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debug/elf: ElfFile.SectionByType() should return a list of matched sections. #59287

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BrytonLee opened this issue Mar 28, 2023 · 5 comments
Closed

debug/elf: ElfFile.SectionByType() should return a list of matched sections. #59287

BrytonLee opened this issue Mar 28, 2023 · 5 comments
Labels
compiler/runtime Issues related to the Go compiler and/or runtime. FrozenDueToAge

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

$ go version
1.19.5

Does this issue reproduce with the latest release?

Yes, there is no change between go 1.19.5 to the latest. The affected file and line number is here: https://github.com/golang/go/blob/master/src/debug/elf/file.go#L246

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

go env Output
$ go env
GO111MODULE=""
GOARCH="arm64"
GOBIN=""
GOCACHE="/Users/lichengdong/Library/Caches/go-build"
GOENV="/Users/lichengdong/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/lichengdong/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/lichengdong/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/opt/homebrew/Cellar/go/1.19.5/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/opt/homebrew/Cellar/go/1.19.5/libexec/pkg/tool/darwin_arm64"
GOVCS=""
GOVERSION="go1.19.5"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/dev/null"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/g4/4_y2t8q179s1n1h40218_3rm0000gn/T/go-build2820814962=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Just send a ELF file for debug/elf to parse it. Then call SectionByType(elf.SHT_PROGBITS), it will return first section with type equals to elf.SHT_PROGBITS. But in a normal ELF file on Linux, there is more than on elf.SHT_PROGBITS section in fact.

What did you expect to see?

returns a list of matched sections.

What did you see instead?

None
@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Mar 28, 2023
@ianlancetaylor
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Unfortunately we can't change the current method, as that would break existing programs. SectionByType is only useful for section types that normally only occur once, such as SHT_DYNAMIC.

@ianlancetaylor ianlancetaylor closed this as not planned Won't fix, can't repro, duplicate, stale Mar 28, 2023
@BrytonLee
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Thanks for your prompt reply.

What if we add a method such as SectionAllByType? Thus doesn't break existing programs.

@ianlancetaylor
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That kind of new API should go through the proposal process: see https://go.dev/s/proposal. But I'm not sure it's really helpful; why not just loop through the sections yourself? Would anybody really call SectionAllByType?

@BrytonLee
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Yeah, sure I can iterate all sections and find out what I need. But, I am a live sample that I was confused by SectionByType(), literally, it implies that user just need to specify section type and get what they need. I am not sure this will continue to confuse other developers as well. :-)

@ianlancetaylor
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I agree that SectionByType is not all that useful, and it may have been a mistake to add it. But now that it exists we aren't going to change it.

@golang golang locked and limited conversation to collaborators Apr 3, 2024
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@BrytonLee @ianlancetaylor @gopherbot