• Kir Kolyshkin's avatar
    os/user: add a way to enforce pure Go implementation · 62f0127d
    Kir Kolyshkin authored
    This provides a way to enforce pure Go implementation of os/user
    lookup functions on UNIX platforms by means of "osusergo" build tag,
    in a manner similar to netgo/netcgo tags in the net package.
    
    If "osusergo" build tag is set, Go implementation is selected.
    
    If "osusergo" build tag is NOT set, the old behavior is retained,
    that is to use cgo (libc-backed) implementation if both cgo and such
    and such implementation are available.
    
    The reason behind this change is to make it possible to build proper
    static binaries on Linux. The problem is, glibc implementation of
    getpw*, getgrp* and getgrouplist functions relies on presense of
    libnss*.so libraries during runtime, making it impossible to build
    a self-contained static binary which uses both cgo and os/user.
    In such case, linker warnings like this are shown:
    
    > warning: Using 'getgrouplist' in statically linked applications
    > requires at runtime the shared libraries from the glibc version
    > used for linking
    
    While this can be solved by recompiling glibc with --enable-static-nss
    flag or using a different libc implementation (like musl on Alpine Linux),
    it is not always practical or even possible.
    
    Fixes #23265
    
    Change-Id: I383a448a2ecf15493ec93dbd5d076b6330cb14cb
    Signed-off-by: 's avatarKir Kolyshkin <kolyshkin@gmail.com>
    Reviewed-on: https://go-review.googlesource.com/92456
    Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
    TryBot-Result: Gobot Gobot <gobot@golang.org>
    Reviewed-by: 's avatarBrad Fitzpatrick <bradfitz@golang.org>
    62f0127d
listgroups_unix.go 1.17 KB