include commit hash in status output

[ansemjo]

This is an alternative to #34 and fixes #22.

• all commit hash definition logic is done in a subshell in the makefile
• both the makefile shell and preprocessor directives in main.c fallback to unknown if the git command fails or VERSION is somehow undefined during compilation
• the subshell uses git describe output when building from a checked-out repository or an inserted commit hash when building from a git-archive (i.e. a downloaded tarball)
• lines 71-74 should be reusable for other projects and languages

[AkihiroSuda]

LGTM thanks, but can we move the version info to slirp4netns --version with runc-style machine-parseable format? (I can open PR for --version) https://github.com/opencontainers/runc/blob/f3ce8221ea760f51b5403a9892a69ace43845c2c/main.go#L55-L63

[giuseppe]

we should be using $abs_srcdir not the build dir. Could you add a cd $abs_srcdir before any other command?

[ansemjo]

do you mean $abs_top_srcdir?

Suggested change

	&& ([ -d .git ] && git describe --always --abbrev || echo unknown) \
	&& (cd "$$abs_top_srcdir" && [ -d .git ] && git describe --always --abbrev || echo unknown) \

[giuseppe]

PACKAGE_VERSION is defined by the configure script. It is then written into the config.h file

[ansemjo]

@AkihiroSuda something like this?

slirp4netns version $PACKAGE_VERSION
commit: $COMMIT_HASH

[AkihiroSuda]

Yes, also it would be great if we can have -dirty suffix for dirty build https://github.com/opencontainers/runc/blob/f3ce8221ea760f51b5403a9892a69ace43845c2c/Makefile#L17

[ansemjo]

current output:

$ ./slirp4netns -v
./slirp4netns version 0.1
commit: bf62e3b-dirty

[AkihiroSuda]

Thanks!

LGTM (if CI green)

[giuseppe]

LGTM as well, merged. Thanks for your contribution!