814e593]
> >
> > goroutine 1 [running]:
> > os.(*File).write(...)
> > /usr/local/go/src/os/file_posix.go:46
> > os.(*File).Write(0x0, {0xc0003a6000?, 0xf, 0x7fe028059f25?})
> > /usr/local/go/src/os/file.go:183 +0x53
> > fmt.Fprintln({0x202f88, 0x0}, {0xc00035af20, 0x1, 0x1})
> > /usr/local/go/src/fmt/print.go:305 +0x6f
> > fmt.Println(...)
> > /usr/local/go/src/fmt/print.go:314
> >
> > To compile the program I ran
> >
> > WORK=/tmp/go-build3183434751
> > /usr/local/go/pkg/tool/linux_amd64/compile -p main -complete
> -installsuffix dynlink -goversion go1.21.0 -c=3 -dynlink -linkshared
> -nolocalimports -importcfg $WORK/b001/importcfg ./file1.go
> >
> > and to link it I ran
> >
> > WORK=/tmp/go-build3183434751
> > /usr/local/go/pkg/tool/linux_amd64/link -o a.out -importcfg
> $WORK/b001/importcfg.link -buildmode=exe -linkshared -w file1.o
> >
> > $WORK/b001/importcfg is
> > packagefile fmt=/usr/local/go/pkg/linux_amd64_dynlink/fmt.a
> > packagefile runtime=/usr/local/go/pkg/linux_amd64_dynlink/runtime.a
> > packagefile
> runtime/cgo=/usr/local/go/pkg/linux_amd64_dynlink/runtime/cgo.a
> >
> > $WORK/b001/importcfg.link is many lines like
> > packagefile fmt=/usr/local/go/pkg/linux_amd64_dynlink/fmt.a
> > packageshlib fmt=/usr/local/go/pkg/linux_amd64_dynlink/libstd.so
> >
> > Both these files were created when I ran the regular "go build
> -linkedshare" command.
> > I have to admit that I don't really understand what these files should
> contain,
> > and I wouldn't be surprised if this is what's causing my problem.
> >
> > Any suggestions for what I'm doing wrong?
>
> Thanks. This looks like a bug. Somehow we must not be testing quite
> this case in our -buildmode=shared testsuite.
>
> I opened https://go.dev/issue/61973.
>
> Ian
>
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