英文:
cmd.StdoutPipe example in go pkg docs does not run in playground
问题
cmd.StdoutPipe的示例在Go文档中（https://pkg.go.dev/os/exec#example-Cmd.StdoutPipe）无法在playground中运行。
https://play.golang.org/p/ek7-_Xa_bN3
错误信息：
fatal error: all goroutines are asleep - deadlock!
goroutine 1 [IO wait]:
internal/poll.runtime_pollWait(0x7faec2ac4e88, 0x72)
/usr/local/go-faketime/src/runtime/netpoll.go:234 +0x89
internal/poll.(*pollDesc).wait(0xc000074180, 0xc000100000, 0x1)
/usr/local/go-faketime/src/internal/poll/fd_poll_runtime.go:84 +0x32
internal/poll.(*pollDesc).waitRead(...)
/usr/local/go-faketime/src/internal/poll/fd_poll_runtime.go:89
internal/poll.(*FD).Read(0xc000074180, {0xc000100000, 0x200, 0x200})
/usr/local/go-faketime/src/internal/poll/fd_unix.go:167 +0x25a
os.(*File).read(...)
/usr/local/go-faketime/src/os/file_posix.go:32
os.(*File).Read(0xc00000e028, {0xc000100000, 0x28, 0xc000060e80})
/usr/local/go-faketime/src/os/file.go:119 +0x5e
encoding/json.(*Decoder).refill(0xc00007e000)
/usr/local/go-faketime/src/encoding/json/stream.go:165 +0x17f
encoding/json.(*Decoder).readValue(0xc00007e000)
/usr/local/go-faketime/src/encoding/json/stream.go:140 +0xbb
encoding/json.(*Decoder).Decode(0xc00007e000, {0x4cf580, 0xc00000c048})
/usr/local/go-faketime/src/encoding/json/stream.go:63 +0x78
main.main()
/tmp/sandbox2294589397/prog.go:24 +0x185
程序已退出。
在本地运行时没有死锁问题。我无法理解为什么在Go Playground中会发生死锁。
英文:
cmd.StdoutPipe example at go documentation: https://pkg.go.dev/os/exec#example-Cmd.StdoutPipe does not run in playground.
https://play.golang.org/p/ek7-_Xa_bN3
Error:
fatal error: all goroutines are asleep - deadlock!
goroutine 1 [IO wait]:
internal/poll.runtime_pollWait(0x7faec2ac4e88, 0x72)
/usr/local/go-faketime/src/runtime/netpoll.go:234 +0x89
internal/poll.(*pollDesc).wait(0xc000074180, 0xc000100000, 0x1)
/usr/local/go-faketime/src/internal/poll/fd_poll_runtime.go:84 +0x32
internal/poll.(*pollDesc).waitRead(...)
/usr/local/go-faketime/src/internal/poll/fd_poll_runtime.go:89
internal/poll.(*FD).Read(0xc000074180, {0xc000100000, 0x200, 0x200})
/usr/local/go-faketime/src/internal/poll/fd_unix.go:167 +0x25a
os.(*File).read(...)
/usr/local/go-faketime/src/os/file_posix.go:32
os.(*File).Read(0xc00000e028, {0xc000100000, 0x28, 0xc000060e80})
/usr/local/go-faketime/src/os/file.go:119 +0x5e
encoding/json.(*Decoder).refill(0xc00007e000)
/usr/local/go-faketime/src/encoding/json/stream.go:165 +0x17f
encoding/json.(*Decoder).readValue(0xc00007e000)
/usr/local/go-faketime/src/encoding/json/stream.go:140 +0xbb
encoding/json.(*Decoder).Decode(0xc00007e000, {0x4cf580, 0xc00000c048})
/usr/local/go-faketime/src/encoding/json/stream.go:63 +0x78
main.main()
/tmp/sandbox2294589397/prog.go:24 +0x185
Program exited.
Locally it's running correctly, no deadlock. I am not able to understand why deadlock happens in go playground.
答案1
得分: 3
根据os.exec包的文档（这个例子就来自这里）：
需要注意的是，这个包中的示例假设是在Unix系统上运行的。它们可能无法在Windows上运行，而且它们也无法在golang.org和godoc.org使用的Go Playground中运行。
这个说明没有提供具体原因，但可以推测的原因是允许用户提供的Unix命令运行会给恶意代码提供更广泛的攻击面。并不是说不可能以相对安全的方式允许这样做，但是有各种权衡考虑，所以禁止使用os.exec是一个自然的选择。
英文:
From the documentation on the os.exec package (which is where this example comes from):
> Note that the examples in this package assume a Unix system. They may
> not run on Windows, and they do not run in the Go Playground used by
> golang.org and godoc.org.
That note doesn't provide a reason, but the reason is presumably that allowing user-provided unix commands to run would give a broader attack surface for malicious code. It's not that it's impossible to allow this in a relatively secure way, but there's various tradeoffs which make disallowing os.exec a natural choice.
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