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cmd/go: invalid -ldflags is silently ignored #43177

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hyangah opened this issue Dec 14, 2020 · 6 comments
Closed

cmd/go: invalid -ldflags is silently ignored #43177

hyangah opened this issue Dec 14, 2020 · 6 comments
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FrozenDueToAge GoCommand cmd/go NeedsFix The path to resolution is known, but the work has not been done.
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Backlog

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@hyangah
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hyangah commented Dec 14, 2020

go version go1.15.5 linux/amd64

$ cat main.go
package main
var X = ""
func main() {	println(X)  }

$ go run -ldflags='-X main.X=Hello' main.go
Hello
$ go run -ldflags='"-X main.X=Hello"' main.go

$

The -ldflags of the second go run is in invalid format, but the go command silently ignores it and keeps working.

$ go run -ldflags='"-X main.X=Hello"' -x main.go
WORK=/tmp/go-build569857493
mkdir -p $WORK/b001/
...
mkdir -p $WORK/b001/exe/
cd .
$GOROOT/pkg/tool/linux_amd64/link -o $WORK/b001/exe/main -importcfg $WORK/b001/importcfg.link -s -w -buildmode=exe -buildid=HYVxxilVrLgdctP3U_YF/h7WWNLZkY13bQM5oqdBD/IUwm0pzLWLHdmcshsYuR/HYVxxilVrLgdctP3U_YF -extld=clang $WORK/b001/_pkg_.a
$WORK/b001/exe/main

See above link command. That's missing -X main.X=Hello
@hyangah hyangah mentioned this issue Dec 14, 2020
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@bcmills
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bcmills commented Dec 14, 2020 •
edited

From what I can tell, that flag is here:

go/src/cmd/go/internal/load/flag.go

Line 17 in 64fae25

BuildLdflags PerPackageFlag // -ldflags

That triggers the parsing case here:

go/src/cmd/go/internal/load/flag.go

Lines 52 to 63 in 64fae25

if !strings.HasPrefix(v, "-") {
i := strings.Index(v, "=")
if i < 0 {
return fmt.Errorf("missing =<value> in <pattern>=<value>")
}
if i == 0 {
return fmt.Errorf("missing <pattern> in <pattern>=<value>")
}
pattern := strings.TrimSpace(v[:i])
match = MatchPackage(pattern, cwd)
v = v[i+1:]
}

...which succeeds because it finds =, and then attempts to match "-X main.X against a package path (which obviously fails to match anything because it's not a syntactically valid package path).

Before we call MatchPackage on the parsed pattern, we should first verify that it is a syntactically valid package pattern.

CC @jayconrod @matloob

@bcmills bcmills added GoCommand cmd/go NeedsFix The path to resolution is known, but the work has not been done. labels Dec 14, 2020
@bcmills bcmills added this to the Backlog milestone Dec 14, 2020
@capnspacehook capnspacehook mentioned this issue Apr 20, 2021
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@gopherbot
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Change https://golang.org/cl/339289 mentions this issue: load: fix ldflags invalid parameters

@mpictor
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mpictor commented Aug 17, 2021 •
edited

Not sure if it's this exact issue, but I just noticed that with go1.16.4 the buildid I set is silently failing, and when it does it wipes out other ldflags.

go build -n -ldflags "'-buildid=my id' -X main.somevar='other value'" -o mybin cmd/go |&tail -n3|head -n1|sed 's/ -/\n -/g'

/usr/local/go/pkg/tool/linux_amd64/link
  -o $WORK/b001/exe/a.out
  -importcfg $WORK/b001/importcfg.link
  -X=cmd/internal/objabi.buildID=34hrmDhOa-Ykhyq3ZhCY/qBDvtQ-RAzWZwV2zip4h/qBDvtQ-RAzWZwV2zip4h/34hrmDhOa-Ykhyq3ZhCY
  -buildmode=exe
  -buildid=34hrmDhOa-Ykhyq3ZhCY/qBDvtQ-RAzWZwV2zip4h/qBDvtQ-RAzWZwV2zip4h/34hrmDhOa-Ykhyq3ZhCY
  -extld=gcc $WORK/b001/_pkg_.a

vs
go build -n -ldflags "-X main.somevar='other value'" -o mybin cmd/go |& tail -n3|head -n1|sed 's/ -/\n -/g'

/usr/local/go/pkg/tool/linux_amd64/link
  -o $WORK/b001/exe/a.out
  -importcfg $WORK/b001/importcfg.link
  -X=cmd/internal/objabi.buildID=ioJGL5vMyH4sJ99fxTWh/qBDvtQ-RAzWZwV2zip4h/qBDvtQ-RAzWZwV2zip4h/ioJGL5vMyH4sJ99fxTWh
  -buildmode=exe
  -buildid=ioJGL5vMyH4sJ99fxTWh/qBDvtQ-RAzWZwV2zip4h/qBDvtQ-RAzWZwV2zip4h/ioJGL5vMyH4sJ99fxTWh
  -X main.somevar='other value'
  -extld=gcc $WORK/b001/_pkg_.a

In the past I was able to set a build id containing spaces using the syntax in the first command, i.e. '-buildid=some value' - so disallowing build id's containing spaces is a regression.

@mpictor
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mpictor commented Aug 18, 2021

It seems the order of args matters:
go build -n -ldflags "-X main.somevar='other value' '-buildid=my id'" -o mybin cmd/go |&tail -n3|head -n1|sed 's/ -/\n -/g'

/usr/local/go/pkg/tool/linux_amd64/link
  -o $WORK/b001/exe/a.out
  -importcfg $WORK/b001/importcfg.link
  -X=cmd/internal/objabi.buildID=g6Bfka0tA1jniKMcsnRZ/-IMjHA-s38sooeR9yuWL/QLyQO3HmDx9HHhrCDZtt/g6Bfka0tA1jniKMcsnRZ
  -buildmode=exe
  -buildid=g6Bfka0tA1jniKMcsnRZ/-IMjHA-s38sooeR9yuWL/QLyQO3HmDx9HHhrCDZtt/g6Bfka0tA1jniKMcsnRZ
  -X main.somevar='other value' "-buildid=my id"
  -extld=gcc /home/mark/.cache/go-build/dc/dc883a0241b3ab0a931f8972d7457b4f52681d8efc982c5537dbef0f34fc766f-d

However, this command results in an error if actualy executed (by removing -r:
go build -ldflags "-X main.somevar='other value' '-buildid=my id'" -o mybin cmd/go

# cmd/go
usage: link [options] main.o
  -B note
        add an ELF NT_GNU_BUILD_ID note when using ELF
...

@gopherbot
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Change https://go.dev/cl/407314 mentions this issue: misc/cgo/testplugin: set the package name in TestIssue19534

gopherbot pushed a commit that referenced this issue May 19, 2022
@gopherbot
misc/cgo/testplugin: set the package name in TestIssue19534
e23cc08 
The fix for #19534 (in CL 40994) adjusted escaping in the
dynamically-linked name lookup logic for the plugin package. However,
the regression test added for it incorrectly included quotes within
the -ldflags flag, causing the flag to inadvertently be ignored.

Possibly in that same CL or possibly at some other point, the
condition that the test thought it was checking stopped working: the
dynamic lookup used the path passed to ldflags, but the object file
actually contained the symbol indexed by the original package name.

Ideally we should stop mucking around with ldflags in this test and
run 'go build' from a suitably-named directory instead, to mimic the
actual conditions in which the original bug was reported. For now, as
a more targeted fix, we can pass the '-p' flag to the compiler to
adjust the package path used at compile time to match the one that
will be set at link time.

For #43177.
Updates #19534.

Change-Id: I9763961feb37cfb05dee543f273492e91a350663
Reviewed-on: https://go-review.googlesource.com/c/go/+/407314
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
@gopherbot
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Change https://go.dev/cl/419594 mentions this issue: .github/workflows: add go1.19rc2 to long/smoke tests

ahrtr added a commit to ahrtr/etcd that referenced this issue Sep 15, 2022
@ahrtr
Bump go 1.19: fix error when building tools such as benchmark
0abf552 
The pipeline error:
```
Building 'tools/benchmark'...
% 'rm' '-f' 'bin/tools/benchmark'
% 'env' 'GO_BUILD_FLAGS=-v' 'CGO_ENABLED=0' 'go' 'build' '-v' '-installsuffix=cgo' '-ldflags='\''-X=go.etcd.io/etcd/api/v3/version.GitSHA=01250c9'\''' '-o=bin/tools/benchmark' './tools/benchmark'
stderr: invalid value "'-X=go.etcd.io/etcd/api/v3/version.GitSHA=01250c9'" for flag -ldflags: parameter may not start with quote character '
stderr: usage: go build [-o output] [build flags] [packages]
stderr: Run 'go help build' for details.
FAIL: (code:2):
  % 'env' 'GO_BUILD_FLAGS=-v' 'CGO_ENABLED=0' 'go' 'build' '-v' '-installsuffix=cgo' '-ldflags='\''-X=go.etcd.io/etcd/api/v3/version.GitSHA=01250c9'\''' '-o=bin/tools/benchmark' './tools/benchmark'
FAIL: 'build' failed at Thu Sep 15 03:13:24 UTC 2022
```

It's caused by golang/go#43177. Previously
invalid -ldflags is silently ignored by go cmd. But it isn't ignored
anymore in go 1.19 due to the fix in PR
https://go-review.googlesource.com/c/go/+/339289.

Signed-off-by: Benjamin Wang <wachao@vmware.com>
ahrtr added a commit to ahrtr/etcd that referenced this issue Sep 17, 2022
@ahrtr
Bump go 1.19: fix error when building tools such as benchmark
7b0e608 
The pipeline error:
```
Building 'tools/benchmark'...
% 'rm' '-f' 'bin/tools/benchmark'
% 'env' 'GO_BUILD_FLAGS=-v' 'CGO_ENABLED=0' 'go' 'build' '-v' '-installsuffix=cgo' '-ldflags='\''-X=go.etcd.io/etcd/api/v3/version.GitSHA=01250c9'\''' '-o=bin/tools/benchmark' './tools/benchmark'
stderr: invalid value "'-X=go.etcd.io/etcd/api/v3/version.GitSHA=01250c9'" for flag -ldflags: parameter may not start with quote character '
stderr: usage: go build [-o output] [build flags] [packages]
stderr: Run 'go help build' for details.
FAIL: (code:2):
  % 'env' 'GO_BUILD_FLAGS=-v' 'CGO_ENABLED=0' 'go' 'build' '-v' '-installsuffix=cgo' '-ldflags='\''-X=go.etcd.io/etcd/api/v3/version.GitSHA=01250c9'\''' '-o=bin/tools/benchmark' './tools/benchmark'
FAIL: 'build' failed at Thu Sep 15 03:13:24 UTC 2022
```

It's caused by golang/go#43177. Previously
invalid -ldflags is silently ignored by go cmd. But it isn't ignored
anymore in go 1.19 due to the fix in PR
https://go-review.googlesource.com/c/go/+/339289.

Signed-off-by: Benjamin Wang <wachao@vmware.com>
@golang golang locked and limited conversation to collaborators Aug 1, 2023
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