musl: getent should support the `-s' switch

[wknapik]

System

• xuname:
  Void 4.18.1-arch1-1-ARCH x86_64-musl GenuineIntel notuptodate r
  (I'm just using the voidlinux/voidlinux-musl docker image for testing)
• package:
  musl

Expected behavior

• getent -s dns hosts eff.org

198.100.177.181 eff.org

• getent -s files hosts localhost

127.0.0.1       localhost.localdomain localhost

Actual behavior

• getent -s dns hosts eff.org

getent: Unknown database `-s': No error information
Usage: getent database [key ...]
        database may be one of:
                ethers group hosts networks passwd protocols services
                shells

• getent -s files hosts localhost

getent: Unknown database `-s': No error information
Usage: getent database [key ...]
        database may be one of:
                ethers group hosts networks passwd protocols services
                shells

Steps to reproduce the behavior

See: above

Further explanation

Since there doesn't seem to be an upstream repo for musl getent, I opened an issue against Alpine and this one for Void. From the Alpine issue:

glibc getent supports a -s switch for choosing services - this feature is missing in the getent implementation from musl-utils.

I use getent to resolve host names in a script and use -s to query either the /etc/hosts file (getent -s files hosts <hosts>), or actual DNS (getent -s dns hosts <hosts>).

The former could be worked around by parsing the hosts file (at the cost of additional code), but there's no way to skip the hosts file lookup to cover the latter case.
Of course, I could use a tool like host/dig, but I intentionally chose getent, to avoid the additional dependency on bind-tools.

Any chance of this feature being added ?

Please see the Alpine issue for further discussion:
https://bugs.alpinelinux.org/issues/9278

PS. I believe this is even more relevant for Void, since it's available both in musl- and glibc-flavor.

[Gottox]

musl does not provide a way to select the sources of a host and I don't think it's feasable to implement a parser /etc/resolv.conf just to have such a switch.