utils: return error from set_home_env() if the user was not found

[kwilczynski]

If a given user cannot be found within the container, for example, because the specific UID does not exist, then return an error and let the callers of the set_home_env() function handle the case of the missing user appropriately.

This will fix an issue where when the user cannot be found, the HOME environment variable is not set, which can cause some software not to work correctly.

The two current callers already correctly handled the case when the user was not found per:

• crun/src/libcrun/container.c

  Lines 1199 to 1207 in bd4f773

  	if (getenv ("HOME") == NULL)
  	{
  	ret = set_home_env (container->container_uid);
  	if (UNLIKELY (ret < 0 && errno != ENOTSUP))
  	{
  	setenv ("HOME", "/", 1);
  	libcrun_warning ("cannot detect HOME environment variable, setting default");
  	}
  	}

• crun/src/libcrun/container.c

  Lines 3406 to 3414 in bd4f773

  	if (getenv ("HOME") == NULL)
  	{
  	ret = set_home_env (container_uid);
  	if (UNLIKELY (ret < 0 && errno != ENOTSUP))
  	{
  	setenv ("HOME", "/", 1);
  	libcrun_warning ("cannot detect HOME environment variable, setting default");
  	}
  	}

The above will issue a warning and correctly set the HOME environment variable to / as a fall-back on error.

Related:

• linux: force HOME to be set #104
• utils: set HOME to root if the user not found #599

[giuseppe]

CI failure being addressed in: #1634

[kwilczynski]

CI failure being addressed in: #1634

@giuseppe, thank you! Will rebase once this change lands.

[kwilczynski]

Rebased against the current main branch.

[packit-as-a-service]

podman system tests failed. @containers/packit-build please check.

[kwilczynski]

/cc @giuseppe
/cc @haircommander
/cc @sohankunkerkar

[sohankunkerkar]

/lgtm

[giuseppe]

LGTM