On Tuesday, August 21, 2018 at 9:50:23 AM UTC+2, Caleb Spare wrote: > > I was recently trying to write a Go program that's something like chpst or > setpriv: it execs another program with an altered process state by changing > the user ID or modifying the ambient capabilities. (My program is > Linux-specific.) > > In Go, when you want to spawn another process (fork+exec in Posix-land) > you have the option of a very high-level API in os/exec or a lower-level > API in the form of os.StartProcess. But os.StartProcess still does a lot of > work. In my program where I need to exec without forking, I did not have > the benefit of either os/exec or os.StartProcess, and I ended up having to > copy Linux-specific code from the syscall package here: > > > https://github.com/golang/go/blob/187a41dbf730117bd52f871009466a9679d6b718/src/syscall/exec_linux.go#L104 > > If I wanted to fork+exec, then I could've implemented my features easily > by using the fields in the platform-specific syscall.SysProcAttr. However, > because I wanted to exec only, no easy options were available to me, and my > code ended up doing about a dozen raw syscalls, using runtime.LockOSThread, > using unsafe, and being generally unpleasant. > > My question is: would it make sense to add an API similar to > os.StartProcess for exec-without-fork? For now I'm just wondering if there > is any showstopper that makes this unreasonable; if there isn't then I'll > file a proposal with more details. > > Here are two potential problems that I considered: > > 1. Is exec-without-fork fundamentally at odds with Go and its runtime > somehow, like fork-without-exec is? I don't see why that would be the case. >
fork without exec simply does not work with multithreading programs: https://thorstenball.com/blog/2014/10/13/why-threads-cant-fork/ Also, fork is not supported on Windows (well, AFAIK it can be implemented but it is an hack). 2. Is the concept of exec-without-fork incoherent on non-Posix systems? I > mainly worry about Windows; after some brief googling it did seem like you > can exec on Windows, though I admit the situation isn't at all clear to me. > > exec is not supported on Windows. > So am I missing any reason why an os.StartProcess-like API for exec-ing > would be untenable? > > Thanks! > Caleb > Manlio -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
